import React, { useState, useEffect } from 'react';
import { useParams, useLocation, useNavigate } from 'react-router-dom';
import { Dialog, DialogContent } from '@/components/ui/dialog';
import { Button } from '@/components/ui/button';
import { Heart, ChevronLeft, ChevronRight, X } from 'lucide-react';
import { likePhoto } from '../services/photosApi';

type Photo = {
  id: number;
  file_path?: string;
  thumbnail_path?: string;
  likes_count?: number;
  created_at?: string;
  task_id?: number;
  task_title?: string;
};

type Task = { id: number; title: string };

interface Props {
  photos?: Photo[];
  currentIndex?: number;
  onClose?: () => void;
  onIndexChange?: (index: number) => void;
  slug?: string;
}

export default function PhotoLightbox({ photos, currentIndex, onClose, onIndexChange, slug }: Props) {
  const params = useParams<{ token?: string; photoId?: string }>();
  const location = useLocation();
  const navigate = useNavigate();
  const photoId = params.photoId;
  const eventSlug = params.token || slug;

  const [standalonePhoto, setStandalonePhoto] = useState<Photo | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [task, setTask] = useState<Task | null>(null);
  const [taskLoading, setTaskLoading] = useState(false);
  const [likes, setLikes] = useState<number>(0);
  const [liked, setLiked] = useState(false);

  // Determine mode and photo
  const isStandalone = !photos || photos.length === 0;
  const currentPhotos = isStandalone ? (standalonePhoto ? [standalonePhoto] : []) : photos || [];
  const currentIndexVal = isStandalone ? 0 : (currentIndex || 0);
  const photo = currentPhotos[currentIndexVal];

  // Fallback onClose for standalone
  const handleClose = onClose || (() => navigate(-1));

  // Fetch single photo for standalone mode
  useEffect(() => {
    if (isStandalone && photoId && !standalonePhoto && eventSlug) {
      const fetchPhoto = async () => {
        setLoading(true);
        setError(null);
        try {
          const res = await fetch(`/api/v1/photos/${photoId}`);
          if (res.ok) {
            const fetchedPhoto: Photo = await res.json();
            setStandalonePhoto(fetchedPhoto);
            // Check state for initial photo
            if (location.state?.photo) {
              setStandalonePhoto(location.state.photo);
            }
          } else {
            setError('Foto nicht gefunden');
          }
        } catch (err) {
          setError('Fehler beim Laden des Fotos');
        } finally {
          setLoading(false);
        }
      };

      fetchPhoto();
    } else if (!isStandalone) {
      setLoading(false);
    }
  }, [isStandalone, photoId, eventSlug, standalonePhoto, location.state]);

  // Update likes when photo changes
  React.useEffect(() => {
    if (photo) {
      setLikes(photo.likes_count ?? 0);
      // Check if liked from localStorage
      try {
        const raw = localStorage.getItem('liked-photo-ids');
        const likedIds = raw ? JSON.parse(raw) : [];
        setLiked(likedIds.includes(photo.id));
      } catch {
        setLiked(false);
      }
    }
  }, [photo]);

  const touchRef = React.useRef<HTMLDivElement>(null);
  const startX = React.useRef(0);
  const currentX = React.useRef(0);

  const handleTouchStart = (e: React.TouchEvent) => {
    startX.current = e.touches[0].clientX;
  };

  const handleTouchMove = (e: React.TouchEvent) => {
    if (!touchRef.current) return;
    currentX.current = e.touches[0].clientX;
    const deltaX = currentX.current - startX.current;
    touchRef.current.style.transform = `translateX(${deltaX}px)`;
  };

  const handleTouchEnd = () => {
    if (!touchRef.current) return;
    const deltaX = currentX.current - startX.current;
    const threshold = 50; // pixels

    touchRef.current.style.transform = 'translateX(0)';

    if (Math.abs(deltaX) > threshold) {
      if (deltaX > 0 && currentIndexVal > 0) {
        // Swipe right - previous
        onIndexChange?.(currentIndexVal - 1);
      } else if (deltaX < 0 && currentIndexVal < currentPhotos.length - 1) {
        // Swipe left - next
        onIndexChange?.(currentIndexVal + 1);
      }
    }
  };


  // Load task info if photo has task_id and event key is available
  React.useEffect(() => {
    if (!photo?.task_id || !eventSlug) {
      setTask(null);
      setTaskLoading(false);
      return;
    }

    const taskId = photo.task_id;

    (async () => {
      setTaskLoading(true);
      try {
        const res = await fetch(`/api/v1/events/${encodeURIComponent(eventSlug)}/tasks`);
        if (res.ok) {
          const tasks = await res.json();
          const foundTask = tasks.find((t: any) => t.id === taskId);
          if (foundTask) {
            setTask({
              id: foundTask.id,
              title: foundTask.title || `Aufgabe ${taskId}`
            });
          } else {
            setTask({
              id: taskId,
              title: `Unbekannte Aufgabe ${taskId}`
            });
          }
        } else {
          setTask({
            id: taskId,
            title: `Unbekannte Aufgabe ${taskId}`
          });
        }
      } catch (error) {
        console.error('Failed to load task:', error);
        setTask({
          id: taskId,
          title: `Unbekannte Aufgabe ${taskId}`
        });
      } finally {
        setTaskLoading(false);
      }
    })();
  }, [photo?.task_id, eventSlug]);

  async function onLike() {
    if (liked || !photo) return;
    setLiked(true);
    try {
      const count = await likePhoto(photo.id);
      setLikes(count);
      // Update localStorage
      try {
        const raw = localStorage.getItem('liked-photo-ids');
        const arr: number[] = raw ? JSON.parse(raw) : [];
        if (!arr.includes(photo.id)) {
          localStorage.setItem('liked-photo-ids', JSON.stringify([...arr, photo.id]));
        }
      } catch {}
    } catch (error) {
      console.error('Like failed:', error);
      setLiked(false);
    }
  }

  function onOpenChange(open: boolean) {
    if (!open) handleClose();
  }

  return (
    <Dialog open={true} onOpenChange={onOpenChange}>
      <DialogContent hideClose className="max-w-5xl border-0 bg-black p-0 text-white">
        {/* Header with controls */}
        <div className="flex items-center justify-between p-2">
          <div className="flex items-center gap-2">
            <Button
              variant="secondary"
              size="sm"
              onClick={onLike}
              disabled={liked}
            >
              <Heart className={`mr-1 h-4 w-4 ${liked ? 'fill-red-400 text-red-400' : ''}`} />
              {likes}
            </Button>
          </div>
          <div className="flex items-center gap-1">
            {currentIndexVal > 0 && (
              <Button
                variant="ghost"
                size="sm"
                onClick={() => onIndexChange?.(currentIndexVal - 1)}
                className="h-8 w-8 p-0"
              >
                <ChevronLeft className="h-4 w-4" />
              </Button>
            )}
            <Button
              variant="ghost"
              size="sm"
              onClick={onClose}
              className="h-8 w-8 p-0"
            >
              <X className="h-4 w-4" />
            </Button>
            {currentIndexVal < currentPhotos.length - 1 && (
              <Button
                variant="ghost"
                size="sm"
                onClick={() => onIndexChange?.(currentIndexVal + 1)}
                className="h-8 w-8 p-0"
              >
                <ChevronRight className="h-4 w-4" />
              </Button>
            )}
          </div>
        </div>

        {/* Task Info Overlay */}
        {task && (
          <div className="absolute bottom-4 left-4 right-4 z-20 bg-black/60 backdrop-blur-sm rounded-xl p-3 border border-white/20 max-w-md">
            <div className="text-sm">
              <div className="font-semibold mb-1 text-white">Task: {task.title}</div>
              {taskLoading && (
                <div className="text-xs opacity-70 text-gray-300">Lade Aufgabe...</div>
              )}
            </div>
          </div>
        )}

        {/* Photo Display */}
        <div
          ref={touchRef}
          className="flex items-center justify-center min-h-[60vh] p-4 relative overflow-hidden"
          onTouchStart={handleTouchStart}
          onTouchMove={handleTouchMove}
          onTouchEnd={handleTouchEnd}
        >
          <img
            src={photo?.file_path || photo?.thumbnail_path}
            alt={`Foto ${photo?.id || ''}${photo?.task_title ? ` - ${photo.task_title}` : ''}`}
            className="max-h-[80vh] max-w-full object-contain transition-transform duration-200"
            onError={(e) => {
              console.error('Image load error:', e);
              (e.target as HTMLImageElement).style.display = 'none';
            }}
          />
        </div>

        {/* Loading state for task */}
        {taskLoading && !task && (
          <div className="absolute top-4 left-4 right-4 z-20 bg-black/60 backdrop-blur-sm rounded-xl p-3 border border-white/20 max-w-md">
            <div className="text-sm text-center">
              <div className="animate-spin rounded-full h-4 w-4 border-b-2 border-white mx-auto mb-1"></div>
              <div className="text-xs opacity-70">Lade Aufgabe...</div>
            </div>
          </div>
        )}
      </DialogContent>
    </Dialog>
  );
}
