// state type
type CounterState = {
  count: number;
};

// action type
type CounterAction =
  | {
      type: 'incre';
    }
  | {
      type: 'decre';
    }
  | {
      type: 'increBy';
      step: number;
    }
  | {
      type: 'decreBy';
      step: number;
    };

// reducer with match
const counterReducer = (
  state: CounterState,
  action: CounterAction
): CounterState => {
  return match(action).case({
    incre: () => ({
      ...state,
      count: state.count + 1,
    }),
    decre: () => ({
      ...state,
      count: state.count - 1,
    }),
    increBy: ({ step }) => ({
      ...state,
      count: state.count + step,
    }),
    decreBy: ({ step }) => ({
      ...state,
      count: state.count - step,
    }),
  });
};

// reducer without match
const counterReducer = (
  state: CounterState,
  action: CounterAction
): CounterState => {
  if (action.type === 'incre') {
    return {
      ...state,
      count: state.count + 1,
    };
  } else if (action.type === 'decre') {
    return {
      ...state,
      count: state.count - 1,
    };
  } else if (action.type === 'increBy') {
    return {
      ...state,
      count: state.count + action.step,
    };
  } else if (action.type === 'decreBy') {
    return {
      ...state,
      count: state.count - action.step,
    };
  }

  throw new Error(`Unexpected action: ${action}`);
};

import { match } from 'coproduct';

export type Option<T> = {
  type: 'Some',
  value: T
} | {
  type: 'None'
}

export const None = {
  type: 'None' as const;
}
export const Some = <T>(value: T) => ({
  type: 'Some' as const,
  value,
});

const show = <T>(data: Option<T>) => {
  return match(data).case({
    Some: data => `some: ${data.value}`,
    None: () => 'none',
  });
};

const value0 = Some(1);
const value1 = None;

expect(show(value0)).toBe('some: 1');
expect(show(value1)).toBe('none');

// you can use if/else to match manually if you want
const show = <T>(data: Option<T>) => {
  if (data.type === 'Some') {
    return `some: ${data.some}`;
  } else if (data.type === 'None') {
    return 'none';
  }
  throw new Error(`Unexpected data: ${data}`);
};

import { match, Option, Some, None, Result, Ok, Err } from 'coproduct';

const show = <T>(data: Option<T>) => {
  return match(data).case({
    Some: data => `some: ${data.value}`,
    None: () => 'none',
  });
};

expect(show(Some(1))).toBe('some: 1');
expect(show(None)).toBe('none');

const showResult = <T>(result: Result<T>) => {
  return match(result).case({
    Ok: data => `ok: ${data.value}`,
    Err: error => `err: ${error.info}`,
  });
};

expect(showResult(Ok(1))).toBe('ok: 1');
expect(showResult(Err('error'))).toBe('err: error');

const match = createMatch('tag');

type Data =
  | {
      tag: 'a';
      value: string;
    }
  | {
      tag: 'b';
      value: number;
    };

const handleData = (data: Data) => {
  return match(data).case({
    a: data => `a: ${data.value}`,
    b: data => `b: ${data.value}`,
  });
};

handleData({ tag: 'a', value: 'hello' }); // 'a: hello'
handleData({ tag: 'b', value: 1 }); // 'b: 1'