'use client';

import Link from 'next/link';
import { useParams, useRouter } from 'next/navigation';
import React, { useMemo, useState } from 'react';
import { AlertCircle, ArrowLeft, Loader2, Trash2 } from 'lucide-react';

import {
  TaskLiveHeader,
  TaskSideRail,
  TaskTimeline,
  type TaskFeedbackItem,
  type TaskFeedbackType,
} from '@/components/task-detail';
import { Button } from '@/components/ui/button';
import { Card, CardContent } from '@/components/ui/card';
import { deleteBackendTask, getBackendTask, submitChatFeedback } from '@/lib/api';
import { pickAppText } from '@/lib/i18n/core';
import { useAppI18n } from '@/lib/i18n/provider';
import { useChatStore } from '@/lib/store';
import { shouldPollTaskDetail, taskDetailDurationMs } from '@/lib/task-detail-refresh';
import { buildTaskTimelineView } from '@/lib/task-timeline-view';
import type { BackendTask } from '@/types';

const TERMINAL_TASK_STATUSES = new Set(['closed', 'abandoned', 'cancelled', 'error']);
const TASK_RESULT_REVIEW_ID = 'task-result-review';

export default function TaskDetailPage() {
  const { locale } = useAppI18n();
  const router = useRouter();
  const params = useParams<{ taskId: string }>();
  const taskId = decodeURIComponent(Array.isArray(params?.taskId) ? params.taskId[0] : params?.taskId ?? '');
  const processRuns = useChatStore((state) => state.processRuns);
  const processEvents = useChatStore((state) => state.processEvents);
  const processArtifacts = useChatStore((state) => state.processArtifacts);
  const setSessionProcess = useChatStore((state) => state.setSessionProcess);
  const updateMessageFeedback = useChatStore((state) => state.updateMessageFeedback);
  const wsStatus = useChatStore((state) => state.wsStatus);

  const [backendTask, setBackendTask] = useState<BackendTask | null>(null);
  const [backendTaskLoading, setBackendTaskLoading] = useState(true);
  const [revision, setRevision] = useState('');
  const [actionError, setActionError] = useState<string | null>(null);
  const [actionBusy, setActionBusy] = useState<string | null>(null);
  const mountedRef = React.useRef(true);

  React.useEffect(() => {
    mountedRef.current = true;
    return () => {
      mountedRef.current = false;
    };
  }, []);

  const loadBackendTask = React.useCallback(async () => {
    if (!taskId) return null;
    setBackendTaskLoading(true);
    try {
      const item = await getBackendTask(taskId);
      if (!mountedRef.current) return item;
      setBackendTask(item);
      setSessionProcess(item.session_id, {
        runs: item.process_runs ?? [],
        events: item.process_events ?? [],
        artifacts: item.process_artifacts ?? [],
      });
      return item;
    } catch {
      if (mountedRef.current) {
        setBackendTask(null);
      }
      return null;
    } finally {
      if (mountedRef.current) {
        setBackendTaskLoading(false);
      }
    }
  }, [setSessionProcess, taskId]);

  React.useEffect(() => {
    void loadBackendTask();
  }, [loadBackendTask]);

  const isTaskLive = backendTask ? !TERMINAL_TASK_STATUSES.has(backendTask.status) : false;

  React.useEffect(() => {
    if (!shouldPollTaskDetail(backendTask)) return;
    const id = window.setInterval(() => {
      void loadBackendTask();
    }, 4000);
    return () => window.clearInterval(id);
  }, [backendTask, loadBackendTask]);

  const timelineView = useMemo(
    () =>
      buildTaskTimelineView({
        task: backendTask,
        liveRuns: processRuns,
        liveEvents: processEvents,
        liveArtifacts: processArtifacts,
        locale,
      }),
    [backendTask, locale, processArtifacts, processEvents, processRuns]
  );
  const timelineCards = timelineView?.cards ?? [];

  const activeLabel =
    [...timelineCards].reverse().find((card) => !['acceptance', 'task_created'].includes(card.type))?.title ?? '-';
  const durationMs = backendTask ? taskDetailDurationMs(backendTask) : null;
  const feedbackRunId = backendTask ? pickFeedbackRunId(backendTask) : null;

  const runAction = async (key: string, action: () => Promise<unknown>) => {
    setActionBusy(key);
    setActionError(null);
    try {
      await action();
    } catch (err: any) {
      setActionError(err.message || pickAppText(locale, '操作失败', 'Action failed'));
    } finally {
      setActionBusy(null);
    }
  };

  const deleteCurrentBackendTask = async () => {
    if (!backendTask) return;
    const title = backendTask.short_title || backendTask.description || backendTask.goal || backendTask.task_id;
    if (!window.confirm(pickAppText(locale, `删除任务“${title}”？`, `Delete task "${title}"?`))) {
      return;
    }
    await runAction('delete-backend-task', async () => {
      await deleteBackendTask(backendTask.task_id);
      router.push('/tasks');
    });
  };

  if (backendTask) {
    const feedbackItems = backendTask.feedback || [];

    return (
      <div className="min-h-screen bg-background">
        <TaskLiveHeader task={backendTask} activeLabel={activeLabel} durationMs={durationMs} reviewTargetId={TASK_RESULT_REVIEW_ID} />

        <main className="mx-auto grid min-w-0 max-w-7xl gap-6 p-4 sm:p-6 xl:grid-cols-[minmax(0,1fr)_360px]">
          <div className="min-w-0 space-y-4">
            <div className="flex justify-end">
              <Button
                variant="ghost"
                size="sm"
                className="h-11 text-destructive hover:text-destructive"
                disabled={Boolean(actionBusy)}
                onClick={() => void deleteCurrentBackendTask()}
              >
                <Trash2 className="mr-2 h-4 w-4" />
                {pickAppText(locale, '删除任务', 'Delete task')}
              </Button>
            </div>

            {actionError ? (
              <Card className="border-destructive">
                <CardContent className="flex items-center gap-2 p-4 text-sm text-destructive">
                  <AlertCircle className="h-4 w-4" />
                  {actionError}
                </CardContent>
              </Card>
            ) : null}

            <TaskTimeline
              cards={timelineCards}
              isLive={isTaskLive && wsStatus === 'connected'}
              reviewTargetId={TASK_RESULT_REVIEW_ID}
              resultAcceptance={{
                sessionId: backendTask.session_id,
                runId: feedbackRunId,
                taskStatus: backendTask.status,
                feedbackItems: feedbackItems as TaskFeedbackItem[],
                actionBusy,
                revision,
                onRevisionChange: setRevision,
                onSubmit: (feedbackType: TaskFeedbackType, comment?: string) =>
                  runAction(`backend-feedback-${feedbackType}`, async () => {
                    if (!feedbackRunId) throw new Error(pickAppText(locale, '暂无可验收的运行记录。', 'No run is available for acceptance yet.'));
                    await submitChatFeedback({
                      sessionId: backendTask.session_id,
                      runId: feedbackRunId,
                      feedbackType,
                      comment,
                    });
                    updateMessageFeedback(feedbackRunId, feedbackType);
                    setRevision('');
                    await loadBackendTask();
                  }),
              }}
            />
          </div>

          <TaskSideRail
            task={backendTask}
            runs={timelineView?.process.runs ?? []}
            artifacts={timelineView?.process.artifacts ?? []}
            cards={timelineCards}
          />
        </main>
      </div>
    );
  }

  return (
    <div className="mx-auto flex max-w-4xl flex-col gap-4 p-6">
      <Button asChild variant="outline" className="h-11 w-fit">
        <Link href="/tasks">
          <ArrowLeft className="mr-2 h-4 w-4" />
          {pickAppText(locale, '返回任务列表', 'Back to tasks')}
        </Link>
      </Button>
      <Card className="border-dashed">
        <CardContent className="py-16 text-center">
          <div className="flex justify-center">
            {backendTaskLoading ? <Loader2 className="mb-4 h-5 w-5 animate-spin text-muted-foreground" /> : null}
          </div>
          <h1 className="text-2xl font-semibold">{pickAppText(locale, '任务不存在', 'Task not found')}</h1>
          <p className="mt-2 text-sm text-muted-foreground">
            {backendTaskLoading
              ? pickAppText(locale, '正在从后端任务库加载任务。', 'Loading the task from the backend task store.')
              : pickAppText(locale, '后端任务库里没有这个任务。', 'The backend task store does not contain this task.')}
          </p>
        </CardContent>
      </Card>
    </div>
  );
}

function pickFeedbackRunId(task: BackendTask): string | null {
  const runIds = task.run_ids.filter(Boolean);
  if (runIds.length > 0) return runIds[runIds.length - 1];
  const runs = task.runs ?? [];
  if (runs.length > 0) return runs[runs.length - 1].run_id;
  return null;
}