module JdbcSpec
  module MsSQL
    def self.column_selector
      [/sqlserver|tds/i, lambda {|cfg,col| col.extend(::JdbcSpec::MsSQL::Column)}]
    end

    def self.adapter_selector
      [/sqlserver|tds/i, lambda {|cfg,adapt| adapt.extend(::JdbcSpec::MsSQL)}]
    end
    
    module Column
      attr_accessor :identity, :is_special
      
      def simplified_type(field_type)
        case field_type
          when /int|bigint|smallint|tinyint/i                        then :integer
          when /float|double|decimal|money|numeric|real|smallmoney/i then @scale == 0 ? :integer : :decimal
          when /datetime|smalldatetime/i                             then :datetime
          when /timestamp/i                                          then :timestamp
          when /time/i                                               then :time
          when /text|ntext/i                                         then :text
          when /binary|image|varbinary/i                             then :binary
          when /char|nchar|nvarchar|string|varchar/i                 then :string
          when /bit/i                                                then :boolean
          when /uniqueidentifier/i                                   then :string
        end
      end

      def type_cast(value)
        return nil if value.nil? || value == "(NULL)"
        case type
        when :string then unquote value
        when :integer then unquote(value).to_i rescue value ? 1 : 0
        when :primary_key then value == true || value == false ? value == true ? 1 : 0 : value.to_i 
        when :decimal   then self.class.value_to_decimal(value)
        when :datetime  then cast_to_datetime(value)
        when :timestamp then cast_to_time(value)
        when :time      then cast_to_time(value)
        when :date      then cast_to_datetime(value)
        when :boolean   then value == true or (value =~ /^t(rue)?$/i) == 0 or unquote(value)=="1"
        when :binary    then unquote value
        else value
        end
      end
      
      def unquote(value)
        value.to_s.sub(/^\([\(\']?/, "").sub(/[\'\)]?\)$/, "")
      end
      
      def cast_to_time(value)
        return value if value.is_a?(Time)
        time_array = ParseDate.parsedate(value)
        time_array[0] ||= 2000
        time_array[1] ||= 1
        time_array[2] ||= 1
        Time.send(ActiveRecord::Base.default_timezone, *time_array) rescue nil
      end

      def cast_to_datetime(value)
        if value.is_a?(Time)
          if value.year != 0 and value.month != 0 and value.day != 0
            return value
          else
            return Time.mktime(2000, 1, 1, value.hour, value.min, value.sec) rescue nil
          end
        end
        return cast_to_time(value) if value.is_a?(Date) or value.is_a?(String) rescue nil
        value
      end

      # These methods will only allow the adapter to insert binary data with a length of 7K or less
      # because of a SQL Server statement length policy.
      def self.string_to_binary(value)
        value.gsub(/(\r|\n|\0|\x1a)/) do
          case $1
            when "\r"   then  "%00"
            when "\n"   then  "%01"
            when "\0"   then  "%02"
            when "\x1a" then  "%03"
          end
        end
      end

      def self.binary_to_string(value)
        value.gsub(/(%00|%01|%02|%03)/) do
          case $1
            when "%00"    then  "\r"
            when "%01"    then  "\n"
            when "%02\0"  then  "\0"
            when "%03"    then  "\x1a"
          end
        end
      end
    end
    
    def modify_types(tp)
      tp[:primary_key] = "int NOT NULL IDENTITY(1, 1) PRIMARY KEY"
      tp[:integer][:limit] = nil
      tp[:boolean][:limit] = nil
      tp[:binary] = { :name => "image"}
      tp
    end
    
    def quote(value, column = nil)
      return value.quoted_id if value.respond_to?(:quoted_id)

      case value
        when TrueClass             then '1'
        when FalseClass            then '0'
        when Time, DateTime        then "'#{value.strftime("%Y%m%d %H:%M:%S")}'"
        when Date                  then "'#{value.strftime("%Y%m%d")}'"
        else                       super
      end
    end

      def quote_string(string)
        string.gsub(/\'/, "''")
      end

      def quote_column_name(name)
        "[#{name}]"
      end
      
        def add_limit_offset!(sql, options)
          if options[:limit] and options[:offset]
            total_rows = select_all("SELECT count(*) as TotalRows from (#{sql.gsub(/\bSELECT(\s+DISTINCT)?\b/i, "SELECT#{$1} TOP 1000000000")}) tally")[0][:TotalRows].to_i

            sql.sub!(/^\s*SELECT(\s+DISTINCT)?/i, "SELECT * FROM (SELECT TOP #{options[:limit]} * FROM (SELECT#{$1} TOP #{options[:limit] + options[:offset]} ")
            sql << ") AS tmp1"
            if options[:order]
              options[:order] = options[:order].split(',').map do |field|
                parts = field.split(" ")
                tc = parts[0]
                if sql =~ /\.\[/ and tc =~ /\./ # if column quoting used in query
                  tc.gsub!(/\./, '\\.\\[')
                  tc << '\\]'
                end
                if sql =~ /#{tc} AS (t\d_r\d\d?)/
                  parts[0] = $1
                elsif parts[0] =~ /\w+\.(\w+)/
                  parts[0] = $1
                end
                parts.join(' ')
              end.join(', ')
              sql << " ORDER BY #{change_order_direction(options[:order])}) AS tmp2 ORDER BY #{options[:order]}"
            else
              sql << " ) AS tmp2"
            end
          elsif sql !~ /^\s*SELECT (@@|COUNT\()/i
            sql.sub!(/^\s*SELECT(\s+DISTINCT)?/i) do
              "SELECT#{$1} TOP #{options[:limit]}"
            end unless options[:limit].nil?
          end
        end
    
      
          def change_order_direction(order)
            order.split(",").collect {|fragment|
              case fragment
                when  /\bDESC\b/i     then fragment.gsub(/\bDESC\b/i, "ASC")
                when  /\bASC\b/i      then fragment.gsub(/\bASC\b/i, "DESC")
                else                  String.new(fragment).split(',').join(' DESC,') + ' DESC'
              end
            }.join(",")
          end
      
    def recreate_database(name)
      drop_database(name)
      create_database(name)
    end
    
    def drop_database(name)
      execute "DROP DATABASE #{name}"
    end

    def create_database(name)
      execute "CREATE DATABASE #{name}"
    end

      def rename_table(name, new_name)
        execute "EXEC sp_rename '#{name}', '#{new_name}'"
      end
      
      def rename_column(table, column, new_column_name)
        execute "EXEC sp_rename '#{table}.#{column}', '#{new_column_name}'"
      end
      
      def change_column(table_name, column_name, type, options = {}) #:nodoc:
        sql_commands = ["ALTER TABLE #{table_name} ALTER COLUMN #{column_name} #{type_to_sql(type, options[:limit])}"]
        if options_include_default?(options)
          remove_default_constraint(table_name, column_name)
          sql_commands << "ALTER TABLE #{table_name} ADD CONSTRAINT DF_#{table_name}_#{column_name} DEFAULT #{quote(options[:default], options[:column])} FOR #{column_name}"
        end
        sql_commands.each {|c|
          execute(c)
        }
      end
      def change_column_default(table_name, column_name, default) #:nodoc:
        execute "ALTER TABLE #{table_name} ADD CONSTRAINT DF_#{table_name}_#{column_name} DEFAULT #{quote(default, column_name)} FOR #{column_name}"
      end
      def remove_column(table_name, column_name)
        remove_default_constraint(table_name, column_name)
        execute "ALTER TABLE #{table_name} DROP COLUMN #{column_name}"
      end
      
      def remove_default_constraint(table_name, column_name)
        defaults = select "select def.name from sysobjects def, syscolumns col, sysobjects tab where col.cdefault = def.id and col.name = '#{column_name}' and tab.name = '#{table_name}' and col.id = tab.id"
        defaults.each {|constraint|
          execute "ALTER TABLE #{table_name} DROP CONSTRAINT #{constraint["name"]}"
        }
      end
      
      def remove_index(table_name, options = {})
        execute "DROP INDEX #{table_name}.#{index_name(table_name, options)}"
      end
      

      def columns(table_name, name = nil)
        cc = super
        cc.each do |col|
          col.identity = true if col.sql_type =~ /identity/i
          col.is_special = true if col.sql_type =~ /text|ntext|image/i
        end
        cc
      end
      
      def _execute(sql, name = nil)
        if sql.lstrip =~ /^insert/i
         if query_requires_identity_insert?(sql)
            table_name = get_table_name(sql)
            with_identity_insert_enabled(table_name) do 
            id = @connection.execute_insert(sql)
        end
         else
            @connection.execute_insert(sql)
         end
      elsif sql.lstrip =~ /^\(?\s*(select|show)/i
      @connection.execute_query(sql)
      else
      @connection.execute_update(sql)
      end
    end
      
      
      private
      # Turns IDENTITY_INSERT ON for table during execution of the block
      # N.B. This sets the state of IDENTITY_INSERT to OFF after the
      # block has been executed without regard to its previous state

      def with_identity_insert_enabled(table_name, &block)
        set_identity_insert(table_name, true)
        yield
      ensure
        set_identity_insert(table_name, false)  
      end
      
      def set_identity_insert(table_name, enable = true)
        execute "SET IDENTITY_INSERT #{table_name} #{enable ? 'ON' : 'OFF'}"
      rescue Exception => e
        raise ActiveRecordError, "IDENTITY_INSERT could not be turned #{enable ? 'ON' : 'OFF'} for table #{table_name}"  
      end

      def get_table_name(sql)
        if sql =~ /^\s*insert\s+into\s+([^\(\s]+)\s*|^\s*update\s+([^\(\s]+)\s*/i
          $1
        elsif sql =~ /from\s+([^\(\s]+)\s*/i
          $1
        else
          nil
        end
      end

      def identity_column(table_name)
        @table_columns = {} unless @table_columns
        @table_columns[table_name] = columns(table_name) if @table_columns[table_name] == nil
        @table_columns[table_name].each do |col|
          return col.name if col.identity
        end

        return nil
      end

      def query_requires_identity_insert?(sql)
        table_name = get_table_name(sql)
        id_column = identity_column(table_name)
        sql =~ /\[#{id_column}\]/ ? table_name : nil
      end
  end
end