# Fluentd output plugin to ingest data to Wendelin system
# Copyright (C) 2015  Nexedi SA and Contributors.
#                     Kirill Smelkov <kirr@nexedi.com>
#
#   This program is free software: you can Use, Study, Modify and Redistribute
#   it under the terms of 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.


# This plugin hooks into Fluentd in a way similiar to out_forward and
# out_secure_forward and outputs event stream to a Wendelin HTTP endpoint.

require 'fluent/output'
require_relative 'wendelin_client'


module Fluent

  class WendelinOutput < ObjectBufferedOutput   # XXX verify base class
    Plugin.register_output('wendelin', self)

    # where Wendelin's Input Stream Tool is located,
    # ex http://example.com/erp5/portal_ingestion_policies/example_ingestion
    config_param    :streamtool_uri,    :string

    # credentials to authenticate this fluentd to wendelin
    # by default credentials are not used
    # TODO user/password -> certificate
    config_param    :user,      :string,  :default => nil
    config_param    :password,  :string,  :default => nil


    def configure(conf)
        super

        credentials = {}
        if @user
            credentials['user']     = @user
            credentials['password'] = @password
        end
        @wendelin = WendelinClient.new(@streamtool_uri, credentials)
    end

    def start
        super
        # TODO
    end

    def shutdown
        super
        # TODO
    end


    # hooked to ObjectBufferedOutput - write out records from a buffer chunk for a tag.
    #
    # NOTE this is called from a separate thread (see OutputThread and BufferedOutput)
    def write_objects(tag, chunk)
        # NOTE if this fail and raises -> it will unroll to BufferedOutput#try_flush
        # which detects errors and retries outputting logs up to retry maxcount
        # times and aborts outputting current logs if all try fail.
        #
        # This way, we don't need to code rescue here.

        # NOTE tag is 1, and chunk stores an event stream, usually [] of
        # (timestamp, record) in msgpack, but it general it could be arbitrary
        # data - we send it as-is.
        data_chunk = chunk.read()

        # for input_stream_ref use tag as-is - it will be processed/translated
        # further on server by Wendelin
        reference = tag

        @wendelin.ingest(reference, data_chunk)
    end

  end

end