/**
 * Unknown Pleasures WebGL Visualizer
 *
 * Uses GPU-accelerated rendering with:
 * - Geometry-based thick lines (quads instead of LINE_STRIP)
 * - Shader-based glow effect (post-processing blur)
 * - Prepared for future ambient haze effects
 */

export class UnknownPleasuresWebGL {
    // Propagation speed: controls how fast waves propagate between lines
    // Higher = faster propagation (1.0 = default, 0.5 = slower, 2.0 = faster)
    static PROPAGATION_SPEED = 0.7;

    // Glow intensity: controls how strong the glow effect is
    static GLOW_INTENSITY = 5.0;

    static NOISE_STRENGTH = 0.04;

    constructor() {
        this.name = 'Unknown Pleasures';
        this.contextType = 'webgl';
        this.historySize = 25;
        this.dataPoints = 96;

        this.history = [];
        this.writeIndex = 0;

        this.pLookup = new Float32Array(this.dataPoints);
        this.xLookup = new Float32Array(this.dataPoints);

        // WebGL state
        this.gl = null;
        this.lineProgram = null;
        this.glowProgram = null;
        this.quadBuffer = null;
        this.framebuffer = null;
        this.sceneTexture = null;

        // Cached values
        this._paletteColor = '';
        this._paletteRGB = null;
        this.rotationAngle = Math.PI / 6;
        this._cos = Math.cos(this.rotationAngle);
        this._sin = Math.sin(this.rotationAngle);

        // Propagation timing
        this._propagationAccum = 0;

        this.reset();
        this._precompute();
    }

    reset() {
        this.history.length = 0;
        for (let i = 0; i < this.historySize; i++) {
            this.history.push(new Float32Array(this.dataPoints));
        }
        this.writeIndex = 0;
    }

    resize(width, height) {
        if (this.gl && this.sceneTexture) {
            this._resizeFramebuffer(this.gl, width, height);
        }
    }

    destroy() {
        this.history.length = 0;
        if (this.gl) {
            if (this.lineProgram) this.gl.deleteProgram(this.lineProgram);
            if (this.glowProgram) this.gl.deleteProgram(this.glowProgram);
            if (this.quadBuffer) this.gl.deleteBuffer(this.quadBuffer);
            if (this.framebuffer) this.gl.deleteFramebuffer(this.framebuffer);
            if (this.sceneTexture) this.gl.deleteTexture(this.sceneTexture);
        }
        this.gl = null;
        this.lineProgram = null;
        this.glowProgram = null;
    }

    _precompute() {
        const pts = this.dataPoints;
        const inv = 1 / (pts - 1);
        for (let i = 0; i < pts; i++) {
            const p = Math.abs(i * inv - 0.5) * 2;
            this.pLookup[i] = 1 - p * p * p;
            this.xLookup[i] = i * inv;
        }
    }

    _createBuffers() {
        this.quadBuffer = this.gl.createBuffer();
        this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.quadBuffer);
        this.gl.bufferData(this.gl.ARRAY_BUFFER, new Float32Array([-1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1]), this.gl.STATIC_DRAW);

        this.lineBuffer = this.gl.createBuffer();
        
        // Pre-allocate vertex buffer (max possible size: historySize * dataPoints * 6 vertices * 3 floats)
        const maxVertices = this.historySize * this.dataPoints * 6; // 6 vertices per segment
        this.vertexBuffer = new Float32Array(maxVertices * 3); // 3 floats per vertex (x,y,edge)
    }

    _initGL(gl, width, height) {
        if (this.lineProgram) return;
        this.gl = gl;

        // === LINE SHADER (draws thick colored lines as quads with AA edges) ===
        const lineVS = `
            attribute vec3 a_posEdge; // xy = position, z = edge distance (-1 to +1)
            varying float v_edge;
            
            void main() {
                gl_Position = vec4(a_posEdge.xy, 0.0, 1.0);
                v_edge = a_posEdge.z;
            }
        `;

        const lineFS = `
            precision mediump float;
            uniform vec3 u_color;
            varying float v_edge;
            
            void main() {
                // Smooth antialiasing at edges
                float edge = abs(v_edge);
                float aa = 1.0 - smoothstep(0.6, 1.0, edge);
                gl_FragColor = vec4(u_color * aa, aa);
            }
        `;

        this.lineProgram = this._createProgram(gl, lineVS, lineFS);
        if (!this.lineProgram) return;

        this.line_a_posEdge = gl.getAttribLocation(this.lineProgram, 'a_posEdge');
        this.line_u_color = gl.getUniformLocation(this.lineProgram, 'u_color');

        // === BRIGHTNESS EXTRACTION SHADER ===
        // This is KEY for bloom - extract bright pixels, blur them, add back
        const brightnessVS = `
            attribute vec2 a_position;
            varying vec2 v_uv;
            
            void main() {
                v_uv = a_position * 0.5 + 0.5;
                gl_Position = vec4(a_position, 0.0, 1.0);
            }
        `;

        const brightnessFS = `
            precision mediump float;
            varying vec2 v_uv;
            uniform sampler2D u_texture;
            uniform float u_threshold;
            uniform float u_isDarkTheme;
            
            void main() {
                // Since Pass 1 now clears to transparent, the scene texture only contains the isolated lines.
                // We don't need to extract brightness by darkening the background anymore.
                // Just pass the lines through so they can be blurred.
                gl_FragColor = texture2D(u_texture, v_uv);
            }
        `;

        this.brightnessProgram = this._createProgram(gl, brightnessVS, brightnessFS);
        if (!this.brightnessProgram) return;

        this.brightness_a_position = gl.getAttribLocation(this.brightnessProgram, 'a_position');
        this.brightness_u_texture = gl.getUniformLocation(this.brightnessProgram, 'u_texture');
        this.brightness_u_threshold = gl.getUniformLocation(this.brightnessProgram, 'u_threshold');
        this.brightness_u_isDarkTheme = gl.getUniformLocation(this.brightnessProgram, 'u_isDarkTheme');

        // === BLUR SHADER (two-pass separable Gaussian) ===
        const blurVS = `
            attribute vec2 a_position;
            varying vec2 v_uv;
            
            void main() {
                v_uv = a_position * 0.5 + 0.5;
                gl_Position = vec4(a_position, 0.0, 1.0);
            }
        `;

        // 9-tap Gaussian blur with small fixed steps for smooth gradients
        // Use multiple passes to extend blur radius
        const blurFS = `
            precision mediump float;
            varying vec2 v_uv;
            uniform sampler2D u_texture;
            uniform vec2 u_resolution;
            uniform vec2 u_direction;
            uniform float u_spread; // Used instead of u_radius
            
            // 9-tap Gaussian with expanding offsets
            void main() {
                // Expanding offsets for stronger glow (Thread Ripper Style)
                vec2 off1 = vec2(1.3846153846) * u_direction * u_spread;
                vec2 off2 = vec2(3.2307692308) * u_direction * u_spread;
                
                vec4 color = texture2D(u_texture, v_uv) * 0.2270270270;
                color += texture2D(u_texture, v_uv + (off1 / u_resolution)) * 0.3162162162;
                color += texture2D(u_texture, v_uv - (off1 / u_resolution)) * 0.3162162162;
                color += texture2D(u_texture, v_uv + (off2 / u_resolution)) * 0.0702702703;
                color += texture2D(u_texture, v_uv - (off2 / u_resolution)) * 0.0702702703;
                
                gl_FragColor = color;
            }
        `;

        this.blurProgram = this._createProgram(gl, blurVS, blurFS);
        if (!this.blurProgram) return;

        this.blur_a_position = gl.getAttribLocation(this.blurProgram, 'a_position');
        this.blur_u_texture = gl.getUniformLocation(this.blurProgram, 'u_texture');
        this.blur_u_resolution = gl.getUniformLocation(this.blurProgram, 'u_resolution');
        this.blur_u_direction = gl.getUniformLocation(this.blurProgram, 'u_direction');
        this.blur_u_spread = gl.getUniformLocation(this.blurProgram, 'u_spread');

        // === COMPOSITE SHADER (combines original + blurred glow) ===
        // === COMPOSITE SHADER (exact copy from Thread Ripper) ===
        const compositeFS = `
            precision mediump float;
            varying vec2 v_uv;
            uniform sampler2D u_scene;
            uniform sampler2D u_blur;
            uniform float u_glowStrength;
            uniform float u_noiseStrength;
            uniform float u_isDarkTheme; // Kept for compatibility but unused in logic below
            uniform float u_time;
            
            float rand(vec2 co) {
                return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
            }

            void main() {
                vec4 original = texture2D(u_scene, v_uv);
                vec4 blur = texture2D(u_blur, v_uv);
                
                // Additive glow on top of original lines
                vec3 rgb = original.rgb + blur.rgb * u_glowStrength;
                
                // Vignette: blur edges for depth
                float dist = distance(v_uv, vec2(0.5));
                float vignette = smoothstep(0.4, 0.8, dist);
                // We handle scaling in the final mix later to avoid breaking the HDR mapping above.
                // The rgb here is the base scene before the final exponential glow math.

                float noise = rand(v_uv * 10.0); 
                float noiseStrength = 0.06; 
                rgb += (noise - 0.5) * noiseStrength;

                // In light mode (u_isDarkTheme == 0.0), the additive glow effect naturally appears weaker 
                // against the bright background. We apply a 1.5x perceptual boost to match dark mode intensity.
                float themeBoost = mix(1.5, 1.0, u_isDarkTheme);
                // Using 1.0 - exp(-x) gives butter-smooth HDR-like falloff, eliminating harsh banding.
                // We square the intensity (gamma 2.0) to dramatically increase the "core" opacity of the glow
                // making it much more visible while preserving the smooth edges.
                vec3 rawGlow = blur.rgb * (u_glowStrength * themeBoost);
                float glowIntensity = max(rawGlow.r, max(rawGlow.g, rawGlow.b));
                
                // Boost density significantly before applying HDR curve
                float density = glowIntensity * glowIntensity * 1.5;
                float smoothGlowAlpha = 1.0 - exp(-density);
                
                // Keep the color strictly within valid premultiplied alpha bounds (rgb <= alpha)
                vec3 safeGlowRgb = glowIntensity > 0.0 ? (rawGlow / glowIntensity) * smoothGlowAlpha : vec3(0.0);
                
                // Additive over the core lines
                rgb = original.rgb + safeGlowRgb;

                // Final alpha is the line's alpha plus the glow's alpha
                float finalAlpha = clamp(original.a + smoothGlowAlpha, 0.0, 1.0);

                // Output RGB and Alpha for PREMULTIPLIED alpha blending
                gl_FragColor = vec4(rgb, finalAlpha); 
            }
        `;

        this.compositeProgram = this._createProgram(gl, blurVS, compositeFS);
        if (!this.compositeProgram) return;

        this.composite_a_position = gl.getAttribLocation(this.compositeProgram, 'a_position');
        this.composite_u_scene = gl.getUniformLocation(this.compositeProgram, 'u_scene');
        this.composite_u_blur = gl.getUniformLocation(this.compositeProgram, 'u_blur');
        this.composite_u_glowStrength = gl.getUniformLocation(this.compositeProgram, 'u_glowStrength');
        this.composite_u_noiseStrength = gl.getUniformLocation(this.compositeProgram, 'u_noiseStrength');
        this.composite_u_isDarkTheme = gl.getUniformLocation(this.compositeProgram, 'u_isDarkTheme');
        this.composite_u_time = gl.getUniformLocation(this.compositeProgram, 'u_time');

        this._createBuffers(); // Use helper
        this._createFramebuffer(gl, width, height);

        gl.enable(gl.BLEND);
        gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
    }

    _createProgram(gl, vsSource, fsSource) {
        const vs = this._compileShader(gl, gl.VERTEX_SHADER, vsSource);
        const fs = this._compileShader(gl, gl.FRAGMENT_SHADER, fsSource);
        if (!vs || !fs) return null;

        const program = gl.createProgram();
        gl.attachShader(program, vs);
        gl.attachShader(program, fs);
        gl.linkProgram(program);

        if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
            console.error('WebGL program link failed:', gl.getProgramInfoLog(program));
            return null;
        }

        return program;
    }

    _compileShader(gl, type, source) {
        const shader = gl.createShader(type);
        gl.shaderSource(shader, source);
        gl.compileShader(shader);
        if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
            console.error('Shader compile error:', gl.getShaderInfoLog(shader));
            gl.deleteShader(shader);
            return null;
        }
        return shader;
    }

    _createFramebuffer(gl, width, height) {
        // Framebuffer 1: Scene (lines) - FULL RESOLUTION
        this.framebuffer = gl.createFramebuffer();
        gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer);

        this.sceneTexture = gl.createTexture();
        gl.bindTexture(gl.TEXTURE_2D, this.sceneTexture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, this.sceneTexture, 0);

        // Blur Resolution (Half size for performance)
        const blurW = Math.max(1, width >> 1);
        const blurH = Math.max(1, height >> 1);

        // Framebuffer 2: Blur intermediate
        this.blurFramebuffer = gl.createFramebuffer();
        gl.bindFramebuffer(gl.FRAMEBUFFER, this.blurFramebuffer);

        this.blurTexture = gl.createTexture();
        gl.bindTexture(gl.TEXTURE_2D, this.blurTexture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, blurW, blurH, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, this.blurTexture, 0);

        // Framebuffer 3: Blur final
        this.blurFinalFramebuffer = gl.createFramebuffer();
        gl.bindFramebuffer(gl.FRAMEBUFFER, this.blurFinalFramebuffer);

        this.blurFinalTexture = gl.createTexture();
        gl.bindTexture(gl.TEXTURE_2D, this.blurFinalTexture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, blurW, blurH, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, this.blurFinalTexture, 0);

        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
    }

    _resizeFramebuffer(gl, width, height) {
        const blurW = Math.max(1, width >> 1);
        const blurH = Math.max(1, height >> 1);

        gl.bindTexture(gl.TEXTURE_2D, this.sceneTexture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
        
        gl.bindTexture(gl.TEXTURE_2D, this.blurTexture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, blurW, blurH, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
        
        gl.bindTexture(gl.TEXTURE_2D, this.blurFinalTexture);
        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, blurW, blurH, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
    }

    _buildPalette(color) {
        // Parse color exactly like Canvas2D version
        const r = parseInt(color.slice(1, 3), 16);
        const g = parseInt(color.slice(3, 5), 16);
        const b = parseInt(color.slice(5, 7), 16);

        // perceptual grayscale (same weights browsers use)
        const gray = 0.299 * r + 0.587 * g + 0.114 * b;

        this._paletteRGB = [];
        for (let i = 0; i < this.historySize; i++) {
            const p = i / (this.historySize - 1);

            // === Saturation gradient (HSL-like) - match Canvas2D exactly ===
            const sat = 3.0 - 2 * p;
            // Clamp to 0-255 like Canvas2D does with | 0
            const rr = Math.max(0, Math.min(255, (gray + (r - gray) * sat) | 0)) / 255;
            const gg = Math.max(0, Math.min(255, (gray + (g - gray) * sat) | 0)) / 255;
            const bb = Math.max(0, Math.min(255, (gray + (b - gray) * sat) | 0)) / 255;

            this._paletteRGB.push([rr, gg, bb]);
        }

        this._paletteColor = color;
    }

    _generateLineQuads(points, thickness, width, height, outBuffer, offset) {
        if (points.length < 2) return 0;

        const n = points.length;
        let ptr = offset;

        // Precompute normals (reuse internal arrays if possible, but for now stack var is fine)
        // Optimization: Single pass miter calculation
        
        // Helper to clip X,Y
        const wInv = 2 / width;
        const hInv = 2 / height;

        for (let i = 0; i < n - 1; i++) {
            const p1 = points[i];
            const p2 = points[i + 1];

            // Calculate segment normal
            let dx = p2.x - p1.x;
            let dy = p2.y - p1.y;
            let len = Math.sqrt(dx * dx + dy * dy);
            let nx, ny;
            
            if (len < 0.001) { nx = 0; ny = -1; } 
            else { nx = -dy / len; ny = dx / len; }

            // Previous normal (for miter)
            let prevNx = nx, prevNy = ny;
            if (i > 0) {
                const p0 = points[i - 1];
                const dx0 = p1.x - p0.x;
                const dy0 = p1.y - p0.y;
                const len0 = Math.sqrt(dx0 * dx0 + dy0 * dy0);
                if (len0 >= 0.001) {
                    prevNx = -dy0 / len0;
                    prevNy = dx0 / len0;
                }
            }

            // Miter at P1
            let m1x = nx + prevNx;
            let m1y = ny + prevNy;
            let m1l = Math.sqrt(m1x * m1x + m1y * m1y);
            if (m1l > 0.001) { m1x /= m1l; m1y /= m1l; }

            // Next normal (for P2 miter)
            let nextNx = nx, nextNy = ny;
            if (i < n - 2) {
                const p3 = points[i + 2];
                const dx2 = p3.x - p2.x;
                const dy2 = p3.y - p2.y;
                const len2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);
                if (len2 >= 0.001) {
                    nextNx = -dy2 / len2;
                    nextNy = dx2 / len2;
                }
            }

            // Miter at P2
            let m2x = nx + nextNx;
            let m2y = ny + nextNy;
            let m2l = Math.sqrt(m2x * m2x + m2y * m2y);
            if (m2l > 0.001) { m2x /= m2l; m2y /= m2l; }

            // Generate vertices
            // P1 Top
            const x1a = (p1.x - m1x * thickness) * wInv - 1;
            const y1a = 1 - (p1.y - m1y * thickness) * hInv;
            
            // P1 Bottom
            const x1b = (p1.x + m1x * thickness) * wInv - 1;
            const y1b = 1 - (p1.y + m1y * thickness) * hInv;

            // P2 Top
            const x2a = (p2.x - m2x * thickness) * wInv - 1;
            const y2a = 1 - (p2.y - m2y * thickness) * hInv;

            // P2 Bottom
            const x2b = (p2.x + m2x * thickness) * wInv - 1;
            const y2b = 1 - (p2.y + m2y * thickness) * hInv;

            // Triangle 1
            outBuffer[ptr++] = x1a; outBuffer[ptr++] = y1a; outBuffer[ptr++] = -1.0;
            outBuffer[ptr++] = x1b; outBuffer[ptr++] = y1b; outBuffer[ptr++] = 1.0;
            outBuffer[ptr++] = x2a; outBuffer[ptr++] = y2a; outBuffer[ptr++] = -1.0;

            // Triangle 2
            outBuffer[ptr++] = x1b; outBuffer[ptr++] = y1b; outBuffer[ptr++] = 1.0;
            outBuffer[ptr++] = x2b; outBuffer[ptr++] = y2b; outBuffer[ptr++] = 1.0;
            outBuffer[ptr++] = x2a; outBuffer[ptr++] = y2a; outBuffer[ptr++] = -1.0;
        }

        return ptr - offset;
    }

    draw(ctx, canvas, analyser, dataArray, params) {
        const gl = ctx;
        const { width, height } = canvas;
        const isDark = document.documentElement.getAttribute('data-theme') !== 'white';

        canvas.style.mixBlendMode = 'normal';

        if (!this.lineProgram) {
            this._initGL(gl, width, height);
        }

        if (this.history.length === 0) {
            this.reset();
        }

        if (!params.paused) {
            this._propagationAccum += UnknownPleasuresWebGL.PROPAGATION_SPEED;
            const pts = this.dataPoints;

            if (this._propagationAccum >= 1.0) {
                this._propagationAccum -= 1.0;

                const sampleRate = analyser.context.sampleRate;
                const nyquist = sampleRate / 2;
                const targetFreq = 22000;
                const scale = Math.min(1.0, targetFreq / nyquist);
                const len = Math.floor(dataArray.length * scale);

                const line = this.history[this.writeIndex];
                if (line) {
                    for (let i = 0; i < pts; i++) {
                        line[i] = (dataArray[(this.xLookup[i] * len) | 0] / 255) * this.pLookup[i];
                    }
                }
                this.writeIndex = (this.writeIndex + 1) % this.historySize;
            }
        }

        if (this._paletteColor !== params.primaryColor) {
            this._buildPalette(params.primaryColor);
        }

        // === PASS 1: Scene ===
        gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer);
        gl.viewport(0, 0, width, height);
        gl.clearColor(0, 0, 0, 0);
        gl.clear(gl.COLOR_BUFFER_BIT);

        // Constants
        const size = Math.max(Math.abs(width * this._cos) + Math.abs(height * this._sin), Math.abs(width * this._sin) + Math.abs(height * this._cos)) * 1.15;
        const horizonY = size * 0.05;
        const frontY = size * 0.9;
        const depth = 2.0;
        const totalH = frontY - horizonY;
        const B = totalH / (1 - 1 / (1 + depth));
        const A = frontY - B;

        // --- BATCH GEOMETRY GENERATION ---
        // Fill the vertex buffer with ALL lines for this frame
        let bufferOffset = 0;
        // Store draw commands to execute later: { start, count, colorIndex }
        const drawCommands = [];
        
        // Reuse temporary points array
        if (!this._tempPoints) this._tempPoints = [];
        const points = this._tempPoints;
        const pts = this.dataPoints;
        const cx = width / 2;
        const cy = height / 2;
        const cosR = this._cos;
        const sinR = this._sin;
        const offsetX = -size / 2;
        const offsetY = -size / 2;

        for (let i = this.historySize - 1; i >= 0; i--) {
            const idx = (this.writeIndex + i) % this.historySize;
            const historyLine = this.history[idx];

            const p = 1 - i / (this.historySize - 1);
            const z = 1 + p * depth;
            const scale = 1 / z;
            const y = A + B / z;

            const lw = size * scale * 1.5;
            const margin = (size - lw) * 0.5;
            const amp = 200 * scale;
            const lineWidth = Math.max(1, 8 * scale + params.kick * 3);

            // Generate points
            points.length = 0;
            for (let j = 0; j < pts; j++) {
                const rx = margin + this.xLookup[j] * lw;
                const ry = y - historyLine[j] * amp;
                const dx = rx + offsetX;
                const dy = ry + offsetY;
                points.push({ x: dx * cosR - dy * sinR + cx, y: dx * sinR + dy * cosR + cy });
            }

            // Write to buffer
            const vertexCount = this._generateLineQuads(points, lineWidth / 2, width, height, this.vertexBuffer, bufferOffset);
            
            if (vertexCount > 0) {
                drawCommands.push({
                    start: bufferOffset / 3, // Start vertex index
                    count: vertexCount / 3,  // Number of vertices
                    colorIndex: i
                });
                bufferOffset += vertexCount; // Advance by number of floats
            }
        }

        // --- UPLOAD ONCE ---
        gl.bindBuffer(gl.ARRAY_BUFFER, this.lineBuffer);
        // Upload only the used portion of the pre-allocated buffer
        gl.bufferData(gl.ARRAY_BUFFER, this.vertexBuffer.subarray(0, bufferOffset), gl.DYNAMIC_DRAW);
        gl.enableVertexAttribArray(this.line_a_posEdge);
        gl.vertexAttribPointer(this.line_a_posEdge, 3, gl.FLOAT, false, 0, 0);

        // --- DRAW BATCH ---
        gl.useProgram(this.lineProgram);
        gl.enable(gl.BLEND);
        if (isDark) {
            gl.blendFunc(gl.ONE, gl.ONE);
        } else {
            gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
        }

        for (const cmd of drawCommands) {
            const color = this._paletteRGB[cmd.colorIndex] || [1, 1, 1];
            gl.uniform3f(this.line_u_color, color[0], color[1], color[2]);
            gl.drawArrays(gl.TRIANGLES, cmd.start, cmd.count);
        }

        gl.disable(gl.BLEND);

        // === PASS 2: Bloom (Half Res) ===
        const blurW = Math.max(1, width >> 1);
        const blurH = Math.max(1, height >> 1);

        gl.bindFramebuffer(gl.FRAMEBUFFER, this.blurFramebuffer);
        gl.viewport(0, 0, blurW, blurH);
        gl.clearColor(0, 0, 0, 0);
        gl.clear(gl.COLOR_BUFFER_BIT);

        gl.useProgram(this.brightnessProgram);
        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, this.sceneTexture);
        gl.uniform1i(this.brightness_u_texture, 0);
        gl.uniform1f(this.brightness_u_threshold, 0.0);
        gl.uniform1f(this.brightness_u_isDarkTheme, isDark ? 1.0 : 0.0);

        gl.bindBuffer(gl.ARRAY_BUFFER, this.quadBuffer);
        gl.enableVertexAttribArray(this.brightness_a_position);
        gl.vertexAttribPointer(this.brightness_a_position, 2, gl.FLOAT, false, 0, 0);
        gl.drawArrays(gl.TRIANGLES, 0, 6);

        // === PASS 3: Gaussian Blur (Ping Pong) ===
        gl.useProgram(this.blurProgram);
        
        const iterations = 4;
        let horizontal = true;

        for (let i = 0; i < iterations * 2; i++) {
            const destFBO = horizontal ? this.blurFinalFramebuffer : this.blurFramebuffer;
            const srcTex = horizontal ? this.blurTexture : this.blurFinalTexture;
            const spread = 1.0 + i * 0.75; 

            gl.bindFramebuffer(gl.FRAMEBUFFER, destFBO);
            gl.activeTexture(gl.TEXTURE0);
            gl.bindTexture(gl.TEXTURE_2D, srcTex);
            gl.uniform1i(this.blur_u_texture, 0);
            gl.uniform2f(this.blur_u_resolution, blurW, blurH);
            gl.uniform2f(this.blur_u_direction, horizontal ? 1.0 : 0.0, horizontal ? 0.0 : 1.0);
            gl.uniform1f(this.blur_u_spread, spread);

            gl.drawArrays(gl.TRIANGLES, 0, 6);
            horizontal = !horizontal;
        }

        // === PASS 4: Composite ===
        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
        gl.viewport(0, 0, width, height);

        if (params.mode !== 'blended') {
            const bg = isDark ? [0.02, 0.02, 0.02, 1] : [0.9, 0.9, 0.9, 1];
            gl.clearColor(bg[0], bg[1], bg[2], bg[3]);
        } else if (isDark) {
            gl.clearColor(0, 0, 0, 0.4);
        } else {
            gl.clearColor(0.95, 0.95, 0.95, 0.4);
        }
        gl.clear(gl.COLOR_BUFFER_BIT);

        gl.enable(gl.BLEND);
        gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);

        gl.useProgram(this.compositeProgram);
        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, this.sceneTexture);
        gl.uniform1i(this.composite_u_scene, 0);

        gl.activeTexture(gl.TEXTURE1);
        gl.bindTexture(gl.TEXTURE_2D, horizontal ? this.blurTexture : this.blurFinalTexture);
        gl.uniform1i(this.composite_u_blur, 1);

        const glowBoost = 1.0 + params.kick;
        gl.uniform1f(this.composite_u_glowStrength, UnknownPleasuresWebGL.GLOW_INTENSITY * glowBoost);
        gl.uniform1f(this.composite_u_noiseStrength, UnknownPleasuresWebGL.NOISE_STRENGTH);
        gl.uniform1f(this.composite_u_isDarkTheme, isDark ? 1.0 : 0.0);
        gl.uniform1f(this.composite_u_time, performance.now() / 1000.0);

        gl.bindBuffer(gl.ARRAY_BUFFER, this.quadBuffer);
        gl.enableVertexAttribArray(this.composite_a_position);
        gl.vertexAttribPointer(this.composite_a_position, 2, gl.FLOAT, false, 0, 0);
        gl.drawArrays(gl.TRIANGLES, 0, 6);
    }
}