import { NextRequest, NextResponse } from 'next/server'
import fs from 'fs'
import path from 'path'

// Use /data for Hugging Face persistent storage, fallback to local for development
const DATA_DIR = process.env.NODE_ENV === 'production' && fs.existsSync('/data')
  ? '/data'
  : path.join(process.cwd(), 'data')
const DOCS_DIR = path.join(DATA_DIR, 'documents')

export async function GET(request: NextRequest) {
  try {
    const searchParams = request.nextUrl.searchParams
    const filePath = searchParams.get('path')
    const preview = searchParams.get('preview') === 'true'

    if (!filePath) {
      return NextResponse.json({ error: 'File path required' }, { status: 400 })
    }

    // Normalize the path to handle both forward and backward slashes
    const normalizedPath = filePath.replace(/\\/g, '/')
    const fullPath = path.resolve(path.join(DOCS_DIR, normalizedPath))
    const resolvedDocsDir = path.resolve(DOCS_DIR)

    // Security check - ensure the resolved path is within the allowed directory
    if (!fullPath.startsWith(resolvedDocsDir)) {
      return NextResponse.json({ error: 'Invalid path - access denied' }, { status: 400 })
    }

    if (!fs.existsSync(fullPath)) {
      return NextResponse.json({ error: 'File not found' }, { status: 404 })
    }

    const stats = fs.statSync(fullPath)
    if (stats.isDirectory()) {
      return NextResponse.json({ error: 'Cannot download directory' }, { status: 400 })
    }

    const fileBuffer = fs.readFileSync(fullPath)
    const fileName = path.basename(normalizedPath)
    const ext = path.extname(fileName).toLowerCase()

    // Determine content type
    let contentType = 'application/octet-stream'
    const mimeTypes: Record<string, string> = {
      '.pdf': 'application/pdf',
      '.doc': 'application/msword',
      '.docx': 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
      '.xls': 'application/vnd.ms-excel',
      '.xlsx': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
      '.ppt': 'application/vnd.ms-powerpoint',
      '.pptx': 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
      '.txt': 'text/plain',
      '.md': 'text/markdown',
      '.json': 'application/json',
      '.html': 'text/html',
      '.css': 'text/css',
      '.js': 'text/javascript',
      '.ts': 'text/typescript',
      '.py': 'text/x-python',
      '.java': 'text/x-java',
      '.cpp': 'text/x-c++',
      '.jpg': 'image/jpeg',
      '.jpeg': 'image/jpeg',
      '.png': 'image/png',
      '.gif': 'image/gif',
      '.svg': 'image/svg+xml',
      '.mp3': 'audio/mpeg',
      '.mp4': 'video/mp4',
      '.zip': 'application/zip',
      '.rar': 'application/x-rar-compressed',
      '.tex': 'text/x-tex',
      '.latex': 'text/x-latex',
      '.dart': 'text/x-dart',
      '.flutter': 'text/x-dart',
      '.yaml': 'text/yaml',
      '.yml': 'text/yaml',
      '.xml': 'text/xml',
      '.csv': 'text/csv',
      '.rtf': 'application/rtf',
      '.odt': 'application/vnd.oasis.opendocument.text',
      '.ods': 'application/vnd.oasis.opendocument.spreadsheet',
      '.odp': 'application/vnd.oasis.opendocument.presentation'
    }

    if (mimeTypes[ext]) {
      contentType = mimeTypes[ext]
    }

    const headers = new Headers({
      'Content-Type': contentType,
      'Content-Length': fileBuffer.length.toString(),
    })

    // If not preview mode, add download header
    if (!preview) {
      headers.set('Content-Disposition', `attachment; filename="${encodeURIComponent(fileName)}"`)
    } else {
      // For preview, use inline disposition for supported types
      if (['application/pdf', 'text/plain', 'text/markdown', 'application/json'].includes(contentType) ||
          contentType.startsWith('image/') || contentType.startsWith('text/')) {
        headers.set('Content-Disposition', `inline; filename="${encodeURIComponent(fileName)}"`)
      } else {
        headers.set('Content-Disposition', `attachment; filename="${encodeURIComponent(fileName)}"`)
      }
    }

    return new NextResponse(fileBuffer, { headers })
  } catch (error) {
    console.error('Error downloading file:', error)
    return NextResponse.json(
      { error: 'Failed to download file' },
      { status: 500 }
    )
  }
}