const API_KEY = "94078593b1c2b2f226fb88d8ee037873da3844db";
let map;
let csvData = null;

// Initialize the map
function initMap() {
    map = L.map('map').setView([20.5937, 78.9629], 5); // Centered on India
    L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
    }).addTo(map);

    // Add click event listener to the map
    map.on('click', onMapClick);
}

// Function to handle the map click event
async function onMapClick(e) {
    const { lat, lng } = e.latlng;
    try {
        const populationDensity = await fetchLULCStatistics(lat, lng);
        // Create popup
        L.popup()
            .setLatLng([lat, lng])
            .setContent(`Latitude: ${lat}<br>Longitude: ${lng}<br>Population Density: ${populationDensity}`)
            .openOn(map);
    } catch (error) {
        console.error("Error fetching data:", error);
    }
}

// Function to fetch LULC Statistics from the Bhuvan API
async function fetchLULCStatistics(latitude, longitude) {
    const apiUrl = `https://bhuvan-api.gov.in/lulc_statistics?lat=${latitude}&lon=${longitude}&token=${API_KEY}`;
    try {
        const response = await fetch(apiUrl);
        if (!response.ok) {
            throw new Error(`HTTP error! status: ${response.status}`);
        }
        const data = await response.json();
        const populationDensity = data.population_density || "Data not available";
        return populationDensity;
    } catch (error) {
        console.error("Failed to fetch LULC statistics:", error);
        return "Error fetching data";
    }
}

// Drag and Drop Functionality
const dropArea = document.getElementById('drop-area');
const csvUpload = document.getElementById('csv-upload');

['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
    dropArea.addEventListener(eventName, preventDefaults, false)
})

function preventDefaults (e) {
    e.preventDefault()
    e.stopPropagation()
}

['dragenter', 'dragover'].forEach(eventName => {
    dropArea.addEventListener(eventName, highlight, false)
})

['dragleave', 'drop'].forEach(eventName => {
    dropArea.addEventListener(eventName, unhighlight, false)
})

function highlight(e) {
    dropArea.classList.add('highlight')
}

function unhighlight(e) {
    dropArea.classList.remove('highlight')
}

dropArea.addEventListener('drop', handleDrop, false)

function handleDrop(e) {
    const dt = e.dataTransfer
    const files = dt.files

    handleFiles(files)
}

csvUpload.addEventListener('change', function() {
    handleFiles(this.files);
});

function handleFiles(files) {
    const file = files[0];
    if (file && file.type === "text/csv") {
        const reader = new FileReader();
        reader.onload = function(event) {
            csvData = event.target.result;
            plotCsvDataOnMap();
        };
        reader.readAsText(file);
    } else {
        alert("Please upload a valid CSV file.");
    }
}

// CSV Parsing and Map Plotting
function parseCSV(csvText) {
    const lines = csvText.trim().split('\n');
    const headers = lines[0].split(',').map(header => header.trim());
    const data = [];

    for (let i = 1; i < lines.length; i++) {
        const values = lines[i].split(',').map(value => value.trim());
        if (values.length === headers.length) {
            const entry = {};
            for (let j = 0; j < headers.length; j++) {
                entry[headers[j]] = values[j];
            }
            data.push(entry);
        }
    }
    return data;
}

// Function to plot CSV data on the map
function plotCsvDataOnMap() {
    if (!csvData) {
        alert("Please upload a CSV file first.");
        return;
    }

    const data = parseCSV(csvData);

    // Clear existing markers on the map (if any)
    map.eachLayer(function (layer) {
        if (layer instanceof L.Marker) {
            map.removeLayer(layer);
        }
    });

    data.forEach(async entry => {
        if (entry.Latitude && entry.Longitude) {
            const latitude = parseFloat(entry.Latitude);
            const longitude = parseFloat(entry.Longitude);

            // Add marker for each location
            L.marker([latitude, longitude]).addTo(map)
                .bindPopup(`Latitude: ${latitude}<br>Longitude: ${longitude}`);
        }
    });
}

// Initialize map when the window loads
window.onload = initMap;