src/stores/block_store.ts


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import * as _ from 'lodash';
import * as Web3 from 'web3';
import {BigNumber} from 'bignumber.js';
import {BlockParamLiteral, InternalZeroExError} from '../types';
import {Web3Wrapper} from '../web3_wrapper';

/**
 * Store for a current latest block number
 */
export class BlockStore {
    private web3Wrapper?: Web3Wrapper;
    private latestBlockNumber?: number;
    constructor(web3Wrapper?: Web3Wrapper) {
        this.web3Wrapper = web3Wrapper;
        // TODO start a subscription
    }
    public getBlockNumberWithNConfirmations(numConfirmations: number): Web3.BlockParam {
        let blockNumber;
        if (numConfirmations === 0) {
            blockNumber = BlockParamLiteral.Pending;
        } else if (numConfirmations === 1) {
            // HACK: We special-case `numConfirmations === 1` so that we can use this block store without actually
            // setting `latestBlockNumber` when block number is latest (in order validation) whhich allows us to omit
            // an async call in a constructor of `ExchangeTransferSimulator`
            blockNumber = BlockParamLiteral.Latest;
        } else {
            if (_.isUndefined(this.latestBlockNumber)) {
                throw new Error(InternalZeroExError.LatestBlockNumberNotSet);
            }
            // Latest block already has 1 confirmation
            blockNumber = this.latestBlockNumber - numConfirmations + 1;
        }
        return blockNumber;
    }
    public setLatestBlock(latestBlockNumber: number): void {
        this.latestBlockNumber = latestBlockNumber;
    }
}