#!/usr/bin/ruby

require_relative 'objects/rcm_file'
require_relative 'objects/rcm_package'
require_relative 'objects/rcm_service'
require_relative 'managers/rcm_package_manager'
require_relative 'managers/rcm_file_manager'
require_relative 'managers/rcm_service_manager'
require_relative 'rcm_utils'
require 'yaml'
require 'logger'

module RCM
  PACKAGES = 'packages'.freeze
  FILES = 'files'.freeze
  SERVICES = 'services'.freeze
  VALID_LOG_LEVELS = %w(fatal error info debug).freeze
  RCM_ENV = ENV.fetch('ENVIRONMENT', '')

  @wanted = {
    PACKAGES => {},
    FILES => {},
    SERVICES => {}
  }

  @got = {
    PACKAGES => {},
    FILES => {},
    SERVICES => {}
  }

  @logger = ::Logger.new(STDOUT)

  @pkg_mgr = ::RCM::Apt.new(@logger)
  @file_mgr = ::RCM::FileManager.new(@logger)
  @svc_mgr = ::RCM::ServiceManager.new(@logger)

  def self.configure_logger
    # Can be exposed as settings but was expanding the scope as this
    # object will need to be passed to all other objects
    @logger.level = ::Logger::DEBUG
    @logger.progname = 'rcm'
  end

  def self.parse_packages(markup)
    @logger.info("Environment = #{RCM_ENV}")
    @pkg_mgr.update unless RCM_ENV == 'dev'

    markup.each do |d|
      # ensure package version exists, if mentioned.
      version = d.fetch('version', '')
      desired_state = d.fetch('desired_state', ::RCM::Package::INSTALLED)

      valid_package_states = [::RCM::Package::INSTALLED, ::RCM::Package::REMOVED]

      if (valid_package_states & [desired_state]).empty?
        raise "Unknown desired_state: #{desired_state}. Valid states: #{valid_package_states.join(', ')}"
      end

      unless version.empty?
        available_versions = @pkg_mgr.get_versions(d['name'])
        if (available_versions & [version]).empty?
          raise "\n\n#{d['name']} = #{version} is not available.\nAvailable versions: #{available_versions.join(', ')}"
        end
      end
      p = RCM::Package.new(d['name'], version, desired_state)
      @wanted[PACKAGES][d['name']] = p
    end
  end

  def self.parse_files(markup)
    valid_file_states = [::RCM::File::PRESENT, ::RCM::File::ABSENT]
    markup.each do |d|
      raise "\n\nFile state can only be one of #{valid_file_states.join (', ')}" if (valid_file_states | [d['desired_state']]).empty?
      raise "\n\n'#{d['local_file']}' is not readable.\n\n" if d['desired_state'] == ::RCM::File::PRESENT && !::File.readable?(d['local_file'])
      f = RCM::File.new(d['path'], d['owner'], d['group'], d['mode'], d['local_file'], d['desired_state'])
      @wanted[FILES][d['path']] = f
    end
  end

  def self.parse_services(markup)
    pkgs = @wanted[PACKAGES]
    files = @wanted[FILES]
    file_dependencies = {}
    package_dependencies = {}
    markup.each do |d|
      dependencies = d.fetch('dependencies', {})
      dependencies.each do |values|
        values.each do |dep_type, dep|
          case dep_type
          when PACKAGES
            dep.each do |pkg_definition|
              pkg_name = pkg_definition['name']
              raise "\n\nPlease ensure #{pkg_name} is managed by this program before adding it as a dependency.\n\n" unless pkgs.key?(pkg_name)
              p = pkgs[pkg_name]
              package_dependencies[pkg_name] = p
            end
          when FILES
            dep.each do |file_defnition|
              path = file_defnition['path']
              raise "\n\nPlease ensure #{path} is managed by this program before adding it as a dependency.\n\n" unless files.key?(path)

              f = files[path]
              file_dependencies[path] = f
            end
          end
        end

      end
      s = RCM::Service.new(d['name'], file_dependencies, package_dependencies)
      @wanted[SERVICES][d['name']] = s
    end
  end

  def self.whachuwant # or parse_config
    # Consume config from YAML, and convert it to usable objects in @wanted.
    config_file = RCM_ENV.empty? ? 'config.yaml' : "config_#{RCM_ENV}.yaml"

    raise "#{config_file} not found." unless ::File.readable?(config_file)

    config = YAML.load_file(config_file)
    config.each do |yaml_objects|
      yaml_objects.each do |collection, resource_definition|
        case collection
        when PACKAGES
          parse_packages(resource_definition)

        when FILES
          parse_files(resource_definition)

        when SERVICES
          parse_services(resource_definition)
        end
      end
    end

  end

  def self.whachugot # or get_current_state
    @got[PACKAGES] = @pkg_mgr.get_current_state(@wanted[PACKAGES])
    @got[FILES] = @file_mgr.get_current_state(@wanted[FILES])
    # @got[SERVICES] = @svc_mgr.get_current_state(@wanted[SERVICES])
  end

  def self.converge_packages
    @wanted[PACKAGES].each do |pkg_name, pkg_obj|
      current_pkg = @got[PACKAGES][pkg_name]

      if current_pkg == pkg_obj
        @logger.info("#{pkg_name} is in expected state.")
        next
      end

      @logger.debug('Missing package:' + pkg_name)
      if current_pkg.version != pkg_obj.version && current_pkg.state == ::RCM::Package::INSTALLED
        # Wrong version is installed. Remove current version and install the correct one.
        # Not the best way to go about it... but we are not implementing a legit solution.
        @logger.debug("#{current_pkg.name}=#{current_pkg.version} is installed. Uninstalling first.")
        @pkg_mgr.remove(pkg_obj)
        @pkg_mgr.install(pkg_obj)
      elsif current_pkg.state == ::RCM::Package::REMOVED
        @pkg_mgr.install(pkg_obj)
      end
    end

  end

  def self.converge_files
    @wanted[FILES].each do |path, file_obj|
      file_on_fs = @got[FILES][path]

      if file_on_fs.state == ::RCM::File::PRESENT && file_obj.state == ::RCM::File::ABSENT
        @logger.info("#{path} is present on disk when it should not be. Removing...")
        @file_mgr.remove(file_obj)
        next
      end

      if file_on_fs == file_obj
        @logger.info("#{path} is in expected state (#{file_on_fs.state}).")
        next
      end

      @logger.info("#{path} is not present on disk.")
      status = @file_mgr.copy(file_obj)
      @file_mgr.apply_attributes(file_obj) if status == 0

    end
  end

  def self.restart_services_if_needed
    @wanted[SERVICES].values.each do |svc_obj|
      @svc_mgr.restart(svc_obj) if @svc_mgr.dependencies_changed?(svc_obj)
    end
  end

  def main
    configure_logger
    whachuwant
    whachugot
    converge_packages
    converge_files
    restart_services_if_needed
  end

  module_function :main
end

RCM.main