Rail3 friendly pagination

gistfile1.rb

# If you are using ActiveRecord and want to paginate it you have to write this:
# PeacefulPaginate.use_for_active_record!
# to end of your config/environment.rb

# If you want to override default .paginate method from WillPaginate gem you have to insert this
# PeacefulPaginate.use_compatible_mod_with_will_paginate!
# to end of your config/environment.rb
# With this you dont have to rewrite nothing else in your application

# In other way how to use it
# PeacefulPaginate.paginate(People.where(:city => "Prague"), :per_page => 10, :page => 2)
# or
# People.where(:city => "Prague").peaceful_paginate(:per_page => 10, :page => 2)
# It will return
# [array_with_paginated_result, hash_with_pagination_informations]

class PeacefulPaginate

  module ActiveRecord
    def self.included(base)
      base.extend ClassMethods
    end

    module ClassMethods
      def peaceful_paginate(options)
        ::PeacefulPaginate.paginate(self,options)
      end
      
      unless defined?(WillPaginate)
        def paginate(options)
          ::PeacefulPaginate.paginate(self,options)
        end
      end
    end
  end

  module OverrideWillPaginate
    def self.included(base)
      base.extend ClassMethods
    end

    module ClassMethods
      def paginate(options)
        ::PeacefulPaginate.paginate(self,options)
      end
    end
  end

  class_eval do
    unless defined? @@will_paginate_compatible_mode
      @@will_paginate_compatible_mode = false
    end
    
    def self.will_paginate_compatible_mode
      @@will_paginate_compatible_mode
    end
    
    def self.will_paginate_compatible_mode=(value)
      @@will_paginate_compatible_mode = value
    end
  end
  
  def self.paginate(object, options = {})
    page      = options[:page] || 1
    per_page  = options[:per_page] || 30
    count     = options[:total_entries] || options[:count]

    if object.superclass == ActiveRecord::Base or object.is_a?(ActiveRecord::Relation)
      
      scoped_object = object.scoped
      
      if will_paginate_compatible_mode
        scopes = options.except :page, :per_page, :total_entries, :count, :finder

        if includes = scopes.delete(:include)
          scoped_object = scoped_object.includes(includes)
        end

        scopes.each_pair do |scope,params|
          scoped_object.send(scope, params)
        end
      end
      
      paged_result = scoped_object.limit(per_page).offset((page.to_i - 1) * per_page.to_i).all
      total_results_count = scoped_object.count
      
      if will_paginate_compatible_mode
        result = WillPaginate::Collection.create(page, per_page) do |pager|
          pager.replace(paged_result)
          pager.total_entries = total_results
        end
      else
        result = [paged_result, {:per_page => per_page, :page => page, :count => total_results_count}]
      end
      
    elsif object.is_a?(Array)
      
      if will_paginate_compatible_mode
        result = object.paginate(:per_page => per_page,:page => page)
      else
        from = (page.to_i - 1) * per_page.to_i
        to = from + per_page.to_i - 1
        result = [object[from..to], {:per_page => per_page, :page => page, :count => object.length}]
      end
      
    else
      raise "Invalid object for pagination"
    end

    return result
  end

  def self.use_for_active_record!
    if defined? ::ActiveRecord
      ::ActiveRecord::Relation.class_eval do
        include PeacefulPaginate::ActiveRecord
      end
      ::ActiveRecord::Base.class_eval do 
        include PeacefulPaginate::ActiveRecord
      end
      true
    else
      false
    end
  end

  def self.use_compatible_mod_with_will_paginate!
    if defined? ::ActiveRecord and defined? WillPaginate
      will_paginate_compatible_mode = true
      
      ::ActiveRecord::Relation.class_eval do
        include PeacefulPaginate::OverrideWillPaginate
      end
      ::ActiveRecord::Base.class_eval do 
        include PeacefulPaginate::OverrideWillPaginate
      end
      true
    else
      false
    end
  end
end