MyCrypto/common/libs/contract.ts

102 lines
2.6 KiB
TypeScript

// TODO support events, constructors, fallbacks, array slots, types
import abi from 'ethereumjs-abi';
// There are too many to enumerate since they're somewhat dynamic, list here
// https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI#types
type ABIType = string;
interface ABITypedSlot {
name: string;
type: ABIType;
}
interface ABIMethod {
name: string;
type: string;
constant?: boolean;
inputs: ABITypedSlot[];
outputs?: ABITypedSlot[];
// default - false
payable?: boolean;
}
export type ABI = ABIMethod[];
export interface DecodedCall {
method: ABIMethod;
// TODO: Type this to be an array of BNs when we switch
args: any[];
}
// Contract helper, returns data for given call
export default class Contract {
public abi: ABI;
constructor(ethJsAbi: ABI) {
// TODO: Check ABI, throw if it's malformed
this.abi = ethJsAbi;
}
public getMethodAbi(name: string): ABIMethod {
const method = this.abi.find(x => x.name === name);
if (!method) {
throw new Error('Unknown method');
}
if (method.type !== 'function') {
throw new Error('Not a function');
}
return method;
}
public getMethodTypes(method: ABIMethod): string[] {
return method.inputs.map(i => i.type);
}
public getMethodSelector(method: ABIMethod): string {
return abi
.methodID(method.name, this.getMethodTypes(method))
.toString('hex');
}
public call(name: string, args: any[]): string {
const method = this.getMethodAbi(name);
return (
'0x' + this.getMethodSelector(method) + this.encodeArgs(method, args)
);
}
public $call(data: string): DecodedCall {
const method = this.abi.find(
mth => data.indexOf(this.getMethodSelector(mth)) !== -1
);
if (!method) {
throw new Error('Unknown method');
}
return {
method,
args: this.decodeArgs(method, data)
};
}
public encodeArgs(method: ABIMethod, args: any[]): string {
if (method.inputs.length !== args.length) {
throw new Error('Invalid number of arguments');
}
const inputTypes = method.inputs.map(input => input.type);
return abi.rawEncode(inputTypes, args).toString('hex');
}
// TODO: Type this return to be an array of BNs when we switch
public decodeArgs(method: ABIMethod, argData: string): any[] {
// Remove method selector from data, if present
argData = argData.replace(`0x${this.getMethodSelector(method)}`, '');
// Convert argdata to a hex buffer for ethereumjs-abi
const argBuffer = new Buffer(argData, 'hex');
// Decode!
return abi.rawDecode(this.getMethodTypes(method), argBuffer);
}
}