import React from "react";
import { useTranslation } from "react-i18next";
import ReactMarkdown from "react-markdown";
import type { Components } from "react-markdown";
import remarkGfm from "remark-gfm";
import type { TaskDetail, TaskStep, TaskTokenUsagePerModel, WorkflowStepResult } from "@fusion/core";
import { costFor, type CostResult, type ModelPricingOverrides } from "../../../core/src/model-pricing";
import { createMermaidCodeComponent, sharedRehypePlugins } from "./markdownPipeline";
import { ProviderIcon } from "./ProviderIcon";
import { linkifyFilePaths, linkifyReactChildren } from "../utils/filePathLinkify";
import { inferProviderIconKey } from "../utils/providerIconKey";

const EMPTY_MARKDOWN_CHILD_SEPARATOR = "";
const STRING_OBJECT_TAG = "[object String]";

const markdownLinkifyCodeComponent: NonNullable<Components["code"]> = ({ children, ...props }) => {
  const text = React.Children.toArray(children).join(EMPTY_MARKDOWN_CHILD_SEPARATOR);
  const linkedChildren = linkifyFilePaths(text);
  if (linkedChildren.length === 1 && Object.prototype.toString.call(linkedChildren[0]) === STRING_OBJECT_TAG) {
    return <code {...props}>{children}</code>;
  }
  return <code {...props}>{linkedChildren}</code>;
};

const markdownLinkifyComponents: Components = {
  p: ({ children, ...props }) => <p {...props}>{linkifyReactChildren(children)}</p>,
  li: ({ children, ...props }) => <li {...props}>{linkifyReactChildren(children)}</li>,
  code: createMermaidCodeComponent("task-summary-mermaid-diagram", markdownLinkifyCodeComponent),
};

interface TaskSummaryTabProps {
  task: TaskDetail;
  pricingOverrides?: ModelPricingOverrides;
}

function getCompletedSteps(steps: TaskStep[] | undefined): TaskStep[] {
  return (steps ?? []).filter((step) => step.status === "done" || step.status === "skipped");
}

function getRenderableWorkflowResults(results: WorkflowStepResult[] | undefined): WorkflowStepResult[] {
  return (results ?? []).filter((result) => result.status !== "pending");
}

interface TokenCostRow {
  key: string;
  label: string;
  modelProvider?: string;
  modelId?: string;
  inputTokens: number;
  outputTokens: number;
  cachedTokens: number;
  cacheWriteTokens: number;
  totalTokens: number;
  cost: CostResult;
}

function formatCount(n: number): string {
  return Number.isFinite(n) ? Math.round(n).toLocaleString() : "0";
}

function formatCost(usd: number | null, unavailable: boolean): string {
  if (unavailable || usd === null || !Number.isFinite(usd)) {
    return "—";
  }
  return `$${usd.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;
}

function toTokenBucketKey(bucket: Pick<TaskTokenUsagePerModel, "modelProvider" | "modelId">): string {
  return `${bucket.modelProvider ?? ""}:${bucket.modelId ?? ""}`;
}

function toTokenCostRow(
  bucket: Pick<TaskTokenUsagePerModel, "modelProvider" | "modelId" | "inputTokens" | "outputTokens" | "cachedTokens" | "cacheWriteTokens" | "totalTokens">,
  unknownLabel: string,
  now: number,
  pricingOverrides?: ModelPricingOverrides,
): TokenCostRow {
  const modelId = bucket.modelId?.trim() || undefined;
  const modelProvider = bucket.modelProvider?.trim() || undefined;
  const label = modelId ?? unknownLabel;
  return {
    key: toTokenBucketKey({ modelProvider, modelId }),
    label,
    modelProvider,
    modelId,
    inputTokens: bucket.inputTokens,
    outputTokens: bucket.outputTokens,
    cachedTokens: bucket.cachedTokens,
    cacheWriteTokens: bucket.cacheWriteTokens,
    totalTokens: bucket.totalTokens,
    cost: costFor(
      {
        inputTokens: bucket.inputTokens,
        outputTokens: bucket.outputTokens,
        cachedTokens: bucket.cachedTokens,
        cacheWriteTokens: bucket.cacheWriteTokens,
      },
      { provider: modelProvider, model: modelId },
      now,
      pricingOverrides,
    ),
  };
}

/**
 * FNXC:TaskDetailSummaryTokenCost 2026-06-27-00:00:
 * Done-task Summary shows durable token usage broken down by model with derived USD cost. Use already-loaded task.tokenUsage.perModel buckets plus costFor and global pricing overrides threaded from TaskDetailModal; do not fetch or persist cost here. Unpriced models render “—” instead of $0 and make the task total unavailable so estimates are never understated.
 */
function buildTokenCostRows(task: TaskDetail, unknownLabel: string, pricingOverrides?: ModelPricingOverrides): TokenCostRow[] {
  const tokenUsage = task.tokenUsage;
  if (!tokenUsage) return [];

  const buckets = tokenUsage.perModel?.length
    ? tokenUsage.perModel
    : [
        {
          modelProvider: tokenUsage.modelProvider,
          modelId: tokenUsage.modelId,
          inputTokens: tokenUsage.inputTokens,
          outputTokens: tokenUsage.outputTokens,
          cachedTokens: tokenUsage.cachedTokens,
          cacheWriteTokens: tokenUsage.cacheWriteTokens,
          totalTokens: tokenUsage.totalTokens,
        },
      ];

  const merged = new Map<string, Pick<TaskTokenUsagePerModel, "modelProvider" | "modelId" | "inputTokens" | "outputTokens" | "cachedTokens" | "cacheWriteTokens" | "totalTokens">>();
  buckets.forEach((bucket) => {
    const modelProvider = bucket.modelProvider?.trim() || undefined;
    const modelId = bucket.modelId?.trim() || undefined;
    const key = toTokenBucketKey({ modelProvider, modelId });
    const current = merged.get(key);
    if (!current) {
      merged.set(key, { ...bucket, modelProvider, modelId });
      return;
    }
    current.inputTokens += bucket.inputTokens;
    current.outputTokens += bucket.outputTokens;
    current.cachedTokens += bucket.cachedTokens;
    current.cacheWriteTokens += bucket.cacheWriteTokens;
    current.totalTokens += bucket.totalTokens;
  });

  const now = Date.now();
  return Array.from(merged.values()).map((bucket) => toTokenCostRow(bucket, unknownLabel, now, pricingOverrides));
}

function totalCostForRows(rows: TokenCostRow[]): { usd: number | null; unavailable: boolean } {
  let usd = 0;
  let unavailable = false;
  rows.forEach((row) => {
    if (row.totalTokens <= 0) return;
    if (row.cost.unavailable || row.cost.usd === null || !Number.isFinite(row.cost.usd)) {
      unavailable = true;
      return;
    }
    usd += row.cost.usd;
  });
  return { usd: unavailable ? null : usd, unavailable };
}

/**
 * FNXC:TaskDetailSummaryTab 2026-06-27-00:00:
 * TaskSummaryTab aggregates read-only completion data already loaded on TaskDetail: agent-written summary, changed-file metadata, implementation steps, workflow-step outcomes, and retry counts. It does not fetch, persist, or generate AI content so done-task details remain a front-end composition only.
 */
export function TaskSummaryTab({ task, pricingOverrides }: TaskSummaryTabProps) {
  const { t } = useTranslation("app");
  const summary = task.summary?.trim();
  const changedFiles = task.mergeDetails?.landedFiles?.length
    ? task.mergeDetails.landedFiles
    : task.modifiedFiles ?? [];
  const completedSteps = getCompletedSteps(task.steps);
  const workflowResults = getRenderableWorkflowResults(task.workflowStepResults);
  const retryTotal = task.retrySummary?.total ?? 0;
  const hasChangedStats = task.mergeDetails?.filesChanged != null
    || task.mergeDetails?.insertions != null
    || task.mergeDetails?.deletions != null;
  const hasChangedContent = changedFiles.length > 0 || hasChangedStats || Boolean(task.mergeDetails?.commitSha);
  const hasAgentWork = completedSteps.length > 0 || workflowResults.length > 0 || retryTotal > 0;
  const tokenCostRows = buildTokenCostRows(task, t("taskDetail.summaryTab.unknownModel", "(unknown)"), pricingOverrides);
  const totalCost = totalCostForRows(tokenCostRows);

  return (
    <div className="task-summary-tab" data-testid="task-summary-tab">
      <section className="task-summary-section task-summary-section--completion">
        <h4>{t("taskDetail.summaryTab.completionHeading", "Completion summary")}</h4>
        {summary ? (
          <div className="markdown-body task-summary-markdown">
            <ReactMarkdown remarkPlugins={[remarkGfm]} rehypePlugins={sharedRehypePlugins} components={markdownLinkifyComponents}>
              {summary}
            </ReactMarkdown>
          </div>
        ) : (
          <p className="task-summary-empty">{t("taskDetail.summaryTab.noCompletionSummary", "No completion summary was recorded for this task.")}</p>
        )}
      </section>

      {hasChangedContent ? (
        <section className="task-summary-section task-summary-section--changes">
          <h4>{t("taskDetail.summaryTab.changedHeading", "What changed")}</h4>
          {(hasChangedStats || task.mergeDetails?.commitSha) && (
            <dl className="task-summary-stats">
              {task.mergeDetails?.commitSha && (
                <div>
                  <dt>{t("taskDetail.summaryTab.commit", "Commit")}</dt>
                  <dd><code>{task.mergeDetails.commitSha.slice(0, 7)}</code></dd>
                </div>
              )}
              {task.mergeDetails?.filesChanged != null && (
                <div>
                  <dt>{t("taskDetail.summaryTab.filesChanged", "Files")}</dt>
                  <dd>{task.mergeDetails.filesChanged}</dd>
                </div>
              )}
              {task.mergeDetails?.insertions != null && (
                <div>
                  <dt>{t("taskDetail.summaryTab.insertions", "Added")}</dt>
                  <dd className="task-summary-diff-add">+{task.mergeDetails.insertions}</dd>
                </div>
              )}
              {task.mergeDetails?.deletions != null && (
                <div>
                  <dt>{t("taskDetail.summaryTab.deletions", "Removed")}</dt>
                  <dd className="task-summary-diff-del">-{task.mergeDetails.deletions}</dd>
                </div>
              )}
            </dl>
          )}
          {changedFiles.length > 0 ? (
            <ul className="task-summary-file-list">
              {changedFiles.map((path) => (
                <li key={path}><bdo dir="ltr">{path}</bdo></li>
              ))}
            </ul>
          ) : (
            <p className="task-summary-empty">{t("taskDetail.summaryTab.noChangedFiles", "No changed-file list is available for this task.")}</p>
          )}
        </section>
      ) : null}

      {task.tokenUsage ? (
        <section className="task-summary-section task-summary-section--tokens" data-testid="task-summary-token-cost-section">
          <h4>{t("taskDetail.summaryTab.tokenCostHeading", "Token usage & cost")}</h4>
          <div className="task-summary-token-table-wrap">
            <table className="task-summary-token-table">
              <thead>
                <tr>
                  <th>{t("taskDetail.summaryTab.model", "Model")}</th>
                  <th>{t("taskDetail.summaryTab.inputTokens", "Input")}</th>
                  <th>{t("taskDetail.summaryTab.outputTokens", "Output")}</th>
                  <th>{t("taskDetail.summaryTab.cachedTokens", "Cached")}</th>
                  <th>{t("taskDetail.summaryTab.totalTokens", "Total")}</th>
                  <th>{t("taskDetail.summaryTab.cost", "Cost")}</th>
                </tr>
              </thead>
              <tbody>
                {tokenCostRows.map((row) => (
                  <tr key={row.key || row.label} data-testid="task-summary-token-row">
                    <td data-label={t("taskDetail.summaryTab.model", "Model")}>
                      <span className="task-summary-model-label">
                        <ProviderIcon provider={inferProviderIconKey(row.modelId ?? "")} size="sm" />
                        <span>{row.label}</span>
                      </span>
                    </td>
                    <td data-label={t("taskDetail.summaryTab.inputTokens", "Input")}>{formatCount(row.inputTokens)}</td>
                    <td data-label={t("taskDetail.summaryTab.outputTokens", "Output")}>{formatCount(row.outputTokens)}</td>
                    <td data-label={t("taskDetail.summaryTab.cachedTokens", "Cached")}>{formatCount(row.cachedTokens)}</td>
                    <td data-label={t("taskDetail.summaryTab.totalTokens", "Total")}>{formatCount(row.totalTokens)}</td>
                    <td data-label={t("taskDetail.summaryTab.cost", "Cost")}>
                      {row.cost.unavailable || row.cost.usd === null ? (
                        <span className="task-summary-cost-unavailable" title={t("taskDetail.summaryTab.costUnavailable", "No pricing for this model")}>—</span>
                      ) : (
                        formatCost(row.cost.usd, row.cost.unavailable)
                      )}
                    </td>
                  </tr>
                ))}
              </tbody>
              <tfoot>
                <tr>
                  <th scope="row" colSpan={5}>{t("taskDetail.summaryTab.totalCost", "Total cost")}</th>
                  <td data-label={t("taskDetail.summaryTab.totalCost", "Total cost")}>{formatCost(totalCost.usd, totalCost.unavailable)}</td>
                </tr>
              </tfoot>
            </table>
          </div>
        </section>
      ) : null}

      {hasAgentWork ? (
        <section className="task-summary-section task-summary-section--agent-work">
          <h4>{t("taskDetail.summaryTab.agentWorkHeading", "Work done by agents")}</h4>
          {completedSteps.length > 0 && (
            <div className="task-summary-subsection">
              <h5>{t("taskDetail.summaryTab.completedSteps", "Completed steps")}</h5>
              <ul className="task-summary-work-list">
                {completedSteps.map((step, index) => (
                  <li key={`${step.name}-${index}`}>
                    <span className={`task-summary-status task-summary-status--${step.status}`}>{step.status}</span>
                    <span>{step.name}</span>
                  </li>
                ))}
              </ul>
            </div>
          )}
          {workflowResults.length > 0 && (
            <div className="task-summary-subsection">
              <h5>{t("taskDetail.summaryTab.workflowResults", "Workflow results")}</h5>
              <ul className="task-summary-work-list">
                {workflowResults.map((result) => (
                  <li key={`${result.workflowStepId}-${result.completedAt ?? result.startedAt ?? result.workflowStepName}`}>
                    <span className={`task-summary-status task-summary-status--${result.status}`}>{result.status.replace("_", " ")}</span>
                    <span>{result.workflowStepName}</span>
                  </li>
                ))}
              </ul>
            </div>
          )}
          {retryTotal > 0 && (
            <p className="task-summary-retries">
              {t("taskDetail.summaryTab.retries", "Agents retried this task {{count}} time{{plural}}.", { count: retryTotal, plural: retryTotal === 1 ? "" : "s" })}
            </p>
          )}
        </section>
      ) : (
        <section className="task-summary-section task-summary-section--agent-work">
          <h4>{t("taskDetail.summaryTab.agentWorkHeading", "Work done by agents")}</h4>
          <p className="task-summary-empty">{t("taskDetail.summaryTab.noAgentWork", "No completed steps or workflow results are available for this task.")}</p>
        </section>
      )}
    </div>
  );
}