"use client";

import { useState, useRef, useCallback } from "react";
import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import api from "@/lib/api";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Textarea } from "@/components/ui/textarea";
import { Dialog, DialogContent, DialogHeader, DialogTitle } from "@/components/ui/dialog";
import { toast } from "sonner";
import { useAuthStore } from "@/stores/auth";
import {
  BookOpen,
  Upload,
  FileText,
  Trash2,
  Plus,
  Database,
  Search,
} from "lucide-react";

interface KnowledgeBase {
  id: string;
  name: string;
  description: string;
  visibility: string;
  document_count: number;
  total_chars: number;
  status: string;
  created_at: string;
  updated_at: string;
}

interface KBDocument {
  id: string;
  filename: string;
  file_size: number;
  file_type: string;
  status: string;
  created_at: string;
}

function formatFileSize(bytes: number): string {
  if (bytes < 1024) return bytes + " B";
  if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + " KB";
  return (bytes / (1024 * 1024)).toFixed(1) + " MB";
}

function getStatusBadge(status: string) {
  switch (status) {
    case "completed":
      return <Badge className="bg-emerald-50 text-emerald-700 border-emerald-200">已完成</Badge>;
    case "indexing":
      return <Badge className="bg-amber-50 text-amber-700 border-amber-200">索引中</Badge>;
    case "failed":
      return <Badge variant="destructive">失败</Badge>;
    default:
      return <Badge variant="secondary">{status}</Badge>;
  }
}

function getVisibilityLabel(v: string) {
  switch (v) {
    case "public": return "全单位";
    case "department": return "本科室";
    default: return "私有";
  }
}

export default function KnowledgePage() {
  const queryClient = useQueryClient();
  const user = useAuthStore((s) => s.user);
  const orgId = user?.org_id;
  const [showCreate, setShowCreate] = useState(false);
  const [selectedKB, setSelectedKB] = useState<KnowledgeBase | null>(null);
  const [form, setForm] = useState({ name: "", description: "", visibility: "private" });
  const [searchTerm, setSearchTerm] = useState("");
  const fileInputRef = useRef<HTMLInputElement>(null);

  const { data: knowledgeBases, isLoading: kbLoading } = useQuery({
    queryKey: ["knowledgeBases", orgId],
    queryFn: () => api.get<KnowledgeBase[]>(`/api/v1/knowledge/${orgId ? `?org_id=${orgId}` : ""}`),
  });

  const { data: documents } = useQuery({
    queryKey: ["kbDocuments", selectedKB?.id],
    queryFn: () => api.get<KBDocument[]>(`/api/v1/knowledge/${selectedKB!.id}/documents`),
    enabled: !!selectedKB,
  });

  const createKB = useMutation({
    mutationFn: () => api.post("/api/v1/knowledge/", form),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["knowledgeBases"] });
      setShowCreate(false);
      setForm({ name: "", description: "", visibility: "private" });
      toast.success("知识库创建成功");
    },
    onError: (err: Error) => toast.error(err.message),
  });

  const deleteKB = useMutation({
    mutationFn: (id: string) => api.delete(`/api/v1/knowledge/${id}`),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["knowledgeBases"] });
      if (selectedKB) setSelectedKB(null);
      toast.success("知识库已删除");
    },
    onError: (err: Error) => toast.error(err.message),
  });

  const uploadDoc = useMutation({
    mutationFn: async (file: File) => {
      const formData = new FormData();
      formData.append("file", file);
      const res = await fetch(`/api/v1/knowledge/${selectedKB!.id}/documents`, {
        method: "POST",
        headers: { Authorization: `Bearer ${localStorage.getItem("token")}` },
        body: formData,
      });
      if (!res.ok) throw new Error("上传失败");
      return res.json();
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["kbDocuments"] });
      queryClient.invalidateQueries({ queryKey: ["knowledgeBases"] });
      toast.success("文档上传成功");
    },
    onError: (err: Error) => toast.error(err.message),
  });

  const deleteDoc = useMutation({
    mutationFn: (docId: string) =>
      api.delete(`/api/v1/knowledge/${selectedKB!.id}/documents/${docId}`),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["kbDocuments"] });
      queryClient.invalidateQueries({ queryKey: ["knowledgeBases"] });
      toast.success("文档已删除");
    },
    onError: (err: Error) => toast.error(err.message),
  });

  const handleFileUpload = useCallback(() => {
    fileInputRef.current?.click();
  }, []);

  const onFileChange = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    if (file) {
      uploadDoc.mutate(file);
      e.target.value = "";
    }
  }, [uploadDoc]);

  const filteredKBs = knowledgeBases?.filter(
    (kb) => !searchTerm || kb.name.includes(searchTerm) || kb.description?.includes(searchTerm)
  );

  return (
    <div className="mx-auto w-full max-w-7xl px-6 lg:px-8 py-6">
      <div className="flex items-center justify-between mb-6">
        <div className="flex items-center gap-3">
          <div className="flex h-10 w-10 items-center justify-center rounded-xl bg-blue-100 text-blue-700">
            <Database className="h-5 w-5" />
          </div>
          <div>
            <h1 className="text-xl font-bold">知识库管理</h1>
            <p className="text-sm text-muted-foreground">管理政策法规、制度文件等知识资源</p>
          </div>
        </div>
        <Button onClick={() => setShowCreate(true)} className="gap-2">
          <Plus className="h-4 w-4" />
          新建知识库
        </Button>
      </div>

      <div className="grid grid-cols-1 lg:grid-cols-3 gap-6">
        <div className="lg:col-span-1 space-y-3">
          <div className="relative">
            <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
            <Input
              placeholder="搜索知识库..."
              value={searchTerm}
              onChange={(e) => setSearchTerm(e.target.value)}
              className="pl-9"
            />
          </div>

          {kbLoading && (
            <div className="space-y-3">
              {[1, 2].map((i) => (
                <Card key={i} className="animate-pulse">
                  <CardContent className="py-6">
                    <div className="h-4 bg-muted rounded w-3/4 mb-2" />
                    <div className="h-3 bg-muted rounded w-1/2" />
                  </CardContent>
                </Card>
              ))}
            </div>
          )}

          {!kbLoading && filteredKBs?.length === 0 && (
            <Card>
              <CardContent className="py-10 text-center">
                <BookOpen className="h-10 w-10 mx-auto text-muted-foreground/40 mb-3" />
                <p className="text-sm text-muted-foreground">
                  {searchTerm ? "未找到匹配的知识库" : "暂无知识库，点击上方按钮创建"}
                </p>
              </CardContent>
            </Card>
          )}

          {filteredKBs?.map((kb) => (
            <Card
              key={kb.id}
              className={`cursor-pointer transition-all ${
                selectedKB?.id === kb.id
                  ? "border-primary ring-1 ring-primary/20"
                  : "hover:border-muted-foreground/30"
              }`}
              onClick={() => setSelectedKB(kb)}
            >
              <CardHeader className="pb-2">
                <div className="flex items-center justify-between">
                  <CardTitle className="text-sm flex items-center gap-2">
                    <BookOpen className="h-4 w-4 text-blue-600" />
                    {kb.name}
                  </CardTitle>
                  <Badge variant="secondary" className="text-xs">{kb.document_count} 文档</Badge>
                </div>
              </CardHeader>
              <CardContent>
                <p className="text-xs text-muted-foreground line-clamp-2 mb-2">
                  {kb.description || "暂无描述"}
                </p>
                <div className="flex items-center justify-between">
                  <div className="flex items-center gap-2">
                    <Badge variant="outline" className="text-xs">{getVisibilityLabel(kb.visibility)}</Badge>
                    <span className="text-xs text-muted-foreground">
                      {new Date(kb.updated_at).toLocaleDateString("zh-CN")}
                    </span>
                  </div>
                  <Button
                    variant="ghost"
                    size="sm"
                    className="text-destructive h-6 px-2"
                    onClick={(e) => {
                      e.stopPropagation();
                      if (confirm("确定要删除该知识库吗？所有文档将一并删除。")) {
                        deleteKB.mutate(kb.id);
                      }
                    }}
                  >
                    <Trash2 className="h-3.5 w-3.5" />
                  </Button>
                </div>
              </CardContent>
            </Card>
          ))}
        </div>

        <div className="lg:col-span-2">
          {selectedKB ? (
            <Card>
              <CardHeader>
                <div className="flex items-center justify-between">
                  <div>
                    <CardTitle className="flex items-center gap-2">
                      <BookOpen className="h-5 w-5 text-blue-600" />
                      {selectedKB.name}
                    </CardTitle>
                    <p className="text-sm text-muted-foreground mt-1">{selectedKB.description}</p>
                    <div className="flex items-center gap-2 mt-2">
                      <Badge variant="outline">{getVisibilityLabel(selectedKB.visibility)}</Badge>
                      <span className="text-xs text-muted-foreground">{selectedKB.document_count} 个文档</span>
                    </div>
                  </div>
                  <div>
                    <input
                      ref={fileInputRef}
                      type="file"
                      className="hidden"
                      accept=".txt,.md,.pdf,.docx,.csv,.xlsx"
                      onChange={onFileChange}
                    />
                    <Button onClick={handleFileUpload} disabled={uploadDoc.isPending} className="gap-2">
                      <Upload className="h-4 w-4" />
                      {uploadDoc.isPending ? "上传中..." : "上传文档"}
                    </Button>
                  </div>
                </div>
              </CardHeader>
              <CardContent>
                {documents?.length === 0 ? (
                  <div className="text-center py-12 text-muted-foreground">
                    <FileText className="h-10 w-10 mx-auto text-muted-foreground/40 mb-3" />
                    <p className="text-sm">暂无文档</p>
                    <p className="text-xs mt-1">支持上传 PDF、DOCX、TXT、MD、CSV、XLSX 格式</p>
                  </div>
                ) : (
                  <div className="border rounded-lg overflow-hidden">
                    <table className="w-full text-sm">
                      <thead className="bg-muted/50">
                        <tr>
                          <th className="text-left p-3 font-medium">文件名</th>
                          <th className="text-left p-3 font-medium">类型</th>
                          <th className="text-left p-3 font-medium">大小</th>
                          <th className="text-left p-3 font-medium">状态</th>
                          <th className="text-left p-3 font-medium">上传时间</th>
                          <th className="text-left p-3 font-medium">操作</th>
                        </tr>
                      </thead>
                      <tbody>
                        {documents?.map((doc) => (
                          <tr key={doc.id} className="border-t hover:bg-muted/30 transition-colors">
                            <td className="p-3 font-medium flex items-center gap-2">
                              <FileText className="h-4 w-4 text-blue-500 shrink-0" />
                              <span className="truncate max-w-[200px]">{doc.filename}</span>
                            </td>
                            <td className="p-3 text-muted-foreground uppercase text-xs">{doc.file_type || "-"}</td>
                            <td className="p-3 text-muted-foreground">{formatFileSize(doc.file_size)}</td>
                            <td className="p-3">{getStatusBadge(doc.status)}</td>
                            <td className="p-3 text-muted-foreground text-xs">{new Date(doc.created_at).toLocaleString("zh-CN")}</td>
                            <td className="p-3">
                              <Button
                                variant="ghost"
                                size="sm"
                                className="text-destructive h-7 px-2"
                                onClick={() => deleteDoc.mutate(doc.id)}
                              >
                                <Trash2 className="h-3.5 w-3.5" />
                              </Button>
                            </td>
                          </tr>
                        ))}
                      </tbody>
                    </table>
                  </div>
                )}
              </CardContent>
            </Card>
          ) : (
            <Card>
              <CardContent className="py-20 text-center text-muted-foreground">
                <Database className="h-12 w-12 mx-auto text-muted-foreground/30 mb-4" />
                <p className="text-sm">请从左侧选择一个知识库查看文档</p>
                <p className="text-xs mt-1">或点击"新建知识库"创建政策法规资源库</p>
              </CardContent>
            </Card>
          )}
        </div>
      </div>

      <Dialog open={showCreate} onOpenChange={setShowCreate}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle className="flex items-center gap-2">
              <BookOpen className="h-5 w-5 text-blue-600" />
              新建知识库
            </DialogTitle>
          </DialogHeader>
          <div className="space-y-4">
            <div className="space-y-2">
              <Label>名称 *</Label>
              <Input
                value={form.name}
                onChange={(e) => setForm({ ...form, name: e.target.value })}
                placeholder="例如：科技局政策法规库"
              />
            </div>
            <div className="space-y-2">
              <Label>描述</Label>
              <Textarea
                value={form.description}
                onChange={(e) => setForm({ ...form, description: e.target.value })}
                placeholder="简要描述知识库的用途和包含的文档类型"
                rows={3}
              />
            </div>
            <div className="space-y-2">
              <Label>可见范围</Label>
              <div className="grid grid-cols-3 gap-2">
                {[
                  { value: "private", label: "私有" },
                  { value: "department", label: "本科室" },
                  { value: "public", label: "全单位" },
                ].map((opt) => (
                  <button
                    key={opt.value}
                    onClick={() => setForm({ ...form, visibility: opt.value })}
                    className={`p-2.5 rounded-lg border text-sm text-center transition-colors ${
                      form.visibility === opt.value
                        ? "border-primary bg-primary/5 text-primary font-medium"
                        : "border-border hover:border-primary/30"
                    }`}
                  >
                    {opt.label}
                  </button>
                ))}
              </div>
            </div>
            <div className="flex justify-end gap-2 pt-2">
              <Button variant="outline" onClick={() => setShowCreate(false)}>取消</Button>
              <Button
                onClick={() => createKB.mutate()}
                disabled={!form.name.trim() || createKB.isPending}
              >
                创建
              </Button>
            </div>
          </div>
        </DialogContent>
      </Dialog>
    </div>
  );
}