const fs = require('fs-extra');
const path = require('path');
const os = require('os');

const PRIMARY_UNROUTED_DIR = '/cadroute/__NON_SMISTATI';
const HOME_UNROUTED_DIR = path.join(os.homedir(), '.cadroute', '__NON_SMISTATI');

let resolvedUnroutedDirPromise = null;

async function resolveUnroutedDir() {
  if (!resolvedUnroutedDirPromise) {
    resolvedUnroutedDirPromise = (async () => {
      try {
        await fs.ensureDir(PRIMARY_UNROUTED_DIR);
        return PRIMARY_UNROUTED_DIR;
      } catch {
        await fs.ensureDir(HOME_UNROUTED_DIR);
        return HOME_UNROUTED_DIR;
      }
    })();
  }

  return resolvedUnroutedDirPromise;
}

async function getUniquePath(destinationDir, fileName) {
  const parsed = path.parse(fileName);
  let candidate = path.join(destinationDir, fileName);
  let counter = 1;

  while (await fs.pathExists(candidate)) {
    candidate = path.join(destinationDir, `${parsed.name}__${counter}${parsed.ext}`);
    counter += 1;
  }

  return candidate;
}

async function getUnroutedTarget(fileName) {
  const destinationDir = await resolveUnroutedDir();
  const destinationPath = await getUniquePath(destinationDir, fileName);

  return {
    destinationDir,
    destinationPath,
  };
}

module.exports = {
  getUnroutedTarget,
  PRIMARY_UNROUTED_DIR,
  HOME_UNROUTED_DIR,
};