src/visualizer/MeshFactory.js

import * as THREE from 'three';
import { CONFIG, STATE } from '../core/State.js';
import { vertexShader, fragmentShader } from '../engine/Shaders.js';
import { updateThreadTransform } from './LayoutEngine.js';
import { updateThreadVisibility } from './ThreadManager.js';
import { createLabelSprite } from './LabelHelper.js';
import { PALETTE_3D, getActivationColorPerceptual as getActivationColor } from '../engine/palette.js';

// ─── Helpers CPU ────────────────────────────────────────────────────────────
function lerp(a, b, t) { return a + (b - a) * t; }
// ─────────────────────────────────────────────────────────────────────────

export function createThread(label, embedding, scene, colorHex, tokenID = 0) {
    if (CONFIG.debug) console.log(`[VISUALIZER] Creating thread for: "${label}" (ID: ${tokenID}) with color: ${colorHex.toString(16)}`);

    const count = embedding.length;
    STATE.vertexCount = count;

    // 1. Data Prep
    const points      = [];
    const intensities = [];
    const indices     = [];

    // Color dominante del thread: valor con mayor |activación| → define el color de la línea
    let maxAbsVal = 0, dominantVal = 0;
    for (let i = 0; i < count; i++) {
        const absV = Math.abs(embedding[i]);
        if (absV > maxAbsVal) { maxAbsVal = absV; dominantVal = embedding[i]; }
    }
    const lineActivation = getActivationColor(dominantVal);
    // Normalizador: garantiza que el mayor valor llegue a ±1.0 en el shader
    const safeMax = maxAbsVal > 0 ? maxAbsVal : 1.0;

    for (let i = 0; i < count; i++) {
        const val = embedding[i];
        const x = 0; // Geometría extendida a lo largo del eje Z
        const y = val * CONFIG.amplitudeScale;
        const z = i * CONFIG.pointSpacing;

        points.push(x, y, z);
        intensities.push(val / safeMax); // Normalizado → rango [-1, 1]
        indices.push(i);
    }

    const geometry = new THREE.BufferGeometry();
    geometry.setAttribute('position',    new THREE.Float32BufferAttribute(points,      3));
    geometry.setAttribute('intensity',   new THREE.Float32BufferAttribute(intensities, 1));
    geometry.setAttribute('vertexIndex', new THREE.Float32BufferAttribute(indices,     1));

    // 2. Línea: color uniforme derivado del valor dominante del thread
    const lineMaterial = new THREE.LineBasicMaterial({
        color:       new THREE.Color(lineActivation.r, lineActivation.g, lineActivation.b),
        linewidth:   CONFIG.threadThickness || 1.0,
        opacity:     0.6,
        transparent: true
    });
    const lineMesh = new THREE.Line(geometry, lineMaterial);
    // PREVENT FRUSTRUM CULLING ISSUES (Common cause of disappearing meshes)
    lineMesh.frustumCulled = false;

    // 3. Points Mesh (Heatmap Shader)
    const uniforms = {
        highlightIndex: { value: -1.0 },
        pointSpacing: { value: CONFIG.pointSpacing },
        dotSize:      { value: CONFIG.pointSpacing * CONFIG.amplitudeScale * 0.8 },
        opacity: { value: 1.0 },
        color: { value: new THREE.Color(colorHex) }
    };

    const pointsMaterial = new THREE.ShaderMaterial({
        uniforms: uniforms,
        vertexShader: vertexShader,
        fragmentShader: fragmentShader,
        transparent: true,
        depthWrite: false,
        blending: THREE.NormalBlending
    });

    const pointsMesh = new THREE.Points(geometry, pointsMaterial);
    pointsMesh.frustumCulled = false;

    // 4. Critical: Add to Scene
    scene.add(lineMesh);
    scene.add(pointsMesh);

    // 5. Label Sprite
    const labelText = `${label} [${tokenID}]`;
    const sprite = createLabelSprite(labelText, 0, embedding[0] * CONFIG.amplitudeScale + 0.5, 0, new THREE.Color(colorHex));
    scene.add(sprite);

    const thread = {
        id: Date.now() + Math.random(),
        label: label,
        lineMesh,
        pointsMesh,
        uniforms,
        embedding,
        color: new THREE.Color(colorHex),
        tokenID: tokenID,
        labelSprite: sprite
    };

    // Apply Transform (Position/Rotation) based on current mode
    updateThreadTransform(thread);

    // Apply initial visibility based on current state
    const hasFocus = STATE.focusedThreads.size > 0;
    // New threads are not focused by default if focus mode is on
    const initialOpacity = hasFocus ? 0.05 : 1.0;

    lineMesh.material.opacity = initialOpacity;
    uniforms.opacity.value = initialOpacity;

    updateThreadVisibility();

    return thread;
}

export function createGhostThread(vectorArray, label, scene, tokenID = 0) {
    if (CONFIG.debug) console.log(`[VISUALIZER] Creating Ghost Thread: "${label}" (ID: ${tokenID})`);

    const count = vectorArray.length;
    const points = [];

    for (let i = 0; i < count; i++) {
        const x = 0;
        const y = vectorArray[i] * CONFIG.amplitudeScale;
        const z = i * CONFIG.pointSpacing;
        points.push(new THREE.Vector3(x, y, z));
    }

    const geometry = new THREE.BufferGeometry().setFromPoints(points);

    // CRITICAL: LineDashedMaterial requires computeLineDistances
    // Result Thread Styling: Neon Fuchsia, thicker, on top
    const material = new THREE.LineDashedMaterial({
        color: PALETTE_3D.THREAD_RESULT, // Neon Fuchsia
        dashSize: 3.0,
        gapSize: 1.0,
        linewidth: 3, // Attempt thicker line
        scale: 1,
        opacity: 1.0,
        transparent: true,
        depthTest: false // Always render on top
    });

    const line = new THREE.Line(geometry, material);
    line.frustumCulled = false;
    line.renderOrder = 999; // High render order

    // Add to Scene
    scene.add(line);
    line.computeLineDistances(); // Essential for dashes to appear

    // Label Sprite for Ghost
    // Note: zPos is 0 initially, updated by updateThreadTransform
    const labelText = `${label} [${tokenID}]`;
    const sprite = createLabelSprite(labelText, 0, vectorArray[0] * CONFIG.amplitudeScale + 1.0, 0, new THREE.Color(PALETTE_3D.THREAD_RESULT));
    scene.add(sprite);

    const thread = {
        id: 'ghost-' + Date.now(),
        label: label,
        lineMesh: line,
        embedding: vectorArray,
        isGhost: true,
        color: new THREE.Color(PALETTE_3D.THREAD_RESULT),
        tokenID: tokenID,
        labelSprite: sprite
    };

    // Apply Transform
    updateThreadTransform(thread);

    // Apply initial visibility
    const hasFocus = STATE.focusedThreads.size > 0;
    // Ghost thread is usually the result, so maybe we want to see it?
    // But if focus mode is strictly "only focused items", and it's not focused, it should be dimmed.
    // However, usually the user wants to see the result.
    // For now, adhere to strict logic: if not in focusedThreads, dim it.
    // But wait, the user might want to focus the result.
    const initialOpacity = hasFocus ? 0.05 : 1.0;
    line.material.opacity = initialOpacity;

    updateThreadVisibility();

    return thread;
}