var map = L.map('map').setView([55.68, 12.57], 13);
L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
    maxZoom: 19,
    attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>'
}).addTo(map);

let known_store_chains;
let icons = {};

var markers =  L.featureGroup().addTo(map);
var polygons =  L.featureGroup().addTo(map);
var heatmap =  L.featureGroup().addTo(map);

const CategoryField = document.getElementById('Category');
const CountryField = document.getElementById('Country');
const LoadingIndicator = document.getElementById('LoadingIndicator');
const SubmitButton = document.getElementById('SubmitButton');
const form = document.getElementById('QueryForm');
const heatmap_intensity_element = document.getElementById("HeatmapIntensity");
const heatmap_radius_element = document.getElementById("HeatmapRadius");

var shops;

const DefaultSearchValue = "supermarket";
var Categories = []

var overlayMaps = {
    "POI markers": markers,
    "Nearest POI polygons": polygons,
    "POI heatmap": heatmap
};

var layerControl = L.control.layers({},overlayMaps).addTo(map);



form.addEventListener('submit', (event) => {
    event.preventDefault(); // Prevents the default form submission
    changeCategory();
});

heatmap_intensity_element.addEventListener('input', (event) => {
    changeHeatmap();
});

heatmap_radius_element.addEventListener('input', (event) => {
    changeHeatmap();
});

function changeHeatmap() {
    const url = new URL(location);
    url.searchParams.set("HeatmapIntensity", heatmap_intensity_element.value);
    history.pushState({}, "", url);
    url.searchParams.set("HeatmapRadius", heatmap_radius_element.value);
    history.pushState({}, "", url);
    drawHeatmap();
}

function changeCategory() {
    if (!SubmitButton.disabled) { // Disallow double queries
        SubmitButton.disabled = true;
        LoadingIndicator.hidden = false;
        const url = new URL(location);
        url.searchParams.set("category", CategoryField.value);
        history.pushState({}, "", url);


        markers.clearLayers();
        polygons.clearLayers();
        fetchAll(CountryField.value, CategoryField.value);
    }
}

function alterHeatMapParameter(event) {
    event.srcElement.value;
}

async function fetchCategories() {
	let response;
	try {
			response = await fetch("categories.json");

		if (!response.ok) {
			// If the response status is not OK, throw an error
			throw new Error(`HTTP error! Status: ${response.status}`);
		}
		} catch (error) {
			alert(`Failed to fetch categories\n${error.message}`)
		}
	categories = await response.json();
	CategoryField.pattern = categories.join('|');
	const CategoriesDataList = document.getElementById('CategoriesDataList');
	categories.forEach(function(item){
		var option = document.createElement('option');
		option.value = item;
		option.innerHTML = item;
		CategoriesDataList.appendChild(option);
	});


}

async function fetchChains() {
	try {
		const response = await fetch("chains.json");
		known_store_chains = await response.json();
		if (!response.ok) {
			// If the response status is not OK, throw an error
			throw new Error(`HTTP error! Status: ${response.status}`);
		}
	} catch (error) {
		alert(`Failed to fetch chains\n${error.message}`)
	}

    icons["Unknown"] = L.icon({
        iconUrl: 'icons/Unknown.png',
        iconSize: [10, 16],
        iconAnchor: [5, 8],
    });
    for (let known_store_chain in known_store_chains) {
        icons[known_store_chain] = L.icon({
            iconUrl: `icons/${known_store_chain}.png`,
            iconAnchor: [8, 8],
        });
    }

    const queryString = window.location.search;
    const urlParams = new URLSearchParams(queryString);
    const urlParam = urlParams.get('category')
    const fieldValue = CategoryField.value
    // Retains saved value from input field on reload
    if (urlParam)
    {
        fetchAll(CountryField.value, urlParam);
        CategoryField.value = urlParam;

    } else if (fieldValue !== "")
    {
        fetchAll(CountryField.value, fieldValue);
    }  else
    {
        CategoryField.value = DefaultSearchValue;
        fetchAll(CountryField.value, DefaultSearchValue);
    }
}


function addPolygon(store) {
    let color;
    if (known_store_chains.hasOwnProperty(store.brand)) {
        color = known_store_chains[store.brand];
    } else {
        color = 'grey';
    }
    L.polygon(store.polygon, {color: color}).addTo(polygons);
}

function addShop(shop) {
    let icon;

    if (known_store_chains.hasOwnProperty(shop.brand)){
        icon = icons[shop.brand];
    } else {
        icon = icons["Unknown"];
    }

    L.marker([shop.lat, shop.long], {
        title: shop.name,
        icon: icon,
    }).addTo(markers);
    addPolygon(shop);
}

function drawHeatmap() {
  const queryString = window.location.search;
  const urlParams = new URLSearchParams(queryString);
  const HeatmapIntensityUrlParam = urlParams.get("HeatmapIntensity")
  if (HeatmapIntensityUrlParam){
     heatmap_intensity_element.value = HeatmapIntensityUrlParam;
  }
  const HeatmapRadiusUrlParam = urlParams.get("HeatmapRadius")
  if (HeatmapRadiusUrlParam){
     heatmap_radius_element.value = HeatmapRadiusUrlParam;
  }

  heatmap.clearLayers();
  const shops_heatmap_format = shops.map(r => [r.lat, r.long, parseInt(heatmap_intensity_element.value)]); // Convert data to heatmap format
  var heat = L.heatLayer(shops_heatmap_format, {radius: parseInt(heatmap_radius_element.value)}).addTo(heatmap);
}

async function fetchAll(country, category) {
	let response;
	try {
		response = await fetch(`all.json?country=${country}&category=${category}`)
		if (!response.ok) {
			// If the response status is not OK, throw an error
			throw new Error(`HTTP error! Status: ${response.status}`);
		}
	} catch (error) {
		alert(`Failed to fetch data\n${error.message}`)
	}

	shops = await response.json();

  shops.forEach((shop) => addShop(shop)); // Add icons and polygons

  drawHeatmap();

  LoadingIndicator.hidden = true;
  SubmitButton.disabled = false;
}

fetchChains();
fetchCategories();