# frozen_string_literal: true

module Kaminari
  module Generators
    # rails g kaminari:views THEME
    class ViewsGenerator < Rails::Generators::NamedBase # :nodoc:
      source_root File.expand_path('../../../../app/views/kaminari', __FILE__)

      class_option :template_engine, type: :string, aliases: '-e', desc: 'Template engine for the views. Available options are "erb", "haml", and "slim".'
      class_option :views_prefix, type: :string, desc: 'Prefix for path to put views in.'

      class << self
        def banner #:nodoc:
          <<-BANNER.chomp
rails g kaminari:views THEME [options]

    Copies all paginator partial templates to your application.
    You can choose a template THEME by specifying one from the list below:

        - default
            The default one.
            This one is used internally while you don't override the partials.
#{themes.map {|t| "        - #{t.name}\n#{t.description}"}.join("\n")}
BANNER
        end

        private

        def themes
          @themes ||= GitHubApiHelper.get_files_in_master.group_by {|fn, _| fn[0...(fn.index('/') || 0)]}.delete_if {|fn, _| fn.blank?}.map do |name, files|
            Theme.new name, files
          end
        rescue SocketError
          []
        end
      end

      desc ''
      def copy_or_fetch #:nodoc:
        return copy_default_views if file_name == 'default'

        if (theme = self.class.themes.detect {|t| t.name == file_name})
          if download_templates(theme).empty?
            say "template_engine: #{template_engine} is not available for theme: #{file_name}"
          end
        else
          say "no such theme: #{file_name}\n  available themes: #{self.class.themes.map(&:name).join ', '}"
        end
      end

      private

      def download_templates(theme)
        theme.templates_for(template_engine).each do |template|
          say "      downloading #{template.name} from kaminari_themes..."
          create_file view_path_for(template.name), GitHubApiHelper.get_content_for("#{theme.name}/#{template.name}")
        end
      end

      def copy_default_views
        filename_pattern = File.join self.class.source_root, "*.html.#{template_engine}"
        Dir.glob(filename_pattern).map {|f| File.basename f}.each do |f|
          copy_file f, view_path_for(f)
        end
      end

      def view_path_for(file)
        ['app', 'views', views_prefix, 'kaminari', File.basename(file)].compact.join('/')
      end

      def views_prefix
        options[:views_prefix].try(:to_s)
      end

      def template_engine
        engine = options[:template_engine].try(:to_s).try(:downcase)

        if engine == 'haml' || engine == 'slim'
          Kaminari.deprecator.warn 'The -e option is deprecated and will be removed in the near future. Please use the html2slim gem or the html2haml gem ' \
            'to convert erb templates manually.'
        end

        engine || 'erb'
      end
    end

    Template = Struct.new(:name, :sha) do
      def description?
        name == 'DESCRIPTION'
      end

      def view?
        name =~ /^app\/views\//
      end

      def engine #:nodoc:
        File.extname(name).sub(/^\./, '')
      end
    end

    class Theme
      attr_accessor :name
      def initialize(name, templates) #:nodoc:
        @name, @templates = name, templates.map {|fn, sha| Template.new fn.sub(/^#{name}\//, ''), sha}
      end

      def description #:nodoc:
        file = @templates.detect(&:description?)
        return "#{' ' * 12}#{name}" unless file
        GitHubApiHelper.get_content_for("#{@name}/#{file.name}").chomp.gsub(/^/, ' ' * 12)
      end

      def templates_for(template_engine) #:nodoc:
        @templates.select {|t| t.engine == template_engine }
      end
    end

    module GitHubApiHelper
      require 'open-uri'

      def get_files_in_master
        master_tree_sha = URI.open('https://api.github.com/repos/amatsuda/kaminari_themes/git/refs/heads/master') do |json|
          ActiveSupport::JSON.decode(json.read)['object']['sha']
        end
        URI.parse("https://api.github.com/repos/amatsuda/kaminari_themes/git/trees/#{master_tree_sha}?recursive=1").open do |json|
          blobs = ActiveSupport::JSON.decode(json.read)['tree'].find_all {|i| i['type'] == 'blob' }
          blobs.map do |blob|
            [blob['path'], blob['sha']]
          end
        end
      end
      module_function :get_files_in_master

      def get_content_for(path)
        URI.parse("https://api.github.com/repos/amatsuda/kaminari_themes/contents/#{path}").open do |json|
          Base64.decode64(ActiveSupport::JSON.decode(json.read)['content'])
        end
      end
      module_function :get_content_for
    end
  end
end
