import { useEffect, useMemo, useState } from "react";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import { LayoutTemplate } from "lucide-react";

import { taskBriefApi, type TaskBriefTemplate } from "@/api/taskBriefs";
import { ConfigSubpageHeader } from "@/components/ai-config/ConfigSubpageHeader";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Input } from "@/components/ui/input";
import { Textarea } from "@/components/ui/textarea";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";

export default function TaskBriefTemplatePage() {
  const queryClient = useQueryClient();
  const [selectedId, setSelectedId] = useState<string>("");
  const [name, setName] = useState("");
  const [description, setDescription] = useState("");
  const [content, setContent] = useState("");

  const templatesQuery = useQuery({
    queryKey: ["task-brief-templates"],
    queryFn: () => taskBriefApi.listTemplates(),
  });
  const templates = templatesQuery.data || [];

  const selectedTemplate = useMemo(
    () => templates.find((item) => item.id === selectedId) || null,
    [templates, selectedId]
  );

  useEffect(() => {
    if (!selectedTemplate) return;
    setName(selectedTemplate.name || "");
    setDescription(selectedTemplate.description || "");
    setContent(selectedTemplate.content || "");
  }, [selectedTemplate]);

  const createMutation = useMutation({
    mutationFn: (payload: { name: string; description: string; content: string }) =>
      taskBriefApi.createTemplate({
        name: payload.name,
        description: payload.description || undefined,
        content: payload.content,
      }),
    onSuccess: (created: TaskBriefTemplate) => {
      queryClient.invalidateQueries({ queryKey: ["task-brief-templates"] });
      setSelectedId(created.id);
    },
  });

  const updateMutation = useMutation({
    mutationFn: (payload: { id: string; name: string; description: string; content: string }) =>
      taskBriefApi.updateTemplate(payload.id, {
        name: payload.name,
        description: payload.description || undefined,
        content: payload.content,
      }),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["task-brief-templates"] });
    },
  });

  const templatesErrorText = templatesQuery.error instanceof Error ? templatesQuery.error.message : "请检查后端服务。";

  return (
    <div className="space-y-6">
      <ConfigSubpageHeader
        title="任务包模板管理"
        description="统一维护增量任务包模板，保障跨任务输出结构一致。"
        icon={<LayoutTemplate className="h-5 w-5" />}
        tone="violet"
        meta={<span>{templatesQuery.isError ? "模板读取失败" : `模板总数 ${templates.length}`}</span>}
      />

      <div className="grid gap-6 xl:grid-cols-[1.1fr,0.9fr]">
        <Card className="border-slate-200/80 bg-white/90 shadow-sm backdrop-blur-sm dark:border-slate-800 dark:bg-slate-900/85">
          <CardHeader>
            <CardTitle className="text-base">模板编辑器</CardTitle>
            <CardDescription>支持新建与覆盖更新。</CardDescription>
          </CardHeader>
          <CardContent className="space-y-3">
            <div className="grid gap-3 md:grid-cols-2">
              <Input value={name} onChange={(e) => setName(e.target.value)} placeholder="模板名称" />
              <Input
                value={description}
                onChange={(e) => setDescription(e.target.value)}
                placeholder="模板描述（可选）"
              />
            </div>
            <Textarea
              rows={12}
              value={content}
              onChange={(e) => setContent(e.target.value)}
              placeholder="模板正文"
            />
            <div className="flex flex-wrap items-center gap-2">
              <Button
                className="bg-blue-600 text-white hover:bg-blue-700"
                disabled={createMutation.isPending || !name.trim() || !content.trim()}
                onClick={() => createMutation.mutate({ name, description, content })}
              >
                {createMutation.isPending ? "创建中..." : "新建模板"}
              </Button>
              <Button
                variant="outline"
                disabled={updateMutation.isPending || !selectedId || !name.trim() || !content.trim()}
                onClick={() => updateMutation.mutate({ id: selectedId, name, description, content })}
              >
                {updateMutation.isPending ? "保存中..." : "保存当前模板"}
              </Button>
            </div>
            {createMutation.isError || updateMutation.isError ? (
              <p className="text-xs text-rose-600 dark:text-rose-300">
                保存失败：
                {createMutation.error instanceof Error
                  ? createMutation.error.message
                  : updateMutation.error instanceof Error
                    ? updateMutation.error.message
                    : "请重试"}
              </p>
            ) : null}
          </CardContent>
        </Card>

        <Card className="border-slate-200/80 bg-white/90 shadow-sm backdrop-blur-sm dark:border-slate-800 dark:bg-slate-900/85">
          <CardHeader>
            <CardTitle className="text-base">模板列表</CardTitle>
            <CardDescription>点击“编辑”可回填到左侧编辑器。</CardDescription>
          </CardHeader>
          <CardContent>
            {templatesQuery.isLoading ? (
              <p className="text-sm text-slate-500 dark:text-slate-400">加载中...</p>
            ) : templatesQuery.isError ? (
              <div className="rounded-xl border border-rose-200/70 bg-rose-50/80 p-4 dark:border-rose-900/40 dark:bg-rose-950/30">
                <p className="text-sm font-medium text-rose-700 dark:text-rose-200">模板读取失败：{templatesErrorText}</p>
                <Button
                  className="mt-3"
                  variant="outline"
                  size="sm"
                  onClick={() => void templatesQuery.refetch()}
                  disabled={templatesQuery.isFetching}
                >
                  {templatesQuery.isFetching ? "重试中..." : "重试"}
                </Button>
              </div>
            ) : templates.length === 0 ? (
              <p className="text-sm text-slate-500 dark:text-slate-400">暂无模板。</p>
            ) : (
              <div className="overflow-x-auto rounded-xl border border-slate-200/90 dark:border-slate-700">
                <Table>
                  <TableHeader>
                    <TableRow>
                      <TableHead>名称</TableHead>
                      <TableHead>描述</TableHead>
                      <TableHead>更新时间</TableHead>
                      <TableHead className="text-right">操作</TableHead>
                    </TableRow>
                  </TableHeader>
                  <TableBody>
                    {templates.map((item) => (
                      <TableRow
                        key={item.id}
                        className={
                          item.id === selectedId
                            ? "bg-blue-50/80 dark:bg-blue-950/35"
                            : "hover:bg-slate-50/70 dark:hover:bg-slate-800/60"
                        }
                      >
                        <TableCell className="font-medium">{item.name}</TableCell>
                        <TableCell className="max-w-[320px] truncate">{item.description || "-"}</TableCell>
                        <TableCell>{item.updated_at || "-"}</TableCell>
                        <TableCell className="text-right">
                          <Button size="sm" variant="outline" onClick={() => setSelectedId(item.id)}>
                            编辑
                          </Button>
                        </TableCell>
                      </TableRow>
                    ))}
                  </TableBody>
                </Table>
              </div>
            )}
          </CardContent>
        </Card>
      </div>
    </div>
  );
}