<?php
namespace Vichan\Functions\Metadata;


/**
 * All image formats supported by vichan.
 */
const SUPPORTED_IMAGE_MIME_TYPES = [
	'image/jpeg',
	'image/png',
	'image/gif',
	'image/webp',
	'image/bmp',
	'image/avif'
];

/**
 * Non-image file types for which only thumbnail generation is supported.
 */
const SUPPORTED_THUMB_MIME_TYPES = [
	'text/plain',
	'application/pdf'
];

/**
 * @param string $mime Lowercase valid mime type.
 * @return ?string Vichan's preferred extension for the given mime type, if any.
 */
function mime_to_ext(string $mime): ?string {
	static $mime_to_ext = [
		'image/jpeg' => 'jpg',
		'image/png' => 'png',
		'image/gif' => 'gif',
		'image/webp' => 'webp',
		'image/bmp' => 'bmp',
		'image/avif' => 'avif',
		'text/plain' => 'txt',
		'application/pdf' => 'pdf'
	];
	return $mime_to_ext[$mime] ?? null;
}

/**
 * @param string $mime Lowercase extension.
 * @return ?string Vichan's preferred mime type for the given extensions, if any.
 */
function ext_to_mime(string $ext): ?string {
	static $ext_to_mime = [
		'jpg' => 'image/jpeg',
		'jpeg' => 'image/jpeg',
		'png' => 'image/png',
		'gif' => 'image/gif',
		'webp' => 'image/webp',
		'bmp' => 'image/bmp',
		'avif' => 'image/avif',
		'txt' => 'text/plain',
		'pdf' => 'application/pdf'
	];
	return $ext_to_mime[$ext] ?? null;
}

/**
 * Sniffs the image content.
 *
 * @param string $file_path The path to an image file.
 * @return array An array with the image's width, height and mime type.
 * @throws \RuntimeException On error, or on non-image files.
 */
function sniff_image(string $file_path): array {
	$ret = \getimagesize($file_path);
	if ($ret === false) {
		throw new \RuntimeException("Could not read image sizes of '$file_path'");
	}
	if ($ret[2] == \IMAGETYPE_UNKNOWN) {
		throw new \RuntimeException("Error '$file_path' is not an image");
	}

	$width = $ret[0];
	$height = $ret[1];
	$mime = $ret['mime'];

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