import { getNanoSpawn } from "./nanoSpawn";
import { join } from "node:path";
import { env } from "../config/env";
import which from "which";
import { existsSync } from "fs-extra";
import logger from "./logger";

export async function preparePython() {
  const spawn = await getNanoSpawn();
  const venvPath = env.VENV;
  const venvBin = join(venvPath, "bin");

  // 1. Locate python3
  let pythonCmd;
  try {
    pythonCmd = which.sync("python3");
  } catch {
    throw new Error("Python not found in PATH.");
  }

  // 2. Create venv if missing
  if (!existsSync(venvPath)) {
    logger.debug("Creating Python venv...");
    await spawn(pythonCmd, ["-m", "venv", venvPath], {
      cwd: env.APP_DIR,
    });
    logger.debug("Python venv created.");
  } else {
    logger.debug("Using existing Python venv.");
  }

  // 3. Install requirements.txt
  const pipCmd = join(venvBin, "pip");
  logger.debug("Installing requirements.txt...");
  await spawn(pipCmd, ["install", "-r", "requirements.txt"], {
    cwd: env.APP_DIR,
  });
  logger.debug("requirements.txt installed.");

  // 4. Confirm vcsi CLI binary exists
  const vcsiBinary = join(venvBin, "vcsi");
  if (!existsSync(vcsiBinary)) {
    logger.error("vcsi binary not found in venv after installing requirements.");
    logger.error("Make sure 'vcsi' is listed in requirements.txt and that it installs a CLI.");
    throw new Error("vcsi installation failed or did not expose CLI.");
  }

  logger.debug("vcsi CLI is available at", vcsiBinary);
}