Man-O-War JS Fundamentaks

function manOWar(input) {
    let pirateShip = input.shift().split('>').map(Number);
    let warShip = input.shift().split('>').map(Number);
    let maxHealth = Number(input.shift());


    for (let i = 0; i < input.length; i++) {
        let commands = input[i].split(' ');
        let command = commands[0];
        let values = commands.slice(1).map(x => Number(x));

        switch (command) {
            case "Fire": fire(warShip, values[0], values[1]); break;
            case "Defend": defend(pirateShip, values[0], values[1], values[2]); break;
            case "Repair": repair(pirateShip, values[0], values[1], maxHealth); break;
            case "Status": status(pirateShip, maxHealth); break;
            case "Retire": {
                console.log(`Pirate ship status: ${pirateShip.reduce((a, c) => a + c, 0)}`);
                console.log(`Warship status: ${warShip.reduce((a, c) => a + c, 0)}`);
                break;
            }
        }
        if (isShipDead(warShip)) {
            console.log(`You won! The enemy ship has sunken.`);
            break;
        }
        if (isShipDead(pirateShip)) {
            console.log(`You lost! The pirate ship has sunken.`);
            break;
        }
    }

    function isShipDead(ship) {
        let deadSections = ship.filter(x => x <= 0);
        return deadSections.length > 0;
    }

    function fire(warShip, index, damage) {
        if (index >= 0 && index < warShip.length) {
            warShip[index] -= damage;
        }
    }

    function defend(warShip, startIndex, endIndex, damage) {
        if (startIndex >= 0 && startIndex < warShip.length && endIndex >= 0 && endIndex < warShip.length) {
            for (let i = startIndex; i <= endIndex; i++) {
                warShip[i] -= damage;
            }
        }
    }

    function repair(ship, index, heal, maxHealth) {
        if (index >= 0 && index < ship.length) {
            let missingHealth = maxHealth - ship[index];
            ship[index] += Math.min(missingHealth, heal);
        }
    }

    function status(ship, maxHealth) {
        let damagedSections = ship.filter(x => x < (maxHealth * 0.2));
        console.log(`${damagedSections.length} sections need repair.`);
    }
}