// scene.js
import { resolveBlock } from './blockstate.js';
import { mat4Identity, mat4Translate } from './math.js';
// ... imports for loading assets ...

export class SceneBuilder {
    constructor(renderer, atlas) {
        this.renderer = renderer;
        this.atlas = atlas;
        
        // Cache parsed geometries by model ID so we only build them once
        this.geometryCache = new Map(); 
    }

    async buildFromWorld(world) {
        // 1. Group all instances by their resolved Model ID
        const instancePool = new Map(); // "block/stone" -> [ matrix1, matrix2, ... ]

        for (const block of world.blocks.values()) {
            const stateJSON = await loadBlockstate(block.id);
            const parts = resolveBlock(stateJSON, block.props);

            for (const part of parts) {
                if (!instancePool.has(part.model)) {
                    instancePool.set(part.model, { 
                        parts: [], 
                        modelId: part.model 
                    });
                }
                
                // Calculate the world position matrix
                const matrix = mat4Identity(new Float32Array(16));
                mat4Translate(matrix, matrix, [block.x, block.y, block.z]);
                
                instancePool.get(part.model).parts.push({
                    matrix: matrix,
                    variant: part // Pass variant so geometry builder handles local rotation
                });
            }
        }

        // 2. We now have a list of models and every place they appear.
        // The next step is to ensure geometry is built, and pack those matrices 
        // into Float32Arrays for the WebGL instanced buffers.
        
        return instancePool;
    }
}