/*
  Here's a chatbot that helps outdoor enthusiasts find great trail to hike.
  So far it can respond to a few basic commands. If it doesn't know the command,
  it falls back to a default one.
*/

const hikes = ['Lost Lake', 'Canyon Creek Meadows'];
const randomHike = () => hikes[Math.floor(Math.random() * hikes.length)];

// if-else-based responder
const responder_IfElse = (message) => {
  if (message === 'list hikes') {
    return hikes.join('\n');
  } else if (message === 'recommend hike') {
    return `I recommend ${randomHike()}!`;
  } else if (message.startsWith('add hike')) {
    const hike = message.slice(9);
    hikes.push(hike);
    return `Added ${hike}!`;
  }
  return "Sorry, I don't understand that."
}

console.log('Before: ');

console.log(responder_IfElse('list hikes'));
// => Lost Lake
// => Canyon Creek Meadows

console.log(responder_IfElse('recommend hike'));
// => I recommend Mirror Lake!

console.log(responder_IfElse('add hike Mirror Lake'));
// => Added Mirror Lake!

console.log(responder_IfElse('where is Mirror Lake'));
// => Sorry, I don't understand that.

/* --------------------------------------------------------------------- */

const defaultFallback = () => "Sorry, I don't understand that";

const responses_object = {
  'list hikes': () => hikes.join('\n'),
  'recommend hike': () => `I recommend ${randomHike()}!`,
  'add hike': (message) => {
    const hike = message.slice(9);
    hikes.push(hike);
    return `Added ${hike}!`;
  },
  '': defaultFallback,
}

const responses_array = [
  {
    command: /^list hikes$/,
    response: () => hikes.join('\n'),
  },
  {
    command: /^recommend hike$/,
    response: () => `I recommend ${randomHike()}!`
  },
  {
    command: /^add hike (.*)$/,
    response: ([hike]) => {
      hikes.push(hike);
      return `Added ${hike}!`;
    }
  },
  {
    command: /^(.*)$/,
    response: defaultFallback
  },
];

const responder_RouterSimple = (message) => {
  const response = responses_object[message] || defaultFallback;
  return response(message);
}

const responder_RouterComplex_Object = (message) => {
  const [command, response] = Object.entries(responses_object)
    .find(([command, response]) => message.startsWith(command));
  return response(message);
}

const responder_RouterComplex_Array = (message) => {
  const { command, response } = responses_array
    .find(({ command, response }) => command.test(message));
  return response(
    command.exec(message).slice(1)
  );
}

console.log('After: ');

console.log(responder_RouterComplex_Array('list hikes'));
// => Lost Lake
// => Canyon Creek Meadows

console.log(responder_RouterComplex_Array('recommend hike'));
// => I recommend Mirror Lake!

console.log(responder_RouterComplex_Array('add hike Mirror Lake'));
// => Added Mirror Lake!

console.log(responder_RouterComplex_Array('where is Mirror Lake'));
// => Sorry, I don't understand that.