functional-js-final

const selectRandom = numbers => {
  return numbers[Math.floor(Math.random() * numbers.length)];
}

const strategy1 = numbers => {
  return numbers[0];
}

const strategy2 = numbers => {
  return selectRandom(numbers);
}

const without = (numbers, value) => {
  let index = numbers.indexOf(value);
  return [...numbers.slice(0, index), ...numbers.slice(index + 1)];
}

const winMessage = score => {
  if (score[0] > score[1]) {
    return `Player1 won`;
  } else if (score[1] > score[0]) {
    return `Player2 won`;
  } else {
    return `Draw`;
  }
}

const endMessage = state => {
  return `Total: ${state.score} \n ${winMessage(state.score)}`;
}

const turnMessage = state => {
  return `Player1 chose ${state.num1}` +
         `\nPlayer2 chose ${state.num2}`;
}

const newScore = ([score1, score2], num1, num2) => {
  if (num1 > num2) {
    return [score1 + 1, score2];
  } else if (num2 > num1) {
    return [score1, score2 + 1];
  } else {
    return [score1, score2];
  }
}

const nextState = state => {
  let num1 = strategy1(state.numbers1);
  let num2 = strategy2(state.numbers2);

  return { numbers1: without(state.numbers1, num1),
           numbers2: without(state.numbers2, num2),
           score: newScore(state.score, num1, num2),
           num1,
           num2
  }
}

const last = arr => {
  return arr[arr.length - 1];
}

const report = (states, onTurn, onEnd) => {
  return states.slice(1).map(onTurn).join("\n") +
         "\n" + onEnd(last(states));
}

const recur = (states, stateChange, endCondition) => {
  if(endCondition(last(states))) {
    return states;
  } else {
    return recur(states.concat(stateChange(last(states))), stateChange, endCondition);
  }
}

const runGame = () => {
  let states = [{numbers1: [4, 5, 3],
                 numbers2: [4, 5, 3],
                 score: [0, 0]}];
  return recur(states, nextState, (state) => {return state.numbers1.length === 0});
}

console.log(report(runGame(), turnMessage, endMessage));