imgproxy/imgproxy

    @Throws(Exception::class)
    fun generateSignedUrl(
        key: ByteArray,
        salt: ByteArray,
        url: String,
        preset: String,
        resize: String,
        width: Int,
        height: Int,
        enlarge: Int,
        gravity: String,
        extension: String?,
    ): String {

        val encryptionAlgorithmKey = "HmacSHA256"
        val encodedUrl: String = Base64.getUrlEncoder().withoutPadding().encodeToString(url.toByteArray())

        val path = "preset:$preset/resize:$resize:$width:$height:$enlarge/gravity:$gravity/$encodedUrl"
        val encryptionAlgorithm: Mac = Mac.getInstance(encryptionAlgorithmKey)
        val secretKey = SecretKeySpec(key, encryptionAlgorithmKey)
        encryptionAlgorithm.init(secretKey)
        encryptionAlgorithm.update(salt)

        val hash: String = Base64.getUrlEncoder().withoutPadding().encodeToString(encryptionAlgorithm.doFinal(path.toByteArray()))

        val imageProxyInstanceURL = ConfigProvider.getConfig().getValue(IMAGE_PROXY_INSTANCE_URL, String::class.java)
        return "$imageProxyInstanceURL/$hash/$path"
    }

    fun stringToByteArray(hex: String): ByteArray {
        val hexLength = hex.length
        val data = ByteArray(hexLength / 2)
        var i = 0
        while (i < hexLength) {
            data[i / 2] = ((Character.digit(hex[i], 16) shl 4) + Character.digit(hex[i + 1], 16)).toByte()
            i += 2
        }
        return data
    }

    fun getResizedURL(url: String, width: Int, height: Int): String {
        val key: ByteArray = stringToByteArray("KEY_VALUE")
        val salt: ByteArray = stringToByteArray("SALT_VALU")E
        val preset = "sharp"
        val resize = "fill"
        val gravity = "no"
        val enlarge = 0
        return generateSignedUrl(key, salt, url, preset, resize, width, height, enlarge, gravity, extension = null)
    }