// SPDX-License-Identifier: MIT

import { readFile } from "node:fs/promises";
import os from "node:os";
import path from "node:path";

export function getUserConfigDir() {
  if (process.platform === "win32") {
    return process.env.LOCALAPPDATA ?? path.join(os.homedir(), "AppData", "Local");
  }

  return process.env.XDG_CONFIG_HOME ?? path.join(os.homedir(), ".config");
}

async function loadConfig(configFileName) {
  if (typeof configFileName !== "string" || configFileName.trim() === "") {
    throw new Error(
      'Invalid config file name. Expected a non-empty string like "public-config.json" or "confidential-config.json".',
    );
  }

  const config = {
    tenantId: process.env.AZURE_TENANT_ID,
    clientId: process.env.AZURE_CLIENT_ID,
  };

  const configPath = path.join(getUserConfigDir(), "sk-az-tools", configFileName);
  return readFile(configPath, "utf8")
    .then((configJson) => JSON.parse(configJson))
    .catch((err) => {
      if (err?.code === "ENOENT") {
        return {};
      }
      throw err;
    })
    .then((json) => ({
      tenantId: json.tenantId || config.tenantId,
      clientId: json.clientId || config.clientId,
    }));
}

export function loadPublicConfig() {
  return loadConfig("public-config.json");
}

export function loadConfidentialConfig() {
  return loadConfig("confidential-config.json");
}