import { NextApiRequest, NextApiResponse } from 'next'
import { IncomingForm, File as FormidableFile } from 'formidable'
import FormData from 'form-data'
import fs from 'fs'
import { Readable } from 'stream'

const MAX_FILE_SIZE = 50 * 1024 * 1024 // 50MB

export const config = {
  api: {
    bodyParser: false, // Disable bodyParser to handle multipart
  },
}

interface ParseResult {
  fields: Record<string, string[]>
  files: Record<string, FormidableFile[]>
}

export default async function handler(req: NextApiRequest, res: NextApiResponse) {
  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method not allowed' })
  }

  // Get target endpoint from query or use default
  const targetEndpoint = (req.query.endpoint as string) || 'https://picstr.build/api/v1/upload'

  try {
    // Parse multipart form data
    // formidable needs the raw Node.js IncomingMessage, which NextApiRequest extends
    const form = new IncomingForm({
      maxFileSize: MAX_FILE_SIZE,
      keepExtensions: true,
    })

    const parseResult = await new Promise<ParseResult>((resolve, reject) => {
      // Cast req to any to work with formidable - NextApiRequest extends IncomingMessage
      form.parse(req as any, (err, fields, files) => {
        if (err) {
          console.error('Formidable parse error:', err)
          reject(err)
        } else {
          resolve({ fields: fields as Record<string, string[]>, files: files as Record<string, FormidableFile[]> })
        }
      })
    })

    const { fields, files } = parseResult

    // Get the file from the parsed form
    const fileField = files.file?.[0]
    if (!fileField) {
      return res.status(400).json({ error: 'No file provided' })
    }

    // Create FormData for the target endpoint
    const formData = new FormData()
    const fileStream = fs.createReadStream(fileField.filepath)
    formData.append('file', fileStream, {
      filename: fileField.originalFilename || fileField.newFilename || 'upload',
      contentType: fileField.mimetype || 'application/octet-stream',
    })

    // Forward to target endpoint
    const response = await fetch(targetEndpoint, {
      method: 'POST',
      body: formData as unknown as BodyInit,
      headers: {
        ...formData.getHeaders(),
      },
    })

    // Clean up temporary file
    try {
      fs.unlinkSync(fileField.filepath)
    } catch (unlinkError) {
      console.error('Error deleting temp file:', unlinkError)
    }

    if (!response.ok) {
      const errorText = await response.text()
      return res.status(response.status).json({
        error: errorText || `Upload failed: ${response.status} ${response.statusText}`,
      })
    }

    const result = await response.json()
    return res.status(200).json(result)
  } catch (error) {
    console.error('NIP-95 proxy error:', error)
    return res.status(500).json({
      error: error instanceof Error ? error.message : 'Internal server error',
    })
  }
}