// Global variables
let ecgData = [];
let bpmHistory = [];
let historyRecords = [];
let isPaused = false;
let updateInterval;
let ecgChart;

// Initialize the application
document.addEventListener('DOMContentLoaded', function() {
    initializeChart();
    startMonitoring();
    setupEventListeners();
});

function initializeChart() {
    const ctx = document.getElementById('ecgChart').getContext('2d');
    
    ecgChart = new Chart(ctx, {
        type: 'line',
        data: {
            labels: Array(100).fill(''),
            datasets: [{
                label: 'ECG',
                data: Array(100).fill(0),
                borderColor: '#EF4444',
                borderWidth: 2,
                tension: 0.1,
                pointRadius: 0
            }]
        },
        options: {
            responsive: true,
            maintainAspectRatio: false,
            scales: {
                y: {
                    min: -2,
                    max: 2,
                    display: false
                },
                x: {
                    display: false
                }
            },
            animation: {
                duration: 0
            },
            plugins: {
                legend: {
                    display: false
                }
            }
        }
    });
}

function startMonitoring() {
    // Initial data
    generateInitialData();
    
    // Start updating the chart every second
    updateInterval = setInterval(updateECGData, 1000);
}

function generateInitialData() {
    // Generate some initial random ECG-like data
    for (let i = 0; i < 100; i++) {
        ecgData.push(generateECGPoint(i));
    }
    updateChart();
}

function generateECGPoint(index) {
    // Simulate ECG data with some randomness
    const position = index % 100;
    
    // Generate a basic ECG waveform with some randomness
    if (position > 90) {
        return 0.2 + Math.random() * 0.1;
    } else if (position > 80) {
        return -0.5 - Math.random() * 0.2;
    } else if (position > 70) {
        return 1.5 + Math.random() * 0.3;
    } else if (position > 60) {
        return -0.8 - Math.random() * 0.2;
    } else if (position > 50) {
        return 0.3 + Math.random() * 0.1;
    } else {
        // Baseline with some small noise
        return (Math.random() - 0.5) * 0.2;
    }
}

function updateECGData() {
    if (isPaused) return;
    
    // Remove first point and add new one
    ecgData.shift();
    ecgData.push(generateECGPoint(Math.floor(Math.random() * 100)));
    
    // Update chart
    updateChart();
    
    // Calculate and display BPM
    const bpm = 60 + Math.floor(Math.random() * 60);
    updateBPM(bpm);
    
    // Check for irregularity (10% chance)
    const isIrregular = Math.random() < 0.1;
    updateIrregularityStatus(isIrregular, bpm);
    
    // Add to history
    addToHistory(bpm, isIrregular);
    
    // Update stats
    updateStats();
}

function updateChart() {
    ecgChart.data.datasets[0].data = ecgData;
    ecgChart.update();
}

function updateBPM(bpm) {
    document.getElementById('bpmDisplay').textContent = bpm;
    document.getElementById('currentBpm').textContent = bpm;
    bpmHistory.push(bpm);
    
    // Limit history to last 100 readings
    if (bpmHistory.length > 100) {
        bpmHistory.shift();
    }
}

function updateIrregularityStatus(isIrregular, bpm) {
    const statusElement = document.getElementById('irregularityStatus');
    const heartStatus = document.getElementById('heartStatus');
    
    if (isIrregular) {
        statusElement.innerHTML = `
            <i data-feather="alert-circle" class="inline mr-2"></i>
            <span>Irregular heartbeat detected (${bpm} BPM)</span>
        `;
        statusElement.className = 'text-center py-4 px-6 rounded-lg irregular mb-4';
        heartStatus.innerHTML = `
            <span class="h-4 w-4 rounded-full bg-yellow-500 animate-pulse mr-2"></span>
            <span class="text-gray-600">Irregular</span>
        `;
    } else {
        statusElement.innerHTML = `
            <i data-feather="check-circle" class="inline mr-2"></i>
            <span>Regular heartbeat (${bpm} BPM)</span>
        `;
        statusElement.className = 'text-center py-4 px-6 rounded-lg regular mb-4';
        heartStatus.innerHTML = `
            <span class="h-4 w-4 rounded-full bg-green-500 animate-pulse mr-2"></span>
            <span class="text-gray-600">Regular</span>
        `;
    }
    feather.replace();
}

function addToHistory(bpm, isIrregular) {
    const now = new Date();
    const timeString = now.toLocaleTimeString();
    
    historyRecords.unshift({
        time: timeString,
        bpm: bpm,
        isIrregular: isIrregular,
        timestamp: now.getTime()
    });
    
    // Limit history to 50 records
    if (historyRecords.length > 50) {
        historyRecords.pop();
    }
    
    updateHistoryTable();
}

function updateHistoryTable() {
    const tableBody = document.getElementById('historyTable');
    tableBody.innerHTML = '';
    
    historyRecords.forEach(record => {
        const row = document.createElement('tr');
        
        row.innerHTML = `
            <td class="px-6 py-4 whitespace-nowrap text-sm text-gray-500">${record.time}</td>
            <td class="px-6 py-4 whitespace-nowrap text-sm font-medium ${record.isIrregular ? 'text-yellow-600' : 'text-gray-900'}">${record.bpm}</td>
            <td class="px-6 py-4 whitespace-nowrap text-sm">
                <span class="px-2 inline-flex text-xs leading-5 font-semibold rounded-full ${record.isIrregular ? 'bg-yellow-100 text-yellow-800' : 'bg-green-100 text-green-800'}">
                    ${record.isIrregular ? 'Irregular' : 'Regular'}
                </span>
            </td>
            <td class="px-6 py-4 whitespace-nowrap text-sm text-gray-500">
                <button class="text-blue-500 hover:text-blue-700">
                    <i data-feather="info" class="w-4 h-4"></i>
                </button>
            </td>
        `;
        
        tableBody.appendChild(row);
    });
    
    feather.replace();
}

function updateStats() {
    if (bpmHistory.length === 0) return;
    
    const sum = bpmHistory.reduce((a, b) => a + b, 0);
    const avg = Math.round(sum / bpmHistory.length);
    const min = Math.min(...bpmHistory);
    const max = Math.max(...bpmHistory);
    
    document.getElementById('averageBpm').textContent = avg;
    document.getElementById('minBpm').textContent = min;
    document.getElementById('maxBpm').textContent = max;
    
    // Update irregular beats count
    const irregularCount = historyRecords.filter(r => r.isIrregular).length;
    document.getElementById('irregularBeats').textContent = irregularCount;
    
    // Update last irregularity time
    const lastIrregular = historyRecords.find(r => r.isIrregular);
    if (lastIrregular) {
        document.getElementById('lastIrregularity').textContent = lastIrregular.time;
    }
}

function setupEventListeners() {
    // Pause/Resume button
    document.getElementById('pauseBtn').addEventListener('click', function() {
        isPaused = !isPaused;
        this.innerHTML = isPaused ? 
            '<i data-feather="play"></i> Resume' : 
            '<i data-feather="pause"></i> Pause';
        feather.replace();
    });
    
    // Export button
    document.getElementById('exportBtn').addEventListener('click', function() {
        alert('Data exported successfully!');
    });
    
    // Clear button
    document.getElementById('clearBtn').addEventListener('click', function() {
        if (confirm('Are you sure you want to clear all history?')) {
            historyRecords = [];
            bpmHistory = [];
            updateHistoryTable();
            updateStats();
        }
    });
}