89 lines
2.2 KiB
TypeScript
89 lines
2.2 KiB
TypeScript
import { checkHttpStatus, parseJSON } from './utils';
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import { Omit } from 'react-redux';
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const MAX_GAS_FAST = 250;
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interface RawGasEstimates {
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safeLow: number;
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standard: number;
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fast: number;
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fastest: number;
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block_time: number;
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blockNum: number;
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}
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export interface GasEstimates {
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safeLow: number;
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standard: number;
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fast: number;
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fastest: number;
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time: number;
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chainId: number;
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isDefault: boolean;
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}
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interface GasExpressResponse {
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block_time: number;
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blockNum: number;
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fast: number;
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fastest: number;
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safeLow: number;
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standard: number;
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}
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export function fetchGasEstimates(): Promise<GasEstimates> {
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return fetch('https://dev.blockscale.net/api/gasexpress.json', {
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mode: 'cors'
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})
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.then(checkHttpStatus)
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.then(parseJSON)
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.then((res: GasExpressResponse) => {
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// Make sure it looks like a raw gas estimate, and it has valid values
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const keys: (keyof Omit<GasExpressResponse, 'block_time' | 'blockNum'>)[] = [
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'safeLow',
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'standard',
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'fast',
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'fastest'
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];
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keys.forEach(key => {
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if (typeof res[key] !== 'number') {
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throw new Error(
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`Gas estimate API has invalid shape: Expected numeric key '${key}' in response, got '${
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res[key]
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}' instead`
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);
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}
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});
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// Make sure the estimate isn't totally crazy
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const estimateRes = res as RawGasEstimates;
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if (estimateRes.fast > MAX_GAS_FAST) {
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throw new Error(
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`Gas estimate response estimate too high: Max fast is ${MAX_GAS_FAST}, was given ${
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estimateRes.fast
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}`
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);
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}
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if (
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estimateRes.safeLow > estimateRes.standard ||
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estimateRes.standard > estimateRes.fast ||
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estimateRes.fast > estimateRes.fastest
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) {
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throw new Error(
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`Gas esimates are in illogical order: should be safeLow < standard < fast < fastest, received ${
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estimateRes.safeLow
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} < ${estimateRes.standard} < ${estimateRes.fast} < ${estimateRes.fastest}`
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);
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}
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return estimateRes;
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})
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.then((res: RawGasEstimates) => ({
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...res,
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time: Date.now(),
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chainId: 1,
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isDefault: false
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}));
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}
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