"use client";

import { FileSignature, Save, Send, Trash2 } from "lucide-react";
import { useCallback, useEffect, useState } from "react";
import { adminApi, errMessage, type Draft } from "@/lib/admin-api";
import {
  Badge,
  Button,
  Card,
  EmptyState,
  ErrorState,
  LoadingBlock,
  Pagination,
  TextInput,
  cn,
  formatTime,
  statusTone,
  useToast,
} from "@/components/admin/ui";

function draftKey(draft: Draft) {
  return String(draft.draft_id ?? draft.id ?? "");
}

export function DraftsSection() {
  const toast = useToast();
  const [items, setItems] = useState<Draft[]>([]);
  const [total, setTotal] = useState(0);
  const [totalPages, setTotalPages] = useState(0);
  const [page, setPage] = useState(1);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState("");

  const [activeKey, setActiveKey] = useState("");
  const [title, setTitle] = useState("");
  const [content, setContent] = useState("");
  const [dirty, setDirty] = useState(false);
  const [busy, setBusy] = useState(false);

  const load = useCallback(async () => {
    setLoading(true);
    setError("");
    try {
      const result = await adminApi.drafts({ page, page_size: 20 });
      setItems(result.items ?? []);
      setTotal(result.total ?? 0);
      setTotalPages(result.total_pages ?? 0);
    } catch (e) {
      setError(errMessage(e, "草稿列表加载失败"));
    } finally {
      setLoading(false);
    }
  }, [page]);

  useEffect(() => {
    void load();
  }, [load]);

  async function choose(draft: Draft) {
    if (dirty && !window.confirm("当前草稿有未保存的修改，确认切换？")) return;
    setBusy(true);
    try {
      const detail = await adminApi.draft(draftKey(draft));
      setActiveKey(draftKey(draft));
      setTitle(detail.title ?? "");
      setContent(detail.content ?? "");
      setDirty(false);
    } catch (e) {
      toast(errMessage(e, "草稿详情加载失败"), "error");
    } finally {
      setBusy(false);
    }
  }

  async function run(action: "save" | "send" | "discard") {
    if (!activeKey) return;
    if (action === "send" && !window.confirm("确认发送该草稿？发送后将进入终审并触达客户。")) return;
    if (action === "discard" && !window.confirm("确认废弃该草稿？废弃后不可恢复。")) return;
    setBusy(true);
    try {
      if (action === "save") await adminApi.saveDraft(activeKey, { title, content: content });
      if (action === "send") await adminApi.sendDraft(activeKey);
      if (action === "discard") await adminApi.discardDraft(activeKey);
      toast(action === "save" ? "草稿已保存" : action === "send" ? "草稿已发送" : "草稿已废弃");
      setDirty(false);
      if (action !== "save") {
        setActiveKey("");
        setTitle("");
        setContent("");
      }
      await load();
    } catch (e) {
      toast(errMessage(e, "操作失败"), "error");
    } finally {
      setBusy(false);
    }
  }

  return (
    <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_minmax(0,1.2fr)]">
      <Card title="草稿列表" description="由投顾 Agent 生成，可编辑后发送" bodyClassName="p-0">
        {loading ? (
          <LoadingBlock />
        ) : error ? (
          <ErrorState message={error} onRetry={() => void load()} />
        ) : items.length === 0 ? (
          <EmptyState text="暂无草稿" />
        ) : (
          <>
            <ul className="max-h-[520px] divide-y divide-slate-100 overflow-y-auto">
              {items.map((draft) => (
                <li key={draftKey(draft) || draft.title}>
                  <button
                    onClick={() => void choose(draft)}
                    className={cn(
                      "w-full px-4 py-3 text-left text-sm transition-colors",
                      draftKey(draft) === activeKey
                        ? "bg-indigo-50 text-indigo-700"
                        : "text-slate-600 hover:bg-slate-50"
                    )}
                  >
                    <div className="flex items-center justify-between gap-2">
                      <span className="truncate font-medium">{draft.title ?? "未命名草稿"}</span>
                      <Badge tone={statusTone(draft.status)}>{draft.status ?? "草稿"}</Badge>
                    </div>
                    <p className="mt-1 truncate text-xs text-slate-400">
                      {draft.customer_id ? `客户 #${draft.customer_id} · ` : ""}
                      {formatTime(draft.update_time ?? draft.create_time)}
                    </p>
                  </button>
                </li>
              ))}
            </ul>
            <Pagination page={page} totalPages={totalPages} total={total} onChange={setPage} />
          </>
        )}
      </Card>

      <Card
        title={activeKey ? "编辑草稿" : "选择草稿"}
        description={activeKey ? `草稿 ID：${activeKey}` : "从左侧列表选择一份草稿进行编辑"}
        actions={
          activeKey ? (
            <>
              <Button size="sm" variant="primary" loading={busy} onClick={() => void run("save")}>
                <Save className="h-3.5 w-3.5" />
                保存
              </Button>
              <Button size="sm" loading={busy} onClick={() => void run("send")}>
                <Send className="h-3.5 w-3.5" />
                发送
              </Button>
              <Button size="sm" variant="danger" loading={busy} onClick={() => void run("discard")}>
                <Trash2 className="h-3.5 w-3.5" />
                废弃
              </Button>
            </>
          ) : undefined
        }
      >
        {!activeKey ? (
          <EmptyState text="暂无选中的草稿" />
        ) : (
          <div className="space-y-4">
            <div>
              <label className="mb-1 block text-xs text-slate-500">草稿标题</label>
              <TextInput
                value={title}
                onChange={(event) => {
                  setTitle(event.target.value);
                  setDirty(true);
                }}
                placeholder="请输入草稿标题"
              />
            </div>
            <div>
              <label className="mb-1 block text-xs text-slate-500">草稿内容</label>
              <textarea
                value={content}
                onChange={(event) => {
                  setContent(event.target.value);
                  setDirty(true);
                }}
                className="min-h-[360px] w-full rounded-lg border border-slate-200 px-3 py-2 text-sm leading-6 text-slate-700 transition-colors focus:border-indigo-400 focus:outline-none"
                placeholder="请输入建议内容"
              />
            </div>
            {dirty && (
              <p className="flex items-center gap-2 text-xs text-amber-600">
                <FileSignature className="h-3.5 w-3.5" />
                有未保存的修改
              </p>
            )}
          </div>
        )}
      </Card>
    </div>
  );
}