<?php

namespace App\Services;

use Illuminate\Http\UploadedFile;
use RuntimeException;

class EventMediaImageProcessor
{
    private const MAX_ORIGINAL_SIDE = 3508;

    private const PREVIEW_MAX_SIDE = 900;

    private const THUMBNAIL_SIZE = 320;

    /**
     * @return array{
     *     original: string,
     *     preview: string,
     *     thumbnail: string,
     *     width: int,
     *     height: int,
     *     preview_width: int,
     *     preview_height: int,
     *     thumbnail_width: int,
     *     thumbnail_height: int,
     *     mime_type: string,
     *     size: int
     * }
     */
    public function process(UploadedFile $file): array
    {
        $source = imagecreatefromstring((string) file_get_contents($file->getRealPath()));

        if (! $source) {
            throw new RuntimeException('The uploaded image could not be processed.');
        }

        $sourceWidth = imagesx($source);
        $sourceHeight = imagesy($source);

        $original = $this->resizeContain($source, $sourceWidth, $sourceHeight, self::MAX_ORIGINAL_SIDE);
        $preview = $this->resizeContain($source, $sourceWidth, $sourceHeight, self::PREVIEW_MAX_SIDE, 84);
        $thumbnail = $this->resizeCover($source, $sourceWidth, $sourceHeight, self::THUMBNAIL_SIZE);

        imagedestroy($source);

        return [
            'original' => $original['contents'],
            'preview' => $preview['contents'],
            'thumbnail' => $thumbnail['contents'],
            'width' => $original['width'],
            'height' => $original['height'],
            'preview_width' => $preview['width'],
            'preview_height' => $preview['height'],
            'thumbnail_width' => self::THUMBNAIL_SIZE,
            'thumbnail_height' => self::THUMBNAIL_SIZE,
            'mime_type' => 'image/jpeg',
            'size' => strlen($original['contents']),
        ];
    }

    /**
     * @return array{contents: string, width: int, height: int}
     */
    private function resizeContain(
        \GdImage $source,
        int $sourceWidth,
        int $sourceHeight,
        int $maxSide,
        int $quality = 90
    ): array {
        $scale = min(1, $maxSide / max($sourceWidth, $sourceHeight));
        $width = max(1, (int) round($sourceWidth * $scale));
        $height = max(1, (int) round($sourceHeight * $scale));

        $canvas = imagecreatetruecolor($width, $height);
        $this->fillCanvas($canvas, $width, $height);
        imagecopyresampled($canvas, $source, 0, 0, 0, 0, $width, $height, $sourceWidth, $sourceHeight);

        return [
            'contents' => $this->encodeJpeg($canvas, $quality),
            'width' => $width,
            'height' => $height,
        ];
    }

    /**
     * @return array{contents: string, width: int, height: int}
     */
    private function resizeCover(\GdImage $source, int $sourceWidth, int $sourceHeight, int $size): array
    {
        $scale = max($size / $sourceWidth, $size / $sourceHeight);
        $width = (int) round($sourceWidth * $scale);
        $height = (int) round($sourceHeight * $scale);
        $x = (int) round(($size - $width) / 2);
        $y = (int) round(($size - $height) / 2);

        $canvas = imagecreatetruecolor($size, $size);
        $this->fillCanvas($canvas, $size, $size);
        imagecopyresampled($canvas, $source, $x, $y, 0, 0, $width, $height, $sourceWidth, $sourceHeight);

        return [
            'contents' => $this->encodeJpeg($canvas, 80),
            'width' => $size,
            'height' => $size,
        ];
    }

    private function fillCanvas(\GdImage $canvas, int $width, int $height): void
    {
        $background = imagecolorallocate($canvas, 255, 255, 255);
        imagefilledrectangle($canvas, 0, 0, $width, $height, $background);
    }

    private function encodeJpeg(\GdImage $image, int $quality): string
    {
        ob_start();
        imagejpeg($image, null, $quality);
        $contents = (string) ob_get_clean();
        imagedestroy($image);

        return $contents;
    }
}