# 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 GNU General Public License version 3, or (at your
# option) any later version, as published by the Free Software Foundation.
#
# You can also Link and Combine this program with other software covered by
# the terms of any of the Free Software licenses or any of the Open Source
# Initiative approved licenses and Convey the resulting work. Corresponding
# source of such a combination shall include the source code for all other
# software used.
#
# This program is distributed WITHOUT ANY WARRANTY; without even the implied
# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#
# See COPYING file for full licensing terms.
# See https://www.nexedi.com/licensing for rationale and options.



# 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/plugin/output'
require_relative 'wendelin_client'


module Fluent::Plugin

  class WendelinOutput < Output
    Fluent::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

    config_param    :use_keep_alive,  :bool,  :default => false

    config_param    :ssl_timeout,        :integer,  :default => 60
    config_param    :open_timeout,       :integer,  :default => 60
    config_param    :read_timeout,       :integer,  :default => 60
    config_param    :keep_alive_timeout, :integer,  :default => 300
	
	config_section :buffer do
	  config_set_default :chunk_keys, ["tag"]
	end
	
    def configure(conf)
        super
		
		unless @chunk_key_tag
		  raise Fluent::ConfigError, "buffer chunk key must include 'tag' for wendelin output"
		end

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

    def start
        super
        # TODO
    end

    def shutdown
        super
        # TODO
    end

    # Use normal "Synchronous Buffer" - write out records from a buffer chunk for a tag.
    #
    def write(chunk)
	    return if chunk.empty?
        # NOTE if this fail and raises -> it will unroll to Output#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 = chunk.metadata.tag

        if @use_keep_alive
          @wendelin.ingest_with_keep_alive(reference, data_chunk)
        else
          @wendelin.ingest(reference, data_chunk)
        end
    end

  end

end