import { useEffect, useState } from "react";
import { useParams, Link } from "react-router-dom";
import Layout from "@/components/Layout";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Separator } from "@/components/ui/separator";
import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar";
import {
  Github,
  ExternalLink,
  LayoutDashboard,
  Calendar,
  Cpu,
  Activity,
} from "lucide-react";

const API_BASE = import.meta.env.VITE_API_BASE || "";

interface Project {
  id: string;
  title: string;
  description?: string | null;
  status?: string | null;
  technologies?: string[] | null;
  github_url?: string | null;
  live_url?: string | null;
  image_url?: string | null;
  engine?: string | null;
  priority?: string | null;
  progress?: number | null;
  created_at?: string | null;
  updated_at?: string | null;
}

interface Owner {
  id: string;
  username?: string | null;
  full_name?: string | null;
  avatar_url?: string | null;
}

const STATUS_COLORS: Record<string, string> = {
  planning: "bg-slate-500/20 text-slate-300 border-slate-600",
  in_progress: "bg-blue-500/20 text-blue-300 border-blue-600",
  completed: "bg-green-500/20 text-green-300 border-green-600",
  on_hold: "bg-yellow-500/20 text-yellow-300 border-yellow-600",
};

const STATUS_LABELS: Record<string, string> = {
  planning: "Planning",
  in_progress: "In Progress",
  completed: "Completed",
  on_hold: "On Hold",
};

const formatDate = (v?: string | null) => {
  if (!v) return null;
  const d = new Date(v);
  if (isNaN(d.getTime())) return null;
  return d.toLocaleDateString(undefined, { dateStyle: "medium" });
};

export default function ProjectDetail() {
  const { projectId } = useParams<{ projectId: string }>();
  const [project, setProject] = useState<Project | null>(null);
  const [owner, setOwner] = useState<Owner | null>(null);
  const [loading, setLoading] = useState(true);
  const [notFound, setNotFound] = useState(false);

  useEffect(() => {
    if (!projectId) return;
    setLoading(true);
    fetch(`${API_BASE}/api/projects/${projectId}`)
      .then((r) => {
        if (r.status === 404) { setNotFound(true); return null; }
        return r.json();
      })
      .then((body) => {
        if (!body) return;
        setProject(body.project);
        setOwner(body.owner);
      })
      .catch(() => setNotFound(true))
      .finally(() => setLoading(false));
  }, [projectId]);

  if (loading) {
    return (
      <Layout>
        <div className="flex items-center justify-center min-h-[60vh]">
          <div className="animate-pulse text-slate-400">Loading project…</div>
        </div>
      </Layout>
    );
  }

  if (notFound || !project) {
    return (
      <Layout>
        <div className="flex flex-col items-center justify-center min-h-[60vh] gap-4">
          <p className="text-xl text-slate-300">Project not found.</p>
          <Button asChild variant="outline">
            <Link to="/projects">Browse projects</Link>
          </Button>
        </div>
      </Layout>
    );
  }

  const statusKey = project.status ?? "planning";
  const statusClass = STATUS_COLORS[statusKey] ?? STATUS_COLORS.planning;
  const statusLabel = STATUS_LABELS[statusKey] ?? statusKey;

  const ownerSlug = owner?.username ?? owner?.id;
  const ownerName = owner?.full_name || owner?.username || "Unknown";
  const ownerInitials = ownerName
    .split(" ")
    .map((w) => w[0])
    .join("")
    .slice(0, 2)
    .toUpperCase();

  return (
    <Layout>
      <div className="max-w-4xl mx-auto px-4 py-10 space-y-8">
        {/* Header */}
        <div className="space-y-3">
          <div className="flex flex-wrap items-center gap-3">
            <Badge className={`text-xs border ${statusClass}`}>
              {statusLabel}
            </Badge>
            {project.priority && (
              <Badge variant="outline" className="text-xs border-slate-600 text-slate-400">
                {project.priority} priority
              </Badge>
            )}
          </div>
          <h1 className="text-3xl font-bold text-white">{project.title}</h1>
          {project.description && (
            <p className="text-slate-300 leading-relaxed text-base max-w-2xl">
              {project.description}
            </p>
          )}
        </div>

        {/* Action buttons */}
        <div className="flex flex-wrap gap-3">
          <Button asChild>
            <Link to={`/projects/${project.id}/board`}>
              <LayoutDashboard className="mr-2 h-4 w-4" />
              Project Board
            </Link>
          </Button>
          {project.github_url && (
            <Button asChild variant="outline">
              <a href={project.github_url} target="_blank" rel="noopener noreferrer">
                <Github className="mr-2 h-4 w-4" />
                Repository
              </a>
            </Button>
          )}
          {project.live_url && (
            <Button asChild variant="outline">
              <a href={project.live_url} target="_blank" rel="noopener noreferrer">
                <ExternalLink className="mr-2 h-4 w-4" />
                Live
              </a>
            </Button>
          )}
        </div>

        <Separator className="border-slate-700" />

        <div className="grid grid-cols-1 md:grid-cols-3 gap-6">
          {/* Meta card */}
          <Card className="bg-slate-900/60 border-slate-700 md:col-span-1 space-y-0">
            <CardHeader className="pb-3">
              <CardTitle className="text-sm text-slate-400 uppercase tracking-wide">
                Details
              </CardTitle>
            </CardHeader>
            <CardContent className="space-y-4 text-sm">
              {owner && (
                <div className="flex items-center gap-3">
                  <Avatar className="h-8 w-8">
                    <AvatarImage src={owner.avatar_url ?? undefined} />
                    <AvatarFallback className="bg-slate-700 text-slate-300 text-xs">
                      {ownerInitials}
                    </AvatarFallback>
                  </Avatar>
                  <div>
                    <p className="text-slate-400 text-xs">Owner</p>
                    {ownerSlug ? (
                      <Link
                        to={`/u/${ownerSlug}`}
                        className="text-aethex-300 hover:underline font-medium"
                      >
                        {ownerName}
                      </Link>
                    ) : (
                      <span className="text-slate-200">{ownerName}</span>
                    )}
                  </div>
                </div>
              )}

              {project.engine && (
                <div className="flex items-start gap-2 text-slate-300">
                  <Cpu className="h-4 w-4 mt-0.5 text-slate-500 shrink-0" />
                  <div>
                    <p className="text-slate-400 text-xs">Engine</p>
                    <p>{project.engine}</p>
                  </div>
                </div>
              )}

              {typeof project.progress === "number" && (
                <div className="space-y-1">
                  <div className="flex items-center gap-2 text-slate-400 text-xs">
                    <Activity className="h-3.5 w-3.5" />
                    <span>Progress — {project.progress}%</span>
                  </div>
                  <div className="w-full bg-slate-700 rounded-full h-1.5">
                    <div
                      className="bg-aethex-500 h-1.5 rounded-full transition-all"
                      style={{ width: `${Math.min(100, project.progress)}%` }}
                    />
                  </div>
                </div>
              )}

              {(project.created_at || project.updated_at) && (
                <div className="flex items-start gap-2 text-slate-300">
                  <Calendar className="h-4 w-4 mt-0.5 text-slate-500 shrink-0" />
                  <div className="space-y-0.5">
                    {project.created_at && (
                      <p className="text-xs text-slate-400">
                        Created {formatDate(project.created_at)}
                      </p>
                    )}
                    {project.updated_at && (
                      <p className="text-xs text-slate-400">
                        Updated {formatDate(project.updated_at)}
                      </p>
                    )}
                  </div>
                </div>
              )}
            </CardContent>
          </Card>

          {/* Technologies */}
          {project.technologies && project.technologies.length > 0 && (
            <Card className="bg-slate-900/60 border-slate-700 md:col-span-2">
              <CardHeader className="pb-3">
                <CardTitle className="text-sm text-slate-400 uppercase tracking-wide">
                  Technologies
                </CardTitle>
              </CardHeader>
              <CardContent>
                <div className="flex flex-wrap gap-2">
                  {project.technologies.map((tech) => (
                    <Badge
                      key={tech}
                      variant="outline"
                      className="border-slate-600 text-slate-300 text-xs"
                    >
                      {tech}
                    </Badge>
                  ))}
                </div>
              </CardContent>
            </Card>
          )}
        </div>
      </div>
    </Layout>
  );
}