package com.example.utils

import kotlin.math.pow

sealed interface Encryptable {
    val data: ByteArray
    val type:Int

    data class Encrypt( override val data: ByteArray, override val type: Int = 1
    ): Encryptable {
        override fun equals(other: Any?): Boolean {
            if (this === other) return true
            if (javaClass != other?.javaClass) return false

            other as Encrypt

            if (type != other.type) return false
            if (!data.contentEquals(other.data)) return false

            return true
        }

        override fun hashCode(): Int {
            var result = type
            result = 31 * result + data.contentHashCode()
            return result
        }

    }

    data class Decrypt(override val data: ByteArray, override val type:Int = -1): Encryptable {
        override fun equals(other: Any?): Boolean {
            if (this === other) return true
            if (javaClass != other?.javaClass) return false

            other as Decrypt

            if (type != other.type) return false
            if (!data.contentEquals(other.data)) return false

            return true
        }

        override fun hashCode(): Int {
            var result = type
            result = 31 * result + data.contentHashCode()
            return result
        }
    }
}

private fun Byte.encryption(key: Byte, method: Int): Byte {
    // key的预处理，处理结果0<=key&&key<8
    val msg = this
    var key = key
    key = (method * (key % 8)).toByte()
    key = (if (key >= 0) key else key + 8).toByte()

    // msg的预处理，避免msg首位为1
    var nMsg = msg.toInt() and 255
    // 移位掩码，tmp保存低位溢出信息
    val mask = 2.0.pow(key.toDouble()).toInt() - 1
    var tmp = nMsg and mask

    // 循环移位
    nMsg = nMsg shr key.toInt()
    tmp = tmp shl 8 - key // 低位溢出信息移至高位
    nMsg = nMsg or tmp
    return (255 and nMsg).toByte() // 取出低8位
}

fun ByteArray.encryption(encryptable: Encryptable): ByteArray {
    val result = ByteArray(encryptable.data.size)
    encryptable.data.forEachIndexed { index, byte ->
        result[index] = byte.encryption(this[index % size], encryptable.type)
    }
    return result
}