import React, { useEffect, useRef, useState } from 'react';
import { View, Text, Modal, TouchableOpacity, ScrollView, Share, Alert, useWindowDimensions } from 'react-native';
import * as Sharing from 'expo-sharing';
import { X, Share2, Download, Trash2 } from 'lucide-react-native';
import { PhotoEntry } from '../types';
import ZoomableImage from './ZoomableImage';

// Session photo viewer: swipe left/right across every photo taken/exported in
// this session. Top shows preset name + index/total; trash deletes the photo
// being viewed (confirm modal first); share/save as before. Opened from the
// thumbnail button (camera mode) or automatically after a library export —
// NOT after a camera capture (that only fills the thumbnail).
interface PhotoViewerModalProps {
  visible: boolean;
  photos: PhotoEntry[];
  initialIndex: number;
  onClose: () => void;
  // Remove photo id from the session history (App also deletes cache + gallery copy).
  onDelete: (id: string) => void;
  // Save the (unsaved) photo id to the gallery; App stores the resulting assetId.
  onSave: (id: string) => Promise<void>;
}

export default function PhotoViewerModal({
  visible,
  photos,
  initialIndex,
  onClose,
  onDelete,
  onSave,
}: PhotoViewerModalProps) {
  const { width } = useWindowDimensions();
  const [index, setIndex] = useState(Math.max(0, Math.min(initialIndex, photos.length - 1)));
  const scrollRef = useRef<ScrollView>(null);
  const [saving, setSaving] = useState(false);
  const wasOpen = useRef(false);

  // Opening the modal (or reopening on a different photo): jump to initialIndex.
  // Shrinks of the list while open (deletion) must NOT re-scroll — the strip
  // shifts left by one page and the same page slot keeps showing the next photo.
  useEffect(() => {
    if (!visible) {
      wasOpen.current = false;
      return;
    }
    if (!wasOpen.current) {
      wasOpen.current = true;
      if (photos.length > 0) {
        const i = Math.max(0, Math.min(initialIndex, photos.length - 1));
        setIndex(i);
        requestAnimationFrame(() => {
          scrollRef.current?.scrollTo({ x: i * width, animated: false });
        });
      }
    }
  }, [visible, initialIndex, width, photos.length]);

  // Keep the page state in bounds when the list shrinks underneath us.
  useEffect(() => {
    if (visible && photos.length > 0 && index >= photos.length) {
      const i = photos.length - 1;
      setIndex(i);
      scrollRef.current?.scrollTo({ x: i * width, animated: false });
    }
  }, [visible, index, photos.length, width]);

  const photo = photos[index] || null;

  const handleShare = async () => {
    if (!photo) return;
    try {
      if (await Sharing.isAvailableAsync()) {
        await Sharing.shareAsync(photo.uri, {
          mimeType: 'image/jpeg',
          dialogTitle: `Share with RecipesCam - Preset: ${photo.recipeName}`,
          UTI: 'public.jpeg',
        });
      } else {
        await Share.share({
          url: photo.uri,
          message: `Captured with RecipesCam - Preset: ${photo.recipeName}`,
        });
      }
    } catch (error) {
      console.error('Sharing failed:', error);
    }
  };

  const handleDeletePress = () => {
    if (!photo) return;
    if (photo.savedToLibrary) {
      // The gallery copy exists → Android itself shows its per-item delete
      // confirmation, so no app modal in front of it.
      onDelete(photo.id);
      return;
    }
    // Never reached the gallery — no system prompt will happen, keep an app
    // confirm as the only guard against an accidental trash tap.
    Alert.alert(
      'Delete Photo',
      'Delete this photo? It was never saved to your gallery.',
      [
        { text: 'Cancel', style: 'cancel' },
        { text: 'Delete', style: 'destructive', onPress: () => onDelete(photo.id) },
      ]
    );
  };

  const handleDone = async () => {
    if (!photo || photo.savedToLibrary || saving) {
      onClose();
      return;
    }
    setSaving(true);
    try {
      await onSave(photo.id);
      onClose();
    } catch (e) {
      console.error('Save failed:', e);
    } finally {
      setSaving(false);
    }
  };

  if (!visible) return null; // see PhotoViewerModal

  return (
    <Modal visible={visible} animationType="fade" transparent={false} onRequestClose={onClose}>
      <View className="flex-1 bg-black">
        {/* Top bar: preset + index/total (left), trash + close (right) */}
        <View className="pt-12 pb-2 px-4 flex-row justify-between items-center">
          <View className="flex-1 pr-2">
            <Text className="text-zinc-500 font-mono text-xs">
              {photo ? photo.recipeName.toUpperCase() : ''}
            </Text>
            <Text className="text-zinc-600 font-mono text-[10px] mt-0.5">
              {photos.length > 0 ? `${index + 1} / ${photos.length}` : ''}
            </Text>
          </View>
          <View className="flex-row items-center">
            {photo && (
              <TouchableOpacity
                onPress={handleDeletePress}
                className="w-9 h-9 rounded-full bg-zinc-900 flex items-center justify-center mr-2"
                activeOpacity={0.7}
              >
                <Trash2 size={17} color="#ef4444" />
              </TouchableOpacity>
            )}
            <TouchableOpacity
              onPress={onClose}
              className="w-9 h-9 rounded-full bg-zinc-900 flex items-center justify-center"
              activeOpacity={0.7}
            >
              <X size={18} color="#ffffff" />
            </TouchableOpacity>
          </View>
        </View>

        {/* Swipeable photo strip */}
        {photos.length > 0 ? (
          <ScrollView
            ref={scrollRef}
            horizontal
            pagingEnabled
            showsHorizontalScrollIndicator={false}
            onMomentumScrollEnd={(e) => {
              const i = Math.round(e.nativeEvent.contentOffset.x / width);
              setIndex(Math.max(0, Math.min(i, photos.length - 1)));
            }}
          >
            {photos.map((p) => (
              <View key={p.id} style={{ width }} className="justify-center items-center">
                <ZoomableImage uri={p.uri} width={width} />
              </View>
            ))}
          </ScrollView>
        ) : (
          <View className="flex-1 items-center justify-center">
            <Text className="text-zinc-400 font-mono text-sm">NO PHOTOS</Text>
          </View>
        )}

        {/* Bottom bar */}
        <View className="pb-10 pt-3 px-4">
          {photo && !photo.savedToLibrary && (
            <Text className="text-amber-500 font-mono text-[10px] text-center mb-2">
              NOT SAVED TO GALLERY - SAVE & DONE TO KEEP
            </Text>
          )}
          <View className="flex-row justify-around items-center px-4">
            <TouchableOpacity
              onPress={handleShare}
              disabled={!photo}
              className="flex-row items-center bg-zinc-900 border border-zinc-800 px-6 py-3 rounded-full"
              activeOpacity={0.7}
            >
              <Share2 size={16} color="#f59e0b" />
              <Text className="text-white font-mono text-xs font-bold ml-2">SHARE</Text>
            </TouchableOpacity>
            <TouchableOpacity
              onPress={handleDone}
              disabled={!photo || saving}
              className="flex-row items-center bg-amber-500 px-6 py-3 rounded-full"
              activeOpacity={0.7}
            >
              <Download size={16} color="#000000" />
              <Text className="text-black font-mono text-xs font-bold ml-2">
                {saving ? 'SAVING...' : photo && !photo.savedToLibrary ? 'SAVE & DONE' : 'DONE'}
              </Text>
            </TouchableOpacity>
          </View>
        </View>
      </View>
    </Modal>
  );
}