const {
    sha1,
    toSignedLittleBuffer,
    readBufferFromBigInt,
    readBigIntFromBuffer,
} = require('../Helpers');
const BinaryReader = require('../extensions/BinaryReader');
const { sleep } = require('../Helpers');

class AuthKey {

    constructor(value, hash) {
        if (!hash || !value) {
            return;
        }
        this._key = value;
        this._hash = hash;
        const reader = new BinaryReader(hash);
        this.auxHash = reader.readLong(false);
        reader.read(4);
        this.keyId = reader.readLong(false);
    }

    async setKey(value) {
        if (!value) {
            this._key = this.auxHash = this.keyId = this._hash = null;
            return;
        }
        if (value instanceof AuthKey) {
            this._key = value._key;
            this.auxHash = value.auxHash;
            this.keyId = value.keyId;
            this._hash = value._hash;
            return;
        }
        this._key = value;
        this._hash = await sha1(this._key);
        const reader = new BinaryReader(this._hash);
        this.auxHash = reader.readLong(false);
        reader.read(4);
        this.keyId = reader.readLong(false);
    }

    async waitForKey() {
        while (!this.keyId) {
            await sleep(20);
        }
    }

    getKey() {
        return this._key;
    }

    // TODO : This doesn't really fit here, it's only used in authentication

    /**
     * Calculates the new nonce hash based on the current class fields' values
     * @param newNonce
     * @param number
     * @returns {bigint}
     */
    async calcNewNonceHash(newNonce, number) {
        newNonce = toSignedLittleBuffer(newNonce, 32);
        const n = Buffer.alloc(1);
        n.writeUInt8(number, 0);
        const data = Buffer.concat([newNonce,
            Buffer.concat([n, readBufferFromBigInt(this.auxHash, 8, true)])]);

        // Calculates the message key from the given data
        const shaData = (await sha1(data)).slice(4, 20);
        return readBigIntFromBuffer(shaData, true, true);
    }

    equals(other) {
        return other instanceof this.constructor && this._key && other.getKey() && other.getKey()
            .equals(this._key);
    }
}

module.exports = AuthKey;