/**
 * Canonical @fusion/core and @fusion/engine mock helpers for dashboard server tests.
 *
 * If a route test starts failing with "No \"X\" export is defined", update this
 * helper first instead of adding another full inline export map in the test file.
 */
import { vi, type Mock } from "vitest";

type AnyModule = Record<string, unknown>;
type AnyMock = Mock;

const fallbackFns = new Map<string, AnyMock>();

function getFallback(name: string): AnyMock {
  if (!fallbackFns.has(name)) fallbackFns.set(name, vi.fn());
  return fallbackFns.get(name)!;
}

function withFallbackFunctions(actual: AnyModule, moduleValue: AnyModule): AnyModule {
  return new Proxy(moduleValue, {
    get(target, prop, receiver) {
      if (typeof prop !== "string") return Reflect.get(target, prop, receiver);
      if (Reflect.has(target, prop)) return Reflect.get(target, prop, receiver);
      if (["then", "catch", "finally"].includes(prop)) return undefined;

      const actualValue = actual[prop];
      if (typeof actualValue === "function" || actualValue === undefined) {
        const fn = getFallback(prop);
        target[prop] = fn;
        return fn;
      }
      return actualValue;
    },
  });
}

export async function createCoreMock(
  importActual: () => Promise<AnyModule>,
  overrides: AnyModule = {},
): Promise<AnyModule> {
  const actual = await importActual();
  return withFallbackFunctions(actual, { ...actual, ...overrides });
}

export function createEngineMock(overrides: AnyModule = {}): AnyModule {
  const actual: AnyModule = {};
  return withFallbackFunctions(actual, {
    createFnAgent: vi.fn(),
    promptWithFallback: vi.fn(),
    ...overrides,
  });
}

export function resetDashboardServerMockState(): void {
  for (const fn of fallbackFns.values()) fn.mockReset();
}