import { AssetData, AssetProxyId, ERC20AssetData, ERC721AssetData, MultiAssetData } from '@0x/types';
import { AbiEncoder, BigNumber } from '@0x/utils';
import { MethodAbi } from 'ethereum-types';
import * as _ from 'lodash';

import { constants } from './constants';

const encodingRules: AbiEncoder.EncodingRules = { optimize: true };
const decodingRules: AbiEncoder.DecodingRules = { structsAsObjects: true };

export const assetDataUtils = {
    /**
     * Encodes an ERC20 token address into a hex encoded assetData string, usable in the makerAssetData or
     * takerAssetData fields in a 0x order.
     * @param tokenAddress  The ERC20 token address to encode
     * @return The hex encoded assetData string
     */
    encodeERC20AssetData(tokenAddress: string): string {
        const abiEncoder = new AbiEncoder.Method(constants.ERC20_METHOD_ABI as MethodAbi);
        const args = [tokenAddress];
        const assetData = abiEncoder.encode(args, encodingRules);
        return assetData;
    },
    /**
     * Decodes an ERC20 assetData hex string into it's corresponding ERC20 tokenAddress & assetProxyId
     * @param assetData Hex encoded assetData string to decode
     * @return An object containing the decoded tokenAddress & assetProxyId
     */
    decodeERC20AssetData(assetData: string): ERC20AssetData {
        assetDataUtils.validateERC20AssetDataThrow(assetData);
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        const abiEncoder = new AbiEncoder.Method(constants.ERC20_METHOD_ABI as MethodAbi);
        const [tokenAddress] = abiEncoder.decode(assetData, decodingRules);
        return {
            assetProxyId,
            tokenAddress,
        };
    },
    /**
     * Encodes an ERC721 token address into a hex encoded assetData string, usable in the makerAssetData or
     * takerAssetData fields in a 0x order.
     * @param tokenAddress  The ERC721 token address to encode
     * @param tokenId  The ERC721 tokenId to encode
     * @return The hex encoded assetData string
     */
    encodeERC721AssetData(tokenAddress: string, tokenId: BigNumber): string {
        const abiEncoder = new AbiEncoder.Method(constants.ERC721_METHOD_ABI as MethodAbi);
        const args = [tokenAddress, tokenId];
        const assetData = abiEncoder.encode(args, encodingRules);
        return assetData;
    },
    /**
     * Decodes an ERC721 assetData hex string into it's corresponding ERC721 tokenAddress, tokenId & assetProxyId
     * @param assetData Hex encoded assetData string to decode
     * @return An object containing the decoded tokenAddress, tokenId & assetProxyId
     */
    decodeERC721AssetData(assetData: string): ERC721AssetData {
        assetDataUtils.validateERC721AssetDataOrThrow(assetData);
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        const abiEncoder = new AbiEncoder.Method(constants.ERC721_METHOD_ABI as MethodAbi);
        const [tokenAddress, tokenId] = abiEncoder.decode(assetData, decodingRules);
        return {
            assetProxyId,
            tokenAddress,
            tokenId,
        };
    },
    /**
     * Encodes assetData for multiple AssetProxies into a single hex encoded assetData string, usable in the makerAssetData or
     * takerAssetData fields in a 0x order.
     * @param amounts Amounts of each asset that correspond to a ginle unit within an order.
     * @param nestedAssetData assetData strings that correspond to a valid assetProxyId.
     * @return The hex encoded assetData string
     */
    encodeMultiAssetData(amounts: BigNumber[], nestedAssetData: string[]): string {
        if (amounts.length !== nestedAssetData.length) {
            throw new Error(
                `Invalid MultiAsset arguments. Expected length of 'amounts' (${
                    amounts.length
                }) to equal length of 'nestedAssetData' (${nestedAssetData.length})`,
            );
        }
        _.forEach(nestedAssetData, assetDataElement => assetDataUtils.validateAssetDataOrThrow(assetDataElement));
        const abiEncoder = new AbiEncoder.Method(constants.MULTI_ASSET_METHOD_ABI as MethodAbi);
        const args = [amounts, nestedAssetData];
        const assetData = abiEncoder.encode(args, encodingRules);
        return assetData;
    },
    /**
     * Decodes a MultiAsset assetData hex string into it's corresponding amounts and nestedAssetData
     * @param assetData Hex encoded assetData string to decode
     * @return An object containing the decoded amounts and nestedAssetData
     */
    decodeMultiAssetData(assetData: string): MultiAssetData {
        assetDataUtils.validateMultiAssetDataOrThrow(assetData);
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        const abiEncoder = new AbiEncoder.Method(constants.MULTI_ASSET_METHOD_ABI as MethodAbi);
        const [amounts, nestedAssetData] = abiEncoder.decode(assetData, decodingRules);
        if (amounts.length !== nestedAssetData.length) {
            throw new Error(
                `Invalid MultiAsset assetData. Expected length of 'amounts' (${
                    amounts.length
                }) to equal length of 'nestedAssetData' (${nestedAssetData.length})`,
            );
        }
        return {
            assetProxyId,
            amounts,
            nestedAssetData,
        };
    },
    /**
     * Decode and return the assetProxyId from the assetData
     * @param assetData Hex encoded assetData string to decode
     * @return The assetProxyId
     */
    decodeAssetProxyId(assetData: string): AssetProxyId {
        if (assetData.length < constants.SELECTOR_CHAR_LENGTH_WITH_PREFIX) {
            throw new Error(
                `Could not decode assetData. Expected length of encoded data to be at least 10. Got ${
                    assetData.length
                }`,
            );
        }
        const assetProxyId = assetData.slice(0, constants.SELECTOR_CHAR_LENGTH_WITH_PREFIX);
        if (
            assetProxyId !== AssetProxyId.ERC20 &&
            assetProxyId !== AssetProxyId.ERC721 &&
            assetProxyId !== AssetProxyId.MultiAsset
        ) {
            throw new Error(`Invalid assetProxyId: ${assetProxyId}`);
        }
        return assetProxyId;
    },
    /**
     * Throws if the length or assetProxyId are invalid for the ERC20Proxy.
     * @param assetData Hex encoded assetData string
     */
    validateERC20AssetDataThrow(assetData: string): void {
        if (assetData.length < constants.ERC20_ASSET_DATA_MIN_CHAR_LENGTH_WITH_PREFIX) {
            throw new Error(
                `Could not decode ERC20 Proxy Data. Expected length of encoded data to be at least ${
                    constants.ERC20_ASSET_DATA_MIN_CHAR_LENGTH_WITH_PREFIX
                }. Got ${assetData.length}`,
            );
        }
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        if (assetProxyId !== AssetProxyId.ERC20) {
            throw new Error(
                `Could not decode ERC20 assetData. Expected assetProxyId to be ERC20 (${
                    AssetProxyId.ERC20
                }), but got ${assetProxyId}`,
            );
        }
    },
    /**
     * Throws if the length or assetProxyId are invalid for the ERC721Proxy.
     * @param assetData Hex encoded assetData string
     */
    validateERC721AssetDataOrThrow(assetData: string): void {
        if (assetData.length < constants.ERC721_ASSET_DATA_MIN_CHAR_LENGTH_WITH_PREFIX) {
            throw new Error(
                `Could not decode ERC721 assetData. Expected length of encoded data to be at least ${
                    constants.ERC721_ASSET_DATA_MIN_CHAR_LENGTH_WITH_PREFIX
                }. Got ${assetData.length}`,
            );
        }
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        if (assetProxyId !== AssetProxyId.ERC721) {
            throw new Error(
                `Could not decode ERC721 assetData. Expected assetProxyId to be ERC721 (${
                    AssetProxyId.ERC721
                }), but got ${assetProxyId}`,
            );
        }
    },
    /**
     * Throws if the length or assetProxyId are invalid for the MultiAssetProxy.
     * @param assetData Hex encoded assetData string
     */
    validateMultiAssetDataOrThrow(assetData: string): void {
        if (assetData.length < constants.MULTI_ASSET_DATA_MIN_CHAR_LENGTH_WITH_PREFIX) {
            throw new Error(
                `Could not decode MultiAsset assetData. Expected length of encoded data to be at least ${
                    constants.MULTI_ASSET_DATA_MIN_CHAR_LENGTH_WITH_PREFIX
                }. Got ${assetData.length}`,
            );
        }
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        if (assetProxyId !== AssetProxyId.MultiAsset) {
            throw new Error(
                `Could not decode MultiAsset assetData. Expected assetProxyId to be MultiAsset (${
                    AssetProxyId.MultiAsset
                }), but got ${assetProxyId}`,
            );
        }
    },
    /**
     * Throws if the length or assetProxyId are invalid for the corresponding AssetProxy.
     * @param assetData Hex encoded assetData string
     */
    validateAssetDataOrThrow(assetData: string): void {
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        switch (assetProxyId) {
            case AssetProxyId.ERC20:
                assetDataUtils.validateERC20AssetDataThrow(assetData);
                break;
            case AssetProxyId.ERC721:
                assetDataUtils.validateERC721AssetDataOrThrow(assetData);
                break;
            case AssetProxyId.MultiAsset:
                assetDataUtils.validateMultiAssetDataOrThrow(assetData);
                break;
            default:
                throw new Error(`Unrecognized asset proxy id: ${assetProxyId}`);
        }
    },
    /**
     * Decode any assetData into it's corresponding assetData object
     * @param assetData Hex encoded assetData string to decode
     * @return Either a ERC20 or ERC721 assetData object
     */
    decodeAssetDataOrThrow(assetData: string): AssetData {
        const assetProxyId = assetDataUtils.decodeAssetProxyId(assetData);
        switch (assetProxyId) {
            case AssetProxyId.ERC20:
                const erc20AssetData = assetDataUtils.decodeERC20AssetData(assetData);
                return erc20AssetData;
            case AssetProxyId.ERC721:
                const erc721AssetData = assetDataUtils.decodeERC721AssetData(assetData);
                return erc721AssetData;
            case AssetProxyId.MultiAsset:
                const multiAssetData = assetDataUtils.decodeMultiAssetData(assetData);
                return multiAssetData;
            default:
                throw new Error(`Unrecognized asset proxy id: ${assetProxyId}`);
        }
    },
};