import { default as spawn } from 'cross-spawn'
import type { EnvCmdOptions, Environment } from './types.ts'
import { TermSignals } from './signal-termination.js'
import { getEnvVars } from './get-env-vars.js'
import { expandEnvs } from './expand-envs.js'
import * as processLib from 'node:process'

/**
 * The main env-cmd program. This will spawn a new process and run the given command using
 * various environment file solutions.
 *
 * @export
 * @param {EnvCmdOptions} { command, commandArgs, envFile, rc, options }
 * @returns {Promise<Environment>} Returns an object containing [environment variable name]: value
 */
export async function EnvCmd(
  {
    command,
    commandArgs,
    envFile,
    rc,
    options = {},
  }: EnvCmdOptions,
): Promise<Environment> {
  let env: Environment = {}
  try {
    env = await getEnvVars({ envFile, rc, verbose: options.verbose })
  }
  catch (e) {
    if (!(options.silent ?? false)) {
      throw e
    }
  }
  // Override the merge order if --no-override flag set
  if (options.noOverride === true) {
    env = Object.assign({}, env, processLib.env)
  }
  else {
    // Add in the system environment variables to our environment list
    env = Object.assign({}, processLib.env, env)
  }

  if (options.expandEnvs === true) {
    command = expandEnvs(command, env)
    commandArgs = commandArgs.map(arg => expandEnvs(arg, env))
  }

  if (!command) {
    throw new Error(
      'env-cmd cannot be used as a standalone command. ' +
        'Refer to the documentation for usage examples: https://npm.im/env-cmd',
    );
  }

  // Execute the command with the given environment variables
  const proc = spawn(command, commandArgs, {
    stdio: 'inherit',
    shell: options.useShell,
    env,
  })

  // Handle any termination signals for parent and child proceses
  const signals = new TermSignals({ verbose: options.verbose })
  signals.handleUncaughtExceptions()
  signals.handleTermSignals(proc)

  return env
}