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 * as pdfjsLib from 'pdfjs-dist';
import '../../../public/utils/pdf.worker.mjs';
import { v4 as uuidv4 } from 'uuid';
import { fileTypeFromBuffer } from 'file-type';

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

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

async function extractTextFromPdf(pdfPath: string): Promise<string> {
  console.log("Starting extractTextFromPdf for path:", pdfPath);
  try {
    console.log("Reading PDF file:", pdfPath);
    const data = new Uint8Array(fs.readFileSync(pdfPath));
    console.log("PDF file read successfully. Starting loading document...");
    const loadingTask = pdfjsLib.getDocument({ data });
    console.log("Loading task initiated. Waiting for promise...");
    const pdf = await loadingTask.promise; // Await the PDF loading
    console.log("PDF document loaded successfully. Number of pages:", pdf.numPages);
    let fullText = "";
    const processPages = async () => {
      for (let i = 1; i <= pdf.numPages; i++) {
        console.log("Processing page:", i);
        const page = await pdf.getPage(i);
        console.log("Page", i, "loaded. Getting text content...");
        const textContent = await page.getTextContent();
        console.log("Text content for page", i, "obtained. Processing items...");
        fullText += textContent.items.map((item: any) => item.str ? item.str : '').join(" ");
        console.log("Text from page", i, "added to fullText.");
      }
      console.log("Text extraction completed successfully.");
      console.log("Parsed PDF Text before return:", fullText); // Added log here
      return fullText;
    };
    return await processPages(); // Await the page processing
  } catch (error) {
    console.error("Error extracting text from PDF:", error);
    throw new Error("Error extracting text from PDF");
  } finally {
    console.log("Finished extractTextFromPdf for path:", pdfPath);
  }
}


export async function POST(req: Request) {
  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!");

    console.log("Before PDF parsing");
    const extractedText = await extractTextFromPdf(newFilePath);
    console.log("After PDF parsing");
    console.log("Before generating summary");
    const command = `python3 utils/resume_analysis.py "${extractedText}"`;
    console.log("Executing python command:", command);
    console.log("Extracted Text being passed to python script:", extractedText);
    console.log("Length of extractedText:", extractedText.length); // Log length
    const executionResult: { stdout: string, stderr: string } = await new Promise((resolve, reject) => {
      require('child_process').exec(command, (error: any, stdout: string, stderr: string) => {
        if (error) {
          console.error("Python script execution error:", error);
          console.error("Python script stderr:", stderr);
          reject({ error, stdout, stderr });
        } else {
          console.log("Python script executed successfully");
          console.log("Python script stdout:", stdout);
          resolve({ stdout, stderr });
        }
      });
    });
    const { stdout, stderr } = executionResult;

    if (stderr) {
      console.error("Error from python script (stderr):", stderr);
    }
    const summary: string = stdout.trim();
    console.log("After generating summary");
    return NextResponse.json({ summary: summary }, { status: 200 });

  } catch (error: any) {
    console.error("Error during file processing:", error);
    return NextResponse.json({ message: "Error processing file: " + error.message }, { status: 500 });
  }
}