'use client';

import React, { useState, useEffect } from 'react';
import { useSession } from 'next-auth/react';
import { Button } from '@/components/ui/button';
import { Textarea } from '@/components/ui/textarea';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogHeader,
  AlertDialogTitle,
} from '@/components/ui/alert-dialog';
import { formatDistanceToNow } from 'date-fns';
import { Trash2 } from 'lucide-react';

type User = {
  id: string;
  name: string | null;
  email: string;
  image: string | null;
};

type CommentReply = {
  id: string;
  userId: string;
  commentId: string;
  content: string;
  createdAt: string;
  user: User;
};

type Comment = {
  id: string;
  userId: string;
  videoId: string;
  content: string;
  createdAt: string;
  user: User;
  replies: CommentReply[];
};

interface CommentsSectionProps {
  videoId: string;
}

export function CommentsSection({ videoId }: CommentsSectionProps) {
  const { data: session } = useSession();
  const [comments, setComments] = useState<Comment[]>([]);
  const [newCommentContent, setNewCommentContent] = useState('');
  const [replyingToId, setReplyingToId] = useState<string | null>(null);
  const [replyContent, setReplyContent] = useState('');
  const [isLoading, setIsLoading] = useState(true);
  const [isSubmitting, setIsSubmitting] = useState(false);
  const [deleteDialogOpen, setDeleteDialogOpen] = useState(false);
  const [deletingCommentId, setDeletingCommentId] = useState<string | null>(null);
  const [deleteReplyDialogOpen, setDeleteReplyDialogOpen] = useState(false);
  const [deletingReplyId, setDeletingReplyId] = useState<string | null>(null);
  const [deletingReplyCommentId, setDeletingReplyCommentId] = useState<string | null>(null);
  const isAdmin = (session?.user as any)?.role === 'admin' || (session?.user as any)?.role === 'superadmin';

  const handleDeleteComment = async (commentId: string) => {
    try {
      const res = await fetch(`/api/comments/${commentId}`, {
        method: 'DELETE',
      });

      if (res.ok) {
        setComments(comments.filter((c) => c.id !== commentId));
        setDeleteDialogOpen(false);
        setDeletingCommentId(null);
      }
    } catch (err) {
      console.error('Failed to delete comment:', err);
    }
  };

  const handleDeleteReply = async (replyId: string, commentId: string) => {
    try {
      const res = await fetch(`/api/comments/reply/${replyId}`, {
        method: 'DELETE',
      });

      if (res.ok) {
        setComments(
          comments.map((c) =>
            c.id === commentId
              ? {
                  ...c,
                  replies: c.replies.filter((r) => r.id !== replyId),
                }
              : c
          )
        );
        setDeleteReplyDialogOpen(false);
        setDeletingReplyId(null);
        setDeletingReplyCommentId(null);
      }
    } catch (err) {
      console.error('Failed to delete reply:', err);
    }
  };

  // Fetch comments on mount and when videoId changes
  useEffect(() => {
    const fetchComments = async () => {
      setIsLoading(true);
      try {
        const res = await fetch(`/api/comments?videoId=${videoId}`);
        if (res.ok) {
          const data = await res.json();
          setComments(data);
        }
      } catch (err) {
        console.error('Failed to fetch comments:', err);
      } finally {
        setIsLoading(false);
      }
    };

    fetchComments();
  }, [videoId]);

  const handleCommentSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!session?.user || !newCommentContent.trim()) return;

    setIsSubmitting(true);
    try {
      const res = await fetch('/api/comments', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ videoId, content: newCommentContent }),
      });

      if (res.ok) {
        const newComment = await res.json();
        setComments([newComment, ...comments]);
        setNewCommentContent('');
      }
    } catch (err) {
      console.error('Failed to post comment:', err);
    } finally {
      setIsSubmitting(false);
    }
  };

  const handleReplySubmit = async (e: React.FormEvent, commentId: string) => {
    e.preventDefault();
    if (!session?.user || !replyContent.trim()) return;

    setIsSubmitting(true);
    try {
      const res = await fetch(`/api/comments/${commentId}/reply`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ content: replyContent }),
      });

      if (res.ok) {
        const newReply = await res.json();
        setComments(
          comments.map((c) =>
            c.id === commentId
              ? { ...c, replies: [...c.replies, newReply] }
              : c
          )
        );
        setReplyContent('');
        setReplyingToId(null);
      }
    } catch (err) {
      console.error('Failed to post reply:', err);
    } finally {
      setIsSubmitting(false);
    }
  };

  const getDisplayName = (user: User) => user.name || user.email.split('@')[0];
  const getInitials = (user: User) => {
    const name = getDisplayName(user);
    return name
      .split(' ')
      .map((n) => n[0])
      .join('')
      .toUpperCase();
  };

  if (isLoading) {
    return <div className="py-4 text-sm text-muted-foreground">Loading comments...</div>;
  }

  return (
    <div>
      <h3 className="text-lg font-semibold mb-4">Comments ({comments.length})</h3>

      {/* Add Comment Form */}
      {session?.user ? (
        <form onSubmit={handleCommentSubmit} className="mb-6 pb-4 border-b">
          <div className="flex gap-3">
            <Avatar className="w-8 h-8 shrink-0">
              <AvatarImage src={(session.user as any).image} alt={(session.user as any).name} />
              <AvatarFallback>
                {getInitials({
                  id: (session.user as any).id,
                  name: (session.user as any).name,
                  email: (session.user as any).email,
                  image: (session.user as any).image,
                })}
              </AvatarFallback>
            </Avatar>
            <div className="flex-1">
              <Textarea
                placeholder="Add a comment..."
                value={newCommentContent}
                onChange={(e) => setNewCommentContent(e.target.value)}
                rows={2}
                className="mb-2"
              />
              <div className="flex gap-2 justify-end">
                <Button
                  type="button"
                  variant="outline"
                  size="sm"
                  onClick={() => setNewCommentContent('')}
                >
                  Cancel
                </Button>
                <Button
                  type="submit"
                  size="sm"
                  disabled={!newCommentContent.trim() || isSubmitting}
                >
                  {isSubmitting ? 'Posting...' : 'Comment'}
                </Button>
              </div>
            </div>
          </div>
        </form>
      ) : (
        <div className="mb-6 pb-4 border-b text-sm text-muted-foreground">
          Sign in to comment
        </div>
      )}

      {/* Comments List */}
      <div className="space-y-4">
        {comments.length === 0 ? (
          <p className="text-sm text-muted-foreground">No comments yet. Be the first to comment!</p>
        ) : (
          comments.map((comment) => (
            <div key={comment.id} className="space-y-3">
              {/* Comment */}
              <div className="flex gap-3">
                <Avatar className="w-8 h-8 shrink-0">
                  <AvatarImage src={comment.user.image || undefined} alt={getDisplayName(comment.user)} />
                  <AvatarFallback>{getInitials(comment.user)}</AvatarFallback>
                </Avatar>
                <div className="flex-1">
                  <div className="bg-muted rounded-lg p-3">
                    <div className="flex items-center gap-2 mb-1">
                      <span className="text-sm font-medium">{getDisplayName(comment.user)}</span>
                      <span className="text-xs text-muted-foreground">
                        {formatDistanceToNow(new Date(comment.createdAt), { addSuffix: true })}
                      </span>
                      {isAdmin && (
                        <AlertDialog open={deleteDialogOpen && deletingCommentId === comment.id} onOpenChange={(open) => {
                          if (!open) {
                            setDeleteDialogOpen(false);
                            setDeletingCommentId(null);
                          }
                        }}>
                          <button
                            onClick={() => {
                              setDeleteDialogOpen(true);
                              setDeletingCommentId(comment.id);
                            }}
                            className="ml-auto p-1 hover:bg-destructive/20 rounded"
                            title="Delete comment"
                          >
                            <Trash2 className="w-3 h-3 text-destructive" />
                          </button>
                          <AlertDialogContent>
                            <AlertDialogHeader>
                              <AlertDialogTitle>Delete Comment</AlertDialogTitle>
                              <AlertDialogDescription>
                                Are you sure you want to delete this comment?
                              </AlertDialogDescription>
                            </AlertDialogHeader>
                            <div className="flex gap-2 justify-end">
                              <AlertDialogCancel>Cancel</AlertDialogCancel>
                              <AlertDialogAction
                                onClick={() => handleDeleteComment(comment.id)}
                              >
                                Delete
                              </AlertDialogAction>
                            </div>
                          </AlertDialogContent>
                        </AlertDialog>
                      )}
                    </div>
                    <p className="text-sm">{comment.content}</p>
                  </div>
                  {session?.user && (
                    <Button
                      variant="ghost"
                      size="sm"
                      className="mt-1 text-xs h-auto p-0"
                      onClick={() => setReplyingToId(replyingToId === comment.id ? null : comment.id)}
                    >
                      {replyingToId === comment.id ? 'Cancel' : 'Reply'}
                    </Button>
                  )}
                </div>
              </div>

              {/* Reply Form */}
              {replyingToId === comment.id && session?.user && (
                <form
                  onSubmit={(e) => handleReplySubmit(e, comment.id)}
                  className="ml-8 flex gap-3 mb-3"
                >
                  <Avatar className="w-8 h-8 shrink-0">
                    <AvatarImage src={(session.user as any).image} alt={(session.user as any).name} />
                    <AvatarFallback>
                      {getInitials({
                        id: (session.user as any).id,
                        name: (session.user as any).name,
                        email: (session.user as any).email,
                        image: (session.user as any).image,
                      })}
                    </AvatarFallback>
                  </Avatar>
                  <div className="flex-1">
                    <Textarea
                      placeholder="Add a reply..."
                      value={replyContent}
                      onChange={(e) => setReplyContent(e.target.value)}
                      rows={2}
                      className="mb-2"
                    />
                    <div className="flex gap-2 justify-end">
                      <Button
                        type="button"
                        variant="outline"
                        size="sm"
                        onClick={() => {
                          setReplyContent('');
                          setReplyingToId(null);
                        }}
                      >
                        Cancel
                      </Button>
                      <Button
                        type="submit"
                        size="sm"
                        disabled={!replyContent.trim() || isSubmitting}
                      >
                        {isSubmitting ? 'Replying...' : 'Reply'}
                      </Button>
                    </div>
                  </div>
                </form>
              )}

              {/* Replies */}
              {comment.replies.length > 0 && (
                <div className="ml-8 space-y-3 pt-2 border-l-2 border-muted pl-4">
                  {comment.replies.map((reply) => (
                    <div key={reply.id} className="flex gap-3">
                      <Avatar className="w-8 h-8 shrink-0">
                        <AvatarImage src={reply.user.image || undefined} alt={getDisplayName(reply.user)} />
                        <AvatarFallback>{getInitials(reply.user)}</AvatarFallback>
                      </Avatar>
                      <div className="flex-1">
                        <div className="bg-muted rounded-lg p-3">
                          <div className="flex items-center gap-2 mb-1">
                            <span className="text-sm font-medium">{getDisplayName(reply.user)}</span>
                            <span className="text-xs text-muted-foreground">
                              {formatDistanceToNow(new Date(reply.createdAt), { addSuffix: true })}
                            </span>
                            {isAdmin && (
                              <AlertDialog open={deleteReplyDialogOpen && deletingReplyId === reply.id} onOpenChange={(open) => {
                                if (!open) {
                                  setDeleteReplyDialogOpen(false);
                                  setDeletingReplyId(null);
                                  setDeletingReplyCommentId(null);
                                }
                              }}>
                                <button
                                  onClick={() => {
                                    setDeleteReplyDialogOpen(true);
                                    setDeletingReplyId(reply.id);
                                    setDeletingReplyCommentId(comment.id);
                                  }}
                                  className="ml-auto p-1 hover:bg-destructive/20 rounded"
                                  title="Delete reply"
                                >
                                  <Trash2 className="w-3 h-3 text-destructive" />
                                </button>
                                <AlertDialogContent>
                                  <AlertDialogHeader>
                                    <AlertDialogTitle>Delete Reply</AlertDialogTitle>
                                    <AlertDialogDescription>
                                      Are you sure you want to delete this reply?
                                    </AlertDialogDescription>
                                  </AlertDialogHeader>
                                  <div className="flex gap-2 justify-end">
                                    <AlertDialogCancel>Cancel</AlertDialogCancel>
                                    <AlertDialogAction
                                      onClick={() => handleDeleteReply(reply.id, comment.id)}
                                    >
                                      Delete
                                    </AlertDialogAction>
                                  </div>
                                </AlertDialogContent>
                              </AlertDialog>
                            )}
                          </div>
                          <p className="text-sm">{reply.content}</p>
                        </div>
                      </div>
                    </div>
                  ))}
                </div>
              )}
            </div>
          ))
        )}
      </div>
    </div>
  );
}