/**
 * ResponseTemplate Model
 * Pre-written response templates for common inquiries
 *
 * Framework enforcement: All templates scanned for governance violations
 * (inst_016, inst_017, inst_018, inst_079)
 */

const { ObjectId } = require('mongodb');
const { getCollection } = require('../utils/db.util');
const ContentGovernanceChecker = require('../services/ContentGovernanceChecker.service');

class ResponseTemplate {
  /**
   * Create a new response template
   * Includes framework governance check (inst_016, inst_017, inst_018, inst_079)
   */
  static async create(data) {
    const collection = await getCollection('response_templates');

    // Framework governance check on template content
    const fullText = [data.subject, data.content].filter(Boolean).join('\n');
    const governanceCheck = await ContentGovernanceChecker.scanContent(fullText, {
      type: 'response_template',
      context: {
        name: data.name,
        category: data.category,
        created_by: data.created_by
      }
    });

    const template = {
      // Template identification
      name: data.name,
      description: data.description || null,

      // Template content
      subject: data.subject || null, // For email templates
      content: data.content, // Template text (supports {placeholders})

      // Categorization
      category: data.category || 'general', // general, media, technical, partnership, case, rejection
      language: data.language || 'en',

      // Usage metadata
      projects: data.projects || ['tractatus'], // Which projects can use this template
      tags: data.tags || [],

      // Template variables (placeholders)
      variables: data.variables || [], // [{name: 'contact_name', description: 'Name of the contact', required: true}]

      // Who can use this template
      visibility: data.visibility || 'public', // public, private, team
      created_by: data.created_by ? new ObjectId(data.created_by) : null,

      // Framework governance check results
      governance_check: {
        passed: governanceCheck.success,
        scanned_at: governanceCheck.scannedAt,
        violations: governanceCheck.violations || [],
        summary: governanceCheck.summary
      },

      // Usage statistics
      usage_stats: {
        times_used: 0,
        last_used: null
      },

      // Status
      active: data.active !== undefined ? data.active : true,

      created_at: new Date(),
      updated_at: new Date()
    };

    const result = await collection.insertOne(template);
    return {
      ...template,
      _id: result.insertedId,
      governance_check: governanceCheck // Return full check results
    };
  }

  /**
   * Find template by ID
   */
  static async findById(id) {
    const collection = await getCollection('response_templates');
    return await collection.findOne({ _id: new ObjectId(id) });
  }

  /**
   * List templates with filtering
   */
  static async list(filters = {}, options = {}) {
    const collection = await getCollection('response_templates');
    const { limit = 50, skip = 0 } = options;

    const query = { active: true };
    if (filters.category) query.category = filters.category;
    if (filters.language) query.language = filters.language;
    if (filters.project) query.projects = filters.project;
    if (filters.tag) query.tags = filters.tag;
    if (filters.visibility) query.visibility = filters.visibility;

    return await collection
      .find(query)
      .sort({ name: 1 })
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * Search templates by name or content
   */
  static async search(searchTerm, options = {}) {
    const collection = await getCollection('response_templates');
    const { limit = 20 } = options;

    return await collection
      .find({
        active: true,
        $or: [
          { name: { $regex: searchTerm, $options: 'i' } },
          { description: { $regex: searchTerm, $options: 'i' } },
          { content: { $regex: searchTerm, $options: 'i' } },
          { tags: { $regex: searchTerm, $options: 'i' } }
        ]
      })
      .limit(limit)
      .toArray();
  }

  /**
   * Render template with variables
   */
  static async render(id, variables = {}) {
    const template = await this.findById(id);
    if (!template) {
      throw new Error('Template not found');
    }

    const rendered = {
      subject: template.subject,
      content: template.content
    };

    // Replace placeholders with actual values
    Object.keys(variables).forEach(key => {
      const placeholder = new RegExp(`\\{${key}\\}`, 'g');
      if (rendered.subject) {
        rendered.subject = rendered.subject.replace(placeholder, variables[key]);
      }
      rendered.content = rendered.content.replace(placeholder, variables[key]);
    });

    // Track usage
    await this.incrementUsage(id);

    return rendered;
  }

  /**
   * Increment usage counter
   */
  static async incrementUsage(id) {
    const collection = await getCollection('response_templates');

    await collection.updateOne(
      { _id: new ObjectId(id) },
      {
        $inc: { 'usage_stats.times_used': 1 },
        $set: {
          'usage_stats.last_used': new Date(),
          updated_at: new Date()
        }
      }
    );
  }

  /**
   * Update template
   */
  static async update(id, data) {
    const collection = await getCollection('response_templates');

    const updateData = {
      ...data,
      updated_at: new Date()
    };

    await collection.updateOne(
      { _id: new ObjectId(id) },
      { $set: updateData }
    );

    return await this.findById(id);
  }

  /**
   * Deactivate template (soft delete)
   */
  static async deactivate(id) {
    return await this.update(id, { active: false });
  }

  /**
   * Delete template
   */
  static async delete(id) {
    const collection = await getCollection('response_templates');
    return await collection.deleteOne({ _id: new ObjectId(id) });
  }

  /**
   * Get popular templates
   */
  static async getPopular(limit = 10) {
    const collection = await getCollection('response_templates');

    return await collection
      .find({ active: true })
      .sort({ 'usage_stats.times_used': -1 })
      .limit(limit)
      .toArray();
  }

  /**
   * Get statistics
   */
  static async getStats() {
    const collection = await getCollection('response_templates');

    const [total, active, byCategory, byLanguage, topUsed] = await Promise.all([
      collection.countDocuments(),
      collection.countDocuments({ active: true }),
      collection.aggregate([
        { $match: { active: true } },
        { $group: { _id: '$category', count: { $sum: 1 } } }
      ]).toArray(),
      collection.aggregate([
        { $match: { active: true } },
        { $group: { _id: '$language', count: { $sum: 1 } } }
      ]).toArray(),
      collection.find({ active: true })
        .sort({ 'usage_stats.times_used': -1 })
        .limit(5)
        .toArray()
    ]);

    return {
      total,
      active,
      by_category: byCategory.reduce((acc, item) => {
        acc[item._id] = item.count;
        return acc;
      }, {}),
      by_language: byLanguage.reduce((acc, item) => {
        acc[item._id] = item.count;
        return acc;
      }, {}),
      top_used: topUsed.map(t => ({
        name: t.name,
        times_used: t.usage_stats.times_used
      }))
    };
  }
}

module.exports = ResponseTemplate;