method.ts

import { genericHash } from '../nacl/naclWrappers';
import { ABIType, ABITupleType } from './abi_type';
import { ABITransactionType, abiTypeIsTransaction } from './transaction';
import { ABIReferenceType, abiTypeIsReference } from './reference';
import { ARC28Event } from './event';

function parseMethodSignature(
  signature: string
): { name: string; args: string[]; returns: string } {
  const argsStart = signature.indexOf('(');
  if (argsStart === -1) {
    throw new Error(`Invalid method signature: ${signature}`);
  }

  let argsEnd = -1;
  let depth = 0;
  for (let i = argsStart; i < signature.length; i++) {
    const char = signature[i];

    if (char === '(') {
      depth += 1;
    } else if (char === ')') {
      if (depth === 0) {
        // unpaired parenthesis
        break;
      }

      depth -= 1;
      if (depth === 0) {
        argsEnd = i;
        break;
      }
    }
  }

  if (argsEnd === -1) {
    throw new Error(`Invalid method signature: ${signature}`);
  }

  return {
    name: signature.slice(0, argsStart),
    args: ABITupleType.parseTupleContent(
      signature.slice(argsStart + 1, argsEnd)
    ),
    returns: signature.slice(argsEnd + 1),
  };
}

export interface ABIMethodArgParams {
  type: string;
  name?: string;
  desc?: string;
}

export interface ABIMethodReturnParams {
  type: string;
  desc?: string;
}

export interface ABIMethodParams {
  name: string;
  desc?: string;
  args: ABIMethodArgParams[];
  returns: ABIMethodReturnParams;
  /** Optional, is it a read-only method (according to [ARC-22](https://arc.algorand.foundation/ARCs/arc-0022)) */
  readonly?: boolean;
  /** [ARC-28](https://arc.algorand.foundation/ARCs/arc-0028) events that MAY be emitted by this method */
  events?: ARC28Event[];
}

export type ABIArgumentType = ABIType | ABITransactionType | ABIReferenceType;

export type ABIReturnType = ABIType | 'void';

export class ABIMethod {
  public readonly name: string;
  public readonly description?: string;
  public readonly args: Array<{
    type: ABIArgumentType;
    name?: string;
    description?: string;
  }>;

  public readonly returns: { type: ABIReturnType; description?: string };
  public readonly events?: ARC28Event[];
  public readonly readonly?: boolean;

  constructor(params: ABIMethodParams) {
    if (
      typeof params.name !== 'string' ||
      typeof params.returns !== 'object' ||
      !Array.isArray(params.args)
    ) {
      throw new Error('Invalid ABIMethod parameters');
    }

    this.name = params.name;
    this.description = params.desc;
    this.args = params.args.map(({ type, name, desc }) => {
      if (abiTypeIsTransaction(type) || abiTypeIsReference(type)) {
        return {
          type,
          name,
          description: desc,
        };
      }

      return {
        type: ABIType.from(type),
        name,
        description: desc,
      };
    });
    this.returns = {
      type:
        params.returns.type === 'void'
          ? params.returns.type
          : ABIType.from(params.returns.type),
      description: params.returns.desc,
    };

    this.events = params.events;
    this.readonly = params.readonly;
  }

  getSignature(): string {
    const args = this.args.map((arg) => arg.type.toString()).join(',');
    const returns = this.returns.type.toString();
    return `${this.name}(${args})${returns}`;
  }

  getSelector(): Uint8Array {
    const hash = genericHash(this.getSignature());
    return new Uint8Array(hash.slice(0, 4));
  }

  txnCount(): number {
    let count = 1;
    for (const arg of this.args) {
      if (typeof arg.type === 'string' && abiTypeIsTransaction(arg.type)) {
        count += 1;
      }
    }
    return count;
  }

  toJSON(): ABIMethodParams {
    return {
      name: this.name,
      desc: this.description,
      args: this.args.map(({ type, name, description }) => ({
        type: type.toString(),
        name,
        desc: description,
      })),
      returns: {
        type: this.returns.type.toString(),
        desc: this.returns.description,
      },
      events: this.events,
      readonly: this.readonly,
    };
  }

  static fromSignature(signature: string): ABIMethod {
    const { name, args, returns } = parseMethodSignature(signature);

    return new ABIMethod({
      name,
      args: args.map((arg) => ({ type: arg })),
      returns: { type: returns },
    });
  }
}

export function getMethodByName(methods: ABIMethod[], name: string): ABIMethod {
  if (
    methods === null ||
    !Array.isArray(methods) ||
    !methods.every((item) => item instanceof ABIMethod)
  )
    throw new Error('Methods list provided is null or not the correct type');

  const filteredMethods = methods.filter((m: ABIMethod) => m.name === name);
  if (filteredMethods.length > 1)
    throw new Error(
      `found ${
        filteredMethods.length
      } methods with the same name ${filteredMethods
        .map((m: ABIMethod) => m.getSignature())
        .join(',')}`
    );

  if (filteredMethods.length === 0)
    throw new Error(`found 0 methods with the name ${name}`);

  return filteredMethods[0];
}