Sequel.require %w'shared/mysql utils/stored_procedures', 'adapters'

module Sequel
  module MySQL
    # This module is used by the mysql and mysql2 adapters to support
    # prepared statements and stored procedures.
    module PreparedStatements
      module DatabaseMethods
        disconnect_errors = <<-END.split("\n").map(&:strip)
        Commands out of sync; you can't run this command now
        Can't connect to local MySQL server through socket
        MySQL server has gone away
        Lost connection to MySQL server during query
        This connection is still waiting for a result, try again once you have the result
        closed MySQL connection
        END
        # Error messages for mysql and mysql2 that indicate the current connection should be disconnected
        MYSQL_DATABASE_DISCONNECT_ERRORS = /\A#{Regexp.union(disconnect_errors)}/o
       
        # Support stored procedures on MySQL
        def call_sproc(name, opts=OPTS, &block)
          args = opts[:args] || [] 
          execute("CALL #{name}#{args.empty? ? '()' : literal(args)}", opts.merge(:sproc=>false), &block)
        end
        
        # Executes the given SQL using an available connection, yielding the
        # connection if the block is given.
        def execute(sql, opts=OPTS, &block)
          if opts[:sproc]
            call_sproc(sql, opts, &block)
          elsif sql.is_a?(Symbol)
            execute_prepared_statement(sql, opts, &block)
          else
            synchronize(opts[:server]){|conn| _execute(conn, sql, opts, &block)}
          end
        end
        
        private

        def add_prepared_statements_cache(conn)
          class << conn
            attr_accessor :prepared_statements
          end
          conn.prepared_statements = {}
        end

        # Stupid MySQL doesn't use SQLState error codes correctly, mapping
        # all constraint violations to 23000 even though it recognizes
        # different types.
        def database_specific_error_class(exception, opts)
          case exception.errno
          when 1048
            NotNullConstraintViolation
          when 1062
            UniqueConstraintViolation
          when 1451, 1452
            ForeignKeyConstraintViolation
          else
            super
          end
        end

        # Executes a prepared statement on an available connection.  If the
        # prepared statement already exists for the connection and has the same
        # SQL, reuse it, otherwise, prepare the new statement.  Because of the
        # usual MySQL stupidity, we are forced to name arguments via separate
        # SET queries.  Use @sequel_arg_N (for N starting at 1) for these
        # arguments.
        def execute_prepared_statement(ps_name, opts, &block)
          args = opts[:arguments]
          ps = prepared_statement(ps_name)
          sql = ps.prepared_sql
          synchronize(opts[:server]) do |conn|
            unless conn.prepared_statements[ps_name] == sql
              _execute(conn, "PREPARE #{ps_name} FROM #{literal(sql)}", opts)
              conn.prepared_statements[ps_name] = sql
            end
            i = 0
            _execute(conn, "SET " + args.map {|arg| "@sequel_arg_#{i+=1} = #{literal(arg)}"}.join(", "), opts) unless args.empty?
            opts = opts.merge(:log_sql=>" (#{sql})") if ps.log_sql
            _execute(conn, "EXECUTE #{ps_name}#{" USING #{(1..i).map{|j| "@sequel_arg_#{j}"}.join(', ')}" unless i == 0}", opts, &block)
          end
        end
      end

      module DatasetMethods
        include Sequel::Dataset::StoredProcedures
       
        # Methods to add to MySQL prepared statement calls without using a
        # real database prepared statement and bound variables.
        module CallableStatementMethods
          # Extend given dataset with this module so subselects inside subselects in
          # prepared statements work.
          def subselect_sql_append(sql, ds)
            ps = ds.to_prepared_statement(:select).clone(:append_sql => sql)
            ps.extend(CallableStatementMethods)
            ps = ps.bind(@opts[:bind_vars]) if @opts[:bind_vars]
            ps.prepared_args = prepared_args
            ps.prepared_sql
          end
        end
        
        PreparedStatementMethods = Sequel::Dataset.send(:prepared_statements_module,
          :prepare_bind,
          Sequel::Dataset::UnnumberedArgumentMapper) do
            # Raise a more obvious error if you attempt to call a unnamed prepared statement.
            def call(*)
              raise Error, "Cannot call prepared statement without a name" if prepared_statement_name.nil?
              super
            end
        end
        
        StoredProcedureMethods = Sequel::Dataset.send(:prepared_statements_module,
          "sql = @sproc_name; opts = Hash[opts]; opts[:args] = @sproc_args; opts[:sproc] = true",
          Sequel::Dataset::StoredProcedureMethods, %w'execute execute_dui')
        
        # MySQL is different in that it supports prepared statements but not bound
        # variables outside of prepared statements.  The default implementation
        # breaks the use of subselects in prepared statements, so extend the
        # temporary prepared statement that this creates with a module that
        # fixes it.
        def call(type, bind_arguments={}, *values, &block)
          ps = to_prepared_statement(type, values)
          ps.extend(CallableStatementMethods)
          ps.call(bind_arguments, &block)
        end
        
        # Store the given type of prepared statement in the associated database
        # with the given name.
        def prepare(type, name=nil, *values)
          ps = to_prepared_statement(type, values)
          ps.extend(PreparedStatementMethods)
          if name
            ps.prepared_statement_name = name
            db.set_prepared_statement(name, ps)
          end
          ps
        end
        
        private

        # Extend the dataset with the MySQL stored procedure methods.
        def prepare_extend_sproc(ds)
          ds.extend(StoredProcedureMethods)
        end
        
      end
    end
  end
end
