require 'active_record/connection_adapters/abstract_adapter'

# sqlserver_adapter.rb -- ActiveRecord adapter for Microsoft SQL Server
#
# Author: Joey Gibson <joey@joeygibson.com>
# Date:   10/14/2004
#
# Modifications: DeLynn Berry <delynnb@megastarfinancial.com>
# Date: 3/22/2005
#
# Modifications (ODBC): Mark Imbriaco <mark.imbriaco@pobox.com>
# Date: 6/26/2005
#
module ActiveRecord
  class Base
    def self.sqlserver_connection(config) #:nodoc:
      require_library_or_gem 'dbi' unless self.class.const_defined?(:DBI)
      
      symbolize_strings_in_hash(config)

      mode        = config[:mode] ? config[:mode].to_s.upcase : 'ADO'
      username    = config[:username] ? config[:username].to_s : 'sa'
      password    = config[:password] ? config[:password].to_s : ''
      if mode == "ODBC"
        raise ArgumentError, "Missing DSN. Argument ':dsn' must be set in order for this adapter to work." unless config.has_key?(:dsn)
        dsn       = config[:dsn]
        conn      = DBI.connect("DBI:ODBC:#{dsn}", username, password)
      else
        raise ArgumentError, "Missing Database. Argument ':database' must be set in order for this adapter to work." unless config.has_key?(:database)
        database  = config[:database]
        host      = config[:host] ? config[:host].to_s : 'localhost'
        conn      = DBI.connect("DBI:ADO:Provider=SQLOLEDB;Data Source=#{host};Initial Catalog=#{database};User Id=#{username};Password=#{password};")
      end

      conn["AutoCommit"] = true
      ConnectionAdapters::SQLServerAdapter.new(conn, logger)
    end
  end # class Base

  module ConnectionAdapters
    class ColumnWithIdentity < Column# :nodoc:
      attr_reader :identity, :is_special, :scale

      def initialize(name, default, sql_type = nil, is_identity = false, scale_value = 0)
        super(name, default, sql_type)
        @identity = is_identity
        @is_special = sql_type =~ /text|ntext|image/i ? true : false
        @scale = scale_value
      end

      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 : :float
          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
        end
      end

      def type_cast(value)
        return nil if value.nil? || value =~ /^\s*null\s*$/i
        case type
        when :string    then value
        when :integer   then value == true || value == false ? value == true ? '1' : '0' : value.to_i
        when :float     then value.to_f
        when :datetime  then cast_to_datetime(value)
        when :timestamp then cast_to_time(value)
        when :time      then cast_to_time(value)
        else value
        end
      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(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 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 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

    # In ADO mode, this adapter will ONLY work on Windows systems, 
    # since it relies on Win32OLE, which, to my knowledge, is only 
    # available on Windows.
    #
    # This mode also relies on the ADO support in the DBI module. If you are using the
    # one-click installer of Ruby, then you already have DBI installed, but
    # the ADO module is *NOT* installed. You will need to get the latest
    # source distribution of Ruby-DBI from http://ruby-dbi.sourceforge.net/
    # unzip it, and copy the file 
    # <tt>src/lib/dbd_ado/ADO.rb</tt> 
    # to
    # <tt>X:/Ruby/lib/ruby/site_ruby/1.8/DBD/ADO/ADO.rb</tt> 
    # (you will more than likely need to create the ADO directory).
    # Once you've installed that file, you are ready to go.
    #
    # In ODBC mode, the adapter requires the ODBC support in the DBI module which requires
    # the Ruby ODBC module.  Ruby ODBC 0.996 was used in development and testing,
    # and it is available at http://www.ch-werner.de/rubyodbc/
    #
    # Options:
    #
    # * <tt>:mode</tt>      -- ADO or ODBC. Defaults to ADO.
    # * <tt>:username</tt>  -- Defaults to sa.
    # * <tt>:password</tt>  -- Defaults to empty string.
    #
    # ADO specific options:
    #
    # * <tt>:host</tt>      -- Defaults to localhost.
    # * <tt>:database</tt>  -- The name of the database. No default, must be provided.
    #
    # ODBC specific options:                   
    #
    # * <tt>:dsn</tt>       -- Defaults to nothing.
    #
    # ADO code tested on Windows 2000 and higher systems,
    # running ruby 1.8.2 (2004-07-29) [i386-mswin32], and SQL Server 2000 SP3.
    #
    # ODBC code tested on a Fedora Core 4 system, running FreeTDS 0.63, 
    # unixODBC 2.2.11, Ruby ODBC 0.996, Ruby DBI 0.0.23 and Ruby 1.8.2.
    # [Linux strongmad 2.6.11-1.1369_FC4 #1 Thu Jun 2 22:55:56 EDT 2005 i686 i686 i386 GNU/Linux]
    class SQLServerAdapter < AbstractAdapter
      def native_database_types
        {
          :primary_key => "int NOT NULL IDENTITY(1, 1) PRIMARY KEY",
          :string      => { :name => "varchar(255)" },
          :text        => { :name => "text(16)" },
          :integer     => { :name => "int(4)", :limit => 11 },
          :float       => { :name => "float(8)" },
          :datetime    => { :name => "datetime(8)" },
          :timestamp   => { :name => "datetime(8)" },
          :time        => { :name => "datetime(8)" },
          :date        => { :name => "datetime(8)" },
          :binary      => { :name => "image(16)" },
          :boolean     => { :name => "bit(1)" }
        }
      end

      def adapter_name
        'SQLServer'
      end

      def select_all(sql, name = nil)
        select(sql, name)
      end

      def select_one(sql, name = nil)
        add_limit!(sql, nil)
        result = select(sql, name)
        result.nil? ? nil : result.first
      end

      def columns(table_name, name = nil)
        sql = "SELECT COLUMN_NAME as ColName, COLUMN_DEFAULT as DefaultValue, DATA_TYPE as ColType, COL_LENGTH('#{table_name}', COLUMN_NAME) as Length, COLUMNPROPERTY(OBJECT_ID('#{table_name}'), COLUMN_NAME, 'IsIdentity') as IsIdentity, NUMERIC_SCALE as Scale FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '#{table_name}'"
        # Comment out if you want to have the Columns select statment logged.
        # Personnally, I think it adds unneccessary bloat to the log. 
        # If you do comment it out, make sure to un-comment the "result" line that follows
        result = log(sql, name) { @connection.select_all(sql) }
        #result = @connection.select_all(sql)
        columns = []
        result.each { |field| columns << ColumnWithIdentity.new(field[:ColName], field[:DefaultValue].to_s.gsub!(/[()\']/,"") =~ /null/ ? nil : field[:DefaultValue], "#{field[:ColType]}(#{field[:Length]})", field[:IsIdentity] == 1 ? true : false, field[:Scale]) }
        columns
      end

      def insert(sql, name = nil, pk = nil, id_value = nil)
        begin
          table_name = get_table_name(sql)
          col = get_identity_column(table_name)
          ii_enabled = false

          if col != nil
            if query_contains_identity_column(sql, col)
              begin
                execute enable_identity_insert(table_name, true)
                ii_enabled = true
              rescue Exception => e
                raise ActiveRecordError, "IDENTITY_INSERT could not be turned ON"
              end
            end
          end
          log(sql, name) do
            @connection.execute(sql)
            select_one("SELECT @@IDENTITY AS Ident")["Ident"]
          end
        ensure
          if ii_enabled
            begin
              execute enable_identity_insert(table_name, false)
            rescue Exception => e
              raise ActiveRecordError, "IDENTITY_INSERT could not be turned OFF"
            end
          end
        end
      end

      def execute(sql, name = nil)
        if sql =~ /^INSERT/i
          insert(sql, name)
        elsif sql =~ /^UPDATE|DELETE/i
          log(sql, name) do
            @connection.execute(sql)
            retVal = select_one("SELECT @@ROWCOUNT AS AffectedRows")["AffectedRows"]
          end
        else
          log(sql, name) { @connection.execute(sql) }
        end
      end

      def update(sql, name = nil)
        execute(sql, name)
      end
      alias_method :delete, :update

      def begin_db_transaction
        @connection["AutoCommit"] = false
      rescue Exception => e
        @connection["AutoCommit"] = true
      end

      def commit_db_transaction
        @connection.commit
      ensure
        @connection["AutoCommit"] = true
      end

      def rollback_db_transaction
        @connection.rollback
      ensure
        @connection["AutoCommit"] = true
      end

      def quote(value, column = nil)
        case value
          when String                
            if column && column.type == :binary
              "'#{quote_string(column.string_to_binary(value))}'"
            else
              "'#{quote_string(value)}'"
            end
          when NilClass              then "NULL"
          when TrueClass             then '1'
          when FalseClass            then '0'
          when Float, Fixnum, Bignum then value.to_s
          when Date                  then "'#{value.to_s}'" 
          when Time, DateTime        then "'#{value.strftime("%Y-%m-%d %H:%M:%S")}'"
          else                            "'#{quote_string(value.to_yaml)}'"
        end
      end

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

      def quote_column_name(name)
        "[#{name}]"
      end

      def add_limit_offset!(sql, options)
        if options.has_key?(:limit) and options.has_key?(:offset) and !options[:limit].nil? and !options[:offset].nil?
          options[:order] ||= "id ASC"
          total_rows = @connection.select_all("SELECT count(*) as TotalRows from #{get_table_name(sql)}")[0][:TotalRows].to_i
          if (options[:limit] + options[:offset]) > total_rows
            options[:limit] = (total_rows - options[:offset] > 0) ? (total_rows - options[:offset]) : 1
          end
          sql.gsub!(/SELECT/i, "SELECT * FROM ( SELECT TOP #{options[:limit]} * FROM ( SELECT TOP #{options[:limit] + options[:offset]}")<<" ) AS tmp1 ORDER BY #{change_order_direction(options[:order])} ) AS tmp2 ORDER BY #{options[:order]}"
        else
          sql.gsub!(/SELECT/i, "SELECT TOP #{options[:limit]}") unless options[:limit].nil?
        end
      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

      private
        def select(sql, name = nil)
          rows = []
          repair_special_columns(sql)
          log(sql, name) do
            @connection.select_all(sql) do |row|
              record = {}
              row.column_names.each do |col|
                record[col] = row[col]
              end
              rows << record
            end
          end
          rows
        end

        def enable_identity_insert(table_name, enable = true)
          if has_identity_column(table_name)
            "SET IDENTITY_INSERT #{table_name} #{enable ? 'ON' : 'OFF'}"
          end
        end

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

        def has_identity_column(table_name)
          !get_identity_column(table_name).nil?
        end

        def get_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_contains_identity_column(sql, col)
          sql =~ /\[#{col}\]/
        end

        def change_order_direction(order)
          case order
            when  /DESC/i     then order.gsub(/DESC/i, "ASC")
            when  /ASC/i      then order.gsub(/ASC/i, "DESC")
            else                   String.new(order).insert(-1, " DESC")
          end
        end

        def get_special_columns(table_name)
          special = []
          @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|
            special << col.name if col.is_special
          end
          special
        end

        def repair_special_columns(sql)
          special_cols = get_special_columns(get_table_name(sql))
          for col in special_cols.to_a
            sql.gsub!(Regexp.new(" #{col.to_s} = "), " #{col.to_s} LIKE ")
          end
          sql
        end

    end #class SQLServerAdapter < AbstractAdapter
  end #module ConnectionAdapters
end #module ActiveRecord