const restaurant_no = 5;

function shuffle(array, seed) {
    var m = array.length, t, i;
  
    // While there remain elements to shuffle…
    while (m) {
  
      // Pick a remaining element…
      i = Math.floor(random(seed) * m--);
  
      // And swap it with the current element.
      t = array[m];
      array[m] = array[i];
      array[i] = t;
      ++seed 
    }
  
    return array;
  }
  
function random(seed) {
var x = Math.sin(seed++) * 10000; 
return x - Math.floor(x);
}

async function fetchRestaurants() {
    const response = await fetch('restaurants.json');
    if (!response.ok) {
        throw new Error('Network response was not ok ' + response.statusText);
    }
    const data = await response.json();
    return data;
}


function getRandomRestaurants(restaurants, seed) {
    // Generate three random indices based on the seed
    randomRestaurants = shuffle(restaurants, seed);
    return randomRestaurants.slice(0,restaurant_no);
}

async function displayRestaurants() {
    const today = new Date();
    const day = today.getDay();

    // Format the date
    const options = { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' };
    const formattedDate = today.toLocaleDateString(undefined, options);

    // Display the date
    document.getElementById('currentDate').innerText = `Today is ${formattedDate}`;

    // Only display suggestions on weekdays
    if (day === 0 || day === 6) {
        document.getElementById('restaurants').innerHTML = "No suggestions available today!";
        return;
    }

    const dateKey = today.toISOString().split('T')[0];

    try {
        const restaurants = await fetchRestaurants();
        console.log('Fetched Restaurants:', restaurants); // Debugging: Print fetched restaurants
        const seed = today.getFullYear() * 10000 + (today.getMonth() + 1) * 100 + today.getDate(); // Create a seed from the date
        console.log('Random seed per day: ', seed);
        const randomRestaurants = getRandomRestaurants(restaurants, seed);
        console.log('Random Restaurants:', randomRestaurants); // Debugging: Print random restaurants

        const firstThreeRestaurants = randomRestaurants.slice(0, 3);
        const bonusRestaurants = randomRestaurants.slice(3, 5);

        document.getElementById('restaurants').innerHTML = firstThreeRestaurants.map(restaurant => 
            `<a href="${restaurant[1]}" target="_blank">${restaurant[0]}</a>`
        ).join('<br>');
        document.getElementById('bonusRestaurants').innerHTML = bonusRestaurants.map(restaurant => 
            `<a href="${restaurant[1]}" target="_blank">${restaurant[0]}</a>`
        ).join('<br>');

    } catch (error) {
        console.error('Error fetching restaurants:', error);
        const bestRestaurants = [
            ["돈비고고 (unlimited 돈까스 + 제육 (Pork) for 8.8K)", "https://naver.me/GGUfwvl9"],
            ["Taksim Kebab (Turkish, small place)", "https://maps.app.goo.gl/6rwGVo5qbT9xKZAMA"],
            ["강남역 파스타 (Pasta, large space)", "https://naver.me/xL1EJLfC"],
        ]
        document.getElementById('restaurants').innerHTML = "Failed to load restaurant suggestions. <br>Below are my personal suggestions based on your review!!";
        document.getElementById('bonusHeader').innerHTML = "";        
        document.getElementById('bonusRestaurants').innerHTML = bestRestaurants.map(restaurant => 
            `<a href="${restaurant[1]}" target="_blank">${restaurant[0]}</a>`
        ).join('<br>') + "<br><br>";
    }
}

window.onload = displayRestaurants;