# frozen_string_literal: true

require_relative "../base"
require_relative "../events/event"

module Fusuma
  module Plugin
    module Inputs
      # Inherite this base
      # @abstract Subclass and override {#io} to implement
      class Input < Base
        # Wait multiple inputs until it becomes readable
        # and read lines with nonblock
        # @param inputs [Array<Input>]
        # @return [Event]
        def self.select(inputs)
          ios = IO.select(inputs.map(&:io))
          io = ios&.first&.first

          input = inputs.find { |i| i.io == io }

          begin
            line = io.readline_nonblock("\n").chomp
          rescue EOFError => e
            warn "#{input.class.name}: #{e}"
            warn "Send SIGKILL to fusuma processes"
            inputs.reject { |i| i == input }.each do |i|
              warn "stop process: #{i.class.name.underscore}"
              Process.kill(:SIGKILL, i.pid)
            end
            exit 1
          rescue => e
            warn "#{input.class.name}: #{e}"
            exit 1
          end

          input.create_event(record: line)
        end

        # @return [Integer]
        def pid
          raise NotImplementedError, "override #{self.class.name}##{__method__}"
        end

        # @return [IO]
        def io
          raise NotImplementedError, "override #{self.class.name}##{__method__}"
        end

        # @return [Event]
        def create_event(record: "dummy input")
          e = Events::Event.new(tag: tag, record: record)
          MultiLogger.debug(input_event: e)
          e
        end

        def tag
          self.class.name.split("Inputs::").last.underscore
        end
      end
    end
  end
end

# ref: https://github.com/Homebrew/brew/blob/6b2dbbc96f7d8aa12f9b8c9c60107c9cc58befc4/Library/Homebrew/extend/io.rb
class IO
  def readline_nonblock(sep = $INPUT_RECORD_SEPARATOR)
    line = +""
    buffer = +""

    loop do
      break if buffer == sep

      read_nonblock(1, buffer)
      line.concat(buffer)
    end

    line.freeze
  rescue IO::WaitReadable, EOFError => e
    raise e if line.empty?

    line.freeze
  end
end