import { useQueryClient } from "@tanstack/react-query";
import type { DownloadBoardItem, DownloadBoardRow, DownloadBoardState, DownloadTask } from "@umt/contracts";
import { EventType } from "@umt/contracts";
import { RefreshCw } from "lucide-react";
import { type ReactNode, useEffect, useMemo, useRef, useState } from "react";
import { useSearchParams } from "react-router";
import { useBoardPlanRow, useDownloadBoard, useDownloadTask, usePlan } from "~/api/downloads.ts";
import { isMissingEndpoint } from "~/api/parse.ts";
import { type DataColumn, DataTable } from "~/components/console/data-table.tsx";
import { DetailSheet } from "~/components/console/detail-sheet.tsx";
import { ErrorState, LoadingState } from "~/components/console/empty-state.tsx";
import { PageHeader } from "~/components/console/page-header.tsx";
import { useRecordSheet } from "~/components/console/record-sheet.tsx";
import { StatusBadge } from "~/components/console/status-badge.tsx";
import { readBoardState, writeBoardState } from "~/components/downloads/board-format.ts";
import { CacheVolumes } from "~/components/downloads/cache-volumes.tsx";
import {
  activeColumns,
  BOARD_EMPTY,
  BoardSegments,
  completedColumns,
  TransferLine,
} from "~/components/downloads/download-board.tsx";
import { DownloadDetail } from "~/components/downloads/download-detail.tsx";
import { DROPPED_STATUS, droppedReason } from "~/components/downloads/plan-format.ts";
import { PlanDetail, WhySection } from "~/components/downloads/plan-row.tsx";
import { Button } from "~/components/ui/button.tsx";
import { useSse } from "~/lib/sse.ts";

export const meta = () => [{ title: "下载面板 · UHD 媒体自动化控制台" }];

// DL-2:默认只看进行中;已完成单独一段(本浏览器记住选择)。页面可见时每 4 秒刷新速度,切到后台停。
// DL-3:没提交到下载器的下载(等批准 / 等磁盘空间…)也是「进行中」的行;?plan=<计划 id> 深链打开对应行。
// 记录抽屉(console-ia.md §9):行点开是右侧抽屉,?open=<id>;旧的下载详情页 /console/downloads/:id 跳到这里。

const COMPLETED = new Set(["completed", "importing", "imported"]);

export default function DownloadsPage() {
  // SPA 模式:路由组件只在浏览器渲染,可直接读本地记住的分段
  const [state, setStateRaw] = useState<DownloadBoardState>(readBoardState);
  const setState = (s: DownloadBoardState) => {
    setStateRaw(s);
    writeBoardState(s);
  };
  // 记录抽屉(console-ia.md §9):?open=<下载任务 id 或计划 id>;旧深链 ?plan=<计划 id> 同样打开
  const sheet = useRecordSheet({ scoped: ["plan"] });
  const openId = sheet.id;
  const [params] = useSearchParams();
  const deepPlan = params.get("plan");
  const qc = useQueryClient();
  const board = useDownloadBoard(state);

  const pages = board.data?.pages;
  const allRows = pages?.flatMap((p) => p.items);
  const rows: DownloadBoardRow[] | undefined =
    state === "completed" ? allRows?.filter((r): r is DownloadBoardItem => r.kind === "task") : allRows;
  const inRows = openId ? allRows?.find((t) => t.id === openId) : undefined;
  // 不在当前分段里的:先当下载任务取,取不到再当计划找
  const fetched = useDownloadTask(openId && !inRows && !board.isPending ? openId : undefined);
  const taskMissing = !!fetched.error && isMissingEndpoint(fetched.error);
  const planId = deepPlan ?? (taskMissing ? openId : null);
  const deep = useBoardPlanRow(inRows ? null : planId);

  // 旧深链 ?plan=:切到行所在的分段
  useEffect(() => {
    const row = deep.data;
    if (!row || !deepPlan) return;
    setStateRaw(row.kind === "task" && COMPLETED.has(row.status) ? "completed" : "active");
  }, [deep.data, deepPlan]);

  // 状态变化、阈值事件到达时立即刷新(速度靠轮询)
  useSse(
    [
      EventType.downloadProgress,
      EventType.downloadStatusChanged,
      EventType.downloadSubmitted,
      EventType.downloadThreshold,
    ],
    () => void qc.invalidateQueries({ queryKey: ["downloads"] }),
  );

  const first = pages?.[0];
  const openRow = inRows ?? deep.data ?? null;
  const openTask: DownloadTask | null =
    openRow?.kind === "task" ? openRow : openId && fetched.data?.id === openId ? fetched.data : null;
  const openPlan = openRow?.kind === "plan" ? openRow : null;
  const sheetOpen = !!(openId || deepPlan);
  const columns = useMemo(
    () => (state === "active" ? activeColumns() : (completedColumns() as unknown as DataColumn<DownloadBoardRow>[])),
    [state],
  );
  const empty = BOARD_EMPTY[state];
  const endedPlan = planId && deep.isSuccess && deep.data === null ? planId : null;
  // 关闭动画期间保留刚才的内容
  const last = useRef<{ title: string; body: ReactNode }>({ title: "", body: null });
  if (sheetOpen)
    last.current = {
      title: openTask?.name ?? openPlan?.name ?? "下载",
      body: openTask ? (
        <DownloadDetail task={openTask} live={openRow?.kind === "task" ? openRow.live : null} />
      ) : openPlan ? (
        <PlanDetail p={openPlan} />
      ) : fetched.error && !taskMissing ? (
        <ErrorState plain error={fetched.error} onRetry={() => void fetched.refetch()} />
      ) : (
        <LoadingState rows={5} />
      ),
    };
  const shown = last.current;

  return (
    <>
      <PageHeader
        title="下载面板"
        actions={
          <Button variant="outline" size="sm" onClick={() => void qc.invalidateQueries({ queryKey: ["downloads"] })}>
            <RefreshCw className={board.isFetching ? "animate-spin" : undefined} />
            刷新
          </Button>
        }
      />
      <CacheVolumes />
      <div className="mb-3 flex flex-wrap items-center justify-between gap-x-4 gap-y-2">
        <BoardSegments value={state} counts={first?.counts} onChange={setState} />
        <TransferLine transfer={first?.transfer} />
      </div>
      <DataTable
        paginationKey={state}
        columns={columns}
        rows={rows}
        rowKey={(t) => t.id}
        loading={board.isPending}
        error={board.error}
        onRetry={() => void board.refetch()}
        onRowClick={(t) => sheet.open(t.id)}
        selectedKey={openId}
        hasMore={board.hasNextPage}
        onLoadMore={() => void board.fetchNextPage()}
        loadingMore={board.isFetchingNextPage}
        empty={empty}
      />

      <DetailSheet
        open={sheetOpen && !endedPlan}
        onOpenChange={(o) => !o && sheet.close()}
        width="lg"
        title={shown.title}
      >
        {shown.body}
      </DetailSheet>

      <EndedPlanSheet planId={endedPlan} onClose={sheet.close} />
    </>
  );
}

/** 深链指向已结束的下载(没提交成功 / 已取消 / 已过期):说明原因与来由;作品的下载历史里也有 */
function EndedPlanSheet({ planId, onClose }: { planId: string | null; onClose: () => void }) {
  const plan = usePlan(planId);
  const p = plan.data;
  const ended = p && (p.status === "failed" || p.status === "cancelled" || p.status === "expired") ? p.status : null;
  return (
    <DetailSheet
      open={!!planId}
      onOpenChange={(o) => !o && onClose()}
      title={ended ? "这次下载没有提交" : "下载"}
      description={p ? (droppedReason(p.statusReason) ?? undefined) : undefined}
    >
      {plan.isPending ? (
        <LoadingState rows={3} />
      ) : !p ? (
        <p className="text-sm text-muted-foreground">没找到这次下载，可能已被清理。</p>
      ) : (
        <div className="space-y-5">
          {ended ? (
            <StatusBadge tone={DROPPED_STATUS[ended].tone}>{DROPPED_STATUS[ended].label}</StatusBadge>
          ) : (
            <p className="text-sm text-muted-foreground">这次下载已经结束。</p>
          )}
          <WhySection
            planId={p.id}
            extraTech={[{ label: "状态原码", value: `${p.status} · ${p.statusReason ?? "—"}` }]}
          />
        </div>
      )}
    </DetailSheet>
  );
}