Integrate workbook views and alter serialization

This integrates workbook views and sheet state into serialization.

I also noticed that we were populating defined names during
serialization. While it is good to delay this as late as possible
as there is always the chance that some conditional programming
by the consumer adds, and then removes an autofilter, I am
choosing to risk it at this point for cleaner code.

2 files changed, 44 insertions, 11 deletions

diff --git a/lib/axlsx/workbook/workbook.rb b/lib/axlsx/workbook/workbook.rb
index 0f70f37f..edd1d0d7 100644
--- a/lib/axlsx/workbook/workbook.rb
+++ b/lib/axlsx/workbook/workbook.rb
@@ -37,7 +37,8 @@ require 'axlsx/workbook/worksheet/worksheet_hyperlinks'
 require 'axlsx/workbook/worksheet/break'
 require 'axlsx/workbook/worksheet/row_breaks'
 require 'axlsx/workbook/worksheet/col_breaks'
-
+require 'axlsx/workbook/workbook_view'
+require 'axlsx/workbook/workbook_views'
 
 
 require 'axlsx/workbook/worksheet/worksheet.rb'
@@ -139,6 +140,10 @@ require 'axlsx/workbook/worksheet/selection.rb'
     # @return [SimpleTypedList]
     attr_reader :pivot_tables
 
+    # A collection of views for this workbook
+    def views
+      @views ||= WorkbookViews.new
+    end
 
     # A collection of defined names for this workbook
     # @note The recommended way to manage defined names is Workbook#add_defined_name
@@ -263,6 +268,10 @@ require 'axlsx/workbook/worksheet/selection.rb'
       worksheet
     end
 
+    def add_view(options={})
+      views << WorkbookView.new(options)
+    end
+
     # Adds a defined name to this workbook
     # @return [DefinedName]
     # @param [String] formula @see DefinedName
@@ -327,17 +336,13 @@ require 'axlsx/workbook/worksheet/selection.rb'
     # @param [String] str
     # @return [String]
     def to_xml_string(str='')
-      add_worksheet unless worksheets.size > 0
+      add_worksheet(name: 'Sheet1') unless worksheets.size > 0
       str << '<?xml version="1.0" encoding="UTF-8"?>'
       str << '<workbook xmlns="' << XML_NS << '" xmlns:r="' << XML_NS_R << '">'
       str << '<workbookPr date1904="' << @@date1904.to_s << '"/>'
+      views.to_xml_string(str)
       str << '<sheets>'
-      @worksheets.each_with_index do |sheet, index|
-        str << '<sheet name="' << sheet.name << '" sheetId="' << (index+1).to_s << '" r:id="' << sheet.rId << '"/>'
-        if defined_name = sheet.auto_filter.defined_name
-          add_defined_name defined_name, :name => '_xlnm._FilterDatabase', :local_sheet_id => index, :hidden => 1
-        end
-      end
+      worksheets.each { |sheet| sheet.to_sheet_node_xml_string(str) }
       str << '</sheets>'
       defined_names.to_xml_string(str)
       unless pivot_tables.empty?
diff --git a/lib/axlsx/workbook/worksheet/worksheet.rb b/lib/axlsx/workbook/worksheet/worksheet.rb
index 9937a3f4..2dd5e3af 100644
--- a/lib/axlsx/workbook/worksheet/worksheet.rb
+++ b/lib/axlsx/workbook/worksheet/worksheet.rb
@@ -4,7 +4,7 @@ module Axlsx
   # The Worksheet class represents a worksheet in the workbook.
   class Worksheet
     include Axlsx::OptionsParser
-
+    include Axlsx::SerializedAttributes
     # definition of characters which are less than the maximum width of 0-9 in the default font for use in String#count.
     # This is used for autowidth calculations
     # @return [String]
@@ -24,12 +24,15 @@ module Axlsx
     def initialize(wb, options={})
       self.workbook = wb
       @sheet_protection = nil
-
       initialize_page_options(options)
       parse_options options
       @workbook.worksheets << self
+      @sheet_id = index + 1
+      yield self if block_given?
     end
 
+    serializable_attributes :sheet_id, :name, :state
+
     # Initalizes page margin, setup and print options
     # @param [Hash] options Options passed in from the initializer
     def initialize_page_options(options)
@@ -47,6 +50,22 @@ module Axlsx
       @name ||=  "Sheet" + (index+1).to_s
     end
 
+    # Specifies the visible state of this sheet. Allowed states are
+    # :visible, :hidden or :very_hidden. The default value is :visible.
+    #
+    # Worksheets in the :hidden state can be shown using the sheet formatting properties in excel.
+    # :very_hidden sheets should be inaccessible to end users.
+    # @param [Symbol] sheet_state The visible state for this sheet.
+    def state=(sheet_state)
+      RestrictionValidator.validate "Worksheet#state", [:visible, :hidden, :very_hidden], sheet_state
+      @state = sheet_state
+    end
+
+    # The visibility of this sheet
+    def state
+      @state ||= :visible
+    end
+
     # The sheet calculation properties
     # @return [SheetCalcPr]
     def sheet_calc_pr
@@ -142,7 +161,7 @@ module Axlsx
       @rows.transpose(&block)
     end
 
-    # An range that excel will apply an auto-filter to "A1:B3"
+    # A range that excel will apply an auto-filter to "A1:B3"
     # This will turn filtering on for the cells in the range.
     # The first row is considered the header, while subsequent rows are considered to be data.
     # @return String
@@ -348,6 +367,7 @@ module Axlsx
     def auto_filter=(v)
       DataTypeValidator.validate "Worksheet.auto_filter", String, v
       auto_filter.range = v
+      workbook.add_defined_name auto_filter.defined_name, name: '_xlnm.FilterDatabase', local_sheet_id: index, hidden: 1
     end
 
     # Accessor for controlling whether leading and trailing spaces in cells are
@@ -577,6 +597,14 @@ module Axlsx
       cells.each { |cell| cell.style = style }
     end
 
+    # Returns a sheet node serialization for this sheet in the workbook.
+    def to_sheet_node_xml_string(str='')
+      str << '<sheet '
+      serialized_attributes str
+      str << "r:id='" << rId << "'"
+      str << '></sheet>'
+    end
+
     # Serializes the worksheet object to an xml string
     # This intentionally does not use nokogiri for performance reasons
     # @return [String]