require File.join(File.dirname(__FILE__), '..', 'test_helper.rb')

class PageCollectionTest < Test::Unit::TestCase
  include SimplePagination
  
  context "creating a new instance" do
    should "require :current_offset or :current_page" do
      args = {:page_size => 10, :total_records => 100}
      assert_raise(ArgumentError) {PageCollection.new(args)}
      assert_nothing_raised {PageCollection.new(args.merge(:current_offset => 0))}
      assert_nothing_raised {PageCollection.new(args.merge(:current_page => 1))}
    end
    
    should "require :total_records or :total_pages" do
      args = {:page_size => 10, :current_page => 1}
      assert_raise(ArgumentError) {PageCollection.new(args)}
      assert_nothing_raised {PageCollection.new(args.merge(:total_pages => 10))}
      assert_nothing_raised {PageCollection.new(args.merge(:total_records => 10))}
    end
    
    should "require :page_size" do
      args = {:total_records => 100, :current_offset => 0}
      assert_raise(ArgumentError) {PageCollection.new(args)}
      assert_nothing_raised {PageCollection.new(args.merge(:page_size => 10))}
    end
  end
  
  context "page_size" do
    should "provide page_size accessor" do
      @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_offset => 0)
      assert_equal 10, @collection.page_size
    end
  end
  
  context "length" do
    context "when given total_pages" do
      should "be equal to total_pages" do
        @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_offset => 0)
        assert_equal 10, @collection.length
      end
    end
    
    context "when given total_records" do
      should "be zero when total_records is zero" do
        @collection = PageCollection.new(:total_records => 0, :page_size => 10, :current_offset => 0)
        assert_equal 0, @collection.length
      end

      should "be one if total_records is less than page_size results" do
        @collection = PageCollection.new(:total_records => 5, :page_size => 10, :current_offset => 0)
        assert_equal 1, @collection.length
      end

      should "be ceil(total_records / page_size)" do
        @collection = PageCollection.new(:total_records => 21, :page_size => 10, :current_offset => 0)
        assert_equal 3, @collection.length
      end
    end
  end
  
  context "accessing a numbered page" do
    setup do
      @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_page=>1)
    end

    should "create and return a new Page instance" do
      p = Page.new(1, @collection)
      Page.expects(:new).with(1, @collection).returns(p)
      assert_same p, @collection[1]
    end
    
    should "return the same Page across multiple invocations" do
      assert_same @collection[3], @collection[3]
      assert_not_same @collection[3], @collection[4]
    end
    
    context "when the page is out of bounds" do
      should "return nil" do
        assert_equal nil, @collection[100]
        assert_equal nil, @collection[0]
        assert_equal nil, @collection[-1]
      end
    end
  end
  
  context "current page" do
    context "when given current_page" do
      should "provide page with index == current_page" do
        @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_page => 3)
        @collection.expects(:[]).with(3)
        @collection.current
      end
    end
    
    context "when given current_offset" do
      should "provide page 1 if current_offset is zero" do
        @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_offset => 0)
        @collection.expects(:[]).with(1)
        @collection.current
      end
      
      should "provide page with index == floor(current_offset / page_size) + 1" do
        @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_offset => 21)
        @collection.expects(:[]).with(3)
        @collection.current
      end
    end
  end
  
  context "first page" do
    should "provide page 1" do
      @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_page => 5)
      @collection.expects(:[]).with(1)
      @collection.first
    end
  end
  
  context "last page" do
    # this is not an exhaustive test but I shouldn't need to make it so since
    # the tests for length above do this...
    
    should "provide page with index == length" do
      @collection = PageCollection.new(:total_pages => 10, :page_size => 10, :current_page => 5)
      @collection.expects(:[]).with(10)
      @collection.last
      
      @collection = PageCollection.new(:total_records => 21, :page_size => 10, :current_offset => 0)
      @collection.expects(:[]).with(3)
      @collection.last
    end
  end
end