import 'core-js/features/promise/with-resolvers'; // Polyfill for Promise.withResolvers
import { NextResponse } from "next/server";
import fs from "fs";
import path from "path";
import { v4 as uuidv4 } from 'uuid';
import { fileTypeFromBuffer } from 'file-type';
import escapeStringRegexp from 'escape-string-regexp';
import { exec as childProcessExec } from 'child_process';
import { promisify } from 'util';

const exec = promisify(childProcessExec);

const uploadDir = path.join(process.cwd(), "uploads", "cv");

// Ensure the upload directory exists
if (!fs.existsSync(uploadDir)) {
  fs.mkdirSync(uploadDir, { recursive: true });
}

export async function POST(req: Request): Promise<NextResponse> {
  console.log("Received request for CV file upload");

  try {
    const formData = await req.formData();
    const file: File | null = formData.get('cv') as unknown as File | null;

    if (!file) {
      console.warn("No file uploaded.");
      return NextResponse.json({ message: "No file uploaded." }, { status: 400 });
    }

    const originalFilename = file.name;
    const uniqueFilename = `${uuidv4()}-${originalFilename}`;
    const newFilePath = path.join(uploadDir, uniqueFilename);
    console.log(`Saving file to: ${newFilePath}`);

    const fileBuffer = await file.arrayBuffer();
    const type = await fileTypeFromBuffer(Buffer.from(fileBuffer));
    console.log("Detected file type:", type);

    if (!type || type.mime !== 'application/pdf') {
      return NextResponse.json({ message: "Unsupported file type detected. Only PDF files are allowed." }, { status: 400 });
    }

    await fs.promises.writeFile(newFilePath, Buffer.from(fileBuffer));
    console.log("File uploaded and saved successfully!");

    // Get the PDF file size
    const pdfFileSize = fs.statSync(newFilePath).size;
    console.log(`PDF file size: ${pdfFileSize} bytes`);

    // Extract text from PDF using pdfminer.six
    let textContent = '';
    let extractedTextFilePath = '';
    try {
      const extractTextCommand = `pdf2txt.py "${newFilePath}"`;
      const { stdout, stderr } = await exec(extractTextCommand);
      textContent = stdout;

      // Create extracted text file path
      extractedTextFilePath = newFilePath.replace(/\.pdf$/i, ".txt")
      // Write extracted text to file
      fs.writeFileSync(extractedTextFilePath, textContent);
      console.log(`Extracted text saved to: ${extractedTextFilePath}`);

    } catch (error: any) {
      console.error("Error extracting text from PDF:", error);
      return NextResponse.json({ summary: "Error extracting text from PDF" }, { status: 500 });
    }

    // Execute the resume analysis script
    const { spawn } = require('child_process');
    const pythonProcess = spawn('python3', [path.join(process.cwd(), 'utils', 'resume_analysis.py'), "-f", extractedTextFilePath]);

    let rawOutput = '';
    let pythonProcessError = false;
    let summary: any = null; // Change summary to 'any' type
    let openaiOutputFilePath = path.join(uploadDir, "openai_raw_output.txt"); // Define path here


    pythonProcess.stdout.on('data', (data: Buffer) => {
      const output = data.toString();
      rawOutput += output;
      const lines = output.trim().split('\n'); // Split output into lines
      const jsonOutputLine = lines[lines.length - 1]; // Take the last line as JSON output
      fs.writeFileSync(openaiOutputFilePath, jsonOutputLine); // Save last line to file
    });

    pythonProcess.stderr.on('data', (data: Buffer) => {
      console.error(`stderr: ${data}`);
    });

    pythonProcess.on('close', (code: number) => {
      console.log(`child process exited with code ${code}`);
      if (code !== 0) {
        summary = { error: "Error generating summary" };
        pythonProcessError = true;
      } else {
        try {
          // Parse JSON from the last line of the output
          const lines = rawOutput.trim().split('\n');
          const jsonOutputLine = lines[lines.length - 1];
          console.log("Attempting to parse JSON:", jsonOutputLine); // Log raw JSON string
          try {
            summary = JSON.parse(jsonOutputLine);
          } catch (error) {
            console.error("Failed to parse JSON from python script:", error);
            console.error("Raw JSON string that failed to parse:", jsonOutputLine); // Log the raw JSON string that failed
            summary = { error: "Failed to parse JSON from python script" };
            pythonProcessError = true;
            // Log raw output to file for debugging
            const errorLogPath = path.join(uploadDir, "openai_raw_output.txt");
            const timestamp = new Date().toISOString();
            try {
              if (error instanceof Error) {
                fs.appendFileSync(errorLogPath, `\n--- JSON Parse Error ---\nTimestamp: ${timestamp}\nRaw Output:\n${rawOutput}\nError: ${error.message}\nFailed JSON String:\n${jsonOutputLine}\n`); // Include failed JSON string in log
              } else {
                fs.appendFileSync(errorLogPath, `\n--- JSON Parse Error ---\nTimestamp: ${timestamp}\nRaw Output:\n${rawOutput}\nError: Unknown error\nFailed JSON String:\n${jsonOutputLine}\n`); // Include failed JSON string in log
              }
              console.log(`Raw Python output logged to ${errorLogPath}`);
            } catch (logError: any) { // Explicitly type logError as any
              console.error("Error logging raw output:", logError);
            }
          }
        } catch (outerError) { // Correctly placed catch block for the outer try
          console.error("Outer try block error:", outerError);
        }
      }
    });

    // Add a timeout to the python process
    const timeout = setTimeout(() => {
      console.error("Python process timed out");
      pythonProcess.kill();
      summary = { error: "Error generating summary: Timeout" };
      pythonProcessError = true;
    }, 30000); // 30 seconds

    return new Promise<NextResponse>((resolve) => {
      pythonProcess.on('close', () => {
        clearTimeout(timeout);
        const status = pythonProcessError ? 500 : 200;
        resolve(NextResponse.json(summary, { status }));
      });
    }) as Promise<NextResponse>;

    } catch (error: unknown) {
      console.error("Error during file processing:", error);
      const message = error instanceof Error ? error.message : 'An unknown error occurred';
      return NextResponse.json({ message: "Error processing file: " + message }, { status: 500 });
    }
}