/**
 * Vanilla JS Template Renderer
 * Renders posts using HTML template literals
 */

class VanillaRenderer {
  constructor() {
    this.templates = new Map();
    this.formatters = {
      formatTime: this.formatTime.bind(this),
      formatTimeAgo: this.formatTimeAgo.bind(this),
      formatDateTime: this.formatDateTime.bind(this),
      truncate: this.truncate.bind(this),
      renderMarkdown: this.renderMarkdown.bind(this)
    };
  }

  /**
   * Load a template from HTML file
   */
  async loadTemplate(templateId, templatePath) {
    const response = await fetch(templatePath);
    const html = await response.text();
    const parser = new DOMParser();
    const doc = parser.parseFromString(html, 'text/html');
    const template = doc.querySelector('template');

    if (template) {
      this.templates.set(templateId, template.innerHTML);
    }
  }

  /**
   * Render a post using a template
   */
  render(templateId, postData) {
    const template = this.templates.get(templateId);
    if (!template) {
      throw new Error(`Template ${templateId} not loaded`);
    }

    // Create context with data and helper functions
    const context = { ...postData, ...this.formatters };

    // Use Function constructor to evaluate template literal
    const rendered = new Function(...Object.keys(context), `return \`${template}\`;`)(...Object.values(context));

    return rendered;
  }

  /**
   * Render multiple posts
   */
  renderBatch(templateId, posts, container) {
    const fragment = document.createDocumentFragment();

    posts.forEach(post => {
      const html = this.render(templateId, post);
      const temp = document.createElement('div');
      temp.innerHTML = html;
      fragment.appendChild(temp.firstElementChild);
    });

    container.appendChild(fragment);
  }

  // Helper functions available in templates

  formatTime(timestamp) {
    const date = new Date(timestamp * 1000);
    return date.toLocaleTimeString('en-US', {
      hour: '2-digit',
      minute: '2-digit'
    });
  }

  formatTimeAgo(timestamp) {
    const seconds = Math.floor(Date.now() / 1000 - timestamp);

    const intervals = {
      year: 31536000,
      month: 2592000,
      week: 604800,
      day: 86400,
      hour: 3600,
      minute: 60
    };

    for (const [unit, secondsInUnit] of Object.entries(intervals)) {
      const interval = Math.floor(seconds / secondsInUnit);
      if (interval >= 1) {
        return `${interval} ${unit}${interval !== 1 ? 's' : ''} ago`;
      }
    }

    return 'just now';
  }

  formatDateTime(timestamp) {
    const date = new Date(timestamp * 1000);
    return date.toLocaleString('en-US', {
      year: 'numeric',
      month: 'long',
      day: 'numeric',
      hour: '2-digit',
      minute: '2-digit'
    });
  }

  truncate(text, maxLength) {
    if (text.length <= maxLength) return text;
    return text.substring(0, maxLength).trim() + '...';
  }

  renderMarkdown(text) {
    // Basic markdown rendering (expand as needed)
    return text
      .replace(/\n\n/g, '</p><p>')
      .replace(/\n/g, '<br>')
      .replace(/\*\*(.*?)\*\*/g, '<strong>$1</strong>')
      .replace(/\*(.*?)\*/g, '<em>$1</em>')
      .replace(/\[(.*?)\]\((.*?)\)/g, '<a href="$2" target="_blank">$1</a>');
  }
}

// Export for use
export default VanillaRenderer;