leetcode-fe.ts

interface Action<T> {
  payload?: T;
  type: string;
}

class EffectModule {
  count = 1;
  message = "hello!";

  delay(input: Promise<number>) {
    return input.then(i => ({
      payload: `hello ${i}!`,
      type: 'delay'
    }));
  }

  setMessage(action: Action<Date>) {
    return {
      payload: action.payload!.getMilliseconds(),
      type: "set-message"
    };
  }
}

// 修改 Connect 的类型，让 connected 的类型变成预期的类型
type Connect = (module: EffectModule) => ExtractContainer<EffectModule>

const connect: Connect = m => ({
  delay: (input: number) => ({
    type: 'delay',
    payload: `hello 2`
  }),
  setMessage: (input: Date) => ({
    type: "set-message",
    payload: input.getMilliseconds()
  })
});

type Connected = {
  delay(input: number): Action<string>;
  setMessage(action: Date): Action<number>;
};

type PickFuncKeys<T> = {
  [K in keyof T]: T[K] extends Function ? K : never;
}[keyof T];

type ExtractContainer<P> =  {
  [K in PickFuncKeys<P>]: 
    P[K] extends (arg: Promise<infer T>) => Promise<infer U> ? (arg: T) => U : 
      P[K] extends (arg: Action<infer T>) => Action<infer U> ? (arg: T) => Action<U> : 
        never
}

export const connected: Connected = connect(new EffectModule());