03. Man O War

function manOWar(input) {
    let isIndexValid = (i, ship) => i >= 0 && i < ship.length,
        pirateShip = input.shift().split('>').map(Number),
        warShip = input.shift().split('>').map(Number),
        maxSectionHealth = Number(input.shift()),
        tokens, command, index, finalIndex, damage, health, count = 0;

    while (input[0] !== "Retire") {
        tokens = input.shift().split(' ');
        command = tokens[0];
        index = Number(tokens[1]);

        if (command === "Fire" && isIndexValid(index, warShip)) {
            damage = Number(tokens[2]);
            warShip[index] -= damage;
            if (warShip[index] <= 0) {
                console.log("You won! The enemy ship has sunken.");
                warShip = [];
                break;
            }
        } else if (command === "Defend") {
            finalIndex = Number(tokens[2]);
            if (isIndexValid(index, pirateShip) && isIndexValid(finalIndex, pirateShip)) {
                damage = Number(tokens[3]);
                for (let i = index; i <= finalIndex; i++) {
                    pirateShip[i] -= damage;
                    if (pirateShip[i] <= 0) {
                        console.log("You lost! The pirate ship has sunken.");
                        pirateShip = [];
                        return;
                    }
                }
            }
        } else if (command === "Repair" && isIndexValid(index, pirateShip)) {
            health = Number(tokens[2]);
            pirateShip[index] += health;
            if (pirateShip[index] > maxSectionHealth) {
                pirateShip[index] = maxSectionHealth;
            }
        } else if (command === "Status") {
            count = pirateShip.filter(x => x < maxSectionHealth / 5).length;
            console.log(`${count} sections need repair.`);
        }
    }

    if (pirateShip.length > 0 && warShip.length > 0) {
        let sum = (ship) => ship.reduce((a, b) => a + b, 0);
        console.log(`Pirate ship status: ${sum(pirateShip)}`);
        console.log(`Warship status: ${sum(warShip)}`);
    }
    return;
}