<?php

namespace App\Http\Controllers;

use App\Models\Forum;
use App\Models\Thread;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;

class ThreadController extends Controller
{
    public function index(Request $request): JsonResponse
    {
        $query = Thread::query();

        $forumParam = $request->query('forum');
        if (is_string($forumParam)) {
            $forumId = $this->parseIriId($forumParam);
            if ($forumId !== null) {
                $query->where('forum_id', $forumId);
            }
        }

        $threads = $query
            ->latest('created_at')
            ->get()
            ->map(fn (Thread $thread) => $this->serializeThread($thread));

        return response()->json($threads);
    }

    public function show(Thread $thread): JsonResponse
    {
        return response()->json($this->serializeThread($thread));
    }

    public function store(Request $request): JsonResponse
    {
        $data = $request->validate([
            'title' => ['required', 'string'],
            'body' => ['required', 'string'],
            'forum' => ['required', 'string'],
        ]);

        $forumId = $this->parseIriId($data['forum']);
        $forum = Forum::findOrFail($forumId);

        if ($forum->type !== 'forum') {
            return response()->json(['message' => 'Threads can only be created inside forums.'], 422);
        }

        $thread = Thread::create([
            'forum_id' => $forum->id,
            'user_id' => $request->user()?->id,
            'title' => $data['title'],
            'body' => $data['body'],
        ]);

        return response()->json($this->serializeThread($thread), 201);
    }

    public function destroy(Thread $thread): JsonResponse
    {
        $thread->delete();

        return response()->json(null, 204);
    }

    private function parseIriId(?string $value): ?int
    {
        if (!$value) {
            return null;
        }

        if (preg_match('#/forums/(\d+)$#', $value, $matches)) {
            return (int) $matches[1];
        }

        if (is_numeric($value)) {
            return (int) $value;
        }

        return null;
    }

    private function serializeThread(Thread $thread): array
    {
        return [
            'id' => $thread->id,
            'title' => $thread->title,
            'body' => $thread->body,
            'forum' => "/api/forums/{$thread->forum_id}",
            'user_id' => $thread->user_id,
            'created_at' => $thread->created_at?->toIso8601String(),
            'updated_at' => $thread->updated_at?->toIso8601String(),
        ];
    }
}