<?php
class Cache {
	public static function getCacheFile(string $name, $maxAge = 3600) {
		$cacheFile = CACHE_DIR . "/" . $name;

		if (file_exists($cacheFile) && filemtime($cacheFile) > time() - $maxAge) {
			Logger::log("Cache hit for " . $name, Logger::IOREAD, "Cache");
			return COMPRESS_LOCAL_CACHE ? gzuncompress(file_get_contents($cacheFile)) : file_get_contents($cacheFile);
		}

		return null;
	}

	public static function saveCacheFile(string $name, string $data) {
		$cacheFile = CACHE_DIR . "/" . $name;
		file_put_contents($cacheFile, COMPRESS_LOCAL_CACHE ? gzcompress($data,9) : $data );
		Logger::log("Saved cache file " . $name, Logger::IOWRITE, "Cache");
	}

	public static function publicCacheExists(string $name, bool $skipExtensionCheck = false) {
		// For now cache is not reliable since we use a generated name.
		return false;
		/*if (!$skipExtensionCheck) {
			$ext = substr($name, strrpos($name, ".") + 1);
			if (strtolower($ext) == "jpg" || strtolower($ext) == "jpeg" || strtolower($ext) == "png") {
				$name = str_replace("." . $ext, ".webp", strtolower($name));
			}
		}

		$cacheFile = PUBLIC_CACHE_DIR . "/" . $name;

		try {
			$fe = file_exists($cacheFile);
		} catch (Exception $e) {
			$fe = false;
			Logger::log("Could not check if public cache file " . $name . " exists: " . $e->getMessage(), Logger::ERROR, "Cache");
		}

		return $fe;*/
	}

	public static function savePublicCacheFile(string $name, string $data, int $cacheLevel = 70, bool $skipExtensionCheck = false) {
		$name = strtolower($name);

		$ext = substr($name, strrpos($name, ".") + 1);
		if ($skipExtensionCheck || strtolower($ext) == "jpg" || strtolower($ext) == "jpeg" || strtolower($ext) == "png") {
			$size = strlen($data);
			$img = new Imagick();
			$img->readImageBlob($data);
			$img->setImageFormat('webp');
			$img->setImageCompressionQuality($cacheLevel);
			$img->stripImage();
			$data = $img->getImageBlob();
			$name = str_replace("." . $ext, ".webp", strtolower($name));

			$cacheFile = PUBLIC_CACHE_DIR . "/" . $name;
			$blurhash = self::generateBlurHash($cacheFile, $img, $skipExtensionCheck);
			if (!empty($blurhash)) {
				$name = "BH-" . bin2hex($blurhash) . "-W" . $img->getImageWidth() . "xH" . $img->getImageHeight() . ".webp";
				$cacheFile = PUBLIC_CACHE_DIR . "/" . $name;
			}

			// For now don't transfer file if its generated name exists
			if (file_exists($cacheFile)) {
				Logger::log("Public cache file " . $name . " already exists", Logger::INFO, "Cache");
				return PUBLIC_CACHE_URL . "/" . $name;
			}

			Logger::log("Compressed image from " . $size . " to " . strlen($data) . " bytes", Logger::METRICS, "Cache");
		}

		$context = stream_context_create([
			's3' => [
				'ACL' => 'public-read'
			]
		]);

		file_put_contents($cacheFile, $data, 0, $context);

		Logger::log("Saved public cache file " . $name, Logger::IOWRITE, "Cache");

		return PUBLIC_CACHE_URL . "/" . $name;
	}

	public static function generateBlurHash(string $cacheFile, ?IMagick $img = null, bool $skipExtensionCheck = false):?string {
		$ext = substr($cacheFile, strrpos($cacheFile, ".") + 1);
		if ($skipExtensionCheck || strtolower($ext) == "jpg" || strtolower($ext) == "jpeg" || strtolower($ext) == "png" || strtolower($ext) == "webp") {

			$hashFile = strtolower($cacheFile);
			$hashFileName = substr($hashFile, strrpos($hashFile, "/") + 1);
			if (file_exists($hashFile)) {
				return null;
			}

			$pixels = [];

			if ($img === null) {
				$img = new Imagick();
				$img->readImage($cacheFile);
			}

			$width = $img->getImageWidth();
			$height = $img->getImageHeight();

			for ($y = 0; $y < $height; $y++) {
				$row = [];
				for ($x = 0; $x < $width; $x++) {
					$pixel = $img->getImagePixelColor($x, $y);
					$color = $pixel->getColor();
					$row[] = [$color["r"], $color["g"], $color["b"]];
				}
				$pixels[] = $row;
			}

			$hash = \kornrunner\Blurhash\Blurhash::encode($pixels, BLURHASH_X, BLURHASH_Y);

			return $hash;
		}
	}
}