#
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

module Shell
  module Commands
    class Command

      def initialize(shell)
        @shell = shell
      end

      #wrap an execution of cmd to catch hbase exceptions
      # cmd - command name to execture
      # args - arguments to pass to the command
      def command_safe(debug, cmd = :command, *args)
        # send is internal ruby method to call 'cmd' with *args
        #(everything is a message, so this is just the formal semantics to support that idiom)
        translate_hbase_exceptions(*args) { send(cmd,*args) }
      rescue => e
        rootCause = e
        while rootCause != nil && rootCause.respond_to?(:cause) && rootCause.cause != nil
          rootCause = rootCause.cause
        end
        puts
        puts "ERROR: #{rootCause}"
        puts "Backtrace: #{rootCause.backtrace.join("\n           ")}" if debug
        puts
        puts "Here is some help for this command:"
        puts help
        puts
      end

      def admin
        @shell.hbase_admin
      end

      def table(name)
        @shell.hbase_table(name)
      end

      def replication_admin
        @shell.hbase_replication_admin
      end

      def security_admin
        @shell.hbase_security_admin
      end

      def visibility_labels_admin
        @shell.hbase_visibility_labels_admin
      end

      #----------------------------------------------------------------------

      def formatter
        @shell.formatter
      end

      def format_simple_command
        now = Time.now
        yield
        formatter.header
        formatter.footer(now)
      end

      def format_and_return_simple_command
        now = Time.now
        ret = yield
        formatter.header
        formatter.footer(now)
        return ret
      end

      def translate_hbase_exceptions(*args)
        yield
      rescue => e
        raise e unless e.respond_to?(:cause) && e.cause != nil
        
        # Get the special java exception which will be handled
        cause = e.cause
        if cause.kind_of?(org.apache.hadoop.hbase.TableNotFoundException) then
          raise "Unknown table #{args.first}!"
        end
        if cause.kind_of?(org.apache.hadoop.hbase.regionserver.NoSuchColumnFamilyException) then
          valid_cols = table(args.first).get_all_columns.map { |c| c + '*' }
          raise "Unknown column family! Valid column names: #{valid_cols.join(", ")}"
        end
        if cause.kind_of?(org.apache.hadoop.hbase.TableExistsException) then
          raise "Table already exists: #{args.first}!"
        end
        # To be safe, here only AccessDeniedException is considered. In future
        # we might support more in more generic approach when possible.
        if cause.kind_of?(org.apache.hadoop.hbase.security.AccessDeniedException) then
          str = java.lang.String.new("#{cause}")
          # Error message is merged with stack trace, reference StringUtils.stringifyException
          # This is to parse and get the error message from the whole.
          strs = str.split("\n")
          if strs.size > 0 then
            raise "#{strs[0]}"
          end
        end

        # Throw the other exception which hasn't been handled above       
        raise e
      end
    end
  end
end
