# -*- coding: utf-8 -*-
# -*- mode: ruby -*-
# vi: set ft=ruby :
#
# Tails: The Amnesic Incognito Live System
# Copyright © 2012 Tails developers <tails@boum.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

require 'open3'
require 'rbconfig'
require 'uri'

require_relative 'vagrant/lib/tails_build_settings'

# Path to the directory which holds our Vagrantfile
VAGRANT_PATH = File.expand_path('../vagrant', __FILE__)

# Branches that are considered 'stable' (used to select SquashFS compression)
STABLE_BRANCH_NAMES = ['stable', 'testing']

# Environment variables that will be exported to the build script
EXPORTED_VARIABLES = ['http_proxy', 'MKSQUASHFS_OPTIONS', 'TAILS_RAM_BUILD', 'TAILS_CLEAN_BUILD']

# Let's save the http_proxy set before playing with it
EXTERNAL_HTTP_PROXY = ENV['http_proxy']

# In-VM proxy URL
INTERNAL_HTTP_PROXY = "http://#{VIRTUAL_MACHINE_HOSTNAME}:3142"

class VagrantCommandError < StandardError
end

# Runs the vagrant command, letting stdout/stderr through. Throws an
# exception unless the vagrant command succeeds.
def run_vagrant(*args)
  Process.wait Kernel.spawn('vagrant', *args, :chdir => './vagrant')
  if $?.exitstatus != 0
    raise(VagrantCommandError, "'vagrant #{args}' command failed: " +
                               "#{$?.exitstatus}")
  end
end

# Runs the vagrant command, not letting stdout/stderr through, and
# returns [stdout, stderr, Preocess:Status].
def capture_vagrant(*args)
  stdout, stderr, proc_status =
    Open3.capture3('vagrant', *args, :chdir => './vagrant')
  if proc_status.exitstatus != 0
    raise(VagrantCommandError, "'vagrant #{args}' command failed: " +
                               "#{proc_status.exitstatus}")
  end
  return stdout, stderr
end

def vagrant_ssh_config(key)
  # Cache results
  if $vagrant_ssh_config.nil?
    $vagrant_ssh_config = capture_vagrant('ssh-config').first.split("\n") \
                           .map { |line| line.strip.split(/\s+/, 2) } .to_h
    # The path in the ssh-config output is quoted, which is not what
    # is expected outside of a shell, so let's get rid of the quotes.
    $vagrant_ssh_config['IdentityFile'].gsub!(/^"|"$/, '')
  end
  $vagrant_ssh_config[key]
end

def current_vm_cpus
  capture_vagrant('ssh', '-c', 'grep -c "^processor\s*:" /proc/cpuinfo').first.chomp.to_i
end

def vm_state
  out, _ = capture_vagrant('status')
  status_line = out.split("\n")[2]
  if    status_line['not created']
    return :not_created
  elsif status_line['shutoff']
    return :poweroff
  elsif status_line['running']
    return :running
  else
    raise "could not determine VM state"
  end
end

def enough_free_host_memory_for_ram_build?
  return false unless RbConfig::CONFIG['host_os'] =~ /linux/i

  begin
    usable_free_mem = `free`.split[16].to_i
    usable_free_mem > VM_MEMORY_FOR_RAM_BUILDS * 1024
  rescue
    false
  end
end

def free_vm_memory
  capture_vagrant('ssh', '-c', 'free').first.chomp.split[16].to_i
end

def enough_free_vm_memory_for_ram_build?
  free_vm_memory > BUILD_SPACE_REQUIREMENT * 1024
end

def enough_free_memory_for_ram_build?
  if vm_state == :running
    enough_free_vm_memory_for_ram_build?
  else
    enough_free_host_memory_for_ram_build?
  end
end

def is_release?
  branch_name = `git name-rev --name-only HEAD`
  tag_name = `git describe --exact-match HEAD 2> /dev/null`
  STABLE_BRANCH_NAMES.include? branch_name.chomp or tag_name.chomp.length > 0
end

def system_cpus
  return nil unless RbConfig::CONFIG['host_os'] =~ /linux/i

  begin
    File.read('/proc/cpuinfo').scan(/^processor\s+:/).count
  rescue
    nil
  end
end

task :parse_build_options do
  options = ''

  # Default to in-memory builds if there is enough RAM available
  options += 'ram ' if enough_free_memory_for_ram_build?

  # Default to build using the in-VM proxy
  options += 'vmproxy '

  # Default to fast compression on development branches
  options += 'gzipcomp ' unless is_release?

  # Make sure release builds are clean
  options += 'cleanall ' if is_release?

  # Default to the number of system CPUs when we can figure it out
  cpus = system_cpus
  options += "cpus=#{cpus} " if cpus

  options += ENV['TAILS_BUILD_OPTIONS'] if ENV['TAILS_BUILD_OPTIONS']
  options.split(' ').each do |opt|
    case opt
    # Memory build settings
    when 'ram'
      ENV['TAILS_RAM_BUILD'] = '1'
    when 'noram'
      ENV['TAILS_RAM_BUILD'] = nil
    # Bootstrap cache settings
    # HTTP proxy settings
    when 'extproxy'
      abort "No HTTP proxy set, but one is required by TAILS_BUILD_OPTIONS. Aborting." unless EXTERNAL_HTTP_PROXY
      ENV['http_proxy'] = EXTERNAL_HTTP_PROXY
    when 'vmproxy'
      ENV['http_proxy'] = INTERNAL_HTTP_PROXY
    when 'noproxy'
      ENV['http_proxy'] = nil
    # SquashFS compression settings
    when 'gzipcomp'
      ENV['MKSQUASHFS_OPTIONS'] = '-comp gzip'
    when 'defaultcomp'
      ENV['MKSQUASHFS_OPTIONS'] = nil
    # Clean-up settings
    when 'cleanall'
      ENV['TAILS_CLEAN_BUILD'] = '1'
    # Virtual CPUs settings
    when /cpus=(\d+)/
      ENV['TAILS_BUILD_CPUS'] = $1
    # Git settings
    when 'ignorechanges'
      ENV['TAILS_BUILD_IGNORE_CHANGES'] = '1'
    when 'noprovision'
      ENV['TAILS_NO_AUTO_PROVISION'] = '1'
    end
  end
end

task :ensure_clean_repository do
  git_status = `git status --porcelain`
  unless git_status.empty?
    if ENV['TAILS_BUILD_IGNORE_CHANGES']
      $stderr.puts <<-END_OF_MESSAGE.gsub(/^        /, '')

        You have uncommitted changes in the Git repository. They will
        be ignored for the upcoming build:
        #{git_status}

      END_OF_MESSAGE
    else
      $stderr.puts <<-END_OF_MESSAGE.gsub(/^        /, '')

        You have uncommitted changes in the Git repository. Due to limitations
        of the build system, you need to commit them before building Tails:
        #{git_status}

        If you don't care about those changes and want to build Tails nonetheless,
        please add `ignorechanges` to the TAILS_BUILD_OPTIONS environment
        variable.

      END_OF_MESSAGE
      abort 'Uncommitted changes. Aborting.'
    end
  end
end

def list_artifacts
  user = vagrant_ssh_config('User')
  stdout = capture_vagrant('ssh', '-c', "find '/home/#{user}/' -maxdepth 1 " +
                                        "-name 'tails-*.iso*'").first
  stdout.split("\n")
rescue VagrantCommandError
  return Array.new
end

def remove_artifacts
  list_artifacts.each do |artifact|
    run_vagrant('ssh', '-c', "sudo rm -f '#{artifact}'")
  end
end

desc "Make sure the vagrant user's home directory has no undesired artifacts"
task :ensure_clean_home_directory => ['vm:up'] do
  remove_artifacts
end

task :validate_http_proxy do
  if ENV['http_proxy']
    proxy_host = URI.parse(ENV['http_proxy']).host

    if proxy_host.nil?
      ENV['http_proxy'] = nil
      $stderr.puts "Ignoring invalid HTTP proxy."
      return
    end

    if ['localhost', '[::1]'].include?(proxy_host) || proxy_host.start_with?('127.0.0.')
      abort 'Using an HTTP proxy listening on the loopback is doomed to fail. Aborting.'
    end

    $stderr.puts "Using HTTP proxy: #{ENV['http_proxy']}"
  else
    $stderr.puts "No HTTP proxy set."
  end
end

desc 'Build Tails'
task :build => ['parse_build_options', 'ensure_clean_repository', 'ensure_clean_home_directory', 'validate_http_proxy', 'vm:up'] do

  if ENV['TAILS_RAM_BUILD'] && not(enough_free_memory_for_ram_build?)
    $stderr.puts <<-END_OF_MESSAGE.gsub(/^      /, '')

      The virtual machine is not currently set with enough memory to
      perform an in-memory build. Either remove the `ram` option from
      the TAILS_BUILD_OPTIONS environment variable, or shut the
      virtual machine down using `rake vm:halt` before trying again.

    END_OF_MESSAGE
    abort 'Not enough memory for the virtual machine to run an in-memory build. Aborting.'
  end

  if ENV['TAILS_BUILD_CPUS'] && current_vm_cpus != ENV['TAILS_BUILD_CPUS'].to_i
    $stderr.puts <<-END_OF_MESSAGE.gsub(/^      /, '')

      The virtual machine is currently running with #{current_vm_cpus}
      virtual CPU(s). In order to change that number, you need to
      stop the VM first, using `rake vm:halt`. Otherwise, please
      adjust the `cpus` options accordingly.

    END_OF_MESSAGE
    abort 'The virtual machine needs to be reloaded to change the number of CPUs. Aborting.'
  end

  # Let's make sure that, unless you know what you are doing and
  # explicitly disable this, we always provision in order to ensure
  # a valid, up-to-date build system.
  run_vagrant('provision') unless ENV['TAILS_NO_AUTO_PROVISION']

  exported_env = EXPORTED_VARIABLES.select { |k| ENV[k] }.
                 collect { |k| "#{k}='#{ENV[k]}'" }.join(' ')
  run_vagrant('ssh', '-c', "#{exported_env} build-tails")

  artifacts = list_artifacts
  raise 'No build artifacts was found!' if artifacts.empty?
  user     = vagrant_ssh_config('User')
  hostname = vagrant_ssh_config('HostName')
  key_file = vagrant_ssh_config('IdentityFile')
  $stderr.puts "Retrieving artifacts from Vagrant build box."
  artifacts.each do |artifact|
    run_vagrant('ssh', '-c', "sudo chown #{user} '#{artifact}'")
    Process.wait(
      Kernel.spawn(
        'scp',
        '-i', key_file,
        # We need this since the user will not necessarily have a
        # known_hosts entry. It is safe since an attacker must
        # compromise libvirt's network config or the user running the
        # command to modify the #{hostname} below.
        '-o', 'StrictHostKeyChecking=no',
        "#{user}@#{hostname}:#{artifact}", '.'
      )
    )
    raise "Failed to fetch artifact '#{artifact}'" unless $?.success?
  end
  remove_artifacts
end

namespace :vm do
  desc 'Start the build virtual machine'
  task :up => ['parse_build_options', 'validate_http_proxy'] do
    case vm_state
    when :not_created
      # Do not use non-existant in-VM proxy to download the basebox
      if ENV['http_proxy'] == INTERNAL_HTTP_PROXY
        ENV['http_proxy'] = nil
        restore_internal_proxy = true
      end

      $stderr.puts <<-END_OF_MESSAGE.gsub(/^        /, '')

        This is the first time that the Tails builder virtual machine is
        started. The virtual machine template is about 300 MB to download,
        so the process might take some time.

        Please remember to shut the virtual machine down once your work on
        Tails is done:

            $ rake vm:halt

      END_OF_MESSAGE
    when :poweroff
      $stderr.puts <<-END_OF_MESSAGE.gsub(/^        /, '')

        Starting Tails builder virtual machine. This might take a short while.
        Please remember to shut it down once your work on Tails is done:

            $ rake vm:halt

      END_OF_MESSAGE
    end
    run_vagrant('up')
    ENV['http_proxy'] = INTERNAL_HTTP_PROXY if restore_internal_proxy
  end

  desc 'SSH into the builder VM'
  task :ssh do
    run_vagrant('ssh')
  end

  desc 'Stop the build virtual machine'
  task :halt do
    run_vagrant('halt')
  end

  desc 'Re-run virtual machine setup'
  task :provision => ['parse_build_options', 'validate_http_proxy'] do
    run_vagrant('provision')
  end

  desc 'Destroy build virtual machine (clean up all files)'
  task :destroy do
    run_vagrant('destroy', '--force')
  end
end

namespace :basebox do

  desc 'Generate a new base box'
  task :create do
    box_dir = VAGRANT_PATH + '/definitions/tails-builder'
    Dir.chdir(box_dir) do
      `./generate-tails-builder-box.sh`
      raise 'Base box generation failed!' unless $?.success?
    end
    box = Dir.glob("#{box_dir}/*.box").sort_by {|f| File.mtime(f) } .last
    $stderr.puts <<-END_OF_MESSAGE.gsub(/^      /, '')

      You have successfully generated a new Vagrant base box:

          #{box}

      To install the new base box, please run:

          $ vagrant box add #{box}

      To actually make Tails build using this base box, the `config.vm.box` key
      in `vagrant/Vagrantfile` has to be updated. Please check the documentation
      for details.

    END_OF_MESSAGE
  end

end