import { spawn } from "child_process";
import { writeFile, readFile, mkdir, unlink } from "fs/promises";
import { NextRequest, NextResponse } from "next/server";
import path from "path";
import os from "os";

export async function POST(req: NextRequest) {
  try {
    const formData = await req.formData();
    const file = formData.get("file") as File;

    if (!file) {
      return NextResponse.json({ error: "No file provided" }, { status: 400 });
    }

    const tempDir = path.join(os.tmpdir(), "xgrids-pipeline");
    await mkdir(tempDir, { recursive: true });

    const safeName = file.name.replace(/[^a-z0-9.]/gi, "_").toLowerCase();
    const timestamp = Date.now();
    const inputPath = path.join(tempDir, `${timestamp}_${safeName}`);
    const outputPath = inputPath.replace(/\.(lcc|lci|bin)$/i, ".ply");

    // DETERMINE WHICH SCRIPT TO RUN
    let scriptName = "convert_lci_to_ply.py";
    if (file.name.toLowerCase().includes("environment.bin")) {
      scriptName = "convert_env_to_ply.py";
    }

    const scriptPath = path.join(
      process.cwd(),
      "scripts",
      "preprocess",
      scriptName,
    );

    const buffer = Buffer.from(await file.arrayBuffer());
    await writeFile(inputPath, buffer);

    return new Promise<NextResponse>((resolve) => {
      const pythonProcess = spawn("python3", [
        scriptPath,
        inputPath,
        outputPath,
      ]);

      let errorOutput = "";
      pythonProcess.stderr.on("data", (data) => {
        errorOutput += data.toString();
      });

      pythonProcess.on("close", async (code) => {
        if (code !== 0) {
          await unlink(inputPath).catch(() => {});
          return resolve(
            NextResponse.json(
              { error: `Python failed (${scriptName}): ${errorOutput}` },
              { status: 500 },
            ),
          );
        }

        try {
          const plyBuffer = await readFile(outputPath);
          await Promise.all([
            unlink(inputPath).catch(() => {}),
            unlink(outputPath).catch(() => {}),
          ]);

          resolve(
            new NextResponse(plyBuffer, {
              status: 200,
              headers: {
                "Content-Type": "application/octet-stream",
                "Content-Disposition": `attachment; filename="${file.name.replace(/\.[^/.]+$/, "")}.ply"`,
              },
            }),
          );
        } catch (e) {
          resolve(
            NextResponse.json(
              { error: "Failed to read output PLY" },
              { status: 500 },
            ),
          );
        }
      });
    });
  } catch (error: any) {
    return NextResponse.json({ error: error.message }, { status: 500 });
  }
}