FatCat_Tanks_Challenge/lib/Tank.ts

import { mapR } from "./reducers";
import { doIf, tap } from "./combinators";
import { isLive, setProp, dealDamageToRandom, isReadyToAttack } from "./helpers";

export interface ITank {
  name: string;
  health: number;
  attackDelay: number;
}

type BuildTank = (name: string) => ITank;
export const buildTank: BuildTank = (name) => ({
  name,
  health: 100,
  attackDelay: 0,
} as ITank);

type Attack = (_prevTanks: ITank[], tank: ITank, tIndex: number, tanks: ITank[]) => ITank[];
const attack: Attack = (_acc, tank, _iTank, tanks) => {
  tap(
    doIf(
      isReadyToAttack,
      dealDamageToRandom(tanks)
    )
  )(tank);
  return mapR(setProp("attackDelay", isReadyToAttack(tank) ? Math.floor(tank.health / 10) : tank.attackDelay - 1))(tanks);
};

type Attacks = (tanks: ITank[]) => ITank[];
const attacksRound: Attacks = (tanks) =>
  tanks
    .reduce(attack,  tanks)
    .filter(isLive);

type Battle = (remainingTanks: ITank[]) => ITank;
export const battleItOut: Battle = (remainingTanks: ITank[]) =>
  remainingTanks.length === 1
    ? remainingTanks[0]
    : battleItOut(attacksRound(remainingTanks));