# Copyright (c) 2013-2016 SUSE LLC
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of version 3 of the GNU General Public License as
# published by the Free Software Foundation.
#
# 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, contact SUSE LLC.
#
# To contact SUSE about this file by physical or electronic mail,
# you may find current contact information at www.suse.com

# Renderer is the base class for all text renderer plugins
#
# It defines methods for rendering data which will be called from the
# specialized content methods in the subclasses.
#
# Subclasses can define the output for the `show` and `compare` commands using
# the following `content` methods:
#
# For `machinery show`:
# [content] (required) Defines the output for a scope in `machinery show`
#
# For `machinery compare`:
# [compare_content_only_in] Defines the output of the "only in x" sections. The
#                           default behavior is to fall back to `content`.
# [compare_content_common]  Defines the output of the "in both" section. The
#                           default behavior is to fall back to `content`.
# [compare_content_changed] Defines the output of the "in both with changed
#                           attributes" section for scopes where this is
#                           supported.
#
# The names of the subclasses are 1:1 mappings of the scope areas, e.g.
# the PackagesRenderer class would be used for rendering when the user
# specifies "--scope=packages".
#
# The rendering methods are:
# def heading(s)   - Render a heading
# def puts(s)      - Print one line
# def list(name)   - Start a list. This method takes a block where the items are
#                    created.
# def item(s)      - Print a list item
#
# Accordingly a simple renderer for the "packages" scope could look like this:
#
# class PackagesRenderer < Machinery::Ui::Renderer
#   def content(description)
#     return if description.packages.empty?
#
#     list "Packages" do
#       description.packages.each do |p|
#         item "#{p.name} (#{p.version})"
#       end
#     end
#   end
# end
module Machinery
  class Ui
    class Renderer

      class InvalidStructureError < StandardError; end

      attr_accessor :system_description
      attr_accessor :buffer

      abstract_method :content
      abstract_method :compare_content_changed

      @@renderers = []

      class << self
        def inherited(klass)
          @@renderers << klass
        end

        def all
          @@renderers.map(&:new)
        end

        def for(scope)
          class_name = "Machinery::Ui::#{scope.split("_").map(&:capitalize).join}Renderer"

          begin
            Object.const_get(class_name).new
          rescue NameError
          end
        end
      end

      def scope
        # Return the un-camelcased name of the inspector,
        # e.g. "foo_bar" for "FooBarInspector"
        scope = self.class.name.match(/^Machinery::Ui::(.*)Renderer$/)[1]
        scope.gsub(/([^A-Z])([A-Z])/, "\\1_\\2").downcase
      end

      # Renders one system description using the specialized `content` method
      def render(system_description, options = {})
        @options = options
        @buffer = ""
        @indent = 2
        @stack = []

        if system_description[scope]
          header = display_name
          meta = system_description[scope].meta

          if meta
            header += " [#{meta.hostname}]"
            date = Time.parse(meta.modified).localtime
            date_human = date.strftime "%Y-%m-%d %H:%M:%S"
            header += " (#{date_human})"
          end

          heading(header)
        end

        content(system_description)

        @buffer += "\n" unless @buffer.empty? || @buffer.end_with?("\n\n")

        @buffer
      end

      # Renders the result of a comparison of two system descriptions.
      def render_comparison(comparison, options = {})
        @options = options
        @buffer = ""
        @indent = 0
        @stack = []

        show_heading = if options[:show_all]
          comparison.only_in1 || comparison.only_in2 || comparison.changed || comparison.common
        else
          comparison.only_in1 || comparison.only_in2 || comparison.changed
        end

        heading(display_name) if show_heading

        render_comparison_only_in(comparison.as_description(:one))
        render_comparison_only_in(comparison.as_description(:two))
        render_comparison_changed(comparison) if comparison.changed
        render_comparison_common(comparison.as_description(:common)) if @options[:show_all]
        @buffer
      end

      def render_comparison_only_in(description)
        return if !description[scope] || description[scope].elements.try(:empty?)

        puts "Only in '#{description.name}':"
        indent { compare_content_only_in(description) }
        @buffer += "\n" unless @buffer.empty? || @buffer.end_with?("\n\n")
      end

      def render_comparison_changed(comparison)
        puts "In both with different attributes ('#{comparison.name1}' <> '#{comparison.name2}'):"
        indent { compare_content_changed(comparison.changed) }
        @buffer += "\n" unless @buffer.empty? || @buffer.end_with?("\n\n")
      end

      def render_comparison_common(description)
        return unless description[scope]

        puts "Common to both systems:"
        indent { compare_content_common(description) }
        @buffer += "\n" unless @buffer.empty? || @buffer.end_with?("\n\n")
      end

      def compare_content_only_in(description)
        content(description)
      end

      def compare_content_common(description)
        content(description)
      end

      def render_comparison_missing_scope(description1, description2)
        @buffer = ""
        @indent = 0
        @stack = []
        missing_descriptions = Array.new

        unless description1[scope]
          missing_descriptions << description1.name
        end
        unless description2[scope]
          missing_descriptions << description2.name
        end

        if missing_descriptions.count == 1
          @buffer += "# #{display_name}\n"
          indent { puts "Unable to compare, no data in '#{missing_descriptions.join("', '")}'" }
        end
        @buffer += "\n" unless @buffer.empty? || @buffer.end_with?("\n\n")

        @buffer
      end

      protected

      def heading(s)
        @buffer += "# #{s}\n\n"
      end

      def puts(s)
        print_indented Machinery.scrub(s)
      end

      def list(name = nil, options = {}, &block)
        unless block_given?
          raise InvalidStructureError.new(
            "'list' was called without a block"
          )
        end

        @stack << :list

        if name && !name.empty?
          print_indented "#{name}:"
          indent do
            block.call
          end
        else
          block.call
        end
        @buffer += "\n" unless @buffer.end_with?("\n\n") || options[:sublist]

        @stack.pop
      end

      def item(s, &block)
        unless @stack.last == :list
          raise InvalidStructureError.new(
            "'item' was called outside of a list block"
          )
        end

        print_indented "* #{Machinery.scrub(s)}"

        if block_given?
          @stack << :item
          indent do
            block.call
          end
          @buffer += "\n"
          @stack.pop
        end
      end

      private

      def print_indented(s)
        s.split("\n", -1).each do |line|
          @buffer += if line.empty?
            "\n"
          else
            " " * @indent + line + "\n"
          end
        end
      end

      def indent
        @indent += 2
        yield
        @indent -= 2
      end

      def na_note(s)
        Machinery::Ui.puts "Note: 'N/A' represents a missing #{s} which could not\n" \
          "be gathered during inspection.\n"
      end
    end
  end
end