import React, { useState, useRef } from 'react';
import { X, Upload, Image as ImageIcon, Loader2 } from 'lucide-react';
import { useNotification } from '@/hooks/useNotification';
import { useTourStore } from '@/store/useTourStore';
import { processImageModeration } from '@/hooks/useImageModeration';
import { processAndResizeImage } from '../utils/imageProcessor';
import { getDeviceLocation } from '../utils/geolocation';

interface AddPhotoModalProps {
  isOpen: boolean;
  onClose: () => void;
  tourId: string;
  onSuccess?: () => void;
  isPublicView?: boolean;
}

interface PendingPhoto {
  file: File;
  latitude: number;
  longitude: number;
}

export const AddPhotoModal: React.FC<AddPhotoModalProps> = ({ isOpen, onClose, tourId, onSuccess, isPublicView }) => {
  const [selectedFiles, setSelectedFiles] = useState<PendingPhoto[]>([]);
  const [previews, setPreviews] = useState<string[]>([]);
  const [isUploading, setIsUploading] = useState(false);
  const [isProcessing, setIsProcessing] = useState(false);
  const fileInputRef = useRef<HTMLInputElement>(null);
  const notify = useNotification();
  const fetchTour = useTourStore(state => state.fetchTour);

  if (!isOpen) return null;

  const handleFileChange = async (e: React.ChangeEvent<HTMLInputElement>) => {
    if (e.target.files) {
      const files = Array.from(e.target.files);
      setIsProcessing(true);
      notify({ title: 'Đang kiểm duyệt...', message: 'Đang kiểm tra và lọc hình ảnh của bạn...', type: 'info' });

      try {
        // Fetch device location once to serve as Priority 2 fallback for files without EXIF
        const deviceLocation = await getDeviceLocation();

        const newValidPhotos: PendingPhoto[] = [];
        const newValidPreviews: string[] = [];

        for (const file of files) {
          if (!file || file.size === 0) {
            notify({ title: 'Lỗi tệp', message: `Tệp ${file.name} trống hoặc không khả dụng.`, type: 'error' });
            continue;
          }

          // Process image: Reads EXIF data and forces 2K resizing on device memory
          const { file: processedFile, latitude: exifLat, longitude: exifLng } = await processAndResizeImage(file);
 
          // 2. Chạy kiểm duyệt hình ảnh
          const moderationResult = await processImageModeration(processedFile);
          if (moderationResult.blocked) {
            notify({ title: 'Ảnh bị từ chối', message: `Ảnh ${file.name} chứa nội dung không phù hợp và bị chặn.`, type: 'error' });
            continue;
          }

          const finalProcessedFile = moderationResult.file;
          const previewUrl = URL.createObjectURL(finalProcessedFile);

          // 3. Kiểm tra tính toàn vẹn
          const isValidImage = await new Promise<boolean>((resolve) => {
            const img = new Image();
            img.onload = () => resolve(true);
            img.onerror = () => resolve(false);
            img.src = previewUrl;
          });

          if (isValidImage) {
            // Resolve coordinates based on priority checklist:
            let finalLat: number | null = exifLat;
            let finalLng: number | null = exifLng;

            // Priority 2: Device location
            if ((finalLat === null || finalLng === null) && deviceLocation) {
              finalLat = deviceLocation.latitude;
              finalLng = deviceLocation.longitude;
            }

            // Priority 3: Map view state
            if (finalLat === null || finalLng === null) {
              const lastViewStateStr = localStorage.getItem('map_view_state');
              if (lastViewStateStr) {
                try {
                  const lastViewState = JSON.parse(lastViewStateStr);
                  if (lastViewState && Array.isArray(lastViewState.center) && lastViewState.center.length === 2) {
                    finalLat = Number(lastViewState.center[0]);
                    finalLng = Number(lastViewState.center[1]);
                  }
                } catch (e) {
                  console.error('[AddPhotoModal] Error parsing map_view_state:', e);
                }
              }
            }

            // Priority 4: Fallback defaults
            if (finalLat === null || finalLng === null) {
              finalLat = 10.7769;
              finalLng = 106.7009;
            }

            newValidPhotos.push({
              file: finalProcessedFile,
              latitude: finalLat,
              longitude: finalLng
            });
            newValidPreviews.push(previewUrl);
          } else {
            URL.revokeObjectURL(previewUrl);
            notify({ title: 'Lỗi ảnh', message: `Không thể đọc nội dung ảnh: ${file.name}. Vui lòng kiểm tra lại file.`, type: 'error' });
          }
        }

        setSelectedFiles(prev => [...prev, ...newValidPhotos]);
        setPreviews(prev => [...prev, ...newValidPreviews]);
      } catch (err) {
        console.error('File checking error:', err);
        notify({ title: 'Lỗi', message: 'Lỗi trong quá trình kiểm duyệt ảnh.', type: 'error' });
      } finally {
        setIsProcessing(false);
      }
    }
  };

  const removeFile = (index: number) => {
    // Thu hồi URL khi xóa khỏi danh sách chờ để giải phóng bộ nhớ
    URL.revokeObjectURL(previews[index]);
    setSelectedFiles(prev => prev.filter((_, i) => i !== index));
    setPreviews(prev => prev.filter((_, i) => i !== index));
  };

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (selectedFiles.length === 0) return;

    setIsUploading(true);
    try {
      // Upload each photo sequentially so we can attach its specific coordinates
      for (const item of selectedFiles) {
        const formData = new FormData();
        formData.append('latitude', item.latitude.toString());
        formData.append('longitude', item.longitude.toString());
        formData.append('images', item.file);

        const response = await fetch(`/api/v1/tours/${tourId}/photos`, {
          method: 'POST',
          headers: {
            'Authorization': `Bearer ${localStorage.getItem('token')}`
          },
          body: formData
        });

        if (!response.ok) throw new Error('Tải lên ảnh thất bại');
      }

      
      // Giải phóng bộ nhớ sau khi hoàn tất
      previews.forEach(url => URL.revokeObjectURL(url));
      setSelectedFiles([]);
      setPreviews([]);
      
      // Refresh tour data (applies to both authenticated and public users)
      // This ensures newly uploaded photos appear immediately without requiring a page reload
      fetchTour(tourId);
      if (onSuccess) onSuccess();
      
      // For public users: redirect to landing page after upload (after data refresh)
      // For authenticated users: close modal and show updated tour
      if (isPublicView) {
        onClose();
        // Give time for tour data to refresh before redirecting
        setTimeout(() => {
          localStorage.setItem('fromPublicUpload', 'true');
          window.location.href = '/';
        }, 1500);
      } else {
        onClose();
      }
    } catch (error) {
      notify({
        title: 'Lỗi',
        message: 'Không thể tải ảnh lên. Vui lòng thử lại.',
        type: 'error'
      });
    } finally {
      setIsUploading(false);
    }
  };


  return (
    <div className="fixed inset-0 z-[2500] flex items-end sm:items-center justify-center p-0 sm:p-4">
      <div className="absolute inset-0 bg-gray-900/60 backdrop-blur-sm" onClick={onClose} />
      <div className="relative w-full h-full sm:max-w-lg bg-[var(--surface)] rounded-t-2xl sm:rounded-3xl shadow-2xl overflow-hidden flex flex-col sm:max-h-[85vh] animate-in zoom-in-95 duration-200">
        <div className="flex justify-between items-center mb-6 p-5 sm:p-8 pb-0 sm:pb-0 shrink-0">
          <h2 className="text-2xl font-bold text-[var(--text-primary)] flex items-center gap-2">
            <ImageIcon className="w-6 h-6 text-blue-600" /> Tải ảnh lên
          </h2>
          <button onClick={onClose} className="p-2 hover:bg-[var(--background)] rounded-full transition-colors text-[var(--text-muted)]">
            <X className="w-6 h-6" />
          </button>
        </div>

        <form onSubmit={handleSubmit} className="flex-1 flex flex-col min-h-0 p-5 sm:p-8 pt-0 sm:pt-0">
          <div 
            onClick={() => fileInputRef.current?.click()}
            className="border-2 border-dashed border-[var(--border)] rounded-[32px] p-10 flex flex-col items-center justify-center cursor-pointer hover:bg-[var(--background)]/50 hover:border-blue-200 transition-all mb-6 group"
          >
            <input type="file" ref={fileInputRef} className="hidden" multiple accept="image/*" onChange={handleFileChange} />
            <div className="w-16 h-16 rounded-2xl bg-blue-50 flex items-center justify-center text-blue-600 mb-4 group-hover:scale-110 transition-transform shadow-inner">
              <Upload className="w-8 h-8" />
            </div>
            <p className="text-sm font-black text-[var(--text-secondary)]">Nhấn để chọn ảnh</p>
            <p className="text-xs text-[var(--text-muted)] mt-1 font-medium">Hỗ trợ JPG, PNG, WEBP</p>
          </div>

          {previews.length > 0 && (
            <div className="flex-1 overflow-y-auto mb-6 pr-2">
              <p className="text-[10px] font-black text-[var(--text-muted)] uppercase tracking-widest mb-3">Đã chọn {previews.length} tệp</p>
              <div className="grid grid-cols-3 gap-3">
                {previews.map((src, idx) => (
                  <div key={idx} className="relative aspect-square rounded-2xl overflow-hidden border border-[var(--border)] shadow-sm group">
                    <img src={src} className="w-full h-full object-cover" alt="preview" />
                    <button 
                      type="button"
                      onClick={() => removeFile(idx)}
                      className="absolute top-1.5 right-1.5 p-1.5 bg-red-500/80 backdrop-blur-sm text-white rounded-full opacity-0 group-hover:opacity-100 transition-opacity"
                    >
                      <X className="w-3 h-3" />
                    </button>
                  </div>
                ))}
              </div>
            </div>
          )}

          <button 
            disabled={isUploading || isProcessing || selectedFiles.length === 0}
            className="w-full py-4 bg-blue-600 hover:bg-blue-700 disabled:bg-gray-300 text-white font-black uppercase tracking-widest rounded-2xl flex items-center justify-center gap-2 shadow-lg shadow-blue-100 transition-all active:scale-95"
          >
            {isUploading ? (
              <Loader2 className="w-5 h-5 animate-spin" />
            ) : isProcessing ? (
              <>
                <Loader2 className="w-5 h-5 animate-spin" />
                Đang xử lý ảnh...
              </>
            ) : (
              'Xác nhận tải lên'
            )}
          </button>
        </form>
      </div>
    </div>
  );
};