require 'xcodeproj/workspace'
require 'xcodeproj/project'

require 'active_support/core_ext/string/inflections'
require 'active_support/core_ext/array/conversions'

module Pod
  class Installer

    # The {UserProjectIntegrator} integrates the libraries generated by
    # TargetDefinitions of the {Podfile} with their correspondent user
    # projects.
    #
    class UserProjectIntegrator

      autoload :TargetIntegrator, 'cocoapods/installer/user_project_integrator/target_integrator'

      # @return [Podfile] the podfile that should be integrated with the user
      #         projects.
      #
      attr_reader :podfile

      # @return [Project] the pods project which contains the libraries to
      #         integrate.
      #
      # attr_reader :pods_project

      attr_reader :sandbox

      # @return [Pathname] the path of the installation.
      #
      # @todo This is only used to compute the workspace path in case that it
      #       should be inferred by the project. If the workspace should be in
      #       the same dir of the project, this could be removed.
      #
      attr_reader :installation_root

      # @return [Library] the libraries generated by the installer.
      #
      attr_reader :libraries

      # @param  [Podfile]  podfile @see #podfile
      # @param  [Sandbox]  sandbox @see #sandbox
      # @param  [Pathname] installation_root @see #installation_root
      # @param  [Library]  libraries @see #libraries
      #
      # @todo   Too many initialization arguments
      #
      def initialize(podfile, sandbox, installation_root, libraries)
        @podfile = podfile
        @sandbox = sandbox
        @installation_root = installation_root
        @libraries = libraries
      end

      # Integrates the user projects associated with the {TargetDefinitions}
      # with the Pods project and its products.
      #
      # @return [void]
      #
      def integrate!
        create_workspace
        integrate_user_targets
        warn_about_empty_podfile
      end

      #-----------------------------------------------------------------------#

      private

      # @!group Integration steps

      # Creates and saved the workspace containing the Pods project and the
      # user projects, if needed.
      #
      # @note If the workspace already contains the projects it is not saved
      #       to avoid Xcode from displaying the revert dialog: `Do you want to
      #       keep the Xcode version or revert to the version on disk?`
      #
      # @return [void]
      #
      def create_workspace
        all_projects = user_project_paths.sort.push(sandbox.project_path).uniq
        projpaths = all_projects.map do |path|
          path.relative_path_from(workspace_path.dirname).to_s
        end

        if workspace_path.exist?
          workspace = Xcodeproj::Workspace.new_from_xcworkspace(workspace_path)
          new_projpaths = projpaths - workspace.projpaths
          unless new_projpaths.empty?
            workspace.projpaths.concat(new_projpaths)
            workspace.save_as(workspace_path)
          end

        else
          UI.notice "From now on use `#{workspace_path.basename}`."
          workspace = Xcodeproj::Workspace.new(*projpaths)
          workspace.save_as(workspace_path)
        end
      end

      # Integrates the targets of the user projects with the libraries
      # generated from the {Podfile}.
      #
      # @note   {TargetDefinition} without dependencies are skipped prevent
      #         creating empty libraries for targets definitions which are only
      #         wrappers for others.
      #
      # @return [void]
      #
      def integrate_user_targets
        libraries_to_integrate.sort_by(&:name).each do |lib|
          TargetIntegrator.new(lib).integrate!
        end
      end

      # Warns the user if the podfile is empty.
      #
      # @note   The workspace is created in any case and all the user projects
      #         are added to it, however the projects are not integrated as
      #         there is no way to discern between target definitions which are
      #         empty and target definitions which just serve the purpose to
      #         wrap other ones. This is not an issue because empty target
      #         definitions generate empty libraries.
      #
      # @return [void]
      #
      def warn_about_empty_podfile
        if podfile.target_definitions.values.all?{ |td| td.empty? }
          UI.warn "[!] The Podfile does not contain any dependency."
        end
      end

      private

      # @!group Private Helpers
      #-----------------------------------------------------------------------#

      # @return [Pathname] the path where the workspace containing the Pods
      #         project and the user projects should be saved.
      #
      def workspace_path
        if podfile.workspace_path
          Pathname.new(podfile.workspace_path)
        elsif user_project_paths.count == 1
          project = user_project_paths.first.basename('.xcodeproj')
          installation_root + "#{project}.xcworkspace"
        else
          raise Informative, "Could not automatically select an Xcode " \
            "workspace. Specify one in your Podfile like so:\n\n"       \
            "    workspace 'path/to/Workspace.xcworkspace'\n"
        end
      end

      # @return [Array<Pathname>] the paths of all the user projects referenced
      #         by the target definitions.
      #
      # @note   Empty target definitions are ignored.
      #
      def user_project_paths
        libraries.map do |lib|
          lib.user_project_path
        end.compact.uniq
      end


      def libraries_to_integrate
        libraries.reject { |lib| lib.target_definition.empty? }
      end

      #-----------------------------------------------------------------------#

    end
  end
end
