import * as _ from 'lodash';
import * as BigNumber from 'bignumber.js';
import {bigNumberConfigs} from './bignumber_config';
import * as ethUtil from 'ethereumjs-util';
import contract = require('truffle-contract');
import * as Web3 from 'web3';
import findVersions = require('find-versions');
import compareVersions = require('compare-versions');
import {Web3Wrapper} from './web3_wrapper';
import {constants} from './utils/constants';
import {utils} from './utils/utils';
import {assert} from './utils/assert';
import {ExchangeWrapper} from './contract_wrappers/exchange_wrapper';
import {TokenRegistryWrapper} from './contract_wrappers/token_registry_wrapper';
import {ecSignatureSchema} from './schemas/ec_signature_schema';
import {TokenWrapper} from './contract_wrappers/token_wrapper';
import {ECSignature, ZeroExError, Order, SignedOrder} from './types';
import * as ExchangeArtifacts from './artifacts/Exchange.json';
import {SchemaValidator} from './utils/schema_validator';
import {orderSchema} from './schemas/order_schemas';

// Customize our BigNumber instances
bigNumberConfigs.configure();

const MAX_DIGITS_IN_UNSIGNED_256_INT = 78;

export class ZeroEx {
    public static NULL_ADDRESS = constants.NULL_ADDRESS;

    public exchange: ExchangeWrapper;
    public tokenRegistry: TokenRegistryWrapper;
    public token: TokenWrapper;
    private web3Wrapper: Web3Wrapper;
    /**
     * Verifies that the elliptic curve signature `signature` was generated
     * by signing `dataHex` with the private key corresponding to the `signerAddressHex` address.
     */
    public static isValidSignature(dataHex: string, signature: ECSignature, signerAddressHex: string): boolean {
        assert.isHexString('dataHex', dataHex);
        assert.doesConformToSchema('signature', signature, ecSignatureSchema);
        assert.isETHAddressHex('signerAddressHex', signerAddressHex);

        const dataBuff = ethUtil.toBuffer(dataHex);
        const msgHashBuff = ethUtil.hashPersonalMessage(dataBuff);
        try {
            const pubKey = ethUtil.ecrecover(
                msgHashBuff,
                signature.v,
                ethUtil.toBuffer(signature.r),
                ethUtil.toBuffer(signature.s));
            const retrievedAddress = ethUtil.bufferToHex(ethUtil.pubToAddress(pubKey));
            return retrievedAddress === signerAddressHex;
        } catch (err) {
            return false;
        }
    }
    /**
     * Generates pseudo-random 256 bit salt.
     * The salt is used to ensure that the 0x order generated has a unique orderHash that does
     * not collide with any other outstanding orders.
     */
    public static generatePseudoRandomSalt(): BigNumber.BigNumber {
        // BigNumber.random returns a pseudo-random number between 0 & 1 with a passed in number of decimal places.
        // Source: https://mikemcl.github.io/bignumber.js/#random
        const randomNumber = BigNumber.random(MAX_DIGITS_IN_UNSIGNED_256_INT);
        const factor = new BigNumber(10).pow(MAX_DIGITS_IN_UNSIGNED_256_INT - 1);
        const salt = randomNumber.times(factor).round();
        return salt;
    }
    /**
     * Checks if the supplied hex encoded order hash is valid.
     * Note: Valid means it has the expected format, not that an order with the orderHash exists.
     */
    public static isValidOrderHash(orderHashHex: string): boolean {
        // Since this method can be called to check if any arbitrary string conforms to an orderHash's
        // format, we only assert that we were indeed passed a string.
        assert.isString('orderHashHex', orderHashHex);
        const isValidOrderHash = utils.isValidOrderHash(orderHashHex);
        return isValidOrderHash;
    }
    /**
     * A unit amount is defined as the amount of a token above the specified decimal places (integer part).
     * E.g: If a currency has 18 decimal places, 1e18 or one quintillion of the currency is equivalent
     * to 1 unit.
     */
    public static toUnitAmount(amount: BigNumber.BigNumber, numDecimals: number): BigNumber.BigNumber {
        assert.isBigNumber('amount', amount);
        assert.isNumber('numDecimals', numDecimals);

        const aUnit = new BigNumber(10).pow(numDecimals);
        const unit = amount.div(aUnit);
        return unit;
    }
    /**
     * A baseUnit is defined as the smallest denomination of a token. An amount expressed in baseUnits
     * is the amount expressed in the smallest denomination.
     * E.g: 1 unit of a token with 18 decimal places is expressed in baseUnits as 1000000000000000000
     */
    public static toBaseUnitAmount(amount: BigNumber.BigNumber, numDecimals: number): BigNumber.BigNumber {
        assert.isBigNumber('amount', amount);
        assert.isNumber('numDecimals', numDecimals);

        const unit = new BigNumber(10).pow(numDecimals);
        const baseUnitAmount = amount.times(unit);
        return baseUnitAmount;
    }
    constructor(web3: Web3) {
        this.web3Wrapper = new Web3Wrapper(web3);
        this.token = new TokenWrapper(this.web3Wrapper);
        this.exchange = new ExchangeWrapper(this.web3Wrapper, this.token);
        this.tokenRegistry = new TokenRegistryWrapper(this.web3Wrapper);
    }
    /**
     * Sets a new provider for the web3 instance used by 0x.js
     */
    public async setProviderAsync(provider: Web3.Provider) {
        this.web3Wrapper.setProvider(provider);
        await this.exchange.invalidateContractInstanceAsync();
        this.tokenRegistry.invalidateContractInstance();
        this.token.invalidateContractInstances();
    }
    /**
     * Get addresses via the supplied web3 instance available for sending transactions.
     */
    public async getAvailableAddressesAsync(): Promise<string[]> {
        const availableAddresses = await this.web3Wrapper.getAvailableAddressesAsync();
        return availableAddresses;
    }
    /**
     * Computes the orderHash for a given order and returns it as a hex encoded string.
     */
    public async getOrderHashHexAsync(order: Order|SignedOrder): Promise<string> {
        assert.doesConformToSchema('order', SchemaValidator.convertToJSONSchemaCompatibleObject(order as object),
                                   orderSchema);

        const exchangeContractAddr = await this.getExchangeAddressAsync();
        const orderHashHex = utils.getOrderHashHex(order, exchangeContractAddr);
        return orderHashHex;
    }
    /**
     * Signs an orderHash and returns it's elliptic curve signature.
     * This method currently supports TestRPC, Geth and Parity above and below V1.6.6
     */
    public async signOrderHashAsync(orderHashHex: string, signerAddress: string): Promise<ECSignature> {
        assert.isHexString('orderHashHex', orderHashHex);
        await assert.isSenderAddressAsync('signerAddress', signerAddress, this.web3Wrapper);

        let msgHashHex;
        const nodeVersion = await this.web3Wrapper.getNodeVersionAsync();
        const isParityNode = utils.isParityNode(nodeVersion);
        if (isParityNode) {
            // Parity node adds the personalMessage prefix itself
            msgHashHex = orderHashHex;
        } else {
            const orderHashBuff = ethUtil.toBuffer(orderHashHex);
            const msgHashBuff = ethUtil.hashPersonalMessage(orderHashBuff);
            msgHashHex = ethUtil.bufferToHex(msgHashBuff);
        }

        const signature = await this.web3Wrapper.signTransactionAsync(signerAddress, msgHashHex);

        let signatureData;
        const [nodeVersionNumber] = findVersions(nodeVersion);
        // Parity v1.6.6 and earlier returns the signatureData as vrs instead of rsv as Geth does
        // Later versions return rsv but for the time being we still want to support version < 1.6.6
        // Date: May 23rd 2017
        const latestParityVersionWithVRS = '1.6.6';
        const isVersionBeforeParityFix = compareVersions(nodeVersionNumber, latestParityVersionWithVRS) <= 0;
        if (isParityNode && isVersionBeforeParityFix) {
            const signatureBuffer = ethUtil.toBuffer(signature);
            let v = signatureBuffer[0];
            if (v < 27) {
                v += 27;
            }
            signatureData = {
                v,
                r: signatureBuffer.slice(1, 33),
                s: signatureBuffer.slice(33, 65),
            };
        } else {
            signatureData = ethUtil.fromRpcSig(signature);
        }

        const {v, r, s} = signatureData;
        const ecSignature: ECSignature = {
            v,
            r: ethUtil.bufferToHex(r),
            s: ethUtil.bufferToHex(s),
        };
        const isValidSignature = ZeroEx.isValidSignature(orderHashHex, ecSignature, signerAddress);
        if (!isValidSignature) {
            throw new Error(ZeroExError.INVALID_SIGNATURE);
        }
        return ecSignature;
    }
    private async getExchangeAddressAsync() {
        const networkIdIfExists = await this.web3Wrapper.getNetworkIdIfExistsAsync();
        const exchangeNetworkConfigsIfExists = _.isUndefined(networkIdIfExists) ?
                                       undefined :
                                       (ExchangeArtifacts as any).networks[networkIdIfExists];
        if (_.isUndefined(exchangeNetworkConfigsIfExists)) {
            throw new Error(ZeroExError.CONTRACT_NOT_DEPLOYED_ON_NETWORK);
        }
        const exchangeAddress = exchangeNetworkConfigsIfExists.address;
        return exchangeAddress;
    }
}