'use strict';

// We use this for base 36 maths
import BN = require('bn.js');

import { BigNumber } from './bignumber';
import { arrayify, Arrayish, stripZeros, hexlify } from './convert';
import { keccak256 } from './keccak256';
import { encode } from './rlp';

import errors = require('./errors');


function getChecksumAddress(address: string): string {
    if (typeof(address) !== 'string' || !address.match(/^0x[0-9A-Fa-f]{40}$/)) {
        errors.throwError('invalid address', errors.INVALID_ARGUMENT, { arg: 'address', value: address });
    }

    address = address.toLowerCase();

    let chars = address.substring(2).split('');

    let hashed = new Uint8Array(40);
    for (let i = 0; i < 40; i++) {
        hashed[i] = chars[i].charCodeAt(0);
    }
    hashed = arrayify(keccak256(hashed));

    for (var i = 0; i < 40; i += 2) {
        if ((hashed[i >> 1] >> 4) >= 8) {
            chars[i] = chars[i].toUpperCase();
        }
        if ((hashed[i >> 1] & 0x0f) >= 8) {
            chars[i + 1] = chars[i + 1].toUpperCase();
        }
    }

    return '0x' + chars.join('');
}

// Shims for environments that are missing some required constants and functions
var MAX_SAFE_INTEGER: number = 0x1fffffffffffff;

function log10(x: number): number {
    if (Math.log10) { return Math.log10(x); }
    return Math.log(x) / Math.LN10;
}


// See: https://en.wikipedia.org/wiki/International_Bank_Account_Number

// Create lookup table
var ibanLookup = {};
for (var i = 0; i < 10; i++) { ibanLookup[String(i)] = String(i); }
for (var i = 0; i < 26; i++) { ibanLookup[String.fromCharCode(65 + i)] = String(10 + i); }

// How many decimal digits can we process? (for 64-bit float, this is 15)
var safeDigits = Math.floor(log10(MAX_SAFE_INTEGER));

function ibanChecksum(address: string): string {
    address = address.toUpperCase();
    address = address.substring(4) + address.substring(0, 2) + '00';

    var expanded = '';
    address.split('').forEach(function(c) {
        expanded += ibanLookup[c];
    });

    // Javascript can handle integers safely up to 15 (decimal) digits
    while (expanded.length >= safeDigits){
        var block = expanded.substring(0, safeDigits);
        expanded = parseInt(block, 10) % 97 + expanded.substring(block.length);
    }

    var checksum = String(98 - (parseInt(expanded, 10) % 97));
    while (checksum.length < 2) { checksum = '0' + checksum; }

    return checksum;
};

export function getAddress(address: string, icapFormat?: boolean): string {
    var result = null;

    if (typeof(address) !== 'string') {
        errors.throwError('invalid address', errors.INVALID_ARGUMENT, { arg: 'address', value: address });
    }

    if (address.match(/^(0x)?[0-9a-fA-F]{40}$/)) {

        // Missing the 0x prefix
        if (address.substring(0, 2) !== '0x') { address = '0x' + address; }

        result = getChecksumAddress(address);

        // It is a checksummed address with a bad checksum
        if (address.match(/([A-F].*[a-f])|([a-f].*[A-F])/) && result !== address) {
            errors.throwError('bad address checksum', errors.INVALID_ARGUMENT, { arg: 'address', value: address });
        }

    // Maybe ICAP? (we only support direct mode)
    } else if (address.match(/^XE[0-9]{2}[0-9A-Za-z]{30,31}$/)) {

        // It is an ICAP address with a bad checksum
        if (address.substring(2, 4) !== ibanChecksum(address)) {
            errors.throwError('bad icap checksum', errors.INVALID_ARGUMENT, { arg: 'address', value: address });
        }

        result = (new BN(address.substring(4), 36)).toString(16);
        while (result.length < 40) { result = '0' + result; }
        result = getChecksumAddress('0x' + result);

    } else {
        errors.throwError('invalid address', errors.INVALID_ARGUMENT, { arg: 'address', value: address });
    }

    if (icapFormat) {
        var base36 = (new BN(result.substring(2), 16)).toString(36).toUpperCase();
        while (base36.length < 30) { base36 = '0' + base36; }
        return 'XE' + ibanChecksum('XE00' + base36) + base36;
    }

    return result;
}

// http://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
export function getContractAddress(transaction: { from: string, nonce: Arrayish | BigNumber | number }) {
    if (!transaction.from) { throw new Error('missing from address'); }
    var nonce = transaction.nonce;

    return getAddress('0x' + keccak256(encode([
        getAddress(transaction.from),
        stripZeros(hexlify(nonce))
    ])).substring(26));
}