/**
 * Timeline Animation
 * 
 * Handles scroll timeline animations (scroll-timeline, scroll-loop)
 */

import { Logger } from '../../core/logger.js';

/**
 * TimelineAnimation - Scroll timeline animation
 */
export class TimelineAnimation {
    constructor(element, config = {}) {
        this.element = element;
        this.config = {
            steps: config.steps || null,
            triggerPoint: config.triggerPoint || 0.4,
            loop: config.loop ?? false,
            ...config
        };
        
        this.currentStep = 0;
        this.triggered = false;
        
        // Initialize
        this.init();
    }
    
    /**
     * Initialize timeline animation
     */
    init() {
        // Set initial step
        this.element.setAttribute('data-scroll-step', '0');
        this.element.classList.add('scroll-timeline');
    }
    
    /**
     * Enter animation
     */
    enter() {
        if (this.triggered && !this.config.loop) {
            return;
        }
        
        this.triggered = true;
        this.update();
    }
    
    /**
     * Exit animation
     */
    exit() {
        if (this.config.loop) {
            this.currentStep = 0;
            this.update();
        }
    }
    
    /**
     * Update animation based on scroll position
     */
    update() {
        const rect = this.element.getBoundingClientRect();
        const viewportHeight = window.innerHeight;
        const triggerY = viewportHeight * this.config.triggerPoint;
        
        if (rect.top < triggerY && rect.bottom > 0) {
            // Calculate progress
            const progress = Math.max(0, Math.min(1, (triggerY - rect.top) / (rect.height + viewportHeight)));
            
            if (this.config.steps) {
                // Step-based animation
                const step = Math.floor(progress * this.config.steps);
                this.setStep(step);
            } else {
                // Continuous animation
                this.setProgress(progress);
            }
        }
    }
    
    /**
     * Set step
     */
    setStep(step) {
        if (step === this.currentStep) {
            return;
        }
        
        this.currentStep = step;
        this.element.setAttribute('data-scroll-step', step.toString());
        
        // Remove old step classes
        for (let i = 0; i <= this.config.steps; i++) {
            this.element.classList.remove(`step-${i}`);
        }
        
        // Add new step class
        this.element.classList.add(`step-${step}`);
        
        // Trigger event
        this.triggerStepEvent(step);
    }
    
    /**
     * Set progress (continuous)
     */
    setProgress(progress) {
        this.element.setAttribute('data-scroll-progress', progress.toString());
        this.element.style.setProperty('--scroll-progress', progress.toString());
        
        // Trigger event
        this.triggerProgressEvent(progress);
    }
    
    /**
     * Trigger step event
     */
    triggerStepEvent(step) {
        const event = new CustomEvent('scroll-timeline:step', {
            detail: { step, element: this.element },
            bubbles: true
        });
        this.element.dispatchEvent(event);
    }
    
    /**
     * Trigger progress event
     */
    triggerProgressEvent(progress) {
        const event = new CustomEvent('scroll-timeline:progress', {
            detail: { progress, element: this.element },
            bubbles: true
        });
        this.element.dispatchEvent(event);
    }
    
    /**
     * Destroy animation
     */
    destroy() {
        this.element.removeAttribute('data-scroll-step');
        this.element.removeAttribute('data-scroll-progress');
        this.element.style.removeProperty('--scroll-progress');
        this.element.classList.remove('scroll-timeline');
        
        // Remove step classes
        for (let i = 0; i <= 10; i++) {
            this.element.classList.remove(`step-${i}`);
        }
        
        this.currentStep = 0;
        this.triggered = false;
    }
}