<?php
namespace Vichan\Service\Media;

use Vichan\Data\ThumbGenerationResult;
use Vichan\Functions\{Fs, Mime};


/**
 * Basically a fallback implementation. GD does not handle color profiles outside of webp.
 */
class GdMediaHandler implements MediaHandler {
	private const PHP81 = \PHP_MAJOR_VERSION >= 8 && \PHP_MINOR_VERSION >= 1;


	private bool $strip_redraw;


	private static function imageCreateFrom(string $file, string $mime): mixed {
		switch ($mime) {
			case 'image/jpeg':
				return \imagecreatefromjpeg($file);
			case 'image/png':
				return \imagecreatefrompng($file);
			case 'image/gif':
				return \imagecreatefromgif($file);
			case 'image/webp':
				return \imagecreatefromwbmp($file);
			case 'image/bmp':
				return \imagecreatefrombmp($file);
			case 'image/avif':
				return self::PHP81 ? \imagecreatefromavif($file) : false;
		}
		return false;
	}

	public static function imageSaveTo(mixed $gd, string $file, string $mime) {
		// Somebody should tune the quality and speed values...
		// Won't be me.
		switch ($mime) {
			case 'image/jpeg':
				return \imagejpeg($gd, $file, 50);
			case 'image/png':
				return \imagepng($gd, $file, 7);
			case 'image/gif':
				return \imagegif($gd, $file);
			case 'image/webp':
				return \imagewebp($gd, $file, 50);
			case 'image/bmp':
				return \imagebmp($gd, $file, true);
			case 'image/avif':
				return self::PHP81 ? \imageavif($gd, $file, 30, 6) : false;
		}
		return false;
	}

	private static function createCanvas(string $mime, int $width, int $height) {
		$gd = \imagecreatetruecolor($width, $height);
		switch ($mime) {
			case 'image/png':
				\imagecolortransparent($gd, \imagecolorallocatealpha($gd, 0, 0, 0, 0));
				\imagesavealpha($gd, true);
				\imagealphablending($gd, false);
				break;
			case 'image/gif':
				\imagecolortransparent($gd, \imagecolorallocatealpha($gd, 0, 0, 0, 0));
				\imagesavealpha($gd, true);
				break;
		}
		return $gd;
	}

	private function generateThumbImpl(
		mixed $gd,
		string $source_file_path,
		string $source_file_mime,
		string $source_file_kind,
		string $preferred_out_file_dir,
		string $preferred_out_file_name,
		string $preferred_out_mime,
		int $max_width,
		int $max_height
	) {
		$width = \imagesx($gd);
		$height = \imagesy($gd);

		if ($width <= $max_width && $height <= $max_height) {
			$out_path = $preferred_out_file_dir . DIRECTORY_SEPARATOR . $preferred_out_file_name . '.' . Mime\mime_to_ext($source_file_mime);

			if ($source_file_kind === self::FILE_KIND_UPLOADED) {
				if (!Fs\move_or_copy_uploaded($source_file_path, $out_path)) {
					throw new \RuntimeException("Could not move or copy uploaded file '$source_file_path' to '$out_path'");
				}
			} else {
				if (!Fs\link_or_copy($source_file_path, $out_path)) {
					throw new \RuntimeException("Could not link or copy '$source_file_path' to '$out_path'");
				}
			}

			return new ThumbGenerationResult(
				$out_path,
				$source_file_mime,
				false,
				$width,
				$height
			);
		} else {
			$out_path = $preferred_out_file_dir . DIRECTORY_SEPARATOR . $preferred_out_file_name . '.' . Mime\mime_to_ext($preferred_out_mime);

			$gd_other = self::createCanvas($preferred_out_mime, $max_width, $max_height);
			\imagecopyresampled($gd_other, $gd, 0, 0, 0, 0, $max_width, $max_height, $width, $height);

			if (!self::imageSaveTo($gd_other, $out_path, $preferred_out_mime)) {
				\imagedestroy($gd_other);
				throw new \RuntimeException("Could not create thumbnail file at '$out_path'");
			}

			\imagedestroy($gd_other);

			return new ThumbGenerationResult(
				$out_path,
				$preferred_out_mime,
				false,
				$max_width,
				$max_height
			);
		}
	}

	/**
	 * @param bool $strip_redraw If the EXIF metadata should be stripped by redrawing it.
	 *                           May cause the loss of color profiles. Orientation is still handled.
	 */
	public function __construct(bool $strip_redraw) {
		$this->strip_redraw = $strip_redraw;
	}

	public function supportsMime(string $mime): bool {
		$info = \gd_info();
		return ($mime === 'image/jpeg' && $info['JPEG Support'])
			|| ($mime === 'image/png' && $info['PNG Support'])
			|| ($mime === 'image/gif' && $info['GIF Read Support'] && $info['GIF Create Support'])
			|| ($mime === 'image/webp' && $info['WebP Support'])
			|| $mime === 'image/bmp'
			|| ($mime === 'image/avif' && self::PHP81 && $info['AVIF Support']);
	}

	public function openHandle(string $file_path, string $file_mime, int $file_kind): mixed {
		$gd = self::imageCreateFrom($file_path, $file_mime);
		if ($gd === false) {
			throw new \RuntimeException("Could not open '$file_path'");
		}
		return [ $gd, $file_path, $file_mime, $file_kind ];
	}

	public function closeHandle(mixed $handle) {
		\imagedestroy($handle[0]);
	}

	public function installMediaAndGenerateThumb(
		mixed $handle,
		string $media_preferred_out_file_dir,
		string $media_preferred_out_file_name,
		string $thumb_preferred_out_file_dir,
		string $thumb_preferred_out_file_name,
		string $thumb_preferred_out_mime,
		int $thumb_max_width,
		int $thumb_max_height
	) {
		list($gd, $source_file_path, $source_file_mime, $source_file_kind) = $handle;
		$out_path = $media_preferred_out_file_dir . DIRECTORY_SEPARATOR . $media_preferred_out_file_name . '.' . Mime\mime_to_ext($source_file_mime);

		if ($this->strip_redraw) {
			if (!self::imageSaveTo($gd, $out_path, $source_file_mime)) {
				throw new \RuntimeException("Could not create media file at '$out_path'");
			}
		} else {
			if ($source_file_kind === self::FILE_KIND_UPLOADED) {
				if (!Fs\move_or_copy_uploaded($source_file_path, $out_path)) {
					throw new \RuntimeException("Could not move or copy uploaded file '$source_file_path' to '$out_path'");
				}
			} else {
				if (!Fs\link_or_copy($source_file_path, $out_path)) {
					throw new \RuntimeException("Could not link or copy '$source_file_path' to '$out_path'");
				}
			}
		}

		return $this->generateThumbImpl(
			$gd,
			$source_file_path,
			$source_file_mime,
			$source_file_kind,
			$thumb_preferred_out_file_dir,
			$thumb_preferred_out_file_name,
			$thumb_preferred_out_mime,
			$thumb_max_width,
			$thumb_max_height
		);
	}

	public function generateThumb(
		mixed $handle,
		string $preferred_out_file_dir,
		string $preferred_out_file_name,
		string $preferred_out_mime,
		int $max_width,
		int $max_height
	): ThumbGenerationResult {
		list($gd, $source_file_path, $source_file_mime, $source_file_kind) = $handle;

		return $this->generateThumbImpl(
			$gd,
			$source_file_path,
			$source_file_mime,
			$source_file_kind,
			$preferred_out_file_dir,
			$preferred_out_file_name,
			$preferred_out_mime,
			$max_width,
			$max_height
		);
	}
}