import 'isomorphic-fetch';
import * as _ from 'lodash';
import {BigNumber} from 'bignumber.js';
import * as queryString from 'query-string';
import {assert} from '@0xproject/assert';
import {schemas} from '@0xproject/json-schemas';
import {SignedOrder} from '0x.js';
import {
    Client,
    FeesRequest,
    FeesResponse,
    OrderbookRequest,
    OrderbookResponse,
    OrdersRequest,
    TokenPairsItem,
    TokenPairsRequest,
} from './types';
import {schemas as clientSchemas} from './schemas/schemas';
import {typeConverters} from './utils/type_converters';

interface RequestOptions {
    params?: object;
    payload?: object;
}

enum RequestType {
    Get = 'GET',
    Post = 'POST',
}

/**
 * This class includes all the functionality related to interacting with a set of HTTP endpoints
 * that implement the standard relayer API v0
 */
export class HttpClient implements Client {
    private apiEndpointUrl: string;
    /**
     * Instantiates a new HttpClient instance
     * @param   url    The base url for making API calls
     * @return  An instance of HttpClient
     */
    constructor(url: string) {
        assert.isHttpUrl('url', url);
        this.apiEndpointUrl = url;
    }
    /**
     * Retrieve token pair info from the API
     * @param   request     A TokenPairsRequest instance describing specific token information
     *                      to retrieve
     * @return  The resulting TokenPairsItems that match the request
     */
    public async getTokenPairsAsync(request?: TokenPairsRequest): Promise<TokenPairsItem[]> {
        if (!_.isUndefined(request)) {
            assert.doesConformToSchema('request', request, clientSchemas.relayerTokenPairsRequestSchema);
        }
        const requestOpts = {
            params: request,
        };
        const tokenPairs = await this._requestAsync('/token_pairs', RequestType.Get, requestOpts);
        assert.doesConformToSchema(
            'tokenPairs', tokenPairs, schemas.relayerApiTokenPairsResponseSchema);
        _.each(tokenPairs, (tokenPair: object) => {
            typeConverters.convertStringsFieldsToBigNumbers(tokenPair, [
                'tokenA.minAmount',
                'tokenA.maxAmount',
                'tokenB.minAmount',
                'tokenB.maxAmount',
            ]);
        });
        return tokenPairs;
    }
    /**
     * Retrieve orders from the API
     * @param   request     An OrdersRequest instance describing specific orders to retrieve
     * @return  The resulting SignedOrders that match the request
     */
    public async getOrdersAsync(request?: OrdersRequest): Promise<SignedOrder[]> {
        if (!_.isUndefined(request)) {
            assert.doesConformToSchema('request', request, clientSchemas.relayerOrdersRequestSchema);
        }
        const requestOpts = {
            params: request,
        };
        const orders = await this._requestAsync(`/orders`, RequestType.Get, requestOpts);
        assert.doesConformToSchema('orders', orders, schemas.signedOrdersSchema);
        _.each(orders, (order: object) => typeConverters.convertOrderStringFieldsToBigNumber(order));
        return orders;
    }
    /**
     * Retrieve a specific order from the API
     * @param   orderHash     An orderHash generated from the desired order
     * @return  The SignedOrder that matches the supplied orderHash
     */
    public async getOrderAsync(orderHash: string): Promise<SignedOrder> {
        assert.doesConformToSchema('orderHash', orderHash, schemas.orderHashSchema);
        const order = await this._requestAsync(`/order/${orderHash}`, RequestType.Get);
        assert.doesConformToSchema('order', order, schemas.signedOrderSchema);
        typeConverters.convertOrderStringFieldsToBigNumber(order);
        return order;
    }
    /**
     * Retrieve an orderbook from the API
     * @param   request     An OrderbookRequest instance describing the specific orderbook to retrieve
     * @return  The resulting OrderbookResponse that matches the request
     */
    public async getOrderbookAsync(request: OrderbookRequest): Promise<OrderbookResponse> {
        assert.doesConformToSchema('request', request, clientSchemas.relayerOrderBookRequestSchema);
        const requestOpts = {
            params: request,
        };
        const orderBook = await this._requestAsync('/orderbook', RequestType.Get, requestOpts);
        assert.doesConformToSchema('orderBook', orderBook, schemas.relayerApiOrderBookResponseSchema);
        typeConverters.convertOrderbookStringFieldsToBigNumber(orderBook);
        return orderBook;
    }
    /**
     * Retrieve fee information from the API
     * @param   request     A FeesRequest instance describing the specific fees to retrieve
     * @return  The resulting FeesResponse that matches the request
     */
    public async getFeesAsync(request: FeesRequest): Promise<FeesResponse> {
        assert.doesConformToSchema('request', request, schemas.relayerApiFeesPayloadSchema);
        typeConverters.convertBigNumberFieldsToStrings(request, [
            'makerTokenAmount',
            'takerTokenAmount',
            'expirationUnixTimestampSec',
            'salt',
        ]);
        const requestOpts = {
            payload: request,
        };
        const fees = await this._requestAsync('/fees', RequestType.Post, requestOpts);
        assert.doesConformToSchema('fees', fees, schemas.relayerApiFeesResponseSchema);
        typeConverters.convertStringsFieldsToBigNumbers(fees, ['makerFee', 'takerFee']);
        return fees;
    }
    /**
     * Submit a signed order to the API
     * @param   signedOrder     A SignedOrder instance to submit
     */
    public async submitOrderAsync(signedOrder: SignedOrder): Promise<void> {
        assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
        const requestOpts = {
            payload: signedOrder,
        };
        await this._requestAsync('/order', RequestType.Post, requestOpts);
    }
    private async _requestAsync(path: string, requestType: RequestType, requestOptions?: RequestOptions): Promise<any> {
        const params = _.get(requestOptions, 'params');
        const payload = _.get(requestOptions, 'payload');
        let query = '';
        if (!_.isUndefined(params) && !_.isEmpty(params)) {
            const stringifiedParams = queryString.stringify(params);
            query = `?${stringifiedParams}`;
        }
        const url = `${this.apiEndpointUrl}/v0${path}${query}`;
        const headers = new Headers({
            'content-type': 'application/json',
        });
        const response = await fetch(url, {
            method: requestType,
            body: payload,
            headers,
        });
        if (!response.ok) {
            throw Error(response.statusText);
        }
        const json = await response.json();
        return json;
    }
}