mid exam 03. Easter Shopping

function solve(input) {
    let shopList = input.shift().split(' ');
    let numberOfCommands = Number(input.shift());
    let commands = input;
    for (let line of input) {
        let tokens = line.split(' ');
        let command = tokens[0];
        if (command === 'Include') {
            shopList.push(tokens[1]);
        } else if (command === 'Visit') {
            let numberOfShops = Number(tokens[2]);
            if (numberOfShops <= shopList.length) {
                if (tokens[1] === 'first') {
                    shopList.splice(0, numberOfShops);
                } else if (tokens[1] === 'last') {
                    shopList.splice(shopList.length - numberOfShops, numberOfShops);
                }
            }
        } else if (command === 'Prefer') {
            let firstIndex = Number(tokens[1]);
            let secondIndex = Number(tokens[2]);
            if ((firstIndex >= 0 && firstIndex < shopList.length) && (secondIndex >= 0 && secondIndex < shopList.length)) {
                let firstShop = shopList[firstIndex];
                let secondShop = shopList[secondIndex];
                shopList[firstIndex] = secondShop;
                shopList[secondIndex] = firstShop;
            }
        } else if (command === 'Place') {
            let index = Number(tokens[2]) + 1;
            let shop = tokens[1];
            if (index >= 0 && index <= shopList.length) {
                shopList.splice(index, 0, shop);
            }
        }
    }
    console.log(`Shops left:\n${shopList.join(' ')}`);

}