const { ethers } = require('ethers');

// see https://github.com/ChainAgnostic/namespaces/pull/140
const CAIP350 = Object.fromEntries(Object.entries({
    eip155: '0x0000',
    solana: '0x0002',
}).flatMap(([k,v]) => [[k,v],[v,k]]));

const ENCODERS = {
    eip155: { reference: x => ethers.toBigInt(x).toString(), address: ethers.hexlify },
    solana: { reference: ethers.encodeBase58, address: ethers.encodeBase58 },
}

const decode = value => {
    if (value === undefined || value === null || value === '') return '0x';
    try {
        return ethers.toBeHex(value)
    } catch {}
    try {
        return ethers.toBeHex(ethers.decodeBase58(value));
    } catch {}
    try {
        return ethers.toBeHex(ethers.decodeBase64(value));
    } catch {}
    throw new Error(`Unable to decode ${value}`)
}

const formatERC7913v1 = ({ type, reference, address }) => {
    const chainReferenceHex = decode(reference);
    const addressHex = decode(address);

    const interoperableAddress = ethers.solidityPacked([
        'uint16', // version
        'uint16', // type
        'uint8', // chainReferenceLength
        'bytes', // chainReference
        'uint8', // addressLength
        'bytes', // address
    ], [
        1n,
        CAIP350[type],
        ethers.getBytes(chainReferenceHex).length,
        chainReferenceHex,
        ethers.getBytes(addressHex).length,
        addressHex
    ]);
    const checksum = ethers.keccak256(ethers.getBytes(interoperableAddress).slice(2)).slice(2, 10).toUpperCase();
    const interoperableName = [ address, '@', type, reference && `:${reference}`, '#', checksum ].filter(Boolean).join('');

    return { address : interoperableAddress, name: interoperableName, checksum };
}

const parseERC7913v1 = input => {
    const parse = input.match(/(?<address>[.-:_%a-zA-Z0-9]*)@(?<chain>[.-:_a-zA-Z0-9]*)#(?<checksum>[0-9A-F]{8})/);
    if (parse) {
        const { address, chain, checksum } = parse.groups;
        const [ type, reference ] = chain.split(/:(.*)/s);
        const entry = { type, reference: reference || undefined, address: address || undefined };

        return formatERC7913v1(entry).checksum === checksum
            ? entry
            : null;

    } else if (ethers.isBytesLike(input)) {
        const buffer = ethers.getBytes(input);
        if (ethers.toBigInt(buffer.slice(0, 2)) !== 1n) throw new Error('only version 1 is supported');
        const type = CAIP350[ethers.hexlify(buffer.slice(2,4))];
        const referenceLength = buffer[4];
        const reference = referenceLength ? ENCODERS[type].reference(buffer.slice(5,5+referenceLength)) : undefined;
        const addressLength = buffer[5+referenceLength];
        const address = addressLength ? ENCODERS[type].address(buffer.slice(6+referenceLength,6+referenceLength+addressLength)) : undefined;

        return buffer.length >= 6+referenceLength+addressLength
            ? { type, reference, address }
            : null;
    } else {
        return null;
    }
}

// Examples
[
    {
        type: 'eip155',
        reference: '1',
        address: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045',
    },
    {
        type: 'solana',
        reference: '5eykt4UsFv8P8NJdTREpY1vzqKqZKvdpKuc147dw2N9d',
        address: 'MJKqp326RZCHnAAbew9MDdui3iCKWco7fsK9sVuZTX2',
    },
    {
        type: 'eip155',
        address: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045',
    },
    {
        type: 'solana',
        reference: '5eykt4UsFv8P8NJdTREpY1vzqKqZKvdpKuc147dw2N9d',
    },
    {
        type: 'eip155',
        reference: '42161',
        address: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045',
    },
].forEach(entry => {
    console.log('=========================================================')
    console.log(formatERC7913v1(entry))
    console.log(parseERC7913v1(formatERC7913v1(entry).address))
    console.log(parseERC7913v1(formatERC7913v1(entry).name))
});