/**
 * LiXX Cell Pack Matcher - Main Application
 * Uses Web Workers for non-blocking computation.
 */

// =============================================================================
// Application State
// =============================================================================

const AppState = {
    cells: [],
    cellIdCounter: 0,
    worker: null,
    isRunning: false,
    results: null
};

// =============================================================================
// DOM Elements
// =============================================================================

const DOM = {
    cellsSerial: document.getElementById('cells-serial'),
    cellsParallel: document.getElementById('cells-parallel'),
    configDisplay: document.getElementById('config-display'),
    totalCellsNeeded: document.getElementById('total-cells-needed'),
    cellTbody: document.getElementById('cell-tbody'),
    btnAddCell: document.getElementById('btn-add-cell'),
    btnLoadExample: document.getElementById('btn-load-example'),
    btnClearAll: document.getElementById('btn-clear-all'),
    statCount: document.getElementById('stat-count'),
    statAvgCap: document.getElementById('stat-avg-cap'),
    statAvgIr: document.getElementById('stat-avg-ir'),
    weightCapacity: document.getElementById('weight-capacity'),
    weightIr: document.getElementById('weight-ir'),
    weightCapValue: document.getElementById('weight-cap-value'),
    weightIrValue: document.getElementById('weight-ir-value'),
    algorithmSelect: document.getElementById('algorithm-select'),
    maxIterations: document.getElementById('max-iterations'),
    btnStartMatching: document.getElementById('btn-start-matching'),
    btnStopMatching: document.getElementById('btn-stop-matching'),
    progressSection: document.getElementById('progress-section'),
    progressFill: document.getElementById('progress-fill'),
    progressIteration: document.getElementById('progress-iteration'),
    progressCombinations: document.getElementById('progress-combinations'),
    progressScore: document.getElementById('progress-score'),
    progressTime: document.getElementById('progress-time'),
    progressSpeed: document.getElementById('progress-speed'),
    progressEta: document.getElementById('progress-eta'),
    livePreview: document.getElementById('live-preview'),
    livePreviewContent: document.getElementById('live-preview-content'),
    resultsSection: document.getElementById('results-section'),
    resultScore: document.getElementById('result-score'),
    resultCapVariance: document.getElementById('result-cap-variance'),
    resultIrVariance: document.getElementById('result-ir-variance'),
    resultPackCapacity: document.getElementById('result-pack-capacity'),
    packGrid: document.getElementById('pack-grid'),
    resultsTbody: document.getElementById('results-tbody'),
    excludedCellsSection: document.getElementById('excluded-cells-section'),
    excludedCellsList: document.getElementById('excluded-cells-list'),
    btnExportJson: document.getElementById('btn-export-json'),
    btnExportCsv: document.getElementById('btn-export-csv'),
    btnCopyResults: document.getElementById('btn-copy-results'),
    shortcutsDialog: document.getElementById('shortcuts-dialog'),
    btnCloseShortcuts: document.getElementById('btn-close-shortcuts')
};

// =============================================================================
// Utility Functions
// =============================================================================

function formatDuration(ms) {
    if (ms < 1000) return `${Math.round(ms)}ms`;
    if (ms < 60000) return `${(ms / 1000).toFixed(1)}s`;
    if (ms < 3600000) {
        const mins = Math.floor(ms / 60000);
        const secs = Math.round((ms % 60000) / 1000);
        return `${mins}m ${secs}s`;
    }
    const hours = Math.floor(ms / 3600000);
    const mins = Math.round((ms % 3600000) / 60000);
    return `${hours}h ${mins}m`;
}

function formatNumber(num) {
    if (num === Infinity) return '∞';
    if (num >= 1e9) return `${(num / 1e9).toFixed(1)}B`;
    if (num >= 1e6) return `${(num / 1e6).toFixed(1)}M`;
    if (num >= 1e3) return `${(num / 1e3).toFixed(1)}K`;
    return num.toLocaleString();
}

// =============================================================================
// Combination Calculator
// =============================================================================

function binomial(n, k) {
    if (k > n) return 0;
    if (k === 0 || k === n) return 1;
    let result = 1;
    for (let i = 0; i < k; i++) {
        result = result * (n - i) / (i + 1);
    }
    return Math.round(result);
}

function calculateTotalCombinations(numCells, serial, parallel) {
    const totalNeeded = serial * parallel;
    if (numCells < totalNeeded) return 0;

    let total = 1;
    let remaining = numCells;

    for (let i = 0; i < serial; i++) {
        total *= binomial(remaining, parallel);
        remaining -= parallel;
    }

    return total;
}

function updateMaxIterations() {
    const serial = parseInt(DOM.cellsSerial.value) || 1;
    const parallel = parseInt(DOM.cellsParallel.value) || 1;
    const validCells = AppState.cells.filter(c => c.capacity && c.capacity > 0);

    const totalCombinations = calculateTotalCombinations(validCells.length, serial, parallel);

    // Set max iterations: use total combinations if reasonable, cap at 1,000,000
    const suggested = Math.min(Math.max(totalCombinations, 1000), 1000000);
    DOM.maxIterations.value = suggested;
}

// =============================================================================
// Configuration Management
// =============================================================================

function updateConfigDisplay() {
    const serial = parseInt(DOM.cellsSerial.value) || 1;
    const parallel = parseInt(DOM.cellsParallel.value) || 1;
    const total = serial * parallel;
    DOM.configDisplay.textContent = `${serial}S${parallel}P`;
    DOM.totalCellsNeeded.textContent = total;
    updateMatchingButtonState();
    updateMaxIterations();
}

// =============================================================================
// Cell Management
// =============================================================================

function addCell(cellData = null) {
    const id = AppState.cellIdCounter++;
    const label = cellData?.label || `C${String(AppState.cells.length + 1).padStart(2, '0')}`;
    const capacity = cellData?.capacity || '';
    const ir = cellData?.ir || '';

    const cell = { id, label, capacity: capacity || null, ir: ir || null };
    AppState.cells.push(cell);

    const row = document.createElement('tr');
    row.dataset.cellId = id;
    row.innerHTML = `
        <td>${AppState.cells.length}</td>
        <td><input type="text" class="cell-label-input" value="${label}" aria-label="Cell label" data-field="label"></td>
        <td><input type="number" min="0" max="99999" value="${capacity}" aria-label="Capacity in mAh" data-field="capacity" placeholder="mAh"></td>
        <td><input type="number" min="0" max="9999" step="0.1" value="${ir}" aria-label="Internal resistance in milliohms" data-field="ir" placeholder="optional"></td>
        <td><button type="button" class="btn-remove" aria-label="Remove cell" data-remove="${id}">✕</button></td>
    `;

    DOM.cellTbody.appendChild(row);

    row.querySelectorAll('input').forEach(input => {
        input.addEventListener('change', () => updateCellData(id, input.dataset.field, input.value));
        input.addEventListener('input', () => updateCellData(id, input.dataset.field, input.value));
    });

    row.querySelector('.btn-remove').addEventListener('click', () => removeCell(id));
    updateCellStats();
    updateMatchingButtonState();

    if (!cellData) {
        row.querySelector('input[data-field="capacity"]').focus();
    }
}

function updateCellData(id, field, value) {
    const cell = AppState.cells.find(c => c.id === id);
    if (!cell) return;

    if (field === 'label') cell.label = value || `C${id}`;
    else if (field === 'capacity') cell.capacity = value ? parseFloat(value) : null;
    else if (field === 'ir') cell.ir = value ? parseFloat(value) : null;

    updateCellStats();
    updateMatchingButtonState();
}

function removeCell(id) {
    const index = AppState.cells.findIndex(c => c.id === id);
    if (index === -1) return;

    AppState.cells.splice(index, 1);
    const row = DOM.cellTbody.querySelector(`tr[data-cell-id="${id}"]`);
    if (row) row.remove();

    DOM.cellTbody.querySelectorAll('tr').forEach((row, idx) => {
        row.querySelector('td:first-child').textContent = idx + 1;
    });

    updateCellStats();
    updateMatchingButtonState();
}

function clearAllCells() {
    if (AppState.cells.length > 0 && !confirm('Clear all cells?')) return;
    AppState.cells = [];
    AppState.cellIdCounter = 0;
    DOM.cellTbody.innerHTML = '';
    updateCellStats();
    updateMatchingButtonState();
}

function updateCellStats() {
    const count = AppState.cells.length;
    DOM.statCount.textContent = count;

    if (count === 0) {
        DOM.statAvgCap.textContent = '-';
        DOM.statAvgIr.textContent = '-';
        return;
    }

    const capacities = AppState.cells.filter(c => c.capacity).map(c => c.capacity);
    const irs = AppState.cells.filter(c => c.ir).map(c => c.ir);

    DOM.statAvgCap.textContent = capacities.length > 0
        ? `${Math.round(capacities.reduce((a, b) => a + b, 0) / capacities.length)} mAh` : '-';
    DOM.statAvgIr.textContent = irs.length > 0
        ? `${(irs.reduce((a, b) => a + b, 0) / irs.length).toFixed(1)} mΩ` : '-';

    updateMaxIterations();
}

function loadExampleData() {
    if (AppState.cells.length > 0 && !confirm('Replace current cells with example data?')) return;

    AppState.cells = [];
    AppState.cellIdCounter = 0;
    DOM.cellTbody.innerHTML = '';

    const exampleCells = [
        { label: 'B01', capacity: 3330, ir: 42 }, { label: 'B02', capacity: 3360, ir: 38 },
        { label: 'B03', capacity: 3230, ir: 45 }, { label: 'B04', capacity: 3390, ir: 41 },
        { label: 'B05', capacity: 3280, ir: 44 }, { label: 'B06', capacity: 3350, ir: 39 },
        { label: 'B07', capacity: 3350, ir: 40 }, { label: 'B08', capacity: 3490, ir: 36 },
        { label: 'B09', capacity: 3280, ir: 43 }, { label: 'B10', capacity: 3420, ir: 37 },
        { label: 'B11', capacity: 3350, ir: 41 }, { label: 'B12', capacity: 3420, ir: 38 },
        { label: 'B13', capacity: 3150, ir: 52 }, { label: 'B14', capacity: 3380, ir: 40 }
    ];
    exampleCells.forEach(cell => addCell(cell));
}

// =============================================================================
// Weight Sliders
// =============================================================================

function updateWeights(source) {
    const capWeight = parseInt(DOM.weightCapacity.value);
    if (source === 'capacity') DOM.weightIr.value = 100 - capWeight;
    else DOM.weightCapacity.value = 100 - parseInt(DOM.weightIr.value);

    DOM.weightCapValue.textContent = `${DOM.weightCapacity.value}%`;
    DOM.weightIrValue.textContent = `${DOM.weightIr.value}%`;
}

// =============================================================================
// Matching Control (Web Worker)
// =============================================================================

function updateMatchingButtonState() {
    const serial = parseInt(DOM.cellsSerial.value) || 1;
    const parallel = parseInt(DOM.cellsParallel.value) || 1;
    const needed = serial * parallel;
    const validCells = AppState.cells.filter(c => c.capacity && c.capacity > 0);
    const canStart = validCells.length >= needed && !AppState.isRunning;

    DOM.btnStartMatching.disabled = !canStart;
    DOM.btnStartMatching.title = validCells.length < needed
        ? `Need at least ${needed} cells with capacity data` : '';
}

function startMatching() {
    if (AppState.isRunning) return;

    const serial = parseInt(DOM.cellsSerial.value) || 1;
    const parallel = parseInt(DOM.cellsParallel.value) || 1;
    const validCells = AppState.cells.filter(c => c.capacity && c.capacity > 0);

    if (validCells.length < serial * parallel) {
        alert(`Need at least ${serial * parallel} cells with capacity data.`);
        return;
    }

    AppState.isRunning = true;
    DOM.progressSection.hidden = false;
    DOM.resultsSection.hidden = true;
    DOM.btnStartMatching.disabled = true;
    DOM.progressFill.style.width = '0%';
    DOM.progressIteration.textContent = '0';
    DOM.progressCombinations.textContent = '-';
    DOM.progressScore.textContent = '-';
    DOM.progressTime.textContent = '0s';
    DOM.progressSpeed.textContent = '-';
    DOM.progressEta.textContent = '-';
    DOM.livePreview.hidden = true;

    const algorithmType = DOM.algorithmSelect.value;
    const maxIterations = parseInt(DOM.maxIterations.value) || 5000;
    const capacityWeight = parseInt(DOM.weightCapacity.value) / 100;
    const irWeight = parseInt(DOM.weightIr.value) / 100;

    AppState.worker = new Worker('js/matching-worker.js');

    AppState.worker.onmessage = function (e) {
        const { type, data } = e.data;
        if (type === 'progress') updateProgress(data);
        else if (type === 'complete') handleComplete(data);
        else if (type === 'error') handleError(data);
    };

    AppState.worker.onerror = function (error) {
        console.error('Worker error:', error);
        handleError(error.message);
    };

    AppState.worker.postMessage({
        type: 'start',
        data: {
            cells: validCells.map(c => ({ label: c.label, capacity: c.capacity, ir: c.ir })),
            serial, parallel,
            algorithm: algorithmType,
            options: { maxIterations, capacityWeight, irWeight }
        }
    });
}

function stopMatching() {
    console.log("stopMatching")
    if (AppState.worker) {
        AppState.worker.postMessage({ type: 'stop' });
    }
}

function updateProgress(progress) {
    const percent = (progress.iteration / progress.maxIterations) * 100;
    DOM.progressFill.style.width = `${percent}%`;
    DOM.progressIteration.textContent = formatNumber(progress.iteration);

    DOM.progressCombinations.textContent = progress.totalCombinations
        ? `${formatNumber(progress.evaluatedCombinations)} / ${formatNumber(progress.totalCombinations)}`
        : formatNumber(progress.evaluatedCombinations || progress.iteration);

    DOM.progressScore.textContent = progress.bestScore.toFixed(4);
    DOM.progressTime.textContent = formatDuration(progress.elapsedTime);

    if (progress.iterationsPerSecond > 0) {
        DOM.progressSpeed.textContent = `${formatNumber(Math.round(progress.iterationsPerSecond))}/s`;
    }

    DOM.progressEta.textContent = formatDuration(progress.eta);

    if (progress.currentBest && progress.currentBest.config) {
        renderLivePreview(progress.currentBest.config);
    }
}

function renderLivePreview(config) {
    DOM.livePreview.hidden = false;
    DOM.livePreviewContent.innerHTML = config.map((group, idx) => {
        const cells = group.map(c => c.label).join('+');
        const totalCap = group.reduce((sum, c) => sum + c.capacity, 0);
        return `<div class="live-preview-group"><span class="group-label">S${idx + 1}:</span><span class="group-cells">${cells}</span><span class="group-cap">${totalCap}</span></div>`;
    }).join('');
}

function handleComplete(results) {
    AppState.isRunning = false;
    AppState.results = results;
    if (AppState.worker) { AppState.worker.terminate(); AppState.worker = null; }
    DOM.progressSection.hidden = true;
    DOM.btnStartMatching.disabled = false;
    updateMatchingButtonState();
    displayResults(results);
}

function handleError(errorMessage) {
    AppState.isRunning = false;
    if (AppState.worker) { AppState.worker.terminate(); AppState.worker = null; }
    DOM.progressSection.hidden = true;
    DOM.btnStartMatching.disabled = false;
    updateMatchingButtonState();
    alert('An error occurred during matching: ' + errorMessage);
}

// =============================================================================
// Results Display
// =============================================================================

function displayResults(results) {
    DOM.resultsSection.hidden = false;
    DOM.resultScore.textContent = results.score.toFixed(3);
    DOM.resultCapVariance.textContent = `${results.capacityCV.toFixed(2)}%`;
    DOM.resultIrVariance.textContent = results.irCV ? `${results.irCV.toFixed(2)}%` : 'N/A';

    const packCapacity = Math.min(...results.groupCapacities);
    DOM.resultPackCapacity.textContent = `${packCapacity} mAh`;

    renderPackVisualization(results);
    renderResultsTable(results);

    if (results.excludedCells.length > 0) {
        DOM.excludedCellsSection.hidden = false;
        DOM.excludedCellsList.textContent = results.excludedCells.map(c => c.label).join(', ');
    } else {
        DOM.excludedCellsSection.hidden = true;
    }

    DOM.resultsSection.scrollIntoView({ behavior: 'smooth', block: 'start' });
}

function renderPackVisualization(results) {
    const config = results.configuration;
    const allCapacities = config.flat().map(c => c.capacity);
    const minCap = Math.min(...allCapacities);
    const maxCap = Math.max(...allCapacities);
    const range = maxCap - minCap || 1;

    DOM.packGrid.innerHTML = '';

    config.forEach((group, groupIdx) => {
        const row = document.createElement('div');
        row.className = 'pack-row';

        const label = document.createElement('span');
        label.className = 'pack-row-label';
        label.textContent = `S${groupIdx + 1}`;
        row.appendChild(label);

        const cellsContainer = document.createElement('div');
        cellsContainer.className = 'pack-cells';

        group.forEach(cell => {
            const cellEl = document.createElement('div');
            cellEl.className = 'pack-cell';
            const normalized = (cell.capacity - minCap) / range;
            const hue = normalized * 120;
            cellEl.style.backgroundColor = `hsl(${hue}, 70%, 45%)`;
            cellEl.innerHTML = `<span class="cell-label">${cell.label}</span><span class="cell-capacity">${cell.capacity} mAh</span>${cell.ir ? `<span class="cell-ir">${cell.ir} mΩ</span>` : ''}`;
            cellsContainer.appendChild(cellEl);
        });

        row.appendChild(cellsContainer);
        DOM.packGrid.appendChild(row);
    });
}

function renderResultsTable(results) {
    const config = results.configuration;
    const avgCapacity = results.groupCapacities.reduce((a, b) => a + b, 0) / results.groupCapacities.length;
    DOM.resultsTbody.innerHTML = '';

    config.forEach((group, idx) => {
        const groupCapacity = group.reduce((sum, c) => sum + c.capacity, 0);
        const deviation = ((groupCapacity - avgCapacity) / avgCapacity * 100);
        const irsWithValues = group.filter(c => c.ir);
        const avgIr = irsWithValues.length > 0 ? irsWithValues.reduce((sum, c) => sum + c.ir, 0) / irsWithValues.length : null;

        let deviationClass = 'deviation-good';
        if (Math.abs(deviation) > 2) deviationClass = 'deviation-warning';
        if (Math.abs(deviation) > 5) deviationClass = 'deviation-bad';

        const row = document.createElement('tr');
        row.innerHTML = `<td>S${idx + 1}</td><td>${group.map(c => c.label).join(' + ')}</td><td>${groupCapacity} mAh</td><td>${avgIr ? avgIr.toFixed(1) + ' mΩ' : '-'}</td><td class="${deviationClass}">${deviation >= 0 ? '+' : ''}${deviation.toFixed(2)}%</td>`;
        DOM.resultsTbody.appendChild(row);
    });
}

// =============================================================================
// Export Functions
// =============================================================================

function exportJson() {
    if (!AppState.results) return;
    const data = {
        configuration: `${DOM.cellsSerial.value}S${DOM.cellsParallel.value}P`,
        timestamp: new Date().toISOString(),
        score: AppState.results.score,
        capacityCV: AppState.results.capacityCV,
        irCV: AppState.results.irCV,
        groups: AppState.results.configuration.map((group, idx) => ({
            group: `S${idx + 1}`,
            cells: group.map(c => ({ label: c.label, capacity: c.capacity, ir: c.ir })),
            totalCapacity: group.reduce((sum, c) => sum + c.capacity, 0)
        })),
        excludedCells: AppState.results.excludedCells.map(c => ({ label: c.label, capacity: c.capacity, ir: c.ir }))
    };
    downloadFile(JSON.stringify(data, null, 2), 'cell-matching-results.json', 'application/json');
}

function exportCsv() {
    if (!AppState.results) return;
    const lines = ['Group,Cell Label,Capacity (mAh),IR (mΩ),Group Total'];
    AppState.results.configuration.forEach((group, idx) => {
        const groupTotal = group.reduce((sum, c) => sum + c.capacity, 0);
        group.forEach((cell, cellIdx) => {
            lines.push(`S${idx + 1},${cell.label},${cell.capacity},${cell.ir || ''},${cellIdx === 0 ? groupTotal : ''}`);
        });
    });
    if (AppState.results.excludedCells.length > 0) {
        lines.push('', 'Excluded Cells');
        AppState.results.excludedCells.forEach(cell => lines.push(`-,${cell.label},${cell.capacity},${cell.ir || ''}`));
    }
    downloadFile(lines.join('\n'), 'cell-matching-results.csv', 'text/csv');
}

async function copyResults() {
    if (!AppState.results) return;
    const config = AppState.results.configuration;
    const lines = [`Cell Matching Results - ${DOM.cellsSerial.value}S${DOM.cellsParallel.value}P`, `Score: ${AppState.results.score.toFixed(3)}`, `Capacity CV: ${AppState.results.capacityCV.toFixed(2)}%`, '', 'Pack Configuration:'];
    config.forEach((group, idx) => {
        const cells = group.map(c => `${c.label} (${c.capacity}mAh)`).join(' + ');
        const total = group.reduce((sum, c) => sum + c.capacity, 0);
        lines.push(`  S${idx + 1}: ${cells} = ${total}mAh`);
    });
    if (AppState.results.excludedCells.length > 0) {
        lines.push('', `Excluded: ${AppState.results.excludedCells.map(c => c.label).join(', ')}`);
    }
    try {
        await navigator.clipboard.writeText(lines.join('\n'));
        DOM.btnCopyResults.textContent = 'Copied!';
        setTimeout(() => { DOM.btnCopyResults.textContent = 'Copy to Clipboard'; }, 2000);
    } catch (err) { console.error('Failed to copy:', err); }
}

function downloadFile(content, filename, mimeType) {
    const blob = new Blob([content], { type: mimeType });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
}

// =============================================================================
// Keyboard Navigation & Event Listeners
// =============================================================================

function setupKeyboardShortcuts() {
    document.addEventListener('keydown', (e) => {
        if (e.altKey && e.key === 'a') { e.preventDefault(); addCell(); }
        if (e.altKey && e.key === 's') { e.preventDefault(); if (!DOM.btnStartMatching.disabled) startMatching(); }
        if (e.altKey && e.key === 'e') { e.preventDefault(); loadExampleData(); }
        if (e.key === 'Escape') { if (AppState.isRunning) stopMatching(); if (DOM.shortcutsDialog.open) DOM.shortcutsDialog.close(); }
        if (e.key === '?' && !e.target.matches('input, textarea')) { e.preventDefault(); DOM.shortcutsDialog.showModal(); }
    });
}

function initEventListeners() {
    DOM.cellsSerial.addEventListener('input', updateConfigDisplay);
    DOM.cellsParallel.addEventListener('input', updateConfigDisplay);
    DOM.btnAddCell.addEventListener('click', () => addCell());
    DOM.btnLoadExample.addEventListener('click', loadExampleData);
    DOM.btnClearAll.addEventListener('click', clearAllCells);
    DOM.weightCapacity.addEventListener('input', () => updateWeights('capacity'));
    DOM.weightIr.addEventListener('input', () => updateWeights('ir'));
    DOM.btnStartMatching.addEventListener('click', startMatching);
    DOM.btnStopMatching.addEventListener('click', stopMatching);
    DOM.btnExportJson.addEventListener('click', exportJson);
    DOM.btnExportCsv.addEventListener('click', exportCsv);
    DOM.btnCopyResults.addEventListener('click', copyResults);
    DOM.btnCloseShortcuts.addEventListener('click', () => DOM.shortcutsDialog.close());
}

// =============================================================================
// Initialization
// =============================================================================

function init() {
    initEventListeners();
    setupKeyboardShortcuts();
    updateConfigDisplay();
    updateWeights('capacity');
    updateMatchingButtonState();
    for (let i = 0; i < 3; i++) addCell();
}

if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', init);
else init();