<?php

declare(strict_types=1);

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Support\MarkdownRenderer;
use GdImage;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Http\UploadedFile;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;
use RuntimeException;
use Throwable;

class UploadController extends Controller
{
    private const MAX_FILE_KB = 6144;

    private const MAX_MAIN_WIDTH = 2400;

    private const THUMB_WIDTH = 320;

    private const MAIN_WEBP_QUALITY = 86;

    private const THUMB_WEBP_QUALITY = 80;

    public function markdownPreview(Request $request, MarkdownRenderer $markdownRenderer): JsonResponse
    {
        $validated = $request->validate([
            'markdown' => ['nullable', 'string'],
        ]);

        return response()->json([
            'success' => true,
            'html' => $markdownRenderer->render((string) ($validated['markdown'] ?? '')),
        ]);
    }

    public function markdownImage(Request $request): JsonResponse
    {
        $validated = $request->validate([
            'image' => ['required', 'file', 'image', 'mimes:jpg,jpeg,png,webp,gif', 'max:' . self::MAX_FILE_KB],
        ], [
            'image.required' => '请选择要上传的图片。',
            'image.image' => '仅支持图片文件上传。',
            'image.mimes' => '图片格式仅支持 jpg、jpeg、png、webp、gif。',
            'image.max' => '图片大小不能超过 6MB。',
        ]);

        if (! function_exists('imagecreatefromstring') || ! function_exists('imagewebp')) {
            return response()->json([
                'success' => false,
                'message' => '服务器不支持图片处理能力（GD/WebP）。',
            ], 500);
        }

        /** @var UploadedFile $file */
        $file = $validated['image'];

        $sourceImage = null;
        $mainImage = null;
        $thumbImage = null;

        try {
            [$sourceImage, $sourceWidth, $sourceHeight] = $this->createImageFromUpload($file);

            $mainWidth = min(self::MAX_MAIN_WIDTH, $sourceWidth);
            $mainImage = $this->resizeImage($sourceImage, $sourceWidth, $sourceHeight, $mainWidth);

            $thumbWidth = min(self::THUMB_WIDTH, imagesx($mainImage));
            $thumbImage = $this->resizeImage($mainImage, imagesx($mainImage), imagesy($mainImage), $thumbWidth);

            $mainBinary = $this->encodeWebp($mainImage, self::MAIN_WEBP_QUALITY);
            $thumbBinary = $this->encodeWebp($thumbImage, self::THUMB_WEBP_QUALITY);

            $subDir = now()->format('Y/m/d');
            $baseName = now()->format('YmdHis') . '-' . Str::lower(Str::random(8));
            $mainPath = "markdown-images/{$subDir}/{$baseName}.webp";
            $thumbPath = "markdown-images/{$subDir}/{$baseName}_thumb.webp";

            Storage::disk('public')->put($mainPath, $mainBinary);
            Storage::disk('public')->put($thumbPath, $thumbBinary);

            $mainUrl = '/storage/' . ltrim($mainPath, '/');
            $thumbUrl = '/storage/' . ltrim($thumbPath, '/');

            return response()->json([
                'success' => true,
                'url' => $mainUrl,
                'thumb_url' => $thumbUrl,
                'filename' => basename($mainPath),
                'markdown' => '![](' . $mainUrl . ')',
            ]);
        } catch (Throwable $exception) {
            report($exception);

            return response()->json([
                'success' => false,
                'message' => '图片上传失败，请稍后重试。',
            ], 422);
        } finally {
            if ($sourceImage instanceof GdImage) {
                imagedestroy($sourceImage);
            }

            if ($mainImage instanceof GdImage) {
                imagedestroy($mainImage);
            }

            if ($thumbImage instanceof GdImage) {
                imagedestroy($thumbImage);
            }
        }
    }

    /**
     * @return array{0:GdImage,1:int,2:int}
     */
    private function createImageFromUpload(UploadedFile $file): array
    {
        $path = $file->getRealPath();
        if ($path === false || $path === '') {
            throw new RuntimeException('上传临时文件不可用。');
        }

        $binary = file_get_contents($path);
        if ($binary === false) {
            throw new RuntimeException('读取上传文件失败。');
        }

        $image = @imagecreatefromstring($binary);
        if (! $image instanceof GdImage) {
            throw new RuntimeException('无法解析图片内容。');
        }

        if (! imageistruecolor($image)) {
            imagepalettetotruecolor($image);
        }

        $width = imagesx($image);
        $height = imagesy($image);

        if ($width < 1 || $height < 1) {
            imagedestroy($image);
            throw new RuntimeException('图片尺寸无效。');
        }

        return [$image, $width, $height];
    }

    private function resizeImage(GdImage $source, int $sourceWidth, int $sourceHeight, int $targetWidth): GdImage
    {
        $targetWidth = max(1, $targetWidth);

        if ($sourceWidth === $targetWidth) {
            $targetHeight = $sourceHeight;
        } else {
            $targetHeight = max(1, (int) round($sourceHeight * ($targetWidth / $sourceWidth)));
        }

        $canvas = imagecreatetruecolor($targetWidth, $targetHeight);
        if (! $canvas instanceof GdImage) {
            throw new RuntimeException('创建图片画布失败。');
        }

        $background = imagecolorallocate($canvas, 255, 255, 255);
        imagefill($canvas, 0, 0, $background);

        if (! imagecopyresampled($canvas, $source, 0, 0, 0, 0, $targetWidth, $targetHeight, $sourceWidth, $sourceHeight)) {
            imagedestroy($canvas);
            throw new RuntimeException('图片缩放失败。');
        }

        return $canvas;
    }

    private function encodeWebp(GdImage $image, int $quality): string
    {
        ob_start();
        $saved = imagewebp($image, null, $quality);
        $binary = ob_get_clean();

        if (! $saved || ! is_string($binary) || $binary === '') {
            throw new RuntimeException('WebP 编码失败。');
        }

        return $binary;
    }
}