// =====================================================
// 頭像上傳組件
// =====================================================

'use client';

import { useState, useRef, useEffect } from 'react';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import { Upload, X, Check, AlertCircle } from 'lucide-react';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { isValidImageType, isValidImageSize } from '@/lib/image-utils';

interface AvatarUploadProps {
  userId: string;
  currentAvatar?: string;
  userName?: string;
  onUploadSuccess?: (imageUrl: string) => void;
  onUploadError?: (error: string) => void;
}

export function AvatarUpload({ 
  userId, 
  currentAvatar, 
  userName,
  onUploadSuccess,
  onUploadError 
}: AvatarUploadProps) {
  const [isUploading, setIsUploading] = useState(false);
  const [uploadStatus, setUploadStatus] = useState<'idle' | 'success' | 'error'>('idle');
  const [errorMessage, setErrorMessage] = useState('');
  const [previewUrl, setPreviewUrl] = useState<string | null>(null);
  const fileInputRef = useRef<HTMLInputElement>(null);

  // 監聽 currentAvatar 變化，清除預覽
  useEffect(() => {
    if (currentAvatar) {
      setPreviewUrl(null);
    }
  }, [currentAvatar]);

  const handleFileSelect = (event: React.ChangeEvent<HTMLInputElement>) => {
    const file = event.target.files?.[0];
    if (!file) return;

    // 驗證文件類型
    if (!isValidImageType(file)) {
      setErrorMessage('只支援 JPEG、PNG、WebP 格式的圖片');
      setUploadStatus('error');
      return;
    }

    // 驗證文件大小（限制 5MB）
    if (!isValidImageSize(file, 5)) {
      setErrorMessage('圖片大小不能超過 5MB');
      setUploadStatus('error');
      return;
    }

    // 創建預覽 URL
    const url = URL.createObjectURL(file);
    setPreviewUrl(url);
    setUploadStatus('idle');
    setErrorMessage('');
  };

  const handleUpload = async () => {
    const file = fileInputRef.current?.files?.[0];
    if (!file) return;

    setIsUploading(true);
    setUploadStatus('idle');
    setErrorMessage('');

    try {
      const formData = new FormData();
      formData.append('avatar', file);
      formData.append('userId', userId);

      const response = await fetch('/api/upload/avatar', {
        method: 'POST',
        body: formData,
      });

      const result = await response.json();

      if (result.success) {
        setUploadStatus('success');
        setPreviewUrl(null); // 清除預覽，讓組件顯示實際頭像
        onUploadSuccess?.(result.data.imageUrl);
        console.log('頭像上傳成功:', result.data);
      } else {
        setUploadStatus('error');
        setErrorMessage(result.error || '上傳失敗');
        onUploadError?.(result.error || '上傳失敗');
      }
    } catch (error) {
      setUploadStatus('error');
      const errorMsg = error instanceof Error ? error.message : '上傳失敗';
      setErrorMessage(errorMsg);
      onUploadError?.(errorMsg);
    } finally {
      setIsUploading(false);
    }
  };

  const handleRemoveFile = () => {
    if (fileInputRef.current) {
      fileInputRef.current.value = '';
    }
    setPreviewUrl(null);
    setUploadStatus('idle');
    setErrorMessage('');
  };

  const getDisplayAvatar = () => {
    if (previewUrl) return previewUrl;
    if (currentAvatar && currentAvatar !== '') return currentAvatar;
    return null;
  };

  const getInitials = () => {
    if (userName) {
      return userName.split(' ').map(n => n[0]).join('').toUpperCase();
    }
    return 'U';
  };

  return (
    <Card className="w-full max-w-md">
      <CardHeader>
        <CardTitle className="flex items-center gap-2">
          <Upload className="h-5 w-5" />
          頭像上傳
        </CardTitle>
        <CardDescription>
          支援 JPEG、PNG、WebP 格式，最大 5MB
        </CardDescription>
      </CardHeader>
      <CardContent className="space-y-4">
        {/* 頭像預覽 */}
        <div className="flex justify-center">
          <Avatar className="h-24 w-24">
            <AvatarImage src={getDisplayAvatar() || ''} alt="頭像" />
            <AvatarFallback className="text-lg">
              {getInitials()}
            </AvatarFallback>
          </Avatar>
        </div>

        {/* 文件選擇 */}
        <div className="space-y-2">
          <Label htmlFor="avatar">選擇圖片</Label>
          <Input
            id="avatar"
            type="file"
            accept="image/jpeg,image/jpg,image/png,image/webp"
            onChange={handleFileSelect}
            ref={fileInputRef}
            disabled={isUploading}
          />
        </div>

        {/* 預覽和操作按鈕 */}
        {previewUrl && (
          <div className="space-y-2">
            <div className="flex items-center justify-between">
              <span className="text-sm text-muted-foreground">預覽</span>
              <Button
                variant="ghost"
                size="sm"
                onClick={handleRemoveFile}
                disabled={isUploading}
              >
                <X className="h-4 w-4" />
              </Button>
            </div>
            <div className="flex justify-center">
              <img
                src={previewUrl}
                alt="預覽"
                className="h-16 w-16 rounded-full object-cover border"
              />
            </div>
          </div>
        )}

        {/* 上傳按鈕 */}
        <Button
          onClick={handleUpload}
          disabled={!fileInputRef.current?.files?.[0] || isUploading}
          className="w-full"
        >
          {isUploading ? (
            <>
              <div className="animate-spin rounded-full h-4 w-4 border-b-2 border-white mr-2" />
              上傳中...
            </>
          ) : (
            <>
              <Upload className="h-4 w-4 mr-2" />
              上傳頭像
            </>
          )}
        </Button>

        {/* 狀態提示 */}
        {uploadStatus === 'success' && (
          <Alert>
            <Check className="h-4 w-4" />
            <AlertDescription>
              頭像上傳成功！
            </AlertDescription>
          </Alert>
        )}

        {uploadStatus === 'error' && (
          <Alert variant="destructive">
            <AlertCircle className="h-4 w-4" />
            <AlertDescription>
              {errorMessage}
            </AlertDescription>
          </Alert>
        )}
      </CardContent>
    </Card>
  );
}