require "ostruct"
require "tempfile"

require "log4r"

require "vagrant/util/subprocess"

module Vagrant
  module Easy
    # This class contains all the "operations" that easy commands are able
    # to run. An instance of this is class is what is sent into the callback
    # for all easy commands.
    class Operations
      def initialize(vm)
        @logger = Log4r::Logger.new("vagrant::easy::operations")
        @vm = vm
      end

      # Download a file from the remote virtual machine. If `to` is nil, then
      # the contents are returned as a string.
      #
      # @param [String] from Path on the remote VM to download.
      # @param [String] to Path to a local file to save to.
      # @return [String] File contents if `to` is nil.
      def download(from, to=nil)
        raise Errors::VMNotRunningError if @vm.state != :running

        @logger.info("download: #{from} => #{to}")
        @vm.channel.download(from, to)
      end

      # Runs a command on the local machine. This will return an object where
      # you can access the `exit_code`, `stdout`, and `stderr` easiy:
      #
      #     output = local("echo foo")
      #     puts "Output was #{output.stdout}"
      #
      # (Likewise, `exit_code` and `stderr` are attributes on the return value)
      #
      # It is recommended you use this `local` method rather than trying to
      # manually use Ruby's underlying subprocess tools because this will use
      # the Vagrant `Subprocess` class which has been refined over the years
      # to work equally well on Windows, Mac OS X, Linux as well as on many
      # runtimes such as CRuby and JRuby.
      #
      # @param [String] command Command to run
      # @param [Hash] options Additional options
      def local(command, options=nil)
        @logger.info("local: #{command}")

        block   = nil
        options = { :echo => true }.merge(options || {})

        if options[:echo]
          # If we're echoing data, then setup the block that sends the
          # data to the UI.
          block = Proc.new do |type, data|
            if type == :stdout || type == :stderr
              @vm.ui.info(data.to_s,
                          :prefix => false,
                          :new_line => false)
            end
          end
        end

        Vagrant::Util::Subprocess.execute(command, :notify => [:stdout, :stderr], &block)
      end

      # Run a shell command within the VM. The command will run within a
      # shell environment, and the output and exit code will be returned
      # as an object with attributes: `exit_code, `stdout`, and `stderr`.
      # Example:
      #
      #     output = run("echo foo")
      #     puts "Output was #{output.stdout}"
      #
      # @param [String] command Command to run
      # @param [Hash] options Additional options
      def run(command, options=nil)
        @logger.info("run: #{command}")
        options = { :echo => true }.merge(options || {})
        remote_command(:execute, command, options)
      end

      # Same as {run} except runs the command with superuser privileges
      # via `sudo`.
      #
      # @param [String] command Command
      # @param [Hash] options Additional options
      def sudo(command, options=nil)
        @logger.info("sudo: #{command}")
        options = { :echo => true }.merge(options || {})
        remote_command(:sudo, command, options)
      end

      # Uploads a file to the virtual machine.
      #
      # Note that the `to` path must have proper permissions setup so that the
      # SSH user can upload to it. If it does not, then you should upload
      # to a location you do have permission to, then use {#sudo} to move
      # it.
      #
      # @param [String] from Path to a local file or an IO object.
      # @param [String] to Path where to upload to.
      def upload(from, to)
        raise Errors::VMNotRunningError if @vm.state != :running

        # If we're dealing with an IO object, then save it to a temporary
        # file and upload that. We define `temp = nil` here so that it
        # doesn't go out of scope and get GC'd until after the method
        # closes.
        temp = nil
        if from.is_a?(IO)
          temp = Tempfile.new("vagrant")
          temp.write(from)
          temp.close

          from = temp.path
        end

        # Perform the upload
        @logger.info("upload: #{from} => #{to}")
        @vm.channel.upload(from, to)
      end

      protected

      # Runs a command on the remote host.
      def remote_command(type, command, options)
        # If the VM is not running, then we can't run SSH commands...
        raise Errors::VMNotRunningError if @vm.state != :running

        # Initialize the result object, execute, and store the data
        result = OpenStruct.new
        result.stderr = ""
        result.stdout = ""
        result.exit_code = @vm.channel.send(type, command,
                                            :error_check => false) do |type, data|
          if type == :stdout
            result.stdout += data
          elsif type == :stderr
            result.stderr += data
          end

          # If we're echoing data, then echo it!
          if options[:echo]
            @vm.ui.info(data.to_s,
                        :prefix => false,
                        :new_line => false)
          end
        end

        # Return the result
        result
      end
    end
  end
end