import {
    AbstractMesh,
    Color3,
    MeshBuilder,
    Observable,
    PBRMaterial,
    PhysicsAggregate,
    Texture,
    Vector3,
} from "@babylonjs/core";
import { DefaultScene } from "../../core/defaultScene";
import { RockFactory } from "../../environment/asteroids/rockFactory";
import { ScoreEvent } from "../../ui/hud/scoreboard";
import {
    LevelConfig,
    ShipConfig,
    Vector3Array,
    validateLevelConfig
} from "./levelConfig";
import { FireProceduralTexture } from "@babylonjs/procedural-textures";
import { createSphereLightmap } from "../../environment/celestial/sphereLightmap";
import log from '../../core/logger';
import StarBase from "../../environment/stations/starBase";
import {LevelRegistry} from "../storage/levelRegistry";

/**
 * Deserializes a LevelConfig JSON object and creates all entities in the scene
 */
export class LevelDeserializer {
    private scene = DefaultScene.MainScene;
    private config: LevelConfig;

    constructor(config: LevelConfig) {
        // HYBRID MIGRATION NOTE: If validation fails due to legacy data,
        // consider adding migration logic here before validation:
        //
        // config = migrateLegacyFormat(config);
        //
        // This would allow smooth transition for users with old localStorage data
        // See levelConfig.ts validateLevelConfig() for example migration code

        // Validate config first
        const validation = validateLevelConfig(config);
        if (!validation.valid) {
            throw new Error(`Invalid level config: ${validation.errors.join(', ')}`);
        }

        this.config = config;
    }

    /**
     * Create all entities from the configuration
     * @param scoreObservable - Observable for score events
     */
    public async deserialize(
        scoreObservable: Observable<ScoreEvent>
    ): Promise<{
        startBase: AbstractMesh | null;
        landingAggregate: PhysicsAggregate | null;
        sun: AbstractMesh;
        planets: AbstractMesh[];
        asteroids: AbstractMesh[];
    }> {
        log.debug('Deserializing level:', this.config.difficulty);

        const baseResult = await this.createStartBase();
        const sun = this.createSun();
        const planets = this.createPlanets();
        const asteroids = await this.createAsteroids(scoreObservable);

        return {
            startBase: baseResult.baseMesh,
            landingAggregate: baseResult.landingAggregate,
            sun,
            planets,
            asteroids
        };
    }

    /**
     * Create the start base from config
     */
    private async createStartBase() {
        const position = this.config.startBase?.position;
        const baseGlbPath = this.config.startBase?.baseGlbPath || 'base.glb';
        return await StarBase.buildStarBase(position, baseGlbPath);
    }

    /**
     * Create the sun from config
     */
    private createSun(): AbstractMesh {
        const config = this.config.sun;
        const sun = MeshBuilder.CreateSphere("sun", {
            diameter: config.diameter,
            segments: 32
        }, this.scene);
        sun.position = this.arrayToVector3(config.position);

        // Create PBR sun material with fire texture
        const material = new PBRMaterial("sunMaterial", this.scene);
        material.emissiveTexture = new FireProceduralTexture("fire", 1024, this.scene);
        material.albedoColor = Color3.Black();
        material.emissiveColor = Color3.White();
        material.disableLighting = true;
        //material.emissiveColor.set(0.5, 0.5, 0.1);
        material.unlit = true;
        sun.material = material;

        return sun;
    }

    /**
     * Create planets from config
     */
    private createPlanets(): AbstractMesh[] {
        const planets: AbstractMesh[] = [];
        const sunPosition = this.arrayToVector3(this.config.sun.position);

        for (const planetConfig of this.config.planets) {
            // Use fewer segments for better performance - planets are background objects
            // 16 segments = ~256 vertices vs 32 segments = ~1024 vertices
            const planet = MeshBuilder.CreateSphere(planetConfig.name, {
                diameter: planetConfig.diameter,
                segments: 12  // Reduced from 32 for performance
            }, this.scene);

            const planetPosition = this.arrayToVector3(planetConfig.position);
            planet.position = planetPosition;

            // Calculate direction from planet to sun
            const toSun = sunPosition.subtract(planetPosition).normalize();

            // Create PBR planet material
            const material = new PBRMaterial(planetConfig.name + "-material", this.scene);
            const texture = new Texture(planetConfig.texturePath, this.scene);

            // Create lightmap with bright light pointing toward sun
            const lightmap = createSphereLightmap(
                planetConfig.name + "-lightmap",
                256,
                this.scene,
                toSun,
                1,
                toSun.negate(),
                0.3,
                0.3
            );

            material.albedoTexture = texture;
            material.lightmapTexture = lightmap;
            material.useLightmapAsShadowmap = true;
            material.roughness = 0.8;
            material.metallic = 0;
            material.unlit = true;
            planet.material = material;

            planets.push(planet);
        }

        log.debug(`Created ${planets.length} planets from config`);
        return planets;
    }

    /**
     * Create asteroids from config
     */
    private async createAsteroids(
        scoreObservable: Observable<ScoreEvent>
    ): Promise<AbstractMesh[]> {
        const asteroids: AbstractMesh[] = [];

        for (let i = 0; i < this.config.asteroids.length; i++) {
            const asteroidConfig = this.config.asteroids[i];

            log.debug(`[LevelDeserializer] Creating asteroid ${i} (${asteroidConfig.id}):`);
            log.debug(`[LevelDeserializer]   Position: [${asteroidConfig.position.join(', ')}]`);
            log.debug(`[LevelDeserializer]   Scale: ${asteroidConfig.scale}`);
            log.debug(`[LevelDeserializer]   Linear velocity: [${asteroidConfig.linearVelocity.join(', ')}]`);
            log.debug(`[LevelDeserializer]   Angular velocity: [${asteroidConfig.angularVelocity.join(', ')}]`);

            // Use orbit constraints by default (true if not specified)
            const useOrbitConstraints = this.config.useOrbitConstraints !== false;
            log.debug(`[LevelDeserializer]   Use orbit constraints: ${useOrbitConstraints}`);

            // Use RockFactory to create the asteroid
            const _rock = await RockFactory.createRock(
                i,
                this.arrayToVector3(asteroidConfig.position),
                asteroidConfig.scale,
                this.arrayToVector3(asteroidConfig.linearVelocity),
                this.arrayToVector3(asteroidConfig.angularVelocity),
                scoreObservable,
                useOrbitConstraints
            );

            // Get the actual mesh from the Rock object
            // The Rock class wraps the mesh, need to access it via position getter
            const mesh = this.scene.getMeshByName(asteroidConfig.id);
            if (mesh) {
                asteroids.push(mesh);
            }
        }

        log.debug(`Created ${asteroids.length} asteroids from config`);
        return asteroids;
    }

    /**
     * Get ship configuration (for external use to position ship)
     */
    public getShipConfig(): ShipConfig {
        return this.config.ship;
    }

    /**
     * Helper to convert array to Vector3
     */
    private arrayToVector3(arr: Vector3Array): Vector3 {
        return new Vector3(arr[0], arr[1], arr[2]);
    }

    /**
     * Static helper to load from JSON string
     */
    public static fromJSON(json: string): LevelDeserializer {
        const config = JSON.parse(json) as LevelConfig;
        return new LevelDeserializer(config);
    }

    /**
     * Static helper to load from JSON file URL
     */
    public static async fromURL(url: string): Promise<LevelDeserializer> {
        const response = await fetch(url);
        if (!response.ok) {
            throw new Error(`Failed to load level config from ${url}: ${response.statusText}`);
        }
        const json = await response.text();
        return LevelDeserializer.fromJSON(json);
    }

    /**
     * Static helper to load from uploaded file
     */
    public static async fromFile(file: File): Promise<LevelDeserializer> {
        return new Promise((resolve, reject) => {
            const reader = new FileReader();
            reader.onload = (e) => {
                try {
                    const json = e.target?.result as string;
                    resolve(LevelDeserializer.fromJSON(json));
                } catch (error) {
                    reject(error);
                }
            };
            reader.onerror = () => reject(new Error('Failed to read file'));
            reader.readAsText(file);
        });
    }

    /**
     * Static helper to load from Level Registry by ID
     * This is the preferred method for loading both default and custom levels
     */
    public static async fromRegistry(levelId: string): Promise<LevelDeserializer> {
        const registry = LevelRegistry.getInstance();

        // Ensure registry is initialized
        if (!registry.isInitialized()) {
            await registry.initialize();
        }

        // Get level config from registry (loads if not already loaded)
        const config = await registry.getLevel(levelId);

        if (!config) {
            throw new Error(`Level not found in registry: ${levelId}`);
        }

        return new LevelDeserializer(config);
    }
}