/**
 * Layer 4: Knowledge Management - PDF Parser
 * Extracts knowledge from PDF documents
 * Note: Requires pdf-parse package for production use
 */

import { readFileSync } from 'fs';
import { KnowledgeDocument, KnowledgeSource, SyncResult } from '../schema/knowledge-types';
import { v4 as uuidv4 } from 'uuid';
import * as path from 'path';

export interface PDFParserConfig {
  filePaths?: string[];
  directory?: string;
  recursive?: boolean;
}

export class PDFParser {
  private config: PDFParserConfig;

  constructor(config: PDFParserConfig) {
    this.config = config;
  }

  /**
   * Parse PDF files and extract content
   */
  async sync(): Promise<SyncResult> {
    const result: SyncResult = {
      success: true,
      documentsAdded: 0,
      documentsUpdated: 0,
      documentsFailed: 0,
      errors: [],
    };

    try {
      const filePaths = this.config.filePaths || [];

      for (const filePath of filePaths) {
        try {
          const document = await this.parsePDF(filePath);
          if (document) {
            result.documentsAdded++;
          }
        } catch (error: any) {
          result.documentsFailed++;
          result.errors?.push(`Failed to parse ${filePath}: ${error.message}`);
        }
      }

      result.success = result.documentsFailed === 0;
      return result;
    } catch (error: any) {
      result.success = false;
      result.errors?.push(error.message);
      return result;
    }
  }

  /**
   * Parse a single PDF file
   */
  private async parsePDF(filePath: string): Promise<KnowledgeDocument | null> {
    try {
      // NOTE: This is a placeholder implementation
      // In production, install and use pdf-parse:
      // npm install pdf-parse
      // const pdfParse = require('pdf-parse');
      // const dataBuffer = readFileSync(filePath);
      // const data = await pdfParse(dataBuffer);

      // For now, return a placeholder document
      const fileName = path.basename(filePath, '.pdf');

      return {
        id: `pdf-${uuidv4()}`,
        title: fileName,
        content: `[PDF content would be extracted here from ${filePath}]`,
        metadata: {
          source: KnowledgeSource.PDF,
          sourceId: filePath,
          sourceUrl: `file://${filePath}`,
          tags: ['pdf'],
          customFields: {
            filePath,
            fileName,
            fileSize: 0, // Would get actual size in production
          },
        },
        createdAt: new Date(),
        updatedAt: new Date(),
      };
    } catch (error: any) {
      throw new Error(`Failed to parse PDF: ${error.message}`);
    }
  }

  /**
   * Extract text from PDF buffer (production implementation)
   */
  private async extractTextFromPDF(buffer: Buffer): Promise<string> {
    // Production implementation would use pdf-parse library:
    // const pdfParse = require('pdf-parse');
    // const data = await pdfParse(buffer);
    // return data.text;

    throw new Error('PDF parsing not implemented. Install pdf-parse package.');
  }

  /**
   * Extract metadata from PDF
   */
  private extractPDFMetadata(pdfData: any): {
    title?: string;
    author?: string;
    subject?: string;
    keywords?: string[];
  } {
    // Would extract from PDF metadata in production
    return {};
  }
}

export default PDFParser;