const { PACKET_TYPES_REVERSE, ERROR_PACKET } = require("./commons")

export const decodePacket = (encodedPacket, binaryType) => {
    if (typeof encodedPacket !== "string") {
        return {
            type: "message",
            data: mapBinary(encodedPacket, binaryType)
        }
    }
    const type = encodedPacket.charAt(0)
    if (type === "b") {
        const buffer = Buffer.from(encodedPacket.substring(1), "base64")
        return {
            type: "message",
            data: mapBinary(buffer, binaryType)
        }
    }
    if (!PACKET_TYPES_REVERSE[type]) {
        return ERROR_PACKET
    }
    return encodedPacket.length > 1
        ? {
            type: PACKET_TYPES_REVERSE[type],
            data: encodedPacket.substring(1)
        }
        : {
            type: PACKET_TYPES_REVERSE[type]
        }
}

const mapBinary = (data, binaryType) => {
    switch (binaryType) {
        case "arraybuffer":
            return Buffer.isBuffer(data) ? toArrayBuffer(data) : data
        case "nodebuffer":
        default:
            return data // assuming the data is already a Buffer
    }
}

const toArrayBuffer = buffer => {
    const arrayBuffer = new ArrayBuffer(buffer.length)
    const view = new Uint8Array(arrayBuffer)
    for (let i = 0; i < buffer.length; i++) {
        view[i] = buffer[i]
    }
    return arrayBuffer
}