import {TxData, TxDataPayable} from '@0xproject/types';
import * as _ from 'lodash';
import * as Web3 from 'web3';

export class BaseContract {
    protected _web3ContractInstance: Web3.ContractInstance;
    protected _defaults: Partial<TxData>;
    protected async _applyDefaultsToTxDataAsync<T extends TxData|TxDataPayable>(
        txData: T,
        estimateGasAsync?: (txData: T) => Promise<number>,
    ): Promise<TxData> {
        // Gas amount sourced with the following priorities:
        // 1. Optional param passed in to public method call
        // 2. Global config passed in at library instantiation
        // 3. Gas estimate calculation + safety margin
        const removeUndefinedProperties = _.pickBy;
        const txDataWithDefaults = {
            ...removeUndefinedProperties(this._defaults),
            ...removeUndefinedProperties(txData as any),
            // HACK: TS can't prove that T is spreadable.
            // Awaiting https://github.com/Microsoft/TypeScript/pull/13288 to be merged
        };
        if (_.isUndefined(txDataWithDefaults.gas) && !_.isUndefined(estimateGasAsync)) {
            const estimatedGas = await estimateGasAsync(txData);
            txDataWithDefaults.gas = estimatedGas;
        }
        return txDataWithDefaults;
    }
    constructor(web3ContractInstance: Web3.ContractInstance, defaults: Partial<TxData>) {
        this._web3ContractInstance = web3ContractInstance;
        this._defaults = defaults;
    }
}