src/app/api/upload/route.ts

import { PDFLoader } from "@langchain/community/document_loaders/fs/pdf"
import { DocxLoader } from "@langchain/community/document_loaders/fs/docx"
import { NextResponse } from 'next/server'
import { writeFile } from 'fs/promises'
import { join } from 'path'
import { Document } from '@langchain/core/documents'
import { mkdir } from 'fs/promises'

export async function POST(request: Request) {
  try {
    const formData = await request.formData()
    const files = formData.getAll('files') as File[]
    
    if (!files?.length) {
      return NextResponse.json(
        { error: 'No files uploaded' },
        { status: 400 }
      )
    }

    // Ensure temp directory exists
    const tempDir = '/tmp'
    try {
      await mkdir(tempDir, { recursive: true })
    } catch (err) {
      console.error('Error creating temp directory:', err)
    }

    const documents: { text: string }[] = []

    for (const file of files) {
      try {
        const bytes = await file.arrayBuffer()
        const buffer = Buffer.from(bytes)
        const tempPath = join(tempDir, `${Date.now()}-${file.name}`)
        
        await writeFile(tempPath, buffer)
        console.log('File written to:', tempPath)

        let docs: Document[] = []
        if (file.name.toLowerCase().endsWith('.pdf')) {
          const loader = new PDFLoader(tempPath)
          docs = await loader.load()
        } else if (file.name.toLowerCase().endsWith('.docx')) {
          const loader = new DocxLoader(tempPath)
          docs = await loader.load()
        }

        documents.push(...docs.map(doc => ({ 
          text: doc.pageContent
            .replace(/\s+/g, ' ')
            .trim()
        })))
      } catch (err) {
        console.error(`Error processing file ${file.name}:`, err)
      }
    }

    if (documents.length === 0) {
      return NextResponse.json(
        { error: 'No documents could be processed' },
        { status: 400 }
      )
    }

    return NextResponse.json({ documents })
  } catch (error) {
    console.error('Upload error:', error)
    return NextResponse.json(
      { error: 'Failed to process files' },
      { status: 500 }
    )
  }
}