work

lib/danbooru/paginator.rb

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+require "danbooru/paginator/active_record_extension"
+require "danbooru/paginator/collection_extension"
+require "danbooru/paginator/numbered_collection_extension"
+require "danbooru/paginator/sequential_collection_extension"
+
+ActiveRecord::Base.__send__(:include, Danbooru::Paginator::ActiveRecordExtension)

lib/danbooru/paginator/active_record_extension.rb

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+require 'active_support/concern'
+
+module Danbooru
+  module Paginator
+    module ActiveRecordExtension
+      extend ActiveSupport::Concern
+      
+      module ClassMethods
+        def paginate(page)
+          if use_sequential_paginator?(page)
+            paginate_sequential(page)
+          else
+            paginate_numbered(page)
+          end
+        end
+        
+        def use_sequential_paginator?(page)
+          page =~ /[ab]\d+/i
+        end
+
+        def paginate_sequential(page)
+          if page =~ /b(\d+)/
+            paginate_sequential_before($1)
+          elsif page =~ /a(\d+)/
+            paginate_sequential_after($1)
+          else
+            paginate_numbered(page)
+          end
+        end
+
+        def paginate_sequential_before(before_id)
+          limit(records_per_page).where("id < ?", before_id.to_i).reorder("id desc").tap do |obj|
+            obj.extend(SequentialCollectionExtension)
+            obj.sequential_paginator_mode = :before
+          end
+        end
+
+        def paginate_sequential_after(after_id)
+          limit(records_per_page).where("id > ?", after_id.to_i).reorder("id asc").tap do |obj|
+            obj.extend(SequentialCollectionExtension)
+            obj.sequential_paginator_mode = :after
+          end
+        end
+        
+        def paginate_numbered(page)
+          page = [page.to_i, 1].max
+          limit(records_per_page).offset((page - 1) * records_per_page).tap do |obj|
+            obj.extend(NumberedCollectionExtension)
+            obj.total_pages = (obj.total_count / records_per_page.to_f).ceil
+            obj.current_page = page
+          end
+        end
+        
+        def records_per_page
+          Danbooru.config.posts_per_page
+        end
+
+        # taken from kaminari (https://github.com/amatsuda/kaminari)
+        def total_count
+          c = except(:offset, :limit, :order)
+          c = c.reorder(nil)
+          c = c.count
+          c.respond_to?(:count) ? c.count : c
+        end
+      end
+    end
+  end
+end

lib/danbooru/paginator/collection_extension.rb

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+module Danbooru
+  module Paginator
+    module CollectionExtension
+    end
+  end
+end

lib/danbooru/paginator/numbered_collection_extension.rb

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+module Danbooru
+  module Paginator
+    module NumberedCollectionExtension
+      attr_accessor :current_page, :total_pages
+      
+      def self.extended(obj)
+        obj.extend(Danbooru::Paginator::CollectionExtension)
+      end
+      
+      def is_first_page?
+        current_page == 1
+      end
+      
+      def is_last_page?
+        current_page == total_pages
+      end
+      
+      def is_sequential_paginator?
+        false
+      end
+      
+      def is_numbered_paginator?
+        true
+      end
+    end
+  end
+end

lib/danbooru/paginator/sequential_collection_extension.rb

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+module Danbooru
+  module Paginator
+    module SequentialCollectionExtension
+      attr_accessor :sequential_paginator_mode
+      
+      def self.extended(obj)
+        obj.extend(Danbooru::Paginator::CollectionExtension)
+      end
+      
+      def is_first_page?
+        size == 0
+      end
+      
+      def is_last_page?
+        size == 0
+      end
+      
+      def is_sequential_paginator?
+        true
+      end
+      
+      def is_numbered_paginator?
+        false
+      end
+      
+      def to_a
+        if sequential_paginator_mode == :before
+          super
+        else
+          super.reverse
+        end
+      end
+
+      def before_id
+        if size > 0
+          self[-1].id
+        else
+          nil
+        end
+      end
+      
+      def after_id
+        if size > 0
+          self[0].id
+        else
+          nil
+        end
+      end
+    end
+  end
+end