import fs from 'fs'
import path from 'path'
import * as pdfjsLib from 'pdfjs-dist/legacy/build/pdf.mjs'

if (typeof pdfjsLib.GlobalWorkerOptions !== 'undefined') {
  pdfjsLib.GlobalWorkerOptions.workerSrc = path.join(
    process.cwd(),
    'node_modules/pdfjs-dist/legacy/build/pdf.worker.mjs'
  )
}

interface ExtractedPage {
  pageNumber: number
  text: string
}

export interface ExtractedDocument {
  pages: ExtractedPage[]
  totalPages: number
  metadata: { title?: string; author?: string }
}

export class DocumentExtractionService {
  async extractPdf(filePath: string): Promise<ExtractedDocument> {
    const dataBuffer = fs.readFileSync(filePath)
    const doc = await pdfjsLib.getDocument({
      data: new Uint8Array(dataBuffer),
      useSystemFonts: true,
      useWorkerFetch: false,
      isEvalSupported: false,
    }).promise

    const pages: ExtractedPage[] = []
    for (let i = 1; i <= doc.numPages; i++) {
      const page = await doc.getPage(i)
      const content = await page.getTextContent()
      const text = content.items
        .map((item: any) => item.str)
        .join(' ')
      pages.push({ pageNumber: i, text })
    }

    const metadata = await doc.getMetadata().catch(() => null) as any

    return {
      pages,
      totalPages: doc.numPages,
      metadata: {
        title: metadata?.info?.Title,
        author: metadata?.info?.Author,
      },
    }
  }
}

export const documentExtractionService = new DocumentExtractionService()