'use client';

import { useState, useEffect, useCallback } from 'react';
import { useParams, useRouter } from 'next/navigation';
import Link from 'next/link';
import {
  ArrowLeft,
  Plus,
  Loader2,
  Crown,
  Shield,
  MessageSquare,
  Trash2,
  UserPlus,
} from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import { Badge } from '@/components/ui/badge';
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select';

interface Member {
  id: string;
  role: 'ADMIN' | 'COMMENTATOR';
  userId: string;
  user: {
    id: string;
    name: string | null;
    email: string | null;
    image: string | null;
  };
}

interface Owner {
  id: string;
  name: string | null;
  email: string | null;
  image: string | null;
}

export default function ProjectMembersPage() {
  const params = useParams();
  const router = useRouter();
  const projectId = params.projectId as string;

  const [members, setMembers] = useState<Member[]>([]);
  const [owner, setOwner] = useState<Owner | null>(null);
  const [isLoading, setIsLoading] = useState(true);
  const [inviteEmail, setInviteEmail] = useState('');
  const [inviteRole, setInviteRole] = useState<'ADMIN' | 'COMMENTATOR'>('COMMENTATOR');
  const [isInviting, setIsInviting] = useState(false);
  const [error, setError] = useState('');
  const [success, setSuccess] = useState('');

  const fetchMembers = useCallback(async () => {
    try {
      const res = await fetch(`/api/projects/${projectId}/members`);
      if (!res.ok) {
        if (res.status === 403) router.push('/dashboard');
        return;
      }
      const data = await res.json();
      setMembers(data.data.members);
      setOwner(data.data.owner);
    } catch {
      setError('Failed to load members');
    } finally {
      setIsLoading(false);
    }
  }, [projectId, router]);

  useEffect(() => {
    fetchMembers();
  }, [fetchMembers]);

  const handleInvite = async (e: React.FormEvent) => {
    e.preventDefault();
    setIsInviting(true);
    setError('');
    setSuccess('');

    try {
      const res = await fetch(`/api/projects/${projectId}/members`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ email: inviteEmail, role: inviteRole }),
      });

      const data = await res.json();

      if (!res.ok) {
        setError(data.error || 'Failed to invite member');
        return;
      }

      if (data.user) {
        setSuccess(`Invited ${data.user.name || data.user.email || inviteEmail} as ${inviteRole.toLowerCase()}`);
      } else {
        setSuccess(data.message || `Invitation sent to ${inviteEmail}`);
      }
      setInviteEmail('');
      fetchMembers();
    } catch {
      setError('Something went wrong');
    } finally {
      setIsInviting(false);
    }
  };

  const handleRoleChange = async (memberId: string, newRole: string) => {
    try {
      const res = await fetch(`/api/projects/${projectId}/members/${memberId}`, {
        method: 'PATCH',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ role: newRole }),
      });

      if (!res.ok) {
        const data = await res.json();
        setError(data.error || 'Failed to update role');
        return;
      }

      fetchMembers();
    } catch {
      setError('Failed to update role');
    }
  };

  const handleRemove = async (memberId: string) => {
    if (!confirm('Are you sure you want to remove this member?')) return;

    try {
      const res = await fetch(`/api/projects/${projectId}/members/${memberId}`, {
        method: 'DELETE',
      });

      if (!res.ok) {
        const data = await res.json();
        setError(data.error || 'Failed to remove member');
        return;
      }

      fetchMembers();
    } catch {
      setError('Failed to remove member');
    }
  };

  if (isLoading) {
    return (
      <div className="flex items-center justify-center min-h-[50vh]">
        <Loader2 className="h-8 w-8 animate-spin text-muted-foreground" />
      </div>
    );
  }

  return (
    <div className="px-6 lg:px-8 py-8 w-full max-w-4xl mx-auto">
      <div className="mb-6">
        <Link
          href={`/projects/${projectId}`}
          className="inline-flex items-center text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          <ArrowLeft className="h-4 w-4 mr-1" />
          Back to Project
        </Link>
      </div>

      <div className="mb-8">
        <h1 className="text-3xl font-bold tracking-tight">Project Members</h1>
        <p className="text-muted-foreground mt-1">
          Manage who has access to this project. Admins can manage settings and delete content.
          Commentators can only view and leave comments.
        </p>
      </div>

      {/* Invite Form */}
      <Card className="mb-8">
        <CardHeader>
          <CardTitle className="flex items-center gap-2">
            <UserPlus className="h-5 w-5" />
            Invite Member
          </CardTitle>
          <CardDescription>
            Invite someone by email. They must have an account to be added.
          </CardDescription>
        </CardHeader>
        <CardContent>
          <form onSubmit={handleInvite} className="flex flex-col sm:flex-row gap-3 sm:items-end">
            <div className="w-full sm:flex-1">
              <Label htmlFor="email" className="mb-2 block">Email Address</Label>
              <Input
                id="email"
                type="email"
                placeholder="colleague@example.com"
                value={inviteEmail}
                onChange={(e) => setInviteEmail(e.target.value)}
                required
                disabled={isInviting}
              />
            </div>
            <div className="w-full sm:w-40">
              <Label className="mb-2 block">Role</Label>
              <Select value={inviteRole} onValueChange={(v) => setInviteRole(v as 'ADMIN' | 'COMMENTATOR')}>
                <SelectTrigger className="w-full">
                  <SelectValue />
                </SelectTrigger>
                <SelectContent>
                  <SelectItem value="ADMIN">Admin</SelectItem>
                  <SelectItem value="COMMENTATOR">Commentator</SelectItem>
                </SelectContent>
              </Select>
            </div>
            <Button type="submit" disabled={isInviting} className="w-full sm:w-auto">
              {isInviting ? (
                <Loader2 className="h-4 w-4 animate-spin" />
              ) : (
                <>
                  <Plus className="h-4 w-4 mr-1" />
                  Invite
                </>
              )}
            </Button>
          </form>

          {error && (
            <div className="mt-3 rounded-md bg-destructive/10 p-3 text-sm text-destructive">
              {error}
            </div>
          )}
          {success && (
            <div className="mt-3 rounded-md bg-green-500/10 p-3 text-sm text-green-700 dark:text-green-400">
              {success}
            </div>
          )}
        </CardContent>
      </Card>

      {/* Members List */}
      <Card>
        <CardHeader>
          <CardTitle>Current Members</CardTitle>
          <CardDescription>
            <strong>Admin</strong> — can manage project settings, members, and delete content.{' '}
            <strong>Commentator</strong> — can view and comment only.
          </CardDescription>
        </CardHeader>
        <CardContent className="space-y-3">
          {/* Owner */}
          {owner && (
            <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-4 sm:gap-0 p-3 rounded-lg bg-accent/30">
              <div className="flex items-center gap-3">
                <Avatar className="h-9 w-9">
                  <AvatarImage src={owner.image ?? undefined} />
                  <AvatarFallback>{owner.name?.charAt(0).toUpperCase() ?? 'U'}</AvatarFallback>
                </Avatar>
                <div>
                  <p className="text-sm font-medium">{owner.name || 'Unnamed'}</p>
                  <p className="text-xs text-muted-foreground">{owner.email}</p>
                </div>
              </div>
              <Badge variant="default" className="flex items-center gap-1">
                <Crown className="h-3 w-3" />
                Owner
              </Badge>
            </div>
          )}

          {/* Members */}
          {members.map((member) => (
            <div key={member.id} className="flex flex-col sm:flex-row sm:items-center justify-between gap-4 sm:gap-0 p-3 rounded-lg border">
              <div className="flex items-center gap-3">
                <Avatar className="h-9 w-9">
                  <AvatarImage src={member.user.image ?? undefined} />
                  <AvatarFallback>{member.user.name?.charAt(0).toUpperCase() ?? 'U'}</AvatarFallback>
                </Avatar>
                <div>
                  <p className="text-sm font-medium">{member.user.name || 'Unnamed'}</p>
                  <p className="text-xs text-muted-foreground">{member.user.email}</p>
                </div>
              </div>
              <div className="flex items-center gap-2 w-full sm:w-auto">
                <Select
                  value={member.role}
                  onValueChange={(v) => handleRoleChange(member.id, v)}
                >
                  <SelectTrigger className="w-full sm:w-36 h-8">
                    <SelectValue />
                  </SelectTrigger>
                  <SelectContent>
                    <SelectItem value="ADMIN">
                      <span className="flex items-center gap-1.5">
                        <Shield className="h-3.5 w-3.5" />
                        Admin
                      </span>
                    </SelectItem>
                    <SelectItem value="COMMENTATOR">
                      <span className="flex items-center gap-1.5">
                        <MessageSquare className="h-3.5 w-3.5" />
                        Commentator
                      </span>
                    </SelectItem>
                  </SelectContent>
                </Select>
                <Button
                  variant="ghost"
                  size="icon"
                  className="h-8 w-8 text-destructive hover:text-destructive"
                  onClick={() => handleRemove(member.id)}
                >
                  <Trash2 className="h-4 w-4" />
                </Button>
              </div>
            </div>
          ))}

          {members.length === 0 && (
            <p className="text-sm text-muted-foreground text-center py-4">
              No members yet. Invite someone above.
            </p>
          )}
        </CardContent>
      </Card>
    </div>
  );
}