require 'fileutils'
require 'nokogiri'
require 'securerandom'
require 'time'

module ExpandSync
  # TextExpander Class
  class TextExpander
    # The output filename
    OUTPUT_FILENAME = 'Settings.textexpander'
  
    # The output filepath
    OUTPUT_PATH = File.join(ENV['HOME'], 'Dropbox', 'TextExpander')

    # Stores the initial XML as pulled from Settings.textexpander.
    # @return [Nokogiri::XML::Document] 
    attr_accessor :base_xml

    # Stores the full output path for the produced XML.
    # @return [String]
    attr_accessor :output_file

    # Stores the final XML to save.
    # @return [Nokogiri::XML::Document]
    attr_accessor :snippet_xml

    # Stores an array of snippets.
    # @return [Array]
    attr_accessor :snippets

    # Initialize by loading snippets from TextExpander.
    # @return [void]
    def initialize
      begin
        xpath = "/*/*/array[preceding-sibling::key[1] = 'snippetsTE2']/*"
        @output_file = File.join(OUTPUT_PATH, OUTPUT_FILENAME)
        @base_xml = Nokogiri::XML(File.open(@output_file))
        @snippet_xml = @base_xml

        arr = []
        @base_xml.xpath(xpath).each do |snippet|
          abbreviation = snippet.xpath("string[preceding-sibling::key[1] = 'abbreviation']").text
          value = snippet.xpath("string[preceding-sibling::key[1] = 'plainText']").text
          arr << [abbreviation, value, 'TextExpander'] 
        end
        @snippets = arr
      rescue 
        fail "Invalid TextExpander XML file: #{ @output_file }"
      end
    end

    # Backs up the current TextExpander settings to a
    # timestamped file in the same directory.
    # @return [String]
    def backup
      FileUtils.cp(@output_file, @output_file + "_#{ Time.now.utc.iso8601 }")
    end

    # Modifies the currently held XML data with new snippet
    # information.
    # @param [Array] new_snippets The snippet array to use
    # @return [void]
    def construct_data(new_snippets)
      snippet_uuids = _add_snippets_to_base_xml(new_snippets)
      _add_group_to_base_xml(snippet_uuids)
    end

    # Saves the current snippets to Settings.textexpander.
    # @return [void]
    def save
      File.open(@output_file, 'w') {|f| f.write(@snippet_xml) }
    end

    private
  
    # Creates correct group information for the provided
    # snippets.
    # @param [Array] snippets An array of snippet UUIDs
    # @return [void]
    def _add_group_to_base_xml(snippet_uuids)
      groups_xpath = "/*/*/array[preceding-sibling::key[1] = 'groupsTE2']"
      at_group_xpath = groups_xpath + "/*[string[preceding-sibling::key[1] = 'name'] = 'aText']"
    
      if @snippet_xml.xpath(at_group_xpath).empty?
        xml_builder = Nokogiri::XML::Builder.new do |xml|
          xml.dict {
            xml.key 'expandAfterMode'
            xml.integer '0'
            xml.key 'expanderExceptionsMode'
            xml.integer '4'
            xml.key 'name'
            xml.string 'aText'
            xml.key 'snippetUUIDs'
            xml.array {
              snippet_uuids.each do |u| 
                xml.string u
              end
            }
            xml.key 'suggestAbbreviations'
            xml.integer '1'
            xml.key 'updateFrequency'
            xml.integer '0'
            xml.key 'uuidString'
            xml.string SecureRandom.uuid.upcase
            xml.key 'writable'
            xml.integer '1'
          }
        end
        @snippet_xml.xpath(groups_xpath)[0].add_child(xml_builder.doc.root.to_xml)
      else
        xml_builder = Nokogiri::XML::Builder.new do |xml|
          xml.array {
            snippet_uuids.each do |uuid| 
              xml.string uuid
            end
          }
        end
      
        @snippet_xml.xpath(at_group_xpath + "/array[preceding-sibling::key[1] = 'snippetUUIDs']")[0].add_child(xml_builder.doc.root.children.to_xml)
      end
    end
  
    # Inserts XML for the provided snippets to the base XML
    # @param [Array] snippets An array of snippets to add and returns an array of snippet UUIDs
    # @return [void]
    def _add_snippets_to_base_xml(snippets)
      uuids = []

      xml_builder = Nokogiri::XML::Builder.new do |xml|
        xml.snippets {
          snippets.each do |s|
            uuid = SecureRandom.uuid.upcase
            uuids << uuid
          
            xml.dict {
              xml.key 'abbreviation'
              xml.string s[0]
              xml.key 'abbreviationMode'
              xml.integer '0'
              xml.key 'creationDate'
              xml.date Time.now.utc.iso8601
              xml.key 'flags'
              xml.integer '0'
              xml.key 'label'
              xml.string
              xml.key 'modificationDate'
              xml.date Time.now.utc.iso8601
              xml.key 'plainText'
              xml.string s[1]
              xml.key 'snippetType'
              xml.integer '0'
              xml.key 'useCount'
              xml.integer '0'
              xml.key 'uuidString'
              xml.string uuid
            }
          end
        }
      end
    
      @snippet_xml.xpath("/*/*/array[preceding-sibling::key[1] = 'snippetsTE2']")[0].add_child(xml_builder.doc.root.children.to_xml)
      uuids
    end
  end
end