begin
  require 'sentry-raven'
rescue LoadError
  raise 'Gem sentry-raven is required for logging purposes. Please add the gem "sentry-raven" to your Gemfile.'
end

# Send log messages to sentry
#
# Example:
#   SemanticLogger.add_appender(appender: :sentry)
#
class SemanticLogger::Appender::Sentry < SemanticLogger::Subscriber
  # Create Appender
  #
  # Parameters
  #   level: [:trace | :debug | :info | :warn | :error | :fatal]
  #     Override the log level for this appender.
  #     Default: :error
  #
  #   formatter: [Object|Proc|Symbol|Hash]
  #     An instance of a class that implements #call, or a Proc to be used to format
  #     the output from this appender
  #     Default: Use the built-in formatter (See: #call)
  #
  #   filter: [Regexp|Proc]
  #     RegExp: Only include log messages where the class name matches the supplied.
  #     regular expression. All other messages will be ignored.
  #     Proc: Only include log messages where the supplied Proc returns true
  #           The Proc must return true or false.
  #
  #   host: [String]
  #     Name of this host to appear in log messages.
  #     Default: SemanticLogger.host
  #
  #   application: [String]
  #     Name of this application to appear in log messages.
  #     Default: SemanticLogger.application
  def initialize(level: :error, formatter: nil, filter: nil, application: nil, host: nil, &block)
    # Replace the Sentry Raven logger so that we can identify its log messages and not forward them to Sentry
    Raven.configure { |config| config.logger = SemanticLogger[Raven] }
    super(level: level, formatter: formatter, filter: filter, application: application, host: host, &block)
  end

  # Send an error notification to sentry
  def log(log)
    # Ignore logs coming from Raven itself
    return false if log.name == 'Raven'

    context = formatter.call(log, self)
    attrs                     = {
      level: context.delete(:level),
      extra: context
    }
    if log.exception
      context.delete(:exception)
      Raven.capture_exception(log.exception, attrs)
    else
      attrs[:extra][:backtrace] = log.backtrace if log.backtrace
      Raven.capture_message(context[:message], attrs)
    end
    true
  end

  private

  # Use Raw Formatter by default
  def default_formatter
    SemanticLogger::Formatters::Raw.new
  end

end