MyCrypto/common/api/gas.ts

74 lines
1.9 KiB
TypeScript

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