telegraf-ts/router.js

Well-Typed fork of telegraf

const { compose, lazy, passThru } = require('./composer');

class Router {
  constructor(routeFn, handlers = new Map()) {
    if (!routeFn) {
      throw new Error('Missing routing function');
    }
    this.routeFn = routeFn;
    this.handlers = handlers;
    this.otherwiseHandler = passThru();
  }

  on(route, ...fns) {
    if (fns.length === 0) {
      throw new TypeError('At least one handler must be provided');
    }
    this.handlers.set(route, compose(fns));
    return this;
  }

  otherwise(...fns) {
    if (fns.length === 0) {
      throw new TypeError('At least one otherwise handler must be provided');
    }
    this.otherwiseHandler = compose(fns);
    return this;
  }

  middleware() {
    return lazy(ctx => {
      return Promise.resolve(this.routeFn(ctx)).then(result => {
        if (!result || !result.route || !this.handlers.has(result.route)) {
          return this.otherwiseHandler;
        }
        Object.assign(ctx, result.context);
        Object.assign(ctx.state, result.state);
        return this.handlers.get(result.route);
      });
    });
  }
}

module.exports = Router;