require "ffi"
require "json"
require "logger"

module Rdkafka
  # @private
  module Bindings
    extend FFI::Library

    def self.lib_extension
      if Gem::Platform.local.os.include?("darwin")
        'dylib'
      else
        'so'
      end
    end

    ffi_lib File.join(File.dirname(__FILE__), "../../ext/librdkafka.#{lib_extension}")

    # Polling

    attach_function :rd_kafka_poll, [:pointer, :int], :void, blocking: true
    attach_function :rd_kafka_outq_len, [:pointer], :int, blocking: true

    # Message struct

    class Message < FFI::Struct
      layout :err, :int,
             :rkt, :pointer,
             :partition, :int32,
             :payload, :pointer,
             :len, :size_t,
             :key, :pointer,
             :key_len, :size_t,
             :offset, :int64,
             :_private, :pointer
    end

    attach_function :rd_kafka_message_destroy, [:pointer], :void
    attach_function :rd_kafka_message_timestamp, [:pointer, :pointer], :int64
    attach_function :rd_kafka_topic_new, [:pointer, :string, :pointer], :pointer
    attach_function :rd_kafka_topic_name, [:pointer], :string

    # TopicPartition ad TopicPartitionList structs

    class TopicPartition < FFI::Struct
      layout :topic, :string,
             :partition, :int32,
             :offset, :int64,
             :metadata, :pointer,
             :metadata_size, :size_t,
             :opaque, :pointer,
             :err, :int,
             :_private, :pointer
    end

    class TopicPartitionList < FFI::Struct
      layout :cnt, :int,
             :size, :int,
             :elems, :pointer
    end

    attach_function :rd_kafka_topic_partition_list_new, [:int32], :pointer
    attach_function :rd_kafka_topic_partition_list_add, [:pointer, :string, :int32], :void
    attach_function :rd_kafka_topic_partition_list_set_offset, [:pointer, :string, :int32, :int64], :void
    attach_function :rd_kafka_topic_partition_list_destroy, [:pointer], :void
    attach_function :rd_kafka_topic_partition_list_copy, [:pointer], :pointer

    # Errors

    attach_function :rd_kafka_err2name, [:int], :string
    attach_function :rd_kafka_err2str, [:int], :string

    # Configuration

    enum :kafka_config_response, [
      :config_unknown, -2,
      :config_invalid, -1,
      :config_ok, 0
    ]

    attach_function :rd_kafka_conf_new, [], :pointer
    attach_function :rd_kafka_conf_set, [:pointer, :string, :string, :pointer, :int], :kafka_config_response
    callback :log_cb, [:pointer, :int, :string, :string], :void
    attach_function :rd_kafka_conf_set_log_cb, [:pointer, :log_cb], :void
    callback :stats_cb, [:pointer, :string, :int, :pointer], :int
    attach_function :rd_kafka_conf_set_stats_cb, [:pointer, :stats_cb], :void

    # Log queue
    attach_function :rd_kafka_set_log_queue, [:pointer, :pointer], :void
    attach_function :rd_kafka_queue_get_main, [:pointer], :pointer

    LogCallback = FFI::Function.new(
      :void, [:pointer, :int, :string, :string]
    ) do |_client_ptr, level, _level_string, line|
      severity = case level
                 when 0 || 1 || 2
                   Logger::FATAL
                 when 3
                   Logger::ERROR
                 when 4
                   Logger::WARN
                 when 5 || 6
                   Logger::INFO
                 when 7
                   Logger::DEBUG
                 else
                   Logger::UNKNOWN
                 end
      Rdkafka::Config.logger.add(severity) { "rdkafka: #{line}" }
    end

    StatsCallback = FFI::Function.new(
      :int, [:pointer, :string, :int, :pointer]
    ) do |_client_ptr, json, _json_len, _opaque|
      # Pass the stats hash to callback in config
      if Rdkafka::Config.statistics_callback
        stats = JSON.parse(json)
        Rdkafka::Config.statistics_callback.call(stats)
      end

      # Return 0 so librdkafka frees the json string
      0
    end

    # Handle

    enum :kafka_type, [
      :rd_kafka_producer,
      :rd_kafka_consumer
    ]

    attach_function :rd_kafka_new, [:kafka_type, :pointer, :pointer, :int], :pointer
    attach_function :rd_kafka_destroy, [:pointer], :void

    # Consumer

    attach_function :rd_kafka_subscribe, [:pointer, :pointer], :int
    attach_function :rd_kafka_unsubscribe, [:pointer], :int
    attach_function :rd_kafka_subscription, [:pointer, :pointer], :int
    attach_function :rd_kafka_assign, [:pointer, :pointer], :int
    attach_function :rd_kafka_assignment, [:pointer, :pointer], :int
    attach_function :rd_kafka_committed, [:pointer, :pointer, :int], :int
    attach_function :rd_kafka_commit, [:pointer, :pointer, :bool], :int, blocking: true
    attach_function :rd_kafka_poll_set_consumer, [:pointer], :void
    attach_function :rd_kafka_consumer_poll, [:pointer, :int], :pointer, blocking: true
    attach_function :rd_kafka_consumer_close, [:pointer], :void, blocking: true

    # Stats

    attach_function :rd_kafka_query_watermark_offsets, [:pointer, :string, :int, :pointer, :pointer, :int], :int

    # Producer

    RD_KAFKA_VTYPE_END = 0
    RD_KAFKA_VTYPE_TOPIC = 1
    RD_KAFKA_VTYPE_RKT = 2
    RD_KAFKA_VTYPE_PARTITION = 3
    RD_KAFKA_VTYPE_VALUE = 4
    RD_KAFKA_VTYPE_KEY = 5
    RD_KAFKA_VTYPE_OPAQUE = 6
    RD_KAFKA_VTYPE_MSGFLAGS = 7
    RD_KAFKA_VTYPE_TIMESTAMP = 8

    RD_KAFKA_MSG_F_COPY = 0x2

    attach_function :rd_kafka_producev, [:pointer, :varargs], :int
    callback :delivery_cb, [:pointer, :pointer, :pointer], :void
    attach_function :rd_kafka_conf_set_dr_msg_cb, [:pointer, :delivery_cb], :void

    DeliveryCallback = FFI::Function.new(
      :void, [:pointer, :pointer, :pointer]
    ) do |client_ptr, message_ptr, opaque_ptr|
      message = Message.new(message_ptr)
      delivery_handle_ptr_address = message[:_private].address
      if delivery_handle = Rdkafka::Producer::DeliveryHandle.remove(delivery_handle_ptr_address)
        delivery_handle[:pending] = false
        delivery_handle[:response] = message[:err]
        delivery_handle[:partition] = message[:partition]
        delivery_handle[:offset] = message[:offset]
      end
    end
  end
end