import {
    EIP1193Provider,
    JSONRPCErrorCallback,
    JSONRPCRequestPayload,
    JSONRPCResponsePayload,
    SupportedProvider,
    ZeroExProvider,
} from '../types';
import * as _ from 'lodash';

export const providerUtils = {
    /**
     * Starts the Web3ProviderEngine without excess block polling
     * @param providerEngine The Web3ProviderEngine
     */
    startProviderEngine(providerEngine: any): void {
        if (providerEngine.start === undefined) {
            throw new Error(`Invalid Web3ProviderEngine`);
        }
        // HACK: When calling start() Web3ProviderEngine starts a block polling service
        // this continuously pulls data from the network and can result in high data usage
        // for long running services. If used in a front end application this can cause
        // a high amount of load on a node (one request per user per block).
        providerEngine._ready.go();
        providerEngine._running = true;
    },
    /**
     * Standardize the supported provider types into our internal provider interface
     * or throw if unsupported provider supplied.
     * @param supportedProvider Potentially supported provider instance
     * @return Provider that conforms of our internal provider interface
     */
    standardizeOrThrow(supportedProvider: SupportedProvider): ZeroExProvider {
        if (supportedProvider === undefined) {
            throw new Error(`supportedProvider cannot be 'undefined'`);
        }
        const provider = {
            isStandardizedProvider: true,
            isMetaMask: (supportedProvider as any).isMetaMask,
            isParity: (supportedProvider as any).isParity,
            stop: (supportedProvider as any).stop,
            enable: (supportedProvider as any).enable,
            sendAsync: _.noop.bind(_), // Will be replaced
        };
        if (provider.enable) {
            // Need to bind, metamask can lose reference to function without binding as of 7.7.0
            provider.enable.bind(supportedProvider);
        }
        // Case 1: We've already converted to our ZeroExProvider so noop.
        if ((supportedProvider as any).isStandardizedProvider) {
            // tslint:disable-next-line:no-unnecessary-type-assertion
            return supportedProvider as ZeroExProvider;
            // Case 2: It's a compliant EIP 1193 Provider
            // tslint:disable-next-line:no-unnecessary-type-assertion
        } else if ((supportedProvider as EIP1193Provider).isEIP1193) {
            provider.sendAsync = (payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback) => {
                const method = payload.method;
                const params = payload.params;
                (supportedProvider as any)
                    .send(method, params)
                    .then((result: any) => {
                        callback(null, result);
                    })
                    .catch((err: Error) => {
                        callback(err);
                    });
            };
            return provider;
            // Case 3: The provider has a `sendAsync` method, so we use it.
        } else if ((supportedProvider as any).sendAsync !== undefined) {
            provider.sendAsync = (supportedProvider as any).sendAsync.bind(supportedProvider);
            return provider;
            // Case 4: The provider does not have a `sendAsync` method but does have a `send` method
        } else if ((supportedProvider as any).send !== undefined) {
            // HACK(fabio): Detect if the `send` method has the old interface `send(payload, cb)` such
            // as in versions < Web3.js@1.0.0-beta.37. If so, do a simple re-mapping
            if (_.includes((supportedProvider as any).send.toString().replace(' ', ''), 'function(payload,callback)')) {
                provider.sendAsync = (supportedProvider as any).send.bind(supportedProvider);
                return provider;
            } else {
                // If doesn't have old interface, we assume it has new interface `send(method, payload)`
                // such as in versions > Web3.js@1.0.0-beta.38 and convert it to `sendAsync`
                provider.sendAsync = (payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback) => {
                    const method = payload.method;
                    const params = payload.params;
                    (supportedProvider as any)
                        .send(method, params)
                        .then((result: any) => {
                            callback(null, result);
                        })
                        .catch((err: Error) => {
                            callback(err);
                        });
                };
                return provider;
            }
        }
        throw new Error(
            `Unsupported provider found. Please make sure it conforms to one of the supported providers. See 'Provider' type in 'ethereum-types' package.`,
        );
    },

    /**
     * Retrieve the chain ID from a supported provider.
     * @param supportedProvider A supported provider instance.
     * @return A promise that resolves to the chain ID of the network the provider
     * is connected to.
     */
    async getChainIdAsync(supportedProvider: SupportedProvider): Promise<number> {
        const provider = providerUtils.standardizeOrThrow(supportedProvider);
        // tslint:disable-next-line:custom-no-magic-numbers
        const RPC_ID_MAX = 2 ** 64;
        return new Promise<number>((accept, reject) => {
            provider.sendAsync(
                {
                    jsonrpc: '2.0',
                    id: _.random(1, RPC_ID_MAX),
                    method: 'eth_chainId',
                    params: [],
                },
                (err: Error | null, result?: JSONRPCResponsePayload) => {
                    if (!_.isNil(err)) {
                        reject(err);
                    }
                    if (!result) {
                        throw new Error("Invalid 'eth_chainId' response");
                    }
                    accept(_.toNumber(result.result));
                },
            );
        });
    },
};