<?php
declare(strict_types=1);

/**
 * Creates a thumbnail for an image.
 * 
 * @param string $sourcePath Path to the source image.
 * @param string $targetPath Path where the thumbnail should be saved.
 * @param int $maxWidth Maximum width of the thumbnail.
 * @param int $maxHeight Maximum height of the thumbnail.
 * @return bool True on success, false on failure.
 */
function createThumbnail(string $sourcePath, string $targetPath, int $maxWidth = 400, int $maxHeight = 400): bool {
    if (!file_exists($sourcePath)) {
        return false;
    }

    $imageInfo = getimagesize($sourcePath);
    if ($imageInfo === false) {
        return false;
    }

    list($width, $height, $type) = $imageInfo;
    $sourceImage = null;

    switch ($type) {
        case IMAGETYPE_JPEG:
            $sourceImage = @imagecreatefromjpeg($sourcePath);
            break;
        case IMAGETYPE_PNG:
            $sourceImage = @imagecreatefrompng($sourcePath);
            break;
        case IMAGETYPE_GIF:
            $sourceImage = @imagecreatefromgif($sourcePath);
            break;
        case IMAGETYPE_WEBP:
            $sourceImage = @imagecreatefromwebp($sourcePath);
            break;
        default:
            return false;
    }

    if (!$sourceImage) {
        return false;
    }

    // Calculate dimensions
    $ratio = min($maxWidth / $width, $maxHeight / $height);
    if ($ratio >= 1) {
        $newWidth = $width;
        $newHeight = $height;
    } else {
        $newWidth = (int)($width * $ratio);
        $newHeight = (int)($height * $ratio);
    }

    $thumbnail = imagecreatetruecolor($newWidth, $newHeight);
    
    // Handle transparency for PNG/GIF/WebP
    if ($type == IMAGETYPE_PNG || $type == IMAGETYPE_GIF || $type == IMAGETYPE_WEBP) {
        imagealphablending($thumbnail, false);
        imagesavealpha($thumbnail, true);
        $transparent = imagecolorallocatealpha($thumbnail, 255, 255, 255, 127);
        imagefilledrectangle($thumbnail, 0, 0, $newWidth, $newHeight, $transparent);
    }

    imagecopyresampled($thumbnail, $sourceImage, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);

    if (!is_dir(dirname($targetPath))) {
        mkdir(dirname($targetPath), 0775, true);
    }

    $success = false;
    switch ($type) {
        case IMAGETYPE_JPEG:
            $success = imagejpeg($thumbnail, $targetPath, 85);
            break;
        case IMAGETYPE_PNG:
            $success = imagepng($thumbnail, $targetPath);
            break;
        case IMAGETYPE_GIF:
            $success = imagegif($thumbnail, $targetPath);
            break;
        case IMAGETYPE_WEBP:
            $success = imagewebp($thumbnail, $targetPath);
            break;
    }

    imagedestroy($sourceImage);
    imagedestroy($thumbnail);

    return $success;
}

/**
 * Checks if a mime type is an image.
 */
function isImage(string $mimeType): bool {
    return str_starts_with($mimeType, 'image/');
}

/**
 * Checks if a mime type is a video.
 */
function isVideo(string $mimeType): bool {
    return str_starts_with($mimeType, 'video/');
}