client.cr

# Use this to send commands
require "socket"

client = TCPSocket.new("0.0.0.0", 1234)
message = ARGV[0]
puts message
client << message
client.close

node.cr

# ####################################################
#
# Raft node implementation
# 
# References
# ----------
# https://raft.github.io/slides/raftuserstudy2013.pdf
#
# ####################################################
require "socket"

# Constants
ELECTION_TIMEOUT_RANGE = 150..300

# Enums
enum ElectionState
  Leader
  Candidate
  Follower
end


class Node
  def initialize(id : Int32, port : Int32)
    @id = id
    @port = port
    @timeout = Random.rand(ELECTION_TIMEOUT_RANGE).as(Int32)
    # Start communication channels
    @channel = Channel(String|Nil).new
    @state_channel = Channel(ElectionState).new
  end

  # Fiber - TCPServer
  def start_listener
    puts "Starting the TCP Server at: #{@port}"
    server = TCPServer.new("0.0.0.0", @port)
    loop do
      server.accept do |client|
        message = client.gets
        @channel.send(message)
      end
    end
  end

  def start_election
    puts "Starting Election Fiber..."
    while true
      item = @state_channel.receive
      case item
      when ElectionState::Follower
        puts "[STATE] Now becoming a follower"
      when ElectionState::Candidate
        puts "[STATE] Now becoming a Candidate"
      when ElectionState::Leader
        puts "[STATE] Now becoming a Leader"
      end
    end
  end

  def run
    spawn start_listener
    spawn start_election

    while true
      select
      when message = @channel.receive
        case message
          when "follower"
            @state_channel.send(ElectionState::Follower)
          when "candidate"
            @state_channel.send(ElectionState::Candidate)
          when "leader"
            @state_channel.send(ElectionState::Leader)
          when "exit"
            break
          else
            # TODO: Do great things...
            puts message
        end
      end
    end
  end  

end


node = Node.new(1,1234)
node.run