require "multi_ruby_runner/version"
require 'multi_ruby_runner/version_manager'
require 'multi_ruby_runner/version_manager/none'
require 'multi_ruby_runner/version_manager/rbenv'
require 'multi_ruby_runner/version_manager/rvm'

# Allows calling of Ruby code in various Ruby environments.
class MultiRubyRunner

  def initialize
  end

  # Executes a command in a directory. Command will be executed in the
  # ruby environment specified in `.ruby-version` file in `directory`.
  # Returns stdout in the blocking form and pid of child process in the
  # non-blocking form.
  #
  # @param command_string [String] the shell command to run in directory
  # @param directory [String] the dir containing the ".ruby-version" file
  # @param options [Hash, optional]
  # @option options [String, optional] shell_invocation what shell to use, defaults to bash
  # @option options [Boolean, optional] blocking defaults to true.
  # @option options [String, optional] ruby_engine_invocation_override
  #   Can be used when no Ruby version manager is present, e.g., in a docker install.
  #   Example: "jruby -S "
  # @return [String, Integer, Nil] STDOUT output when blocking, pid when non-blocking.
  def execute_command_in_directory(command_string, directory, options = {})
    shell_path = ENV['SHELL'] || '/bin/bash'
    options = {
      blocking: true,
      shell_invocation: "#{ shell_path } -c",
    }.merge(options)
    process_args = ruby_version_manager.compute_process_args(
      command_string,
      directory,
      options
    )
    execute_command(process_args)
  end

  # Returns the ruby version manager used
  # @return [MultiRubyRunner::VersionManager] 'rbenv', 'rvm', 'none'
  def ruby_version_manager
    VersionManager.detect
  end

protected

  # @param process_args [Hash]
  #     {
  #       entire_command: includes shell invocation,
  #                       ruby version manager activation and command
  #       blocking: Boolean
  #       environment_overrides: {}
  #     }
  def execute_command(process_args)
    if process_args[:blocking]
      # Wait for command to complete
      execute_blocking_command(process_args)
    else
      # Spawn new process, execute command there and return immediately to caller.
      execute_non_blocking_command(process_args)
    end
  end

  def execute_blocking_command(process_args)
    stdout_str = stderr_str = status = nil
    Bundler.with_unbundled_env do
      stdout_str, stderr_str, status = Open3.capture3(
        process_args[:environment_overrides],
        process_args[:entire_command]
      )
    end
    if 0 == status
      # return stdout
      stdout_str
    else
      # Raise exception
      raise "Command failed with status #{ status.inspect }. stderr: #{ stderr_str.inspect }"
    end
  end

  def execute_non_blocking_command(process_args)
    pid = nil
    Bundler.with_unbundled_env do
      pid = Process.spawn(
        process_args[:environment_overrides],
        process_args[:entire_command]
      )
    end
    Process.detach(pid) # Avoid zombie process
    pid # return spawned process' pid
  end

end