ASCILINE/app.js

/**
 * ASCILINE ENGINE - Pure & Performant Logic
 * =========================================
 * No decorative animations. Pure WebSocket streaming
 * and high-performance canvas rendering.
 * Includes an "Invisible Selection Layer" for text selection.
 */

const player    = document.getElementById('ascii-player');
const canvas    = document.getElementById('ascii-canvas');
const ctx       = canvas.getContext('2d');
const statusEl  = document.getElementById('status');
const container = document.getElementById('player-container');
const overlay   = document.getElementById('play-overlay');
const audioEl   = document.getElementById('ascii-audio');
const volumeSlider = document.getElementById('volume-slider');

// ── STATE ──
let state = 'IDLE'; // IDLE | PLAYING
let ws = null;
const frameBuffer = [];
const BUFFER_SIZE = 4;
let targetFps = 24;
let frameInterval = 1000 / targetFps;
let renderMode = 1;
let readyToRender = false;

// Grid & Dimensions
let gridCols = 0, gridRows = 0;
let charWidth = 0, charHeight = 0;
let xPos = null, yPos = null;

// Selection Layer optimization
const textDecoder = new TextDecoder();
let selectionBuffer = null;

// Timing & Metrics
let lastRenderTime = 0;
let frameCount = 0, currentFps = 0, lastFpsUpdate = 0;

const CHAR_LUT = new Array(128);
for (let i = 0; i < 128; i++) CHAR_LUT[i] = String.fromCharCode(i);

// ═══════════════════════════════════════
//  CANVAS SETUP
// ═══════════════════════════════════════

function buildCanvas(cols, rows) {
    gridCols = cols;
    gridRows = rows;
    ctx.font = 'bold 8px Courier New';
    charWidth = Math.ceil(ctx.measureText('M').width);
    charHeight = 8;
    canvas.width  = cols * charWidth;
    canvas.height = rows * charHeight;
    canvas.style.display = 'block';

    // Selection Layer Buffer
    selectionBuffer = new Uint8Array((cols + 1) * rows);
    for (let r = 0; r < rows; r++) selectionBuffer[r * (cols + 1) + cols] = 10; // Newline (\n)

    // Sizing and positioning for both layers
    const syncSize = (el) => {
        el.style.width  = container.clientWidth + 'px';
        el.style.height = container.clientHeight + 'px';
        el.style.objectFit = 'contain';
        el.style.position = 'absolute';
        el.style.top = '0';
        el.style.left = '0';
    };

    syncSize(canvas);
    syncSize(player);

    ctx.font = 'bold 8px Courier New';
    ctx.textBaseline = 'top';
    xPos = new Float32Array(cols);
    yPos = new Float32Array(rows);
    for (let c = 0; c < cols; c++) xPos[c] = c * charWidth;
    for (let r = 0; r < rows; r++) yPos[r] = r * charHeight;
}

// ═══════════════════════════════════════
//  STREAM CONTROL
// ═══════════════════════════════════════

function startStream() {
    if (state !== 'IDLE') return;
    overlay.classList.add('hidden');
    statusEl.textContent = 'Connecting...';
    statusEl.style.color = 'var(--accent-color)';
    connectWebSocket();
}

function connectWebSocket() {
    frameBuffer.length = 0;
    frameCount = 0;
    currentFps = 0;

    if (audioEl) {
        audioEl.src = '/audio?' + Date.now();
        audioEl.volume = volumeSlider ? volumeSlider.value : 1.0;
    }

    const protocol = location.protocol === 'https:' ? 'wss:' : 'ws:';
    ws = new WebSocket(`${protocol}//${location.host}/ws`);
    ws.binaryType = 'arraybuffer';

    ws.onmessage = (event) => {
        if (typeof event.data === 'string') {
            if (event.data.startsWith('Error:')) {
                statusEl.textContent = event.data;
                statusEl.style.color = '#ff0000';
                if (ws) ws.close();
                setTimeout(() => finishStream(), 3000);
                return;
            }
            if (event.data.startsWith('INIT:')) {
                const p = event.data.split(':');
                targetFps = parseFloat(p[1]);
                frameInterval = 1000 / targetFps;
                renderMode = parseInt(p[2]);
                buildCanvas(parseInt(p[3]), parseInt(p[4]));

                // Reload audio on every INIT so each video's audio plays correctly.
                // The server updates current_index BEFORE sending INIT, so /audio
                // will already serve the new video's audio when we request it here.
                if (audioEl) {
                    audioEl.pause();
                    audioEl.src = '/audio?' + Date.now();
                    audioEl.volume = volumeSlider ? volumeSlider.value : 1.0;
                    audioEl.load();
                    audioEl.play().catch(() => {});
                }

                readyToRender = true;
                state = 'PLAYING';
                lastRenderTime = performance.now();
                lastFpsUpdate = lastRenderTime;
                requestAnimationFrame(renderFrame);
                return;
            }
            frameBuffer.push(event.data);
        } else {
            frameBuffer.push(event.data);
        }

        while (frameBuffer.length > BUFFER_SIZE * 3) frameBuffer.shift();
    };

    ws.onopen = () => { statusEl.textContent = 'Buffering...'; };

    ws.onclose = () => {
        if (state === 'PLAYING') {
            statusEl.textContent = 'Stream Ended.';
            statusEl.style.color = '#888';
            if (audioEl) audioEl.pause();
            setTimeout(() => finishStream(), 800);
        }
    };

    ws.onerror = () => {
        statusEl.textContent = 'Connection Error!';
        statusEl.style.color = '#ff0000';
        setTimeout(() => finishStream(), 2000);
    };
}

// ═══════════════════════════════════════
//  RENDER LOOP
// ═══════════════════════════════════════

function renderFrame(now) {
    if (state !== 'PLAYING') return;
    requestAnimationFrame(renderFrame);

    const elapsed = now - lastRenderTime;
    if (elapsed < frameInterval) return;

    frameCount++;
    if (now - lastFpsUpdate >= 1000) {
        currentFps = frameCount;
        frameCount = 0;
        lastFpsUpdate = now;
        const modes = { 2: '512 Color', 3: '32K Color', 4: '262K Color', 5: '16M Ultra' };
        statusEl.textContent = `FPS: ${currentFps}/${Math.round(targetFps)} | Buf: ${frameBuffer.length} | ${modes[renderMode] || 'B&W'}`;
    }

    if (frameBuffer.length === 0) return;
    lastRenderTime = now;
    const frame = frameBuffer.shift();

    if (renderMode === 1) {
        player.style.display = 'block';
        player.style.color = '#fff';
        player.textContent = frame;
    } else {
        const view = new Uint8Array(frame);
        
        // 1. Draw Canvas (Background)
        ctx.fillStyle = '#050505';
        ctx.fillRect(0, 0, canvas.width, canvas.height);
        ctx.font = 'bold 8px Courier New';
        ctx.textBaseline = 'top';

        let col = 0, row = 0, prevPacked = -1;
        for (let idx = 0; idx < view.length; idx += 4) {
            const packed = (view[idx+1] << 16) | (view[idx+2] << 8) | view[idx+3];
            if (packed !== prevPacked) {
                ctx.fillStyle = `rgb(${view[idx+1]},${view[idx+2]},${view[idx+3]})`;
                prevPacked = packed;
            }
            ctx.fillText(CHAR_LUT[view[idx]], xPos[col], yPos[row]);
            
            // Fill Selection Buffer (char code is at view[idx])
            selectionBuffer[row * (gridCols + 1) + col] = view[idx];

            col++;
            if (col >= gridCols) { col = 0; row++; }
        }

        // 2. Update Selection Layer (Foreground)
        player.style.display = 'block';
        player.style.color = 'transparent';
        player.textContent = textDecoder.decode(selectionBuffer);
    }
}

// ═══════════════════════════════════════
//  CLEANUP
// ═══════════════════════════════════════

function finishStream() {
    state = 'IDLE';
    if (ws) { ws.onclose = null; ws.close(); ws = null; }
    if (audioEl) { audioEl.pause(); audioEl.src = ''; }
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    player.textContent = '';
    player.style.display = 'none';
    overlay.classList.remove('hidden');
    statusEl.textContent = 'Ready';
    statusEl.style.color = 'rgba(255,255,255,0.6)';
    readyToRender = false;
    frameBuffer.length = 0;
}

// ── EVENT LISTENERS ──
overlay.addEventListener('click', (e) => {
    e.stopPropagation();
    startStream();
});

if (volumeSlider) {
    volumeSlider.addEventListener('input', () => {
        if (audioEl) audioEl.volume = volumeSlider.value;
    });
}

window.addEventListener('resize', () => {
    const syncSize = (el) => {
        if (!el) return;
        el.style.width  = container.clientWidth + 'px';
        el.style.height = container.clientHeight + 'px';
    };
    syncSize(canvas);
    syncSize(player);
});