import { mkdtempSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { execSync } from "node:child_process";
import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
import { GitHubClient, CreatePrParams, PrComment, isPrMergeReady } from "../github.js";

// Mock the gh-cli module from @fusion/core
vi.mock("@fusion/core", async () => {
  const actual = await vi.importActual<typeof import("@fusion/core")>("@fusion/core");
  return {
    ...actual,
    isGhAvailable: vi.fn(),
    isGhAuthenticated: vi.fn(),
    runGh: vi.fn(),
    runGhAsync: vi.fn(),
    runGhJson: vi.fn(),
    runGhJsonAsync: vi.fn(),
    getGhErrorMessage: vi.fn((err) => err instanceof Error ? err.message : String(err)),
    getCurrentRepo: vi.fn(),
  };
});

import {
  isGhAvailable,
  isGhAuthenticated,
  runGh,
  runGhAsync,
  runGhJson,
  runGhJsonAsync,
  getCurrentRepo,
} from "@fusion/core";

const mockIsGhAvailable = vi.mocked(isGhAvailable);
const mockIsGhAuthenticated = vi.mocked(isGhAuthenticated);
const mockRunGh = vi.mocked(runGh);
const mockRunGhAsync = vi.mocked(runGhAsync);
const mockRunGhJson = vi.mocked(runGhJson);
const mockRunGhJsonAsync = vi.mocked(runGhJsonAsync);
const mockGetCurrentRepo = vi.mocked(getCurrentRepo);

function createGraphQlBatchPayload(repository: Record<string, unknown>) {
  return JSON.stringify({ data: { repository } });
}

describe("GitHubClient", () => {
  let client: GitHubClient;

  beforeEach(() => {
    vi.clearAllMocks();
    mockIsGhAvailable.mockReturnValue(true);
    mockIsGhAuthenticated.mockReturnValue(true);
    // Create client after mocks are set up
    client = new GitHubClient();
  });

  afterEach(() => {
    vi.useRealTimers();
    vi.restoreAllMocks();
  });

  describe("constructor", () => {
    it("can be created without token (gh CLI auth preferred)", () => {
      expect(() => new GitHubClient()).not.toThrow();
    });

    it("can be created with token for REST API fallback", () => {
      expect(() => new GitHubClient("ghp_token123")).not.toThrow();
    });
  });

  describe("createIssue", () => {
    it("falls back to API when gh path fails and token is configured", async () => {
      const clientWithToken = new GitHubClient("ghp_token");
      mockRunGhAsync.mockRejectedValue(new Error("gh failed"));
      const fetchSpy = vi.spyOn(global, "fetch" as any).mockResolvedValue({
        ok: true,
        status: 201,
        json: async () => ({ number: 7, html_url: "https://github.com/o/r/issues/7", created_at: "2026-01-01T00:00:00Z" }),
      } as any);

      const issue = await clientWithToken.createIssue({ owner: "o", repo: "r", title: "t", body: "b" });
      expect(issue).toEqual({ owner: "o", repo: "r", number: 7, htmlUrl: "https://github.com/o/r/issues/7", createdAt: "2026-01-01T00:00:00Z" });
      expect(mockRunGhAsync).toHaveBeenCalled();
      expect(mockRunGhJsonAsync).not.toHaveBeenCalled();
      fetchSpy.mockRestore();
    });

    it("uses API path when gh auth is unavailable and token is configured", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      const clientWithToken = new GitHubClient("ghp_token");
      const fetchSpy = vi.spyOn(global, "fetch" as any).mockResolvedValue({
        ok: true,
        status: 201,
        json: async () => ({ number: 9, html_url: "https://github.com/o/r/issues/9", created_at: "2026-01-03T00:00:00Z" }),
      } as any);

      const issue = await clientWithToken.createIssue({ owner: "o", repo: "r", title: "t", body: "b" });
      expect(issue.number).toBe(9);
      fetchSpy.mockRestore();
    });

    it("throws when gh auth unavailable and no token provided", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      await expect(client.createIssue({ owner: "o", repo: "r", title: "t", body: "b" })).rejects.toThrow("GitHub CLI (gh) is not available");
    });

    it("surfaces 422 API failures with cause", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      const clientWithToken = new GitHubClient("ghp_token");
      vi.spyOn(global, "fetch" as any).mockResolvedValue({ ok: false, status: 422, statusText: "Unprocessable", json: async () => ({ message: "Validation Failed" }) } as any);
      await expect(clientWithToken.createIssue({ owner: "o", repo: "r", title: "t", body: "b" })).rejects.toThrow("Failed to create GitHub issue");
    });

    it("surfaces 404 API failures", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      const clientWithToken = new GitHubClient("ghp_token");
      vi.spyOn(global, "fetch" as any).mockResolvedValue({ ok: false, status: 404, statusText: "Not Found", json: async () => ({ message: "Not Found" }) } as any);
      await expect(clientWithToken.createIssue({ owner: "o", repo: "r", title: "t", body: "b" })).rejects.toThrow("Failed to create GitHub issue");
    });
  });

  describe("GitHubClient.createIssue (gh-cli mode)", () => {
    it("creates an issue from gh stdout and follow-up view metadata", async () => {
      mockRunGhAsync.mockResolvedValue("https://github.com/acme/repo/issues/42\n");
      mockRunGhJsonAsync.mockResolvedValue({
        number: 42,
        url: "https://github.com/acme/repo/issues/42",
        createdAt: "2025-01-02T03:04:05Z",
      } as any);
      const ghClient = new GitHubClient({ forceMode: "gh-cli" });

      const issue = await ghClient.createIssue({ owner: "acme", repo: "repo", title: "T", body: "B" });

      expect(issue).toEqual({
        owner: "acme",
        repo: "repo",
        number: 42,
        htmlUrl: "https://github.com/acme/repo/issues/42",
        createdAt: "2025-01-02T03:04:05Z",
      });
      expect(mockRunGhAsync).toHaveBeenCalledWith([
        "issue",
        "create",
        "--repo",
        "acme/repo",
        "--title",
        "T",
        "--body",
        "B",
      ]);
      expect(mockRunGhAsync).toHaveBeenCalledWith(expect.not.arrayContaining(["--json"]));
      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "issue",
        "view",
        "https://github.com/acme/repo/issues/42",
        "--json",
        "number,url,createdAt",
      ]);
    });

    it("passes labels without adding --json to issue create", async () => {
      mockRunGhAsync.mockResolvedValue("https://github.com/acme/repo/issues/42\n");
      mockRunGhJsonAsync.mockResolvedValue({
        number: 42,
        url: "https://github.com/acme/repo/issues/42",
        createdAt: "2025-01-02T03:04:05Z",
      } as any);
      const ghClient = new GitHubClient({ forceMode: "gh-cli" });

      await ghClient.createIssue({ owner: "acme", repo: "repo", title: "T", body: "B", labels: ["a", "b"] });

      expect(mockRunGhAsync).toHaveBeenCalledWith([
        "issue",
        "create",
        "--repo",
        "acme/repo",
        "--title",
        "T",
        "--body",
        "B",
        "--label",
        "a,b",
      ]);
      expect(mockRunGhAsync).toHaveBeenCalledWith(expect.not.arrayContaining(["--json"]));
    });

    it("rejects malformed gh stdout without calling issue view", async () => {
      mockRunGhAsync.mockResolvedValue("oops");
      const ghClient = new GitHubClient({ forceMode: "gh-cli" });

      await expect(ghClient.createIssue({ owner: "acme", repo: "repo", title: "T", body: "B" })).rejects.toThrow(
        "Failed to parse issue URL from gh output",
      );
      expect(mockRunGhJsonAsync).not.toHaveBeenCalled();
    });
  });

  describe("createPr", () => {
    const mockPrParams: CreatePrParams = {
      owner: "test-owner",
      repo: "test-repo",
      title: "Test PR",
      body: "Test body",
      head: "feature-branch",
      base: "main",
    };

    it("createPr succeeds with gh CLI only (no token)", async () => {
      mockRunGh.mockReturnValue("https://github.com/test-owner/test-repo/pull/42\n");
      const ghOnlyClient = new GitHubClient();

      const result = await ghOnlyClient.createPr(mockPrParams);

      expect(mockRunGh).toHaveBeenCalledWith([
        "pr", "create",
        "--repo", "test-owner/test-repo",
        "--title", "Test PR",
        "--head", "feature-branch",
        "--body", "Test body",
        "--base", "main",
      ]);
      expect(result.number).toBe(42);
      expect(result.url).toBe("https://github.com/test-owner/test-repo/pull/42");
      expect(result.status).toBe("open");
    });

    it("creates PR without body when not provided", async () => {
      mockRunGh.mockReturnValue("https://github.com/test-owner/test-repo/pull/42\n");
      const paramsWithoutBody: CreatePrParams = {
        owner: "test-owner",
        repo: "test-repo",
        title: "Test PR",
        head: "feature-branch",
        // body and base not provided
      };

      await client.createPr(paramsWithoutBody);

      expect(mockRunGh).toHaveBeenCalledWith([
        "pr", "create",
        "--repo", "test-owner/test-repo",
        "--title", "Test PR",
        "--head", "feature-branch",
      ]);
      // Should not include --body or --base when not provided
      const callArgs = mockRunGh.mock.calls[0][0];
      expect(callArgs).not.toContain("--body");
      expect(callArgs).not.toContain("--base");
    });

    it("uses current repo context when owner/repo not specified", async () => {
      mockGetCurrentRepo.mockReturnValue({ owner: "current-owner", repo: "current-repo" });
      mockRunGh.mockReturnValue("https://github.com/current-owner/current-repo/pull/5\n");

      const paramsWithoutRepo = {
        title: "Test PR",
        head: "feature-branch",
      };

      const result = await client.createPr(paramsWithoutRepo);

      expect(mockGetCurrentRepo).toHaveBeenCalled();
      expect(mockRunGh).toHaveBeenCalledWith([
        "pr", "create",
        "--repo", "current-owner/current-repo",
        "--title", "Test PR",
        "--head", "feature-branch",
      ]);
      expect(result.number).toBe(5);
    });

    it("throws error when repo cannot be determined", async () => {
      mockGetCurrentRepo.mockReturnValue(null);

      const paramsWithoutRepo = {
        title: "Test PR",
        head: "feature-branch",
      };

      await expect(client.createPr(paramsWithoutRepo)).rejects.toThrow("Could not determine repository");
    });

    it("falls back to REST API when gh CLI fails and token is available", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("gh command failed");
      });

      // Create client with token for fallback
      const clientWithToken = new GitHubClient("ghp_fallback_token");

      // Mock global fetch for REST API fallback
      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve({
          number: 42,
          html_url: "https://github.com/test-owner/test-repo/pull/42",
          title: "Test PR",
          state: "open",
          head: { ref: "feature-branch" },
          base: { ref: "main" },
          comments: 0,
        }),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.createPr(mockPrParams);

      expect(mockFetch).toHaveBeenCalled();
      expect(result.number).toBe(42);

      // Restore fetch
      vi.restoreAllMocks();
    });

    it("throws gh-auth-focused error when gh CLI fails and no token is available", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("GitHub CLI is not authenticated. Run 'gh auth login'.");
      });

      await expect(client.createPr(mockPrParams)).rejects.toThrow("gh auth login");
    });

    it.each([
      {
        name: "draft true with reviewers",
        draft: true,
        reviewers: ["alice", "bob"],
        expectedFlags: ["--draft", "--reviewer", "alice,bob"],
      },
      {
        name: "no draft and empty reviewers",
        draft: undefined,
        reviewers: [],
        expectedFlags: [],
      },
    ])("passes optional gh create flags: $name", async ({ draft, reviewers, expectedFlags }) => {
      mockRunGh.mockReturnValue("https://github.com/test-owner/test-repo/pull/42\n");

      await client.createPr({
        ...mockPrParams,
        draft,
        reviewers,
      });

      const callArgs = mockRunGh.mock.calls[0][0];
      if (expectedFlags.length > 0) {
        expect(callArgs).toEqual(expect.arrayContaining(expectedFlags));
      } else {
        expect(callArgs).not.toContain("--draft");
        expect(callArgs).not.toContain("--reviewer");
      }
    });

    it("sends draft body + reviewer request via REST API", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("gh command failed");
      });
      const clientWithToken = new GitHubClient("ghp_token");
      const fetchSpy = vi.spyOn(global, "fetch" as any)
        .mockResolvedValueOnce({
          ok: true,
          json: async () => ({
            number: 42,
            html_url: "https://github.com/test-owner/test-repo/pull/42",
            title: "Test PR",
            state: "open",
            draft: true,
            head: { ref: "feature-branch" },
            base: { ref: "main" },
            comments: 0,
          }),
        } as any)
        .mockResolvedValueOnce({ ok: true, json: async () => ({}) } as any);

      const result = await clientWithToken.createPr({
        ...mockPrParams,
        draft: true,
        reviewers: ["alice", "bob"],
      });

      const createPrRequest = fetchSpy.mock.calls[0];
      expect(createPrRequest[0]).toContain("/repos/test-owner/test-repo/pulls");
      expect(createPrRequest[1]?.body).toContain('"draft":true');

      const reviewersRequest = fetchSpy.mock.calls[1];
      expect(reviewersRequest[0]).toContain("/repos/test-owner/test-repo/pulls/42/requested_reviewers");
      expect(reviewersRequest[1]?.body).toBe(JSON.stringify({ reviewers: ["alice", "bob"] }));
      expect(result.draft).toBe(true);

      fetchSpy.mockRestore();
    });

    it("returns PR result when REST reviewer request fails", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("gh command failed");
      });
      const stderrSpy = vi.spyOn(process.stderr, "write").mockReturnValue(true);
      const clientWithToken = new GitHubClient("ghp_token");
      const fetchSpy = vi.spyOn(global, "fetch" as any)
        .mockResolvedValueOnce({
          ok: true,
          json: async () => ({
            number: 99,
            html_url: "https://github.com/test-owner/test-repo/pull/99",
            title: "Test PR",
            state: "open",
            head: { ref: "feature-branch" },
            base: { ref: "main" },
            comments: 0,
          }),
        } as any)
        .mockResolvedValueOnce({
          ok: false,
          status: 422,
          statusText: "Unprocessable",
          json: async () => ({ message: "Reviewers are invalid" }),
        } as any);

      const result = await clientWithToken.createPr({
        ...mockPrParams,
        reviewers: ["alice", "bob"],
      });

      expect(result.number).toBe(99);
      expect(stderrSpy).toHaveBeenCalledWith(expect.stringContaining("failed to request reviewers for PR #99"));
      fetchSpy.mockRestore();
      stderrSpy.mockRestore();
    });
  });

  describe("getPrStatus", () => {
    it("fetches PR status using gh CLI", async () => {
      mockRunGhJsonAsync.mockResolvedValue({
        number: 42,
        url: "https://github.com/owner/repo/pull/42",
        title: "Test PR",
        state: "OPEN",
        isDraft: false,
        baseRefName: "main",
        headRefName: "feature-branch",
      });

      const result = await client.getPrStatus("owner", "repo", 42);

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "pr", "view", "42",
        "--repo", "owner/repo",
        "--json", "number,url,title,state,isDraft,baseRefName,headRefName",
      ]);
      expect(result.number).toBe(42);
      expect(result.status).toBe("open");
      expect(result.title).toBe("Test PR");
    });

    it("maps gh CLI states correctly", async () => {
      const states = [
        { input: "OPEN", expected: "open" },
        { input: "CLOSED", expected: "closed" },
        { input: "MERGED", expected: "merged" },
      ];

      for (const { input, expected } of states) {
        vi.clearAllMocks();
        mockRunGhJsonAsync.mockResolvedValue({
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Test PR",
          state: input,
          baseRefName: "main",
          headRefName: "feature-branch",
        });

        const result = await client.getPrStatus("owner", "repo", 42);
        expect(result.status).toBe(expected);
      }
    });

    it("falls back to REST API when gh CLI fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));

      const clientWithToken = new GitHubClient("ghp_token");

      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve({
          number: 42,
          html_url: "https://github.com/owner/repo/pull/42",
          title: "Test PR",
          state: "open",
          merged: false,
          head: { ref: "feature-branch" },
          base: { ref: "main" },
          comments: 5,
          updated_at: "2024-01-01T00:00:00Z",
        }),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.getPrStatus("owner", "repo", 42);

      expect(mockFetch).toHaveBeenCalled();
      expect(result.number).toBe(42);

      vi.restoreAllMocks();
    });
  });

  describe("listPrComments", () => {
    const mockComments = [
      {
        id: "100",
        body: "First comment",
        author: { login: "user1" },
        createdAt: "2024-01-01T00:00:00Z",
        updatedAt: "2024-01-01T00:00:00Z",
        url: "https://github.com/owner/repo/pull/42#issuecomment-100",
      },
      {
        id: "200",
        body: "Second comment",
        author: { login: "user2" },
        createdAt: "2024-01-02T00:00:00Z",
        updatedAt: "2024-01-02T00:00:00Z",
        url: "https://github.com/owner/repo/pull/42#issuecomment-200",
      },
    ];

    it("fetches PR comments using gh CLI", async () => {
      mockRunGhJsonAsync.mockResolvedValue({ comments: mockComments });

      const result = await client.listPrComments("owner", "repo", 42);

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "pr", "view", "42",
        "--repo", "owner/repo",
        "--json", "comments",
      ]);
      expect(result).toHaveLength(2);
      expect(result[0].id).toBe(100);
      expect(result[0].body).toBe("First comment");
      expect(result[0].user.login).toBe("user1");
    });

    it("filters comments by timestamp when since is provided", async () => {
      mockRunGhJsonAsync.mockResolvedValue({ comments: mockComments });

      const result = await client.listPrComments("owner", "repo", 42, "2024-01-01T12:00:00Z");

      expect(result).toHaveLength(1);
      expect(result[0].id).toBe(200);
    });

    it("returns empty array when no comments", async () => {
      mockRunGhJsonAsync.mockResolvedValue({ comments: [] });

      const result = await client.listPrComments("owner", "repo", 42);

      expect(result).toEqual([]);
    });

    it("falls back to REST API when gh CLI fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));

      const clientWithToken = new GitHubClient("ghp_token");

      const apiComments: PrComment[] = [
        {
          id: 100,
          body: "API comment",
          user: { login: "user1" },
          created_at: "2024-01-01T00:00:00Z",
          updated_at: "2024-01-01T00:00:00Z",
          html_url: "https://github.com/owner/repo/pull/42#issuecomment-100",
        },
      ];

      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve(apiComments),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.listPrComments("owner", "repo", 42);

      expect(mockFetch).toHaveBeenCalled();
      expect(result).toHaveLength(1);

      vi.restoreAllMocks();
    });
  });

  describe("getIssueStatus", () => {
    it("fetches issue status using gh CLI", async () => {
      mockRunGhJsonAsync.mockResolvedValue({
        number: 1,
        url: "https://github.com/owner/repo/issues/1",
        title: "Test Issue",
        state: "OPEN",
      });

      const result = await client.getIssueStatus("owner", "repo", 1);

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "issue", "view", "1",
        "--repo", "owner/repo",
        "--json", "number,url,title,state,stateReason",
      ]);
      expect(result).not.toBeNull();
      expect(result?.number).toBe(1);
      expect(result?.state).toBe("open");
    });

    it("returns null for PRs (not issues)", async () => {
      mockRunGhJsonAsync.mockRejectedValue(
        new Error("Could not resolve to an issue with the number 1")
      );

      const result = await client.getIssueStatus("owner", "repo", 1);

      expect(result).toBeNull();
    });

    it("falls back to REST API when gh CLI fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));

      const clientWithToken = new GitHubClient("ghp_token");

      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve({
          number: 1,
          html_url: "https://github.com/owner/repo/issues/1",
          title: "Test Issue",
          state: "open",
          state_reason: null,
        }),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.getIssueStatus("owner", "repo", 1);

      expect(mockFetch).toHaveBeenCalled();
      expect(result?.number).toBe(1);

      vi.restoreAllMocks();
    });
  });

  describe("commentOnIssue", () => {
    it("posts comment via gh CLI when auth is available", async () => {
      mockRunGh.mockReturnValue("commented");

      await client.commentOnIssue("owner", "repo", 123, "Done ✅");

      expect(mockRunGh).toHaveBeenCalledWith([
        "issue",
        "comment",
        "123",
        "--repo",
        "owner/repo",
        "--body",
        "Done ✅",
      ]);
    });

    it("falls back to REST API when gh CLI is unavailable and token exists", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      const clientWithToken = new GitHubClient("ghp_token");
      const fetchSpy = vi.spyOn(clientWithToken, "fetchThrottled").mockResolvedValue({
        success: true,
        data: { id: 77 },
      });

      await clientWithToken.commentOnIssue("owner", "repo", 77, "Completed");

      expect(fetchSpy).toHaveBeenCalledWith(
        "https://api.github.com/repos/owner/repo/issues/77/comments",
        {
          method: "POST",
          headers: {
            "Content-Type": "application/json",
          },
          body: JSON.stringify({ body: "Completed" }),
        },
      );
    });

    it("falls back to REST API when gh CLI call fails and token exists", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("gh failed");
      });
      const clientWithToken = new GitHubClient("ghp_token");
      const fetchSpy = vi.spyOn(clientWithToken, "fetchThrottled").mockResolvedValue({
        success: true,
        data: { id: 78 },
      });

      await clientWithToken.commentOnIssue("owner", "repo", 78, "Completed");

      expect(fetchSpy).toHaveBeenCalled();
    });

    it("throws when neither gh auth nor token is available", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      mockIsGhAuthenticated.mockReturnValue(false);
      const unauthClient = new GitHubClient();

      await expect(unauthClient.commentOnIssue("owner", "repo", 1, "Done")).rejects.toThrow(
        "GitHub CLI (gh) is not available or not authenticated, and no GITHUB_TOKEN provided.",
      );
    });
  });

  describe("deleteIssue", () => {
    it("deletes an issue via gh CLI", async () => {
      mockRunGh.mockReturnValue("deleted");
      const ghClient = new GitHubClient({ forceMode: "gh-cli" });

      await ghClient.deleteIssue("owner", "repo", 123);

      expect(mockRunGh).toHaveBeenCalledWith([
        "issue",
        "delete",
        "123",
        "--repo",
        "owner/repo",
        "--yes",
      ]);
    });

    it("surfaces gh CLI failures", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("permission denied");
      });
      const ghClient = new GitHubClient({ forceMode: "gh-cli" });

      await expect(ghClient.deleteIssue("owner", "repo", 124)).rejects.toThrow("permission denied");
    });

    it("rejects deletion in token-only mode with explanatory error", async () => {
      const tokenClient = new GitHubClient({ token: "ghp_token", forceMode: "token" });

      await expect(tokenClient.deleteIssue("owner", "repo", 125)).rejects.toThrow(
        "Deleting GitHub issues requires gh CLI authentication. Token-only mode does not support issue deletion.",
      );
    });
  });

  describe("getBatchIssueStatus", () => {
    it("uses the REST issues list endpoint for recent requested issues", async () => {
      mockRunGhJsonAsync.mockResolvedValue([
        {
          number: 250,
          html_url: "https://github.com/owner/repo/issues/250",
          title: "Issue 250",
          state: "open",
          state_reason: null,
        },
        {
          number: 120,
          html_url: "https://github.com/owner/repo/issues/120",
          title: "Issue 120",
          state: "closed",
          state_reason: "completed",
        },
      ]);

      const result = await client.getBatchIssueStatus("owner", "repo", [250, 120]);

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "api",
        "repos/owner/repo/issues?state=all&per_page=100",
      ]);
      expect(mockRunGhAsync).not.toHaveBeenCalled();
      expect(result.get(250)).toMatchObject({ number: 250, state: "open" });
      expect(result.get(120)).toMatchObject({ number: 120, state: "closed", stateReason: "completed" });
    });

    it("falls back for requested issues missing from the REST list response", async () => {
      mockRunGhJsonAsync.mockResolvedValue([
        {
          number: 250,
          html_url: "https://github.com/owner/repo/issues/250",
          title: "Issue 250",
          state: "open",
          state_reason: null,
        },
      ]);
      mockRunGhAsync.mockResolvedValue(
        createGraphQlBatchPayload({
          issue_120: {
            number: 120,
            url: "https://github.com/owner/repo/issues/120",
            title: "Issue 120",
            state: "CLOSED",
            stateReason: "COMPLETED",
          },
          issue_100: null,
        }),
      );

      const result = await client.getBatchIssueStatus("owner", "repo", [250, 120, 100]);

      expect(mockRunGhJsonAsync).toHaveBeenCalledTimes(1);
      expect(mockRunGhAsync).toHaveBeenCalledTimes(1);
      expect(result.get(250)).toMatchObject({ number: 250, state: "open" });
      expect(result.get(120)).toMatchObject({ number: 120, state: "closed", stateReason: "completed" });
      expect(result.has(100)).toBe(false);
      expect(result.size).toBe(2);
    });

    it("returns early for empty input", async () => {
      const result = await client.getBatchIssueStatus("owner", "repo", []);

      expect(result.size).toBe(0);
      expect(mockRunGhJsonAsync).not.toHaveBeenCalled();
      expect(mockRunGhAsync).not.toHaveBeenCalled();
    });

    it("retries transient REST failures with a 5 second backoff", async () => {
      vi.useFakeTimers();
      mockRunGhJsonAsync
        .mockRejectedValueOnce(new Error("secondary rate limit"))
        .mockRejectedValueOnce(new Error("502 Bad Gateway"))
        .mockResolvedValueOnce([
          {
            number: 5,
            html_url: "https://github.com/owner/repo/issues/5",
            title: "Issue 5",
            state: "open",
            state_reason: null,
          },
        ]);

      const promise = client.getBatchIssueStatus("owner", "repo", [5]);
      await vi.advanceTimersByTimeAsync(10_000);
      const result = await promise;

      expect(mockRunGhJsonAsync).toHaveBeenCalledTimes(3);
      expect(result.get(5)?.number).toBe(5);
    });

    it("stops retrying the REST batch call after 3 attempts", async () => {
      vi.useFakeTimers();
      mockRunGhJsonAsync.mockRejectedValue(new Error("secondary rate limit"));

      const exhaustedPromise = client.getBatchIssueStatus("owner", "repo", [6]);
      const rejection = expect(exhaustedPromise).rejects.toThrow("secondary rate limit");
      await vi.advanceTimersByTimeAsync(10_000);
      await rejection;

      expect(mockRunGhJsonAsync).toHaveBeenCalledTimes(3);
    });
  });

  describe("getBatchPrStatus", () => {
    it("uses the REST pulls list endpoint and maps merged PRs correctly", async () => {
      mockRunGhJsonAsync.mockResolvedValue([
        {
          number: 150,
          html_url: "https://github.com/owner/repo/pull/150",
          title: "PR 150",
          state: "closed",
          merged_at: "2026-03-30T12:00:00Z",
          head: { ref: "feature/150" },
          base: { ref: "main" },
          comments: 2,
          updated_at: "2026-03-30T11:00:00Z",
        },
        {
          number: 147,
          html_url: "https://github.com/owner/repo/pull/147",
          title: "PR 147",
          state: "closed",
          merged_at: null,
          head: { ref: "feature/147" },
          base: { ref: "main" },
          comments: 1,
          updated_at: "2026-03-30T11:00:00Z",
        },
      ]);

      const result = await client.getBatchPrStatus("owner", "repo", [150, 147]);

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "api",
        "repos/owner/repo/pulls?state=all&per_page=100",
      ]);
      expect(mockRunGhAsync).not.toHaveBeenCalled();
      expect(result.get(150)?.status).toBe("merged");
      expect(result.get(147)?.status).toBe("closed");
    });

    it("chunks fallback exact lookups when more than 100 requested PRs are missing from the REST list", async () => {
      mockRunGhJsonAsync.mockResolvedValue([]);
      mockRunGhAsync
        .mockResolvedValueOnce(
          createGraphQlBatchPayload(
            Object.fromEntries(
              Array.from({ length: 100 }, (_, index) => {
                const number = 150 - index;
                return [`pr_${number}`, {
                  number,
                  url: `https://github.com/owner/repo/pull/${number}`,
                  title: `PR ${number}`,
                  state: number === 150 ? "MERGED" : number === 147 ? "CLOSED" : "OPEN",
                  baseRefName: "main",
                  headRefName: `feature/${number}`,
                  comments: { totalCount: number % 4, nodes: [{ updatedAt: "2026-03-30T11:00:00Z" }] },
                }];
              }),
            ),
          ),
        )
        .mockResolvedValueOnce(
          createGraphQlBatchPayload({
            pr_50: {
              number: 50,
              url: "https://github.com/owner/repo/pull/50",
              title: "PR 50",
              state: "OPEN",
              baseRefName: "main",
              headRefName: "feature/50",
              comments: { totalCount: 2, nodes: [{ updatedAt: "2026-03-30T11:00:00Z" }] },
            },
          }),
        );

      const requestedNumbers = Array.from({ length: 101 }, (_, index) => 150 - index);
      const result = await client.getBatchPrStatus("owner", "repo", requestedNumbers);

      expect(mockRunGhJsonAsync).toHaveBeenCalledTimes(1);
      expect(mockRunGhAsync).toHaveBeenCalledTimes(2);
      expect(result.size).toBe(101);
      expect(result.get(150)?.status).toBe("merged");
      expect(result.get(149)?.status).toBe("open");
      expect(result.get(147)?.status).toBe("closed");
    });

    it("falls back to REST auth when gh REST batch fetch fails and a token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValueOnce(new Error("gh failed"));
      const clientWithToken = new GitHubClient("ghp_token");
      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        status: 200,
        statusText: "OK",
        json: () => Promise.resolve([
          {
            number: 42,
            html_url: "https://github.com/owner/repo/pull/42",
            title: "PR 42",
            state: "open",
            merged_at: null,
            head: { ref: "feature/42" },
            base: { ref: "main" },
            comments: 1,
            updated_at: "2026-03-30T11:00:00Z",
          },
        ]),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.getBatchPrStatus("owner", "repo", [42]);

      expect(mockFetch).toHaveBeenCalledWith(
        "https://api.github.com/repos/owner/repo/pulls?state=all&per_page=100",
        expect.objectContaining({ headers: expect.any(Object) }),
      );
      expect(result.get(42)?.number).toBe(42);
    });
  });

  describe("listIssues", () => {
    const mockIssues = [
      {
        number: 1,
        title: "Issue 1",
        body: "Body 1",
        url: "https://github.com/owner/repo/issues/1",
        labels: [{ name: "bug" }],
        state: "OPEN" as const,
        updatedAt: "2026-05-16T08:00:00Z",
      },
      {
        number: 2,
        title: "Issue 2",
        body: "Body 2",
        url: "https://github.com/owner/repo/issues/2",
        labels: [{ name: "feature" }],
        state: "CLOSED" as const,
        updatedAt: "2026-05-15T08:00:00Z",
      },
    ];

    it("lists open issues using gh CLI", async () => {
      mockRunGhJsonAsync.mockResolvedValue(mockIssues);

      const result = await client.listIssues("owner", "repo");

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "issue", "list",
        "--repo", "owner/repo",
        "--state", "open",
        "--limit", "30",
        "--json", "number,title,body,url,labels,state,updatedAt",
      ]);
      expect(result).toHaveLength(2);
      expect(result[0].number).toBe(1);
      expect(result[0].state).toBe("open");
      expect(result[0].updatedAt).toBe("2026-05-16T08:00:00Z");
    });

    it("respects limit parameter", async () => {
      mockRunGhJsonAsync.mockResolvedValue(mockIssues.slice(0, 1));

      await client.listIssues("owner", "repo", { limit: 10 });

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith(
        expect.arrayContaining(["--limit", "10"])
      );
    });

    it("filters by labels client-side", async () => {
      mockRunGhJsonAsync.mockResolvedValue(mockIssues);

      const result = await client.listIssues("owner", "repo", { labels: ["bug"] });

      expect(result).toHaveLength(1);
      expect(result[0].number).toBe(1);
    });

    it("supports explicit all-state issue listings", async () => {
      mockRunGhJsonAsync.mockResolvedValue(mockIssues);

      await client.listIssues("owner", "repo", { state: "all" });

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith(
        expect.arrayContaining(["--state", "all"]),
      );
    });

    it("falls back to REST API when gh CLI fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));

      const clientWithToken = new GitHubClient("ghp_token");

      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve([
          {
            number: 1,
            title: "API Issue",
            body: "API body",
            html_url: "https://github.com/owner/repo/issues/1",
            labels: [{ name: "api" }],
            state: "open",
            updated_at: "2026-05-16T10:00:00Z",
          },
          {
            number: 3,
            title: "API Pull Request",
            body: "PR body",
            html_url: "https://github.com/owner/repo/issues/3",
            labels: [{ name: "api" }],
            state: "open",
            updated_at: "2026-05-16T10:00:00Z",
            pull_request: {},
          },
        ]),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.listIssues("owner", "repo");

      expect(mockFetch).toHaveBeenCalled();
      expect(result).toHaveLength(1);
      expect(result[0].state).toBe("open");
      expect(result[0].updatedAt).toBe("2026-05-16T10:00:00Z");

      vi.restoreAllMocks();
    });
  });

  describe("getIssue", () => {
    it("fetches single issue using gh CLI", async () => {
      mockRunGhJsonAsync.mockResolvedValue({
        number: 1,
        title: "Test Issue",
        body: "Test body",
        url: "https://github.com/owner/repo/issues/1",
        state: "OPEN",
        stateReason: "reopened",
      });

      const result = await client.getIssue("owner", "repo", 1);

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "issue", "view", "1",
        "--repo", "owner/repo",
        "--json", "number,title,body,url,state,stateReason",
      ]);
      expect(result).not.toBeNull();
      expect(result?.number).toBe(1);
      expect(result?.state).toBe("open");
      expect(result?.stateReason).toBe("reopened");
    });

    it("returns null for non-existent issues", async () => {
      mockRunGhJsonAsync.mockRejectedValue(
        new Error("HTTP 404: not found")
      );

      const result = await client.getIssue("owner", "repo", 999);

      expect(result).toBeNull();
    });

    it("returns null for PRs", async () => {
      mockRunGhJsonAsync.mockRejectedValue(
        new Error("Could not resolve to an issue")
      );

      const result = await client.getIssue("owner", "repo", 1);

      expect(result).toBeNull();
    });

    it("falls back to REST API when gh CLI fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));

      const clientWithToken = new GitHubClient("ghp_token");

      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve({
          number: 1,
          title: "API Issue",
          body: "API body",
          html_url: "https://github.com/owner/repo/issues/1",
          state: "open",
          state_reason: null,
        }),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.getIssue("owner", "repo", 1);

      expect(mockFetch).toHaveBeenCalled();
      expect(result?.number).toBe(1);

      vi.restoreAllMocks();
    });
  });

  describe("findPrForBranch", () => {
    it("finds an existing PR for a head branch via gh CLI", async () => {
      mockRunGhJsonAsync.mockResolvedValue([
        {
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Existing PR",
          state: "OPEN",
          baseRefName: "main",
          headRefName: "fusion/fn-093",
          mergedAt: null,
        },
      ]);

      const result = await client.findPrForBranch({ owner: "owner", repo: "repo", head: "fusion/fn-093", state: "all" });

      expect(mockRunGhJsonAsync).toHaveBeenCalledWith([
        "pr", "list",
        "--repo", "owner/repo",
        "--head", "fusion/fn-093",
        "--state", "all",
        "--json", "number,url,title,state,baseRefName,headRefName,mergedAt",
      ]);
      expect(result).toEqual(expect.objectContaining({ number: 42, status: "open" }));
    });

    it("falls back to REST API for branch lookup when gh CLI fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));
      const clientWithToken = new GitHubClient("ghp_token");
      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve([
          {
            number: 5,
            html_url: "https://github.com/owner/repo/pull/5",
            title: "API PR",
            state: "open",
            merged_at: null,
            head: { ref: "fusion/fn-093" },
            base: { ref: "main" },
            comments: 2,
          },
        ]),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.findPrForBranch({ owner: "owner", repo: "repo", head: "fusion/fn-093" });

      expect(mockFetch).toHaveBeenCalled();
      expect(result).toEqual(expect.objectContaining({ number: 5, commentCount: 2 }));
      vi.restoreAllMocks();
    });
  });

  describe("getPrConflictDiagnostics", () => {
    function createConflictRepo(): string {
      const repoRoot = mkdtempSync(join(tmpdir(), "fn-4966-conflict-"));
      execSync("git init -b main", { cwd: repoRoot, stdio: "ignore" });
      execSync("git config user.email 'test@example.com'", { cwd: repoRoot, stdio: "ignore" });
      execSync("git config user.name 'Test User'", { cwd: repoRoot, stdio: "ignore" });
      writeFileSync(join(repoRoot, "conflict.txt"), "base\n");
      execSync("git add conflict.txt && git commit -m 'base'", { cwd: repoRoot, stdio: "ignore" });
      execSync("git checkout -b feature", { cwd: repoRoot, stdio: "ignore" });
      writeFileSync(join(repoRoot, "conflict.txt"), "feature\n");
      execSync("git add conflict.txt && git commit -m 'feature'", { cwd: repoRoot, stdio: "ignore" });
      execSync("git checkout main", { cwd: repoRoot, stdio: "ignore" });
      writeFileSync(join(repoRoot, "conflict.txt"), "main\n");
      execSync("git add conflict.txt && git commit -m 'main'", { cwd: repoRoot, stdio: "ignore" });
      execSync("git update-ref refs/remotes/origin/main main", { cwd: repoRoot, stdio: "ignore" });
      execSync("git update-ref refs/remotes/origin/feature feature", { cwd: repoRoot, stdio: "ignore" });
      return repoRoot;
    }

    it("returns conflicting files from local git path", async () => {
      const repoRoot = createConflictRepo();
      const diagnostics = await client.getPrConflictDiagnostics("owner", "repo", 42, {
        baseBranch: "main",
        headBranch: "feature",
        repoRoot,
      });

      expect(diagnostics.conflictingFiles).toContain("conflict.txt");
      expect(diagnostics.suggestedCommands).toEqual([
        "git fetch origin",
        "git checkout feature",
        "git rebase origin/main",
        "# Resolve conflicts then: git add <files> && git rebase --continue",
      ]);
      expect(mockRunGhJsonAsync).not.toHaveBeenCalled();
    });

    it("falls back to gh compare files when local repo path fails", async () => {
      mockRunGhJsonAsync.mockResolvedValueOnce({ files: [{ filename: "a.ts" }, { filename: "b.ts" }] });
      const diagnostics = await client.getPrConflictDiagnostics("owner", "repo", 42, {
        baseBranch: "main",
        headBranch: "feature",
        repoRoot: "/does/not/exist",
      });

      expect(diagnostics.conflictingFiles).toEqual(["a.ts", "b.ts"]);
      expect(diagnostics.suggestedCommands.at(-1)).toContain("file list reflects PR changes");
    });

    it("composes commands for each direct-merge strategy", async () => {
      mockRunGhJsonAsync.mockResolvedValue({ files: [] });

      const squash = await client.getPrConflictDiagnostics("owner", "repo", 1, {
        baseBranch: "main",
        headBranch: "feature",
        directMergeCommitStrategy: "always-squash",
      });
      expect(squash.suggestedCommands).toEqual([
        "git fetch origin",
        "git checkout feature",
        "git merge origin/main",
        "# Resolve conflicts then: git add <files> && git commit",
      ]);

      const rebase = await client.getPrConflictDiagnostics("owner", "repo", 1, {
        baseBranch: "main",
        headBranch: "feature",
        directMergeCommitStrategy: "always-rebase",
      });
      expect(rebase.suggestedCommands[2]).toBe("git rebase origin/main");

      const auto = await client.getPrConflictDiagnostics("owner", "repo", 1, {
        baseBranch: "main",
        headBranch: "feature",
        directMergeCommitStrategy: "auto",
      });
      expect(auto.suggestedCommands[2]).toBe("git rebase origin/main");
    });

    it("returns non-throwing defaults when both detection paths fail", async () => {
      mockRunGhJsonAsync.mockRejectedValueOnce(new Error("gh compare failed"));
      const diagnostics = await client.getPrConflictDiagnostics("owner", "repo", 42, {
        baseBranch: "main",
        headBranch: "feature",
        repoRoot: "/does/not/exist",
      });

      expect(diagnostics.conflictingFiles).toEqual([]);
      expect(diagnostics.suggestedCommands).toEqual([
        "git fetch origin",
        "git checkout feature",
        "git rebase origin/main",
        "# Resolve conflicts then: git add <files> && git rebase --continue",
      ]);
      expect(() => new Date(diagnostics.capturedAt)).not.toThrow();
    });
  });

  describe("getPrMergeStatus", () => {
    it("returns merge-ready status only when required checks pass and review is non-blocking", async () => {
      mockRunGhJsonAsync
        .mockResolvedValueOnce({
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Ready PR",
          state: "OPEN",
          reviewDecision: "APPROVED",
          mergeable: "MERGEABLE",
          mergeStateStatus: "CLEAN",
          baseRefName: "main",
          headRefName: "fusion/fn-093",
        })
        .mockResolvedValueOnce([
          { name: "ci", state: "SUCCESS", link: "https://github.com/owner/repo/actions/runs/1", startedAt: "2026-01-01T00:00:00Z", completedAt: "2026-01-01T00:01:00Z" },
          { name: "lint", state: "SUCCESS" },
        ]);

      const result = await client.getPrMergeStatus("owner", "repo", 42);

      expect(result.mergeReady).toBe(true);
      expect(result.mergeable).toBe("clean");
      expect(result.prInfo.mergeable).toBe("clean");
      expect(result.blockingReasons).toEqual([]);
      expect(result.checks).toEqual([
        {
          name: "ci",
          required: true,
          state: "success",
          detailsUrl: "https://github.com/owner/repo/actions/runs/1",
          startedAt: "2026-01-01T00:00:00Z",
          completedAt: "2026-01-01T00:01:00Z",
        },
        { name: "lint", required: true, state: "success", detailsUrl: undefined, startedAt: undefined, completedAt: undefined },
      ]);
    });

    it("maps DIRTY merge-state to conflicting even when mergeable is unknown", async () => {
      mockRunGhJsonAsync
        .mockResolvedValueOnce({
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Dirty PR",
          state: "OPEN",
          reviewDecision: "APPROVED",
          mergeable: "UNKNOWN",
          mergeStateStatus: "DIRTY",
          baseRefName: "main",
          headRefName: "fusion/fn-093",
        })
        .mockResolvedValueOnce([{ name: "ci", state: "SUCCESS" }]);

      const result = await client.getPrMergeStatus("owner", "repo", 42);
      expect(result.mergeable).toBe("conflicting");
      expect(result.prInfo.mergeable).toBe("conflicting");
    });

    it("maps BEHIND merge-state to behind", async () => {
      mockRunGhJsonAsync
        .mockResolvedValueOnce({
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Behind PR",
          state: "OPEN",
          reviewDecision: "APPROVED",
          mergeStateStatus: "BEHIND",
          baseRefName: "main",
          headRefName: "fusion/fn-093",
        })
        .mockResolvedValueOnce([{ name: "ci", state: "SUCCESS" }]);

      const result = await client.getPrMergeStatus("owner", "repo", 42);
      expect(result.mergeable).toBe("behind");
      expect(result.prInfo.mergeable).toBe("behind");
    });

    it("maps BLOCKED merge-state to blocked", async () => {
      mockRunGhJsonAsync
        .mockResolvedValueOnce({
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Blocked PR",
          state: "OPEN",
          reviewDecision: "APPROVED",
          mergeStateStatus: "BLOCKED",
          baseRefName: "main",
          headRefName: "fusion/fn-093",
        })
        .mockResolvedValueOnce([{ name: "ci", state: "SUCCESS" }]);

      const result = await client.getPrMergeStatus("owner", "repo", 42);
      expect(result.mergeable).toBe("blocked");
      expect(result.prInfo.mergeable).toBe("blocked");
    });

    it("maps missing mergeability fields to unknown", async () => {
      mockRunGhJsonAsync
        .mockResolvedValueOnce({
          number: 42,
          url: "https://github.com/owner/repo/pull/42",
          title: "Unknown PR",
          state: "OPEN",
          reviewDecision: "APPROVED",
          baseRefName: "main",
          headRefName: "fusion/fn-093",
        })
        .mockResolvedValueOnce([{ name: "ci", state: "SUCCESS" }]);

      const result = await client.getPrMergeStatus("owner", "repo", 42);
      expect(result.mergeable).toBe("unknown");
      expect(result.prInfo.mergeable).toBe("unknown");
    });

    it("falls back to GraphQL API when gh CLI merge-status lookup fails and token is available", async () => {
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));
      const clientWithToken = new GitHubClient("ghp_token");
      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve({
          data: {
            repository: {
              pullRequest: {
                number: 42,
                url: "https://github.com/owner/repo/pull/42",
                title: "Fallback PR",
                state: "OPEN",
                reviewDecision: null,
                mergeable: "CONFLICTING",
                mergeStateStatus: "DIRTY",
                baseRefName: "main",
                headRefName: "fusion/fn-093",
                comments: { totalCount: 0 },
                commits: {
                  nodes: [
                    {
                      commit: {
                        statusCheckRollup: {
                          contexts: {
                            nodes: [
                              {
                                __typename: "CheckRun",
                                name: "ci",
                                status: "COMPLETED",
                                conclusion: "SUCCESS",
                                detailsUrl: "https://github.com/owner/repo/actions/runs/2",
                                startedAt: "2026-01-01T00:00:00Z",
                                completedAt: "2026-01-01T00:02:00Z",
                                isRequired: true,
                              },
                              {
                                __typename: "CheckRun",
                                name: "optional-preview",
                                status: "COMPLETED",
                                conclusion: "FAILURE",
                                detailsUrl: "https://github.com/owner/repo/actions/runs/3",
                                isRequired: false,
                              },
                              {
                                __typename: "StatusContext",
                                context: "legacy-status",
                                state: "SUCCESS",
                                targetUrl: "https://github.com/owner/repo/commit/status",
                                isRequired: true,
                              },
                            ],
                          },
                        },
                      },
                    },
                  ],
                },
              },
            },
          },
        }),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.getPrMergeStatus("owner", "repo", 42);

      expect(result.mergeReady).toBe(true);
      expect(result.mergeable).toBe("conflicting");
      expect(result.prInfo.mergeable).toBe("conflicting");
      expect(result.checks).toEqual([
        {
          name: "ci",
          required: true,
          state: "success",
          detailsUrl: "https://github.com/owner/repo/actions/runs/2",
          startedAt: "2026-01-01T00:00:00Z",
          completedAt: "2026-01-01T00:02:00Z",
        },
        {
          name: "legacy-status",
          required: true,
          state: "success",
          detailsUrl: "https://github.com/owner/repo/commit/status",
        },
      ]);
      vi.restoreAllMocks();
    });
  });

  describe("getAllPrChecks", () => {
    it("returns required and non-required checks in gh mode and computes rollup from required checks", async () => {
      mockRunGhJsonAsync.mockResolvedValueOnce([
        { name: "required-ci", state: "SUCCESS", link: "https://example.com/ci", bucket: "pass" },
        { name: "optional-preview", state: "FAILURE", link: "https://example.com/preview", bucket: "none" },
      ]);

      const result = await client.getAllPrChecks("owner", "repo", 42);

      expect(result.rollupRequired).toBe("success");
      expect(result.checks).toEqual([
        { name: "required-ci", required: true, state: "success", detailsUrl: "https://example.com/ci", startedAt: undefined, completedAt: undefined },
        { name: "optional-preview", required: false, state: "failure", detailsUrl: "https://example.com/preview", startedAt: undefined, completedAt: undefined },
      ]);
    });

    it("returns all checks in API mode and ignores non-required failures for rollup", async () => {
      const clientWithToken = new GitHubClient("ghp_token");
      mockRunGhJsonAsync.mockRejectedValue(new Error("gh failed"));
      const mockFetch = vi.fn().mockResolvedValue({
        ok: true,
        json: () => Promise.resolve({
          data: {
            repository: {
              pullRequest: {
                commits: {
                  nodes: [
                    {
                      commit: {
                        statusCheckRollup: {
                          contexts: {
                            nodes: [
                              {
                                __typename: "CheckRun",
                                name: "required-ci",
                                status: "COMPLETED",
                                conclusion: "SUCCESS",
                                detailsUrl: "https://example.com/required",
                                isRequired: true,
                              },
                              {
                                __typename: "StatusContext",
                                context: "optional-legacy",
                                state: "FAILURE",
                                targetUrl: "https://example.com/optional",
                                isRequired: false,
                              },
                            ],
                          },
                        },
                      },
                    },
                  ],
                },
              },
            },
          },
        }),
      });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.getAllPrChecks("owner", "repo", 42);

      expect(result.rollupRequired).toBe("success");
      expect(result.checks).toEqual([
        { name: "required-ci", required: true, state: "success", detailsUrl: "https://example.com/required", startedAt: undefined, completedAt: undefined },
        { name: "optional-legacy", required: false, state: "failure", detailsUrl: "https://example.com/optional" },
      ]);
      vi.restoreAllMocks();
    });
  });

  describe("FN-5181 PR review pagination", () => {
    it("FN-5181 paginates GraphQL review details across comment and review pages", async () => {
      mockIsGhAvailable.mockReturnValue(false);
      const clientWithToken = new GitHubClient("ghp_token");
      const fetchSpy = vi.spyOn(global, "fetch" as any)
        .mockResolvedValueOnce({
          ok: true,
          status: 200,
          statusText: "OK",
          json: async () => ({
            data: {
              repository: {
                pullRequest: {
                  reviewDecision: "CHANGES_REQUESTED",
                  comments: {
                    nodes: [
                      { id: "C_1", body: "first comment", createdAt: "2024-01-01T00:00:00Z", updatedAt: "2024-01-01T00:00:01Z", url: "https://example.com/c1", author: { login: "alice" } },
                    ],
                    pageInfo: { hasNextPage: true, endCursor: "comment-cursor-1" },
                  },
                  reviews: {
                    nodes: [
                      { id: "R_1", state: "COMMENTED", body: "first review", submittedAt: "2024-01-01T00:00:02Z", url: "https://example.com/r1", author: { login: "reviewer-1" } },
                    ],
                    pageInfo: { hasNextPage: true, endCursor: "review-cursor-1" },
                  },
                },
              },
            },
          }),
        } as any)
        .mockResolvedValueOnce({
          ok: true,
          status: 200,
          statusText: "OK",
          json: async () => ({
            data: {
              repository: {
                pullRequest: {
                  reviewDecision: "CHANGES_REQUESTED",
                  comments: {
                    nodes: [
                      { id: "C_2", body: "second comment", createdAt: "2024-01-01T00:00:03Z", updatedAt: "2024-01-01T00:00:04Z", url: "https://example.com/c2", author: { login: "bob" } },
                    ],
                    pageInfo: { hasNextPage: false, endCursor: "comment-cursor-2" },
                  },
                  reviews: {
                    nodes: [
                      { id: "R_2", state: "APPROVED", body: "second review", submittedAt: "2024-01-01T00:00:05Z", url: "https://example.com/r2", author: { login: "reviewer-2" } },
                    ],
                    pageInfo: { hasNextPage: false, endCursor: "review-cursor-2" },
                  },
                },
              },
            },
          }),
        } as any);

      const details = await (clientWithToken as any).getPrReviewDetailsWithApi("owner", "repo", 1);

      expect(details.reviewDecision).toBe("CHANGES_REQUESTED");
      expect(details.comments.map((comment: any) => comment.id)).toEqual(["C_1", "C_2"]);
      expect(details.reviews.map((review: any) => review.id)).toEqual(["R_1", "R_2"]);
      expect(fetchSpy).toHaveBeenCalledTimes(2);
      const firstBody = JSON.parse(String(fetchSpy.mock.calls[0]?.[1]?.body));
      const secondBody = JSON.parse(String(fetchSpy.mock.calls[1]?.[1]?.body));
      expect(firstBody.variables).toEqual(expect.objectContaining({ commentsAfter: null, reviewsAfter: null, fetchComments: true, fetchReviews: true }));
      expect(secondBody.variables).toEqual(expect.objectContaining({ commentsAfter: "comment-cursor-1", reviewsAfter: "review-cursor-1", fetchComments: true, fetchReviews: true }));
      fetchSpy.mockRestore();
    });

    it("FN-5181 paginates gh review details across issue comments, inline comments, and review pages", async () => {
      const issueCommentPageOne = Array.from({ length: 100 }, (_, index) => ({
        id: `issue-${index + 1}`,
        body: `issue comment ${index + 1}`,
        author: { login: `issue-author-${index + 1}` },
        createdAt: new Date(Date.UTC(2024, 0, 1, 0, 0, index)).toISOString(),
        updatedAt: new Date(Date.UTC(2024, 0, 1, 0, 1, index)).toISOString(),
        url: `https://example.com/issue-${index + 1}`,
      }));
      const reviewPageOne = Array.from({ length: 100 }, (_, index) => ({
        id: `review-${index + 1}`,
        state: "COMMENTED",
        body: `review ${index + 1}`,
        submittedAt: new Date(Date.UTC(2024, 0, 1, 0, 2, index)).toISOString(),
        url: `https://example.com/review-${index + 1}`,
        author: { login: `reviewer-${index + 1}` },
      }));

      mockRunGhJsonAsync
        .mockResolvedValueOnce({ reviewDecision: "APPROVED" })
        .mockResolvedValueOnce(issueCommentPageOne)
        .mockResolvedValueOnce([
          { id: "issue-101", body: "issue comment 101", author: { login: "bob" }, createdAt: "2024-01-01T00:10:01Z", updatedAt: "2024-01-01T00:10:02Z", url: "https://example.com/issue-101" },
        ])
        .mockResolvedValueOnce([
          { id: 301, body: "inline comment", user: { login: "carol" }, created_at: "2024-01-01T00:10:03Z", updated_at: "2024-01-01T00:10:04Z", html_url: "https://example.com/inline-301" },
        ])
        .mockResolvedValueOnce(reviewPageOne)
        .mockResolvedValueOnce([
          { id: "review-101", state: "APPROVED", body: "review 101", submittedAt: "2024-01-01T00:10:05Z", url: "https://example.com/review-101", author: { login: "erin" } },
        ]);

      const details = await (client as any).getPrReviewDetailsWithGh("owner", "repo", 1);

      expect(details.reviewDecision).toBe("APPROVED");
      expect(details.comments).toHaveLength(102);
      expect(details.comments[0]?.id).toBe("issue-1");
      expect(details.comments.at(-1)?.id).toBe("301");
      expect(details.comments.at(-1)?.author.login).toBe("carol");
      expect(details.reviews).toHaveLength(101);
      expect(details.reviews[0]?.id).toBe("review-1");
      expect(details.reviews.at(-1)?.id).toBe("review-101");
      expect(mockRunGhJsonAsync).toHaveBeenNthCalledWith(2, ["api", "repos/owner/repo/issues/1/comments?per_page=100&page=1"]);
      expect(mockRunGhJsonAsync).toHaveBeenNthCalledWith(3, ["api", "repos/owner/repo/issues/1/comments?per_page=100&page=2"]);
      expect(mockRunGhJsonAsync).toHaveBeenNthCalledWith(4, ["api", "repos/owner/repo/pulls/1/comments?per_page=100&page=1"]);
      expect(mockRunGhJsonAsync).toHaveBeenNthCalledWith(5, ["api", "repos/owner/repo/pulls/1/reviews?per_page=100&page=1"]);
      expect(mockRunGhJsonAsync).toHaveBeenNthCalledWith(6, ["api", "repos/owner/repo/pulls/1/reviews?per_page=100&page=2"]);
    });
  });

  describe("getPrReviewSnapshot", () => {
    it("normalizes reviews/comments into review-state items and summary", async () => {
      mockRunGhJsonAsync
        .mockResolvedValueOnce({ reviewDecision: "CHANGES_REQUESTED" })
        .mockResolvedValueOnce([
          { id: "c1", body: "nit", createdAt: "2024-01-01T00:00:00Z", updatedAt: "2024-01-01T00:00:01Z", author: { login: "reviewer" }, url: "https://github.com/owner/repo/pull/1#issuecomment-c1" },
        ])
        .mockResolvedValueOnce([])
        .mockResolvedValueOnce([
          { id: "r1", state: "CHANGES_REQUESTED", body: "please fix", submittedAt: "2024-01-01T00:00:00Z", author: { login: "octocat" }, url: "https://github.com/owner/repo/pull/1#review-r1" },
        ])
        .mockResolvedValueOnce({
          number: 1,
          url: "https://github.com/owner/repo/pull/1",
          title: "PR",
          state: "OPEN",
          reviewDecision: "CHANGES_REQUESTED",
          baseRefName: "main",
          headRefName: "fn/fn-1",
        })
        .mockResolvedValueOnce([]);

      const snapshot = await client.getPrReviewSnapshot("owner", "repo", 1);
      expect(snapshot.items).toHaveLength(2);
      expect(snapshot.summary?.reviewDecision).toBe("CHANGES_REQUESTED");
      expect(snapshot.prInfo.number).toBe(1);
      expect(snapshot.commentCount).toBe(1);
      expect(snapshot.summary?.reviewers[0]).toEqual(expect.objectContaining({ login: "octocat", state: "CHANGES_REQUESTED" }));
    });

    it("falls back to API review details when gh fails and token is available", async () => {
      mockRunGhJsonAsync.mockImplementation(() => {
        throw new Error("gh down");
      });
      const clientWithToken = new GitHubClient("ghp_token");
      const mockFetch = vi.fn()
        .mockResolvedValueOnce({
          ok: true,
          json: async () => ({
            data: {
              repository: {
                pullRequest: {
                  reviewDecision: "APPROVED",
                  comments: { nodes: [{ id: "C_1", body: "lgtm", createdAt: "2024-01-01T00:00:00Z", updatedAt: "2024-01-01T00:00:01Z", url: "https://example.com/c1", author: { login: "bot" } }] },
                  reviews: { nodes: [{ id: "R_1", state: "APPROVED", body: "good", submittedAt: "2024-01-01T00:00:00Z", url: "https://example.com/r1", author: { login: "reviewer" } }] },
                },
              },
            },
          }),
        })
        .mockResolvedValueOnce({
          ok: true,
          json: async () => ({
            data: {
              repository: {
                pullRequest: {
                  number: 1,
                  url: "https://github.com/owner/repo/pull/1",
                  title: "PR",
                  state: "OPEN",
                  reviewDecision: "APPROVED",
                  baseRefName: "main",
                  headRefName: "fn/fn-1",
                  comments: { totalCount: 1 },
                  commits: { nodes: [{ commit: { statusCheckRollup: { contexts: { nodes: [] } } } }] },
                },
              },
            },
          }),
        });
      global.fetch = mockFetch as any;

      const snapshot = await clientWithToken.getPrReviewSnapshot("owner", "repo", 1);
      expect(snapshot.summary?.reviewDecision).toBe("APPROVED");
      expect(snapshot.items).toHaveLength(2);
      vi.restoreAllMocks();
    });
  });

  describe("mergePr", () => {
    it("merges a PR with gh CLI and refetches merged status", async () => {
      mockRunGh.mockReturnValue("Merged pull request");
      mockRunGhJsonAsync.mockResolvedValue({
        number: 42,
        url: "https://github.com/owner/repo/pull/42",
        title: "Merged PR",
        state: "MERGED",
        baseRefName: "main",
        headRefName: "fusion/fn-093",
      });

      const result = await client.mergePr({ owner: "owner", repo: "repo", number: 42, method: "squash" });

      expect(mockRunGh).toHaveBeenCalledWith([
        "pr", "merge", "42",
        "--repo", "owner/repo",
        "--squash",
        "--delete-branch",
      ]);
      expect(result.status).toBe("merged");
    });

    it("falls back to REST API merge when gh CLI fails and token is available", async () => {
      mockRunGh.mockImplementation(() => {
        throw new Error("gh failed");
      });
      const clientWithToken = new GitHubClient("ghp_token");
      const mockFetch = vi.fn()
        .mockResolvedValueOnce({ ok: true, json: () => Promise.resolve({ merged: true }) })
        .mockResolvedValueOnce({
          ok: true,
          json: () => Promise.resolve({
            number: 42,
            html_url: "https://github.com/owner/repo/pull/42",
            title: "Merged PR",
            state: "closed",
            merged: true,
            head: { ref: "fusion/fn-093" },
            base: { ref: "main" },
            comments: 0,
            updated_at: "2024-01-01T00:00:00Z",
          }),
        });
      global.fetch = mockFetch as any;

      const result = await clientWithToken.mergePr({ owner: "owner", repo: "repo", number: 42 });

      expect(result.status).toBe("merged");
      vi.restoreAllMocks();
    });
  });

  describe("isPrMergeReady", () => {
    it("blocks closed PRs", () => {
      expect(isPrMergeReady({ status: "closed", reviewDecision: null, checks: [] })).toEqual({
        ready: false,
        blockingReasons: ["PR is closed"],
      });
    });

    it("blocks changes requested review even when checks pass", () => {
      expect(isPrMergeReady({
        status: "open",
        reviewDecision: "CHANGES_REQUESTED",
        checks: [{ name: "ci", required: true, state: "success" }],
      })).toEqual({
        ready: false,
        blockingReasons: ["changes requested review is active"],
      });
    });

    it("blocks pending required checks", () => {
      expect(isPrMergeReady({
        status: "open",
        reviewDecision: null,
        checks: [{ name: "ci", required: true, state: "pending" }],
      })).toEqual({
        ready: false,
        blockingReasons: ["required checks not successful: ci (pending)"],
      });
    });

    it("ignores optional checks when determining readiness", () => {
      expect(isPrMergeReady({
        status: "open",
        reviewDecision: "REVIEW_REQUIRED",
        checks: [
          { name: "required-ci", required: true, state: "success" },
          { name: "optional-preview", required: false, state: "failure" },
        ],
      })).toEqual({ ready: true, blockingReasons: [] });
    });
  });

  describe("error handling when gh CLI not available", () => {
    it("throws error when gh CLI not available and no token", async () => {
      mockIsGhAvailable.mockReturnValue(false);

      await expect(client.createPr({
        title: "Test",
        head: "branch",
      })).rejects.toThrow("GitHub CLI (gh) is not available");
    });

    it("throws error when gh not authenticated and no token", async () => {
      mockIsGhAuthenticated.mockReturnValue(false);

      await expect(client.createPr({
        title: "Test",
        head: "branch",
      })).rejects.toThrow("GitHub CLI (gh) is not available or not authenticated");
    });
  });

  describe("fetchThrottled", () => {
    let fetchSpy: ReturnType<typeof vi.fn>;
    const originalFetch = globalThis.fetch;

    beforeEach(() => {
      fetchSpy = vi.fn();
      globalThis.fetch = fetchSpy as any;
    });

    afterEach(() => {
      globalThis.fetch = originalFetch;
    });

    it("returns success with data on successful request", async () => {
      const mockData = { id: 1, title: "Test Issue" };
      fetchSpy.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: () => Promise.resolve(mockData),
      } as Response);

      const result = await client.fetchThrottled("https://api.github.com/repos/owner/repo/issues/1");

      expect(result.success).toBe(true);
      expect(result.data).toEqual(mockData);
      expect(result.error).toBeUndefined();
    });

    it("returns error on non-429 HTTP error without retry", async () => {
      fetchSpy.mockResolvedValueOnce({
        ok: false,
        status: 404,
        statusText: "Not Found",
        json: () => Promise.resolve({ message: "Not Found" }),
      } as Response);

      const result = await client.fetchThrottled("https://api.github.com/repos/owner/repo/issues/1");

      expect(result.success).toBe(false);
      expect(result.error).toContain("404");
      expect(fetchSpy).toHaveBeenCalledTimes(1); // No retries for non-429 errors
    });

    it("retries on 429 with exponential backoff", async () => {
      fetchSpy
        .mockResolvedValueOnce({
          ok: false,
          status: 429,
          statusText: "Too Many Requests",
          headers: new Headers(),
          json: () => Promise.resolve({ message: "Rate limited" }),
        } as Response)
        .mockResolvedValueOnce({
          ok: true,
          status: 200,
          json: () => Promise.resolve({ id: 1 }),
        } as Response);

      const result = await client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 10, maxRetries: 3 }
      );

      expect(result.success).toBe(true);
      expect(result.data).toEqual({ id: 1 });
      expect(fetchSpy).toHaveBeenCalledTimes(2);
    });

    it("respects Retry-After header on 429", async () => {
      vi.useFakeTimers();
      const headers = new Headers();
      headers.set("Retry-After", "1");

      fetchSpy
        .mockResolvedValueOnce({
          ok: false,
          status: 429,
          statusText: "Too Many Requests",
          headers,
          json: () => Promise.resolve({ message: "Rate limited" }),
        } as Response)
        .mockResolvedValueOnce({
          ok: true,
          status: 200,
          json: () => Promise.resolve({ id: 1 }),
        } as Response);

      const resultPromise = client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 100, maxRetries: 3 }
      );

      await vi.advanceTimersByTimeAsync(999);
      expect(fetchSpy).toHaveBeenCalledTimes(1);

      await vi.advanceTimersByTimeAsync(1);
      const result = await resultPromise;

      expect(result.success).toBe(true);
      expect(fetchSpy).toHaveBeenCalledTimes(2);
    });

    it("returns error with retryAfter after max retries exceeded", async () => {
      vi.useFakeTimers();
      const headers = new Headers();
      headers.set("Retry-After", "1");

      // All attempts return 429
      fetchSpy.mockResolvedValue({
        ok: false,
        status: 429,
        statusText: "Too Many Requests",
        headers,
        json: () => Promise.resolve({ message: "Rate limited" }),
      } as Response);

      const resultPromise = client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 1, maxRetries: 2 }
      );

      await vi.advanceTimersByTimeAsync(2000);
      const result = await resultPromise;

      expect(result.success).toBe(false);
      expect(result.error).toContain("rate limit exceeded");
      expect(result.retryAfter).toBe(1);
      expect(fetchSpy).toHaveBeenCalledTimes(3); // initial + 2 retries
    });

    it("retries on network errors with exponential backoff", async () => {
      fetchSpy
        .mockRejectedValueOnce(new Error("Network error"))
        .mockResolvedValueOnce({
          ok: true,
          status: 200,
          json: () => Promise.resolve({ id: 1 }),
        } as Response);

      const result = await client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 10, maxRetries: 3 }
      );

      expect(result.success).toBe(true);
      expect(result.data).toEqual({ id: 1 });
      expect(fetchSpy).toHaveBeenCalledTimes(2);
    });

    it("returns error after max retries on persistent network errors", async () => {
      fetchSpy.mockRejectedValue(new Error("Network error"));

      const result = await client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 1, maxRetries: 2 }
      );

      expect(result.success).toBe(false);
      expect(result.error).toBe("Network error");
      expect(fetchSpy).toHaveBeenCalledTimes(3); // initial + 2 retries
    });

    it("enforces delay between sequential requests", async () => {
      vi.useFakeTimers();
      vi.setSystemTime(new Date("2026-01-01T00:00:01.000Z"));

      fetchSpy.mockResolvedValue({
        ok: true,
        status: 200,
        json: () => Promise.resolve({ id: 1 }),
      } as Response);

      // First request
      await client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 100 }
      );

      // Second request should be delayed
      const resultPromise = client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/2",
        {},
        { delayMs: 100 }
      );

      expect(fetchSpy).toHaveBeenCalledTimes(1);
      await vi.advanceTimersByTimeAsync(99);
      expect(fetchSpy).toHaveBeenCalledTimes(1);
      await vi.advanceTimersByTimeAsync(1);
      await resultPromise;
      expect(fetchSpy).toHaveBeenCalledTimes(2);
    });

    it("uses custom delayMs option", async () => {
      fetchSpy.mockResolvedValue({
        ok: true,
        status: 200,
        json: () => Promise.resolve({ id: 1 }),
      } as Response);

      const startTime = Date.now();
      await client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 200 }
      );
      const elapsed = Date.now() - startTime;

      // Should be relatively quick since no previous request
      expect(elapsed).toBeLessThan(100);
    });

    it("uses custom maxRetries option", async () => {
      fetchSpy.mockRejectedValue(new Error("Network error"));

      await client.fetchThrottled(
        "https://api.github.com/repos/owner/repo/issues/1",
        {},
        { delayMs: 1, maxRetries: 1 }
      );

      expect(fetchSpy).toHaveBeenCalledTimes(2); // initial + 1 retry
    });
  });
});