const fetchInterval = 500;

// Configuration constants from DemoPage.html
const MEAN = 210;
const WARNING_LIMIT = 2;
const ERROR_LIMIT = 3;
const TARGET_VALUE = 210;
const ACQUISITION_LEN = 500;

// State
let dataPoints = [];
let chart;
let timerInterval;
let isAcquiring = false;
let currentMode = 'live';
let activeSessionData = [];
let currentPage = 1;
let fullDataPage = 1;

// DOM Elements
const startBtn = document.getElementById('startBtn');
const progressBar = document.getElementById('progressBar');
const progressContainer = document.getElementById('progressContainer');
const timerDisplay = document.getElementById('timerDisplay');
const tableBody = document.getElementById('measurementsTable');
const detailPlaceholder = document.getElementById('detailPlaceholder');
const detailContent = document.getElementById('detailContent');
const fullDataTableBody = document.getElementById('fullDataTableBody');
const historyTableBody = document.getElementById('historyTableBody');
const pageInfo = document.getElementById('pageInfo');
const prevBtn = document.getElementById('prevPage');
const nextBtn = document.getElementById('nextPage');
const fullPrevBtn = document.getElementById('fullPrevPage');
const fullNextBtn = document.getElementById('fullNextPage');
const liveDataContainer = document.getElementById('liveDataContainer');
const historyDetailContainer = document.getElementById('historyDetailContainer');
const selectedData = document.getElementById('selectedData');
const plcIpDisplay = document.getElementById('plcIpDisplay');
const connStatusDot = document.getElementById('connStatusDot');
const latencyList = document.getElementById('latencyList');
const acquisitionStatusList = document.getElementById('acquisitionStatusList');

// Initialize Chart.js
function initChart() {
    const ctx = document.getElementById('liveChart').getContext('2d');
    chart = new Chart(ctx, {
        type: 'line',
        data: {
            datasets: [
                { label: 'Value (mm)', data: [], borderColor: '#3b82f6', backgroundColor: 'rgba(59, 130, 246, 0.1)', fill: true, pointRadius: 0, borderWidth: 2, tension: 0 },
                { label: 'Warning UCL', data: [], borderColor: '#facc15', borderWidth: 1, pointRadius: 0, fill: false, borderDash: [5, 5] },
                { label: 'Warning LCL', data: [], borderColor: '#facc15', borderWidth: 1, pointRadius: 0, fill: false, borderDash: [5, 5] },
                { label: 'Error UCL', data: [], borderColor: '#f87171', borderWidth: 1, pointRadius: 0, fill: false, borderDash: [5, 5] },
                { label: 'Error LCL', data: [], borderColor: '#f87171', borderWidth: 1, pointRadius: 0, fill: false, borderDash: [5, 5] },
                { label: 'Target Value', data: [], borderColor: '#22c55e', borderWidth: 1.5, pointRadius: 0, fill: false, tension: 0 }
            ]
        },
        options: {
            responsive: true,
            maintainAspectRatio: false,
            scales: { 
                x: { type: 'linear', min: 0, max: ACQUISITION_LEN, title: { display: true, text: 'Position (mm)' } },
                y: { min: 200, max: 220 }
            },
            animation: false
        }
    });
}

// Fetch data from Flask and update UI
async function updateData() {
    try {
        const response = await fetch('/data');
        if (!response.ok) throw new Error(`HTTP error! status: ${response.status}`);
        const data = await response.json();
        console.log("Data received:", data);

        if (data) {
            const db100 = data.db100;
            
            // Update Connectivity Status
            if (data.connected !== undefined) {
                connStatusDot.className = data.connected 
                    ? 'w-2 h-2 bg-green-400 rounded-full mr-2 animate-pulse' 
                    : 'w-2 h-2 bg-red-600 rounded-full mr-2';
                plcIpDisplay.textContent = data.plc_ip || "Disconnected";
            }

            if (db100) {
                // Update Latencies
                if (db100.duration !== undefined) {
                    latencyList.textContent = `Latency: ${db100.duration.toFixed(2)}ms`;
                }
                
                // Update Live Values (if needed)
                if (db100.params && db100.params.x_live !== undefined) {
                    // Could update a specific UI element for X_Live here
                }
            }

            // Update Chart data if acquiring
            if (isAcquiring && data.db101 && data.db101.values) {
                chart.data.datasets[0].data = data.db101.values.map((v, i) => ({ x: i * (ACQUISITION_LEN / 40), y: v }));
                chart.update();
            }
            
            // Update acquisition status text
            if (isAcquiring) {
                acquisitionStatusList.textContent = `• Mode: Active Acquisition`;
                acquisitionStatusList.parentElement.classList.replace('text-gray-600', 'text-blue-400');
            } else {
                acquisitionStatusList.textContent = `• Mode: Polling (5Hz)`;
                acquisitionStatusList.parentElement.classList.replace('text-blue-400', 'text-gray-600');
            }
        }
    } catch (err) {
        console.error("Error updating data:", err);
    }
}

// Start acquisition (Mocked logic for now to match DemoPage.html)
startBtn.addEventListener('click', () => {
    if (isAcquiring) return;

    dataPoints = [];
    activeSessionData = [];
    chart.data.datasets.forEach(ds => ds.data = []);
    chart.update();

    isAcquiring = true;
    startBtn.disabled = true;
    startBtn.classList.replace('bg-green-600', 'bg-gray-400');
    progressContainer.classList.remove('hidden');
    
    currentMode = 'live';
    toggleDetailVisibility();

    let currentStep = 0;

    let timerInterval = setInterval(() => {
        const point = {
            ts: new Date(),
            val: generateNormal(MEAN, 1),
            x: (currentStep / (TOTAL_SAMPLES - 1)) * ACQUISITION_LEN
        };
        dataPoints.push(point);
        activeSessionData = [...dataPoints];

        // Update Chart data
        chart.data.datasets[0].data.push({x: point.x, y: point.val});
        chart.data.datasets[1].data.push({x: point.x, y: MEAN + WARNING_LIMIT});
        chart.data.datasets[2].data.push({x: point.x, y: MEAN - WARNING_LIMIT});
        chart.data.datasets[3].data.push({x: point.x, y: MEAN + ERROR_LIMIT});
        chart.data.datasets[4].data.push({x: point.x, y: MEAN - ERROR_LIMIT});
        chart.data.datasets[5].data.push({x: point.x, y: TARGET_VALUE});

        if (chart.data.datasets[0].data.length > 100) {
            chart.data.datasets.forEach(ds => ds.data.shift());
        }
        chart.update();

        if (currentStep % 3 === 0) {
            updateTable();
        }

        currentStep++;
        const progress = (currentStep / TOTAL_SAMPLES) * 100;
        progressBar.style.width = `${progress}%`;
        timerDisplay.innerText = `Time Remaining: ${Math.max(0, Math.ceil((TOTAL_SAMPLES - currentStep) / SAMPLE_RATE))}s`;

        if (currentStep >= TOTAL_SAMPLES) {
            clearInterval(timerInterval);
            completeAcquisition();
        }
    }, 1000 / SAMPLE_RATE);
});

function completeAcquisition() {
    isAcquiring = false;
    startBtn.disabled = false;
    startBtn.classList.replace('bg-gray-400', 'bg-green-600');
    timerDisplay.innerText = "Acquisition Complete";
    timerDisplay.classList.replace('text-blue-600', 'text-green-600');

    activeSessionData = [...dataPoints].sort((a, b) => b.ts - a.ts);
    
    liveDataContainer.classList.remove('hidden');
    historyDetailContainer.classList.add('hidden');
    renderFullSessionTable();

    detailPlaceholder.classList.add('hidden');
    detailContent.classList.remove('hidden');
    selectedData.innerText = `Session completed. Captured ${dataPoints.length} points. Mean: ${dataPoints.reduce((a,b)=>a+b.val,0)/dataPoints.length}`;
}

function renderFullSessionTable() {
    fullDataTableBody.innerHTML = '';
    const start = (fullDataPage - 1) * itemsPerPage;
    const end = start + itemsPerPage;
    const pageData = activeSessionData.slice(start, end);

    pageData.forEach((p, i) => {
        const row = document.createElement('tr');
        const diff = Math.abs(p.val - MEAN);
        let status = 'OK';
        let colorClass = 'text-green-600 border-green-600';

        if (diff > ERROR_LIMIT) {
            status = 'ERROR';
            colorClass = 'text-red-600 border-red-600';
        } else if (diff > WARNING_LIMIT) {
            status = 'WARNING';
            colorClass = 'text-yellow-600 border-yellow-600';
        }

        row.innerHTML = `
            <td class="p-2 border-b">${start + i + 1}</td>
            <td class="p-2 border-b">${p.ts.toLocaleTimeString()}</td>
            <td class="p-2 border-b font-mono">${p.val.toFixed(2)}</td>
            <td class="p-2 border-b">
                <span class="px-1 py-0.5 bg-white rounded-full text-[9px] font-bold border ${colorClass}">${status}</span>
            </td>
        `;
        fullDataTableBody.appendChild(row);
    });

    fullPageInfo.innerText = `Page ${fullDataPage} of ${Math.ceil(activeSessionData.length / itemsPerPage)}`;
    fullPrevBtn.disabled = fullDataPage === 1;
    fullNextBtn.disabled = fullDataPage * itemsPerPage >= activeSessionData.length;
}

function toggleDetailVisibility() {
    if (isAcquiring || currentMode === 'history') {
        liveDataContainer.classList.remove('hidden');
        historyDetailContainer.classList.add('hidden');
        if (isAcquiring) {
            activeSessionData = [...dataPoints];
            renderFullSessionTable();
        }
    } else {
        liveDataContainer.classList.add('hidden');
        historyDetailContainer.classList.add('hidden');
        detailPlaceholder.classList.remove('hidden');
    }
}

// Initialization
initChart();
setInterval(updateData, fetchInterval);
updateData();

// Pagination
fullPrevBtn.onclick = () => {
    if (fullDataPage > 1) {
        fullDataPage--;
        renderFullSessionTable();
    }
};

fullNextBtn.onclick = () => {
    if (fullDataPage * itemsPerPage < activeSessionData.length) {
        fullDataPage++;
        renderFullSessionTable();
    }
};