import { useCallback, useEffect, useState } from "react";
import { useAuth } from "../App";
import { ApiError, api } from "../lib/client";
import { PRIORITY_LABEL, STATUS_LABEL } from "../lib/parse";
import type { Activity, Item, ItemDetail, Member, Page, Role, TicketInfo } from "../lib/types";
import {
  Book,
  Clock,
  Flag,
  Link2,
  Lock,
  Sparkle,
  TicketIcon,
  Trash,
  Users,
} from "./icons";
import { Button } from "./ui";
import { Sheet } from "./ui";

interface Comment {
  id: string;
  body_md: string;
  author_id: string;
  created_at: string;
}

type TicketAction = "accept" | "start" | "submit" | "cancel" | "reassign" | "verify";

interface Props {
  wsId: string;
  itemId: string;
  onClose: () => void;
  onChanged: (item: Item) => void;
  onDeleted: (id: string) => void;
  /** 工单状态变化后通知父级刷新角标 */
  onTicketChanged?: () => void;
}

const ACTION_LABEL: Record<string, string> = {
  created: "创建",
  status_changed: "状态变更",
  promoted_to_ticket: "升级成工单",
  ticket_done: "工单验收通过",
  comment_added: "评论",
  assigned: "指派",
  knowledge_status_changed: "知识状态变更",
  title_changed: "改标题",
};

function toLocalInput(iso: string | null): string {
  if (!iso) return "";
  const d = new Date(iso);
  const pad = (n: number) => String(n).padStart(2, "0");
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`;
}

function initials(name: string): string {
  const n = name.trim();
  if (!n) return "?";
  return /^[a-zA-Z]/.test(n) ? n.slice(0, 2).toUpperCase() : n.slice(-2);
}

export function TaskDetail({
  wsId,
  itemId,
  onClose,
  onChanged,
  onDeleted,
  onTicketChanged,
}: Props) {
  const { user } = useAuth();
  const [item, setItem] = useState<ItemDetail | null>(null);
  const [title, setTitle] = useState("");
  const [body, setBody] = useState("");
  const [tags, setTags] = useState("");
  const [due, setDue] = useState("");
  const [comments, setComments] = useState<Comment[]>([]);
  const [draft, setDraft] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [notice, setNotice] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);

  const [role, setRole] = useState<Role>("member");
  const [members, setMembers] = useState<Member[]>([]);
  const [promoteTo, setPromoteTo] = useState("");
  const [note, setNote] = useState("");

  const base = `/workspaces/${wsId}/items/${itemId}`;
  const isAdmin = role === "owner" || role === "admin";

  const hydrate = useCallback((next: ItemDetail) => {
    setItem(next);
    setTitle(next.title);
    setBody(next.body_md);
    setTags(next.tags.map((t) => t.name).join(" "));
    setDue(toLocalInput(next.due_at));
  }, []);

  useEffect(() => {
    let alive = true;
    void (async () => {
      try {
        const detail = await api.get<ItemDetail>(base);
        if (alive) hydrate(detail);
        const page = await api.get<{ items: Comment[] }>(`${base}/comments`);
        if (alive) setComments(page.items);
        const ws = await api.get<{ role: Role }>(`/workspaces/${wsId}`);
        if (alive) setRole(ws.role);
        const roster = await api.get<Page<Member>>(`/workspaces/${wsId}/members`);
        if (alive) {
          setMembers(roster.items);
          setPromoteTo(roster.items.find((m) => m.user_id !== user?.id)?.user_id ?? "");
        }
      } catch (err) {
        if (alive) setError(err instanceof ApiError ? err.message : "加载失败");
      }
    })();
    return () => {
      alive = false;
    };
  }, [base, hydrate, wsId, user?.id]);

  async function patch(values: Record<string, unknown>, label: string): Promise<boolean> {
    if (!item) return false;
    setBusy(true);
    setError(null);
    try {
      const updated = await api.patch<Item>(base, { ...values, version: item.version });
      onChanged(updated);
      hydrate({ ...(item as ItemDetail), ...updated, activities: item.activities });
      void refreshActivities(updated);
      return true;
    } catch (err) {
      if (err instanceof ApiError && err.code === 4009) {
        setError(`${label}没保存：这条刚被别人改过，已刷新为最新内容`);
        const fresh = await api.get<ItemDetail>(base);
        hydrate(fresh);
      } else {
        setError(err instanceof ApiError ? err.message : `${label}没保存`);
      }
      return false;
    } finally {
      setBusy(false);
    }
  }

  async function refreshActivities(updated: Item) {
    try {
      const fresh = await api.get<ItemDetail>(base);
      setItem({ ...fresh, ...updated, activities: fresh.activities });
      setTitle(updated.title);
      setBody(updated.body_md);
      setTags(updated.tags.map((t) => t.name).join(" "));
      setDue(toLocalInput(updated.due_at));
    } catch {
      /* 刷新事件流失败不影响已保存的结果 */
    }
  }

  async function saveTitle() {
    if (!item || !title.trim() || title.trim() === item.title) return;
    await patch({ title: title.trim() }, "标题");
  }

  async function saveBody() {
    if (!item || body === item.body_md) return;
    await patch({ body_md: body }, "备注");
  }

  async function saveTags() {
    if (!item) return;
    const next = tags.split(/[\s,，]+/).filter(Boolean);
    const current = item.tags.map((t) => t.name);
    if (next.join() === current.join()) return;
    await patch({ tag_names: next }, "标签");
  }

  async function saveDue(value: string) {
    if (!item) return;
    if (!value) {
      await patch({ clear_due_at: true }, "截止时间");
      return;
    }
    await patch({ due_at: new Date(value).toISOString() }, "截止时间");
  }

  async function addComment() {
    const text = draft.trim();
    if (!text) return;
    try {
      const created = await api.post<Comment>(`${base}/comments`, { body_md: text });
      setComments((prev) => [...prev, created]);
      setDraft("");
    } catch (err) {
      setError(err instanceof ApiError ? err.message : "评论失败");
    }
  }

  async function remove() {
    if (!item) return;
    if (!window.confirm("删除这条任务？可以在「已删除」视图里找回内容。")) return;
    try {
      await api.del(`${base}?version=${item.version}`);
      onDeleted(item.id);
      onClose();
    } catch (err) {
      setError(err instanceof ApiError ? err.message : "删除失败");
    }
  }

  /** 任务 -> 工单。成功后原任务变「被阻塞」，这条抽屉继续显示任务本身。 */
  async function promote() {
    if (!item || !promoteTo) return;
    setBusy(true);
    setError(null);
    try {
      const result = await api.post<{ task: Item; ticket: Item }>(`${base}/promote`, {
        assignee_id: promoteTo,
        version: item.version,
      });
      onChanged(result.task);
      hydrate({ ...(item as ItemDetail), ...result.task, activities: item.activities });
      void refreshActivities(result.task);
      const who = members.find((m) => m.user_id === promoteTo)?.nickname ?? "同事";
      setNotice(`已把工单交给 ${who}，这条任务现在处于「被阻塞」；对方验收通过后会自动回来。`);
      onTicketChanged?.();
    } catch (err) {
      setError(err instanceof ApiError ? err.message : "升级失败");
    } finally {
      setBusy(false);
    }
  }

  /** 把这件事整理成知识草稿。草稿默认待核对，不直接发布。 */
  async function toKnowledge() {
    if (!item) return;
    setBusy(true);
    setError(null);
    try {
      await api.post(`${base}/knowledge?doc_type=${item.kind === "ticket" ? "postmortem" : "howto"}`);
      setNotice("已生成知识草稿。它现在在「知识 → 待核对」里，核对无误后再发布，才会进入团队检索。");
    } catch (err) {
      if (err instanceof ApiError && err.code === 7002) {
        setNotice("这件事已经有一份知识草稿了，去「知识」页找它。");
      } else {
        setError(err instanceof ApiError ? err.message : "生成失败");
      }
    } finally {
      setBusy(false);
    }
  }

  async function ticketAction(action: TicketAction, extra: Record<string, unknown> = {}) {
    if (!item) return;
    setBusy(true);
    setError(null);
    try {
      const updated = await api.post<Item & { ticket: TicketInfo }>(
        `${base}/ticket/${action}`,
        { note, version: item.version, ...extra },
      );
      onChanged(updated);
      hydrate({ ...(item as ItemDetail), ...updated, activities: item.activities });
      void refreshActivities(updated);
      setNote("");
      onTicketChanged?.();
    } catch (err) {
      if (err instanceof ApiError && err.code === 4009) {
        setError("这条工单刚被改过，已刷新为最新内容");
        hydrate(await api.get<ItemDetail>(base));
      } else {
        setError(err instanceof ApiError ? err.message : "操作失败");
      }
    } finally {
      setBusy(false);
    }
  }

  const ticket = item?.kind === "ticket" ? item.ticket : undefined;
  const isAssignee = !!ticket && !!user && ticket.assignee_id === user.id;
  const isRequester = !!ticket && !!user && ticket.requester_id === user.id;
  const pendingVerify = item?.status === "pending_verify";

  function actionButtons() {
    const buttons: { key: TicketAction | "approve" | "reject"; label: string; show: boolean }[] = [
      { key: "accept", label: "接收", show: isAssignee && item?.status === "open" },
      { key: "start", label: "开始办理", show: isAssignee && item?.status === "accepted" },
      { key: "submit", label: "提交验收", show: isAssignee && item?.status === "in_progress" },
      { key: "approve", label: "通过验收", show: (isRequester || isAdmin) && pendingVerify },
      { key: "reject", label: "驳回", show: (isRequester || isAdmin) && pendingVerify },
      {
        key: "cancel",
        label: "取消工单",
        show:
          (isRequester || isAssignee || isAdmin) &&
          ["open", "accepted", "in_progress", "pending_verify"].includes(item?.status ?? ""),
      },
    ];

    return (
      <div className="flex flex-wrap items-center gap-2">
        {buttons
          .filter((b) => b.show)
          .map((b) => (
            <Button
              key={b.key}
              variant={b.key === "approve" ? "clay" : b.key === "cancel" || b.key === "reject" ? "ghost" : "primary"}
              size="sm"
              disabled={busy}
              onClick={() => {
                if (b.key === "approve") void ticketAction("verify", { approve: true });
                else if (b.key === "reject") void ticketAction("verify", { approve: false });
                else void ticketAction(b.key);
              }}
            >
              {b.label}
            </Button>
          ))}
      </div>
    );
  }

  const meta = item
    ? `${item.kind === "ticket" ? "工单" : item.kind === "knowledge" ? "知识" : "任务"} · ${
        STATUS_LABEL[item.status]
      } · 版本 ${item.version}`
    : "加载中…";

  return (
    <Sheet
      open
      onClose={onClose}
      width="max-w-2xl"
      title={item ? item.title : "打开中…"}
      subtitle={meta}
      footer={
        item ? (
          <div className="flex items-center justify-between gap-2">
            <span className="text-2xs text-ink-400">
              {item.updated_at ? `最后更新 ${new Date(item.updated_at).toLocaleString("zh-CN")}` : ""}
            </span>
            <div className="flex items-center gap-2">
              {/* 工单不提供删除：它该走"取消"，否则原任务永远解不开 */}
              {item.kind !== "ticket" && (
                <Button variant="danger" size="sm" onClick={() => void remove()}>
                  <Trash size={13} />
                  删除
                </Button>
              )}
            </div>
          </div>
        ) : null
      }
    >
      {!item ? (
        <p className="text-sm text-ink-400">{error ?? "加载中…"}</p>
      ) : (
        <div className="space-y-5">
          {ticket ? (
            <section className="rounded-xl border border-line-200 bg-paper-50 p-4">
              <div className="flex flex-wrap items-center gap-x-4 gap-y-2 text-xs">
                <span className="inline-flex items-center gap-1.5 text-ink-600">
                  <Users size={12} className="text-ink-400" />
                  需求人
                  <b className="font-medium text-ink-900">
                    {members.find((m) => m.user_id === ticket.requester_id)?.nickname ?? "—"}
                  </b>
                </span>
                <span className="inline-flex items-center gap-1.5 text-ink-600">
                  办理人
                  <b className="font-medium text-ink-900">
                    {members.find((m) => m.user_id === ticket.assignee_id)?.nickname ?? "—"}
                  </b>
                </span>
                {ticket.reject_count > 0 ? (
                  <span className="pill bg-rust-50 text-rust-500">退回 {ticket.reject_count} 次</span>
                ) : null}
                {ticket.parent_item_id ? (
                  <span className="inline-flex items-center gap-1 text-ink-400">
                    <Link2 size={11} />
                    由任务升级而来
                  </span>
                ) : null}
              </div>

              {ticket.resolution_md ? (
                <div className="mt-3 rounded-lg border border-line-200 bg-white p-3">
                  <p className="text-2xs text-ink-400">验收结论</p>
                  <p className="mt-1 whitespace-pre-wrap text-sm text-ink-800">{ticket.resolution_md}</p>
                </div>
              ) : null}

              <div className="mt-3 space-y-2">
                <input
                  className="input"
                  placeholder="给对方的说明（提交或验收时一并发过去）"
                  value={note}
                  onChange={(e) => setNote(e.target.value)}
                />
                {actionButtons()}
              </div>
            </section>
          ) : null}

          <div>
            <label className="label">标题</label>
            <input
              className="input-flush text-lg font-medium"
              value={title}
              onChange={(e) => setTitle(e.target.value)}
              onBlur={() => void saveTitle()}
              onKeyDown={(e) => {
                if (e.key === "Enter") (e.target as HTMLInputElement).blur();
              }}
            />
          </div>

          <div className="grid grid-cols-2 gap-3">
            <label className="block">
              <span className="label inline-flex items-center gap-1">
                <Flag size={11} />
                优先级
              </span>
              <select
                className="input"
                aria-label="优先级"
                value={item.priority}
                onChange={(e) => void patch({ priority: Number(e.target.value) }, "优先级")}
              >
                {[0, 1, 2, 3].map((p) => (
                  <option key={p} value={p}>
                    {PRIORITY_LABEL[p]}
                  </option>
                ))}
              </select>
            </label>
            <label className="block">
              <span className="label inline-flex items-center gap-1">
                <Clock size={11} />
                截止时间
              </span>
              <input
                type="datetime-local"
                className="input"
                aria-label="截止时间"
                value={due}
                onChange={(e) => setDue(e.target.value)}
                onBlur={(e) => void saveDue(e.target.value)}
              />
            </label>
          </div>

          <label className="block">
            <span className="label">标签（空格分隔）</span>
            <input
              className="input"
              aria-label="标签"
              value={tags}
              onChange={(e) => setTags(e.target.value)}
              onBlur={() => void saveTags()}
              placeholder="周报 客户"
            />
            {item.tags.length > 0 ? (
              <span className="mt-1.5 flex flex-wrap gap-1">
                {item.tags.map((t) => (
                  <span key={t.id} className="chip bg-paper-200 text-ink-600">
                    #{t.name}
                  </span>
                ))}
              </span>
            ) : null}
          </label>

          <label className="block">
            <span className="label">备注</span>
            <textarea
              className="input min-h-32 resize-y leading-relaxed"
              aria-label="备注"
              value={body}
              onChange={(e) => setBody(e.target.value)}
              onBlur={() => void saveBody()}
              placeholder="背景、约束、链接…写下来，将来才想得起来"
            />
          </label>

          {item.kind === "task" && !["done", "canceled"].includes(item.status) ? (
            <section className="rounded-xl border border-clay-200 bg-clay-50/50 p-4">
              <p className="flex items-center gap-1.5 text-sm font-medium text-ink-900">
                <TicketIcon size={15} className="text-clay-600" />
                这件事卡在别人手里？升级成工单
              </p>
              <p className="mt-1 text-xs leading-relaxed text-ink-500">
                升级后这条任务会变成「被阻塞」，工单办好并验收通过后自动回到待办，不用你自己盯。
              </p>
              <div className="mt-3 flex gap-2">
                <select
                  className="input flex-1"
                  aria-label="选择办理人"
                  value={promoteTo}
                  onChange={(e) => setPromoteTo(e.target.value)}
                >
                  <option value="">选择找谁办…</option>
                  {members
                    .filter((m) => m.status === "active")
                    .map((m) => (
                      <option key={m.user_id} value={m.user_id}>
                        {m.nickname}
                        {m.role === "guest" ? "（访客）" : ""}
                      </option>
                    ))}
                </select>
                <Button variant="clay" disabled={busy || !promoteTo} onClick={() => void promote()}>
                  升级成工单
                </Button>
              </div>
            </section>
          ) : null}

          {item.kind !== "knowledge" && item.status !== "canceled" ? (
            <section className="rounded-xl border border-line-200 p-4">
              <p className="flex items-center gap-1.5 text-sm font-medium text-ink-900">
                <Book size={15} className="text-primary-600" />
                这件事值得留下来？沉淀成知识
              </p>
              <p className="mt-1 text-xs leading-relaxed text-ink-500">
                会把标题、备注、时间线和评论整理成一份草稿，默认进「待核对」，不会直接对外发布。
              </p>
              <div className="mt-3">
                <Button variant="ghost" size="sm" disabled={busy} onClick={() => void toKnowledge()}>
                  <Sparkle size={13} className="text-clay-500" />
                  {item.kind === "ticket" ? "沉淀成复盘" : "沉淀成知识"}
                </Button>
              </div>
            </section>
          ) : null}

          {notice ? (
            <div className="rounded-lg border border-sage-500/20 bg-sage-50 px-3 py-2 text-sm text-sage-500">
              {notice}
            </div>
          ) : null}
          {error ? (
            <div className="rounded-lg border border-rust-500/20 bg-rust-50 px-3 py-2 text-sm text-rust-500">
              {error}
            </div>
          ) : null}
          {busy ? <p className="text-2xs text-ink-400">处理中…</p> : null}

          <section>
            <h3 className="mb-2 flex items-center gap-1.5 text-sm font-medium text-ink-800">
              评论
              <span className="text-ink-400">{comments.length}</span>
            </h3>
            <ul className="space-y-2">
              {comments.length === 0 ? (
                <li className="rounded-lg border border-dashed border-line-200 px-3 py-4 text-center text-xs text-ink-400">
                  还没有评论。写一句，将来的你会感谢现在记下来的你。
                </li>
              ) : null}
              {comments.map((c) => (
                <li key={c.id} className="flex gap-2.5">
                  <span className="mt-0.5 grid h-7 w-7 shrink-0 place-items-center rounded-full bg-paper-200 text-[10px] font-medium text-ink-600">
                    {initials(
                      members.find((m) => m.user_id === c.author_id)?.nickname ?? String(c.author_id),
                    )}
                  </span>
                  <div className="min-w-0 flex-1 rounded-xl rounded-tl-sm bg-paper-100 px-3 py-2">
                    <p className="whitespace-pre-wrap text-sm text-ink-800">{c.body_md}</p>
                    <p className="mt-0.5 text-2xs text-ink-400">
                      {new Date(c.created_at).toLocaleString("zh-CN")}
                    </p>
                  </div>
                </li>
              ))}
            </ul>
            <div className="mt-2.5 flex gap-2">
              <input
                className="input flex-1"
                placeholder="补充一句进展…"
                value={draft}
                onChange={(e) => setDraft(e.target.value)}
                onKeyDown={(e) => {
                  if (e.key === "Enter") void addComment();
                }}
              />
              <Button variant="primary" disabled={!draft.trim()} onClick={() => void addComment()}>
                发表
              </Button>
            </div>
          </section>

          <details className="group">
            <summary className="flex cursor-pointer list-none items-center gap-1.5 text-sm font-medium text-ink-800">
              <Clock size={14} className="text-ink-400" />
              动态
              <span className="text-ink-400">{item.activities.length}</span>
              <span className="ml-auto text-2xs font-normal text-ink-400 group-open:hidden">
                展开
              </span>
            </summary>
            <ul className="mt-2 space-y-1.5 border-l border-line-200 pl-3">
              {item.activities.slice(0, 30).map((a: Activity) => (
                <li key={a.id} className="text-xs text-ink-500">
                  <span className="text-ink-400">
                    {new Date(a.created_at).toLocaleString("zh-CN")}
                  </span>
                  <span className="mx-1.5 text-ink-300">·</span>
                  {ACTION_LABEL[a.action] ?? a.action}
                  {a.action === "status_changed" && a.payload
                    ? ` ${STATUS_LABEL[String(a.payload.from ?? "")] ?? String(a.payload.from ?? "")} → ${
                        STATUS_LABEL[String(a.payload.to ?? "")] ?? String(a.payload.to ?? "")
                      }`
                    : ""}
                  {a.action === "ticket_submit" && a.payload?.note
                    ? ` · ${String(a.payload.note)}`
                    : ""}
                </li>
              ))}
              {item.activities.length === 0 ? (
                <li className="text-xs text-ink-400">还没有记录。</li>
              ) : null}
            </ul>
          </details>

          {ticket ? (
            <p className="flex items-start gap-1.5 text-2xs leading-relaxed text-ink-400">
              <Lock size={11} className="mt-0.5 shrink-0" />
              工单不能删除，只能取消；删除会让当初卡住的那条任务永远解不开。
            </p>
          ) : null}
        </div>
      )}
    </Sheet>
  );
}