module ::ActiveRecord
  class Base
    after_save :write_lobs

  private
    def write_lobs
      if connection.is_a?(ArJdbc::Informix)
        self.class.columns.each do |c|
          if [:text, :binary].include? c.type
            value = self[c.name]
            value = value.to_yaml if unserializable_attribute?(c.name, c)

            unless value.nil? || (value == '')
              connection.write_large_object(c.type == :binary,
                                            c.name,
                                            self.class.table_name,
                                            self.class.primary_key,
                                            quote_value(id),
                                            value)
            end
          end
        end
      end
    end
  end
end

module ::ArJdbc
  module Informix
    def self.extended(base)
      @@db_major_version = base.select_one("SELECT dbinfo('version', 'major') version FROM systables WHERE tabid = 1")['version'].to_i
    end

    def self.column_selector
      [ /informix/i,
        lambda { |cfg, column| column.extend(::ArJdbc::Informix::Column) } ]
    end

    def self.jdbc_connection_class
      ::ActiveRecord::ConnectionAdapters::InformixJdbcConnection
    end

    module Column
    private
      # TODO: Test all Informix column types.
      def simplified_type(field_type)
        if field_type =~ /serial/i
          :primary_key
        else
          super
        end
      end
    end

    def modify_types(tp)
      tp[:primary_key] = "SERIAL PRIMARY KEY"
      tp[:string]      = { :name => "VARCHAR", :limit => 255 }
      tp[:integer]     = { :name => "INTEGER" }
      tp[:float]       = { :name => "FLOAT" }
      tp[:decimal]     = { :name => "DECIMAL" }
      tp[:datetime]    = { :name => "DATETIME YEAR TO FRACTION(5)" }
      tp[:timestamp]   = { :name => "DATETIME YEAR TO FRACTION(5)" }
      tp[:time]        = { :name => "DATETIME HOUR TO FRACTION(5)" }
      tp[:date]        = { :name => "DATE" }
      tp[:binary]      = { :name => "BYTE" }
      tp[:boolean]     = { :name => "BOOLEAN" }
      tp
    end

    def prefetch_primary_key?(table_name = nil)
      true
    end

    def supports_migrations?
      true
    end

    def default_sequence_name(table, column)
      "#{table}_seq"
    end

    def add_limit_offset!(sql, options)
      if options[:limit]
        limit = "FIRST #{options[:limit]}"
        # SKIP available only in IDS >= 10
        offset = (@@db_major_version >= 10 && options[:offset]?
                  "SKIP #{options[:offset]}" : "")
        sql.sub!(/^select /i, "SELECT #{offset} #{limit} ")
      end
      sql
    end

    def next_sequence_value(sequence_name)
      select_one("SELECT #{sequence_name}.nextval id FROM systables WHERE tabid=1")['id']
    end

    # TODO: Add some smart quoting for newlines in string and text fields.
    def quote_string(string)
      string.gsub(/\'/, "''")
    end

    def quote(value, column = nil)
      if column && [:binary, :text].include?(column.type)
        # LOBs are updated separately by an after_save trigger.
        "NULL"
      elsif column && column.type == :date
        "'#{value.mon}/#{value.day}/#{value.year}'"
      else
        super
      end
    end

    def create_table(name, options = {})
      super(name, options)
      execute("CREATE SEQUENCE #{name}_seq")
    end

    def rename_table(name, new_name)
      execute("RENAME TABLE #{name} TO #{new_name}")
      execute("RENAME SEQUENCE #{name}_seq TO #{new_name}_seq")
    end

    def drop_table(name)
      super(name)
      execute("DROP SEQUENCE #{name}_seq")
    end

    def remove_index(table_name, options = {})
      @connection.execute_update("DROP INDEX #{index_name(table_name, options)}")
    end

  private
    def select(sql, name = nil)
      # Informix does not like "= NULL", "!= NULL", or "<> NULL".
      execute(sql.gsub(/(!=|<>)\s*null/i, "IS NOT NULL").gsub(/=\s*null/i, "IS NULL"), name)
    end
  end # module Informix
end # module ::ArJdbc