/**
 * Document Model
 * Technical papers, framework documentation, specifications
 */

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

class Document {
  /**
   * Create a new document
   *
   * SECURITY: All new documents default to 'internal' visibility to prevent accidental exposure.
   * Use publish() method to make documents public after review.
   */
  static async create(data) {
    const collection = await getCollection('documents');

    // SECURITY: Require explicit visibility or default to 'internal' for safety
    const visibility = data.visibility || 'internal';

    // SECURITY: Validate visibility is a known value
    const validVisibility = ['public', 'internal', 'confidential', 'archived'];
    if (!validVisibility.includes(visibility)) {
      throw new Error(`Invalid visibility: ${visibility}. Must be one of: ${validVisibility.join(', ')}`);
    }

    // SECURITY: Prevent accidental public uploads - require category for public docs
    if (visibility === 'public' && (!data.category || data.category === 'none')) {
      throw new Error('Public documents must have a valid category (not "none")');
    }

    const document = {
      title: data.title,
      slug: data.slug,
      quadrant: data.quadrant, // STR/OPS/TAC/SYS/STO
      persistence: data.persistence, // HIGH/MEDIUM/LOW/VARIABLE
      audience: data.audience || 'general', // technical, general, researcher, implementer, advocate, business, developer
      visibility, // SECURITY: Defaults to 'internal', explicit required for 'public'
      category: data.category || 'none', // conceptual, practical, reference, archived, project-tracking, research-proposal, research-topic
      order: data.order || 999, // Display order (1-999, lower = higher priority)
      archiveNote: data.archiveNote || null, // Explanation for why document was archived
      workflow_status: 'draft', // SECURITY: Track publish workflow (draft, review, published)
      content_html: data.content_html,
      content_markdown: data.content_markdown,
      toc: data.toc || [],
      security_classification: data.security_classification || {
        contains_credentials: false,
        contains_financial_info: false,
        contains_vulnerability_info: false,
        contains_infrastructure_details: false,
        requires_authentication: false
      },
      metadata: {
        author: data.metadata?.author || 'John Stroh',
        date_created: new Date(),
        date_updated: new Date(),
        version: data.metadata?.version || '1.0',
        document_code: data.metadata?.document_code,
        related_documents: data.metadata?.related_documents || [],
        tags: data.metadata?.tags || []
      },
      translations: data.translations || {},
      search_index: data.search_index || '',
      download_formats: data.download_formats || {}
    };

    const result = await collection.insertOne(document);
    return { ...document, _id: result.insertedId };
  }

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

  /**
   * Find document by slug
   */
  static async findBySlug(slug) {
    const collection = await getCollection('documents');
    return await collection.findOne({ slug });
  }

  /**
   * Find documents by quadrant
   */
  static async findByQuadrant(quadrant, options = {}) {
    const collection = await getCollection('documents');
    const { limit = 50, skip = 0, sort = { 'metadata.date_created': -1 }, publicOnly = false } = options;

    const filter = { quadrant };
    if (publicOnly) {
      filter.visibility = 'public';
    }

    return await collection
      .find(filter)
      .sort(sort)
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * Find documents by audience
   */
  static async findByAudience(audience, options = {}) {
    const collection = await getCollection('documents');
    const { limit = 50, skip = 0, sort = { 'metadata.date_created': -1 }, publicOnly = false } = options;

    const filter = { audience };
    if (publicOnly) {
      filter.visibility = 'public';
    }

    return await collection
      .find(filter)
      .sort(sort)
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * Search documents
   */
  static async search(query, options = {}) {
    const collection = await getCollection('documents');
    const { limit = 20, skip = 0, publicOnly = false } = options;

    const filter = { $text: { $search: query } };
    if (publicOnly) {
      filter.visibility = 'public';
    }

    return await collection
      .find(
        filter,
        { score: { $meta: 'textScore' } }
      )
      .sort({ score: { $meta: 'textScore' } })
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * Update document
   */
  static async update(id, updates) {
    const collection = await getCollection('documents');

    // If updates contains metadata, merge date_updated into it
    // Otherwise set it as a separate field
    const updatePayload = { ...updates };
    if (updatePayload.metadata) {
      updatePayload.metadata = {
        ...updatePayload.metadata,
        date_updated: new Date()
      };
    }

    const result = await collection.updateOne(
      { _id: new ObjectId(id) },
      {
        $set: {
          ...updatePayload,
          ...(updatePayload.metadata ? {} : { 'metadata.date_updated': new Date() })
        }
      }
    );

    return result.modifiedCount > 0;
  }

  /**
   * Delete document
   */
  static async delete(id) {
    const collection = await getCollection('documents');
    const result = await collection.deleteOne({ _id: new ObjectId(id) });
    return result.deletedCount > 0;
  }

  /**
   * Publish a document (make it public after review)
   *
   * SECURITY: Requires explicit category and validates document is ready
   * World-class UX: Clear workflow states and validation feedback
   *
   * @param {string} id - Document ID
   * @param {object} options - Publish options
   * @param {string} options.category - Required category for public docs
   * @param {number} options.order - Display order
   * @returns {Promise<{success: boolean, message: string, document?: object}>}
   */
  static async publish(id, options = {}) {
    const collection = await getCollection('documents');

    // Get document
    const doc = await this.findById(id);
    if (!doc) {
      return { success: false, message: 'Document not found' };
    }

    // Validate document is ready for publishing
    if (!doc.content_markdown && !doc.content_html) {
      return { success: false, message: 'Document must have content before publishing' };
    }

    // SECURITY: Require valid category for public docs
    const category = options.category || doc.category;
    if (!category || category === 'none') {
      return {
        success: false,
        message: 'Document must have a valid category before publishing. Available categories: getting-started, technical-reference, research-theory, advanced-topics, case-studies, business-leadership, archives'
      };
    }

    // Validate category is in allowed list
    const validCategories = [
      'getting-started', 'technical-reference', 'research-theory',
      'advanced-topics', 'case-studies', 'business-leadership', 'archives'
    ];
    if (!validCategories.includes(category)) {
      return {
        success: false,
        message: `Invalid category: ${category}. Must be one of: ${validCategories.join(', ')}`
      };
    }

    // Update to public
    const result = await collection.updateOne(
      { _id: new ObjectId(id) },
      {
        $set: {
          visibility: 'public',
          category,
          order: options.order !== undefined ? options.order : doc.order,
          workflow_status: 'published',
          'metadata.date_updated': new Date(),
          'metadata.published_date': new Date(),
          'metadata.published_by': options.publishedBy || 'admin'
        }
      }
    );

    if (result.modifiedCount > 0) {
      const updatedDoc = await this.findById(id);
      return {
        success: true,
        message: `Document published successfully in category: ${category}`,
        document: updatedDoc
      };
    }

    return { success: false, message: 'Failed to publish document' };
  }

  /**
   * Unpublish a document (revert to internal)
   *
   * @param {string} id - Document ID
   * @param {string} reason - Reason for unpublishing
   * @returns {Promise<{success: boolean, message: string}>}
   */
  static async unpublish(id, reason = '') {
    const collection = await getCollection('documents');

    const result = await collection.updateOne(
      { _id: new ObjectId(id) },
      {
        $set: {
          visibility: 'internal',
          workflow_status: 'draft',
          'metadata.date_updated': new Date(),
          'metadata.unpublished_date': new Date(),
          'metadata.unpublish_reason': reason
        }
      }
    );

    return result.modifiedCount > 0
      ? { success: true, message: 'Document unpublished successfully' }
      : { success: false, message: 'Failed to unpublish document' };
  }

  /**
   * List documents by workflow status
   *
   * @param {string} status - Workflow status (draft, review, published)
   * @param {object} options - List options
   * @returns {Promise<Array>}
   */
  static async listByWorkflowStatus(status, options = {}) {
    const collection = await getCollection('documents');
    const { limit = 50, skip = 0, sort = { 'metadata.date_created': -1 } } = options;

    return await collection
      .find({ workflow_status: status })
      .sort(sort)
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * List all documents
   */
  static async list(options = {}) {
    const collection = await getCollection('documents');
    const { limit = 50, skip = 0, sort = { order: 1, 'metadata.date_created': -1 }, filter = {} } = options;

    return await collection
      .find(filter)
      .sort(sort)
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * List archived documents
   */
  static async listArchived(options = {}) {
    const collection = await getCollection('documents');
    const { limit = 50, skip = 0, sort = { 'metadata.date_created': -1 } } = options;

    return await collection
      .find({ visibility: 'archived' })
      .sort(sort)
      .skip(skip)
      .limit(limit)
      .toArray();
  }

  /**
   * Count documents
   */
  static async count(filter = {}) {
    const collection = await getCollection('documents');
    return await collection.countDocuments(filter);
  }
}

module.exports = Document;