<?php

namespace App\Http\Controllers;

use App\Models\Attachment;
use App\Models\AttachmentExtension;
use App\Models\Post;
use App\Models\Setting;
use App\Models\Thread;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;
use Symfony\Component\HttpFoundation\Response;

class AttachmentController extends Controller
{
    public function index(Request $request): JsonResponse
    {
        $query = Attachment::query()
            ->with(['extension', 'group'])
            ->withoutTrashed();

        $threadParam = $request->query('thread');
        $postParam = $request->query('post');

        if ($threadParam) {
            $threadId = $this->parseThreadId($threadParam);
            if ($threadId !== null) {
                $query->where('thread_id', $threadId);
            }
        }

        if ($postParam) {
            $postId = $this->parsePostId($postParam);
            if ($postId !== null) {
                $query->where('post_id', $postId);
            }
        }

        $attachments = $query
            ->latest('created_at')
            ->get()
            ->map(fn (Attachment $attachment) => $this->serializeAttachment($attachment));

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

    public function store(Request $request): JsonResponse
    {
        $user = $request->user();
        if (!$user) {
            return response()->json(['message' => 'Unauthorized.'], 401);
        }

        $data = $request->validate([
            'thread' => ['nullable', 'string'],
            'post' => ['nullable', 'string'],
            'file' => ['required', 'file'],
        ]);

        $threadId = $this->parseThreadId($data['thread'] ?? null);
        $postId = $this->parsePostId($data['post'] ?? null);

        if (($threadId && $postId) || (!$threadId && !$postId)) {
            return response()->json(['message' => 'Provide either thread or post.'], 422);
        }

        $thread = null;
        $post = null;
        if ($threadId) {
            $thread = Thread::query()->findOrFail($threadId);
            if (!$this->canManageAttachments($user, $thread->user_id)) {
                return response()->json(['message' => 'Not authorized to add attachments.'], 403);
            }
        }

        if ($postId) {
            $post = Post::query()->findOrFail($postId);
            if (!$this->canManageAttachments($user, $post->user_id)) {
                return response()->json(['message' => 'Not authorized to add attachments.'], 403);
            }
        }

        $file = $request->file('file');
        if (!$file) {
            return response()->json(['message' => 'File missing.'], 422);
        }

        $mime = $file->getMimeType() ?? 'application/octet-stream';
        $extension = strtolower((string) $file->getClientOriginalExtension());

        $extensionRow = $this->resolveExtension($extension);
        if (!$extensionRow || !$extensionRow->group || !$extensionRow->group->is_active) {
            return response()->json(['message' => 'File type not allowed.'], 422);
        }

        $group = $extensionRow->group;
        if (!$this->matchesAllowed($mime, $extensionRow->allowed_mimes)) {
            return response()->json(['message' => 'File type not allowed.'], 422);
        }

        $maxSizeBytes = (int) $group->max_size_kb * 1024;
        if ($file->getSize() > $maxSizeBytes) {
            return response()->json(['message' => 'File exceeds allowed size.'], 422);
        }

        $scopeFolder = $threadId ? "threads/{$threadId}" : "posts/{$postId}";
        $filename = Str::uuid()->toString();
        if ($extension !== '') {
            $filename .= ".{$extension}";
        }

        $disk = 'local';
        $path = "attachments/{$scopeFolder}/{$filename}";
        Storage::disk($disk)->putFileAs("attachments/{$scopeFolder}", $file, $filename);

        $thumbnailPayload = $this->maybeCreateThumbnail($file, $scopeFolder);

        $attachment = Attachment::create([
            'thread_id' => $threadId,
            'post_id' => $postId,
            'attachment_extension_id' => $extensionRow->id,
            'attachment_group_id' => $group->id,
            'user_id' => $user->id,
            'disk' => $disk,
            'path' => $path,
            'thumbnail_path' => $thumbnailPayload['path'] ?? null,
            'thumbnail_mime_type' => $thumbnailPayload['mime'] ?? null,
            'thumbnail_size_bytes' => $thumbnailPayload['size'] ?? null,
            'original_name' => $file->getClientOriginalName(),
            'extension' => $extension !== '' ? $extension : null,
            'mime_type' => $mime,
            'size_bytes' => (int) $file->getSize(),
        ]);

        $attachment->loadMissing(['extension', 'group']);

        return response()->json($this->serializeAttachment($attachment), 201);
    }

    public function show(Attachment $attachment): JsonResponse
    {
        if (!$this->canViewAttachment($attachment)) {
            return response()->json(['message' => 'Not found.'], 404);
        }

        $attachment->loadMissing(['extension', 'group']);

        return response()->json($this->serializeAttachment($attachment));
    }

    public function download(Attachment $attachment): Response
    {
        if (!$this->canViewAttachment($attachment)) {
            abort(404);
        }

        $disk = Storage::disk($attachment->disk);
        if (!$disk->exists($attachment->path)) {
            abort(404);
        }

        $mime = $attachment->mime_type ?: 'application/octet-stream';

        return $disk->download($attachment->path, $attachment->original_name, [
            'Content-Type' => $mime,
        ]);
    }

    public function thumbnail(Attachment $attachment): Response
    {
        if (!$this->canViewAttachment($attachment)) {
            abort(404);
        }

        if (!$attachment->thumbnail_path) {
            abort(404);
        }

        $disk = Storage::disk($attachment->disk);
        if (!$disk->exists($attachment->thumbnail_path)) {
            abort(404);
        }

        $mime = $attachment->thumbnail_mime_type ?: 'image/jpeg';

        return $disk->response($attachment->thumbnail_path, null, [
            'Content-Type' => $mime,
        ]);
    }

    public function destroy(Request $request, Attachment $attachment): JsonResponse
    {
        $user = $request->user();
        if (!$user) {
            return response()->json(['message' => 'Unauthorized.'], 401);
        }

        if (!$this->canManageAttachments($user, $attachment->user_id)) {
            return response()->json(['message' => 'Not authorized to delete attachments.'], 403);
        }

        $attachment->delete();

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

    private function resolveExtension(string $extension): ?AttachmentExtension
    {
        if ($extension === '') {
            return null;
        }

        return AttachmentExtension::query()
            ->where('extension', strtolower($extension))
            ->with('group')
            ->first();
    }

    private function matchesAllowed(string $value, ?array $allowed): bool
    {
        if (!$allowed || count($allowed) === 0) {
            return true;
        }

        $normalized = strtolower(trim($value));

        foreach ($allowed as $entry) {
            if (strtolower(trim((string) $entry)) === $normalized) {
                return true;
            }
        }

        return false;
    }

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

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

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

        return null;
    }

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

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

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

        return null;
    }

    private function canViewAttachment(Attachment $attachment): bool
    {
        if ($attachment->trashed()) {
            return false;
        }

        if ($attachment->thread_id) {
            $thread = Thread::withTrashed()->find($attachment->thread_id);
            return $thread && !$thread->trashed();
        }

        if ($attachment->post_id) {
            $post = Post::withTrashed()->find($attachment->post_id);
            if (!$post || $post->trashed()) {
                return false;
            }
            $thread = Thread::withTrashed()->find($post->thread_id);
            return $thread && !$thread->trashed();
        }

        return false;
    }

    private function canManageAttachments($user, ?int $ownerId): bool
    {
        if (!$user) {
            return false;
        }

        if ($user->roles()->where('name', 'ROLE_ADMIN')->exists()) {
            return true;
        }

        return $ownerId !== null && $ownerId === $user->id;
    }

    private function serializeAttachment(Attachment $attachment): array
    {
        $isImage = str_starts_with((string) $attachment->mime_type, 'image/');

        return [
            'id' => $attachment->id,
            'thread_id' => $attachment->thread_id,
            'post_id' => $attachment->post_id,
            'extension' => $attachment->extension,
            'group' => $attachment->group ? [
                'id' => $attachment->group->id,
                'name' => $attachment->group->name,
                'category' => $attachment->group->category,
                'max_size_kb' => $attachment->group->max_size_kb,
            ] : null,
            'original_name' => $attachment->original_name,
            'mime_type' => $attachment->mime_type,
            'size_bytes' => $attachment->size_bytes,
            'download_url' => "/api/attachments/{$attachment->id}/download",
            'thumbnail_url' => $attachment->thumbnail_path
                ? "/api/attachments/{$attachment->id}/thumbnail"
                : null,
            'is_image' => $isImage,
            'created_at' => $attachment->created_at?->toIso8601String(),
        ];
    }

    private function maybeCreateThumbnail($file, string $scopeFolder): ?array
    {
        $enabled = $this->settingBool('attachments.create_thumbnails', true);
        if (!$enabled) {
            return null;
        }

        $mime = $file->getMimeType() ?? '';
        if (!str_starts_with($mime, 'image/')) {
            return null;
        }

        $maxWidth = $this->settingInt('attachments.thumbnail_max_width', 300);
        $maxHeight = $this->settingInt('attachments.thumbnail_max_height', 300);
        if ($maxWidth <= 0 || $maxHeight <= 0) {
            return null;
        }

        $sourcePath = $file->getPathname();
        $info = @getimagesize($sourcePath);
        if (!$info) {
            return null;
        }

        [$width, $height] = $info;
        if ($width <= 0 || $height <= 0) {
            return null;
        }

        if ($width <= $maxWidth && $height <= $maxHeight) {
            return null;
        }

        $ratio = min($maxWidth / $width, $maxHeight / $height);
        $targetWidth = max(1, (int) round($width * $ratio));
        $targetHeight = max(1, (int) round($height * $ratio));

        $sourceImage = $this->createImageFromFile($sourcePath, $mime);
        if (!$sourceImage) {
            return null;
        }

        $thumbImage = imagecreatetruecolor($targetWidth, $targetHeight);
        if (!$thumbImage) {
            imagedestroy($sourceImage);
            return null;
        }

        if (in_array($mime, ['image/png', 'image/gif'], true)) {
            imagecolortransparent($thumbImage, imagecolorallocatealpha($thumbImage, 0, 0, 0, 127));
            imagealphablending($thumbImage, false);
            imagesavealpha($thumbImage, true);
        }

        imagecopyresampled(
            $thumbImage,
            $sourceImage,
            0,
            0,
            0,
            0,
            $targetWidth,
            $targetHeight,
            $width,
            $height
        );

        $quality = $this->settingInt('attachments.thumbnail_quality', 85);
        $thumbBinary = $this->renderImageBinary($thumbImage, $mime, $quality);

        imagedestroy($sourceImage);
        imagedestroy($thumbImage);

        if ($thumbBinary === null) {
            return null;
        }

        $filename = Str::uuid()->toString();
        $extension = strtolower((string) $file->getClientOriginalExtension());
        if ($extension !== '') {
            $filename .= ".{$extension}";
        }

        $disk = 'local';
        $thumbPath = "attachments/{$scopeFolder}/thumbs/{$filename}";
        Storage::disk($disk)->put($thumbPath, $thumbBinary);

        return [
            'path' => $thumbPath,
            'mime' => $mime,
            'size' => strlen($thumbBinary),
        ];
    }

    private function createImageFromFile(string $path, string $mime)
    {
        return match ($mime) {
            'image/jpeg', 'image/jpg' => @imagecreatefromjpeg($path),
            'image/png' => @imagecreatefrompng($path),
            'image/gif' => @imagecreatefromgif($path),
            'image/webp' => function_exists('imagecreatefromwebp') ? @imagecreatefromwebp($path) : null,
            default => null,
        };
    }

    private function renderImageBinary($image, string $mime, int $quality): ?string
    {
        ob_start();
        $success = false;

        if (in_array($mime, ['image/jpeg', 'image/jpg'], true)) {
            $success = imagejpeg($image, null, max(10, min(95, $quality)));
        } elseif ($mime === 'image/png') {
            $compression = (int) round(9 - (max(10, min(95, $quality)) / 100) * 9);
            $success = imagepng($image, null, $compression);
        } elseif ($mime === 'image/gif') {
            $success = imagegif($image);
        } elseif ($mime === 'image/webp' && function_exists('imagewebp')) {
            $success = imagewebp($image, null, max(10, min(95, $quality)));
        }

        $data = ob_get_clean();

        if (!$success) {
            return null;
        }

        return $data !== false ? $data : null;
    }

    private function settingBool(string $key, bool $default): bool
    {
        $value = Setting::query()->where('key', $key)->value('value');
        if ($value === null) {
            return $default;
        }
        return in_array(strtolower($value), ['1', 'true', 'yes', 'on'], true);
    }

    private function settingInt(string $key, int $default): int
    {
        $value = Setting::query()->where('key', $key)->value('value');
        if ($value === null) {
            return $default;
        }
        return (int) $value;
    }
}