(*
 *    client.ml
 *    OCaml version of sample robocup client
 *)

let message_length = 1024 ;;

let resolve_host server =
    let server_addr =
        try
            Unix.inet_addr_of_string server
        with
        | Failure ("inet_addr_of_string") ->
            (Unix.gethostbyname server).Unix.h_addr_list.(0)
    in server_addr
;;

let connect_soccerserver sockaddr =
    let sock = Unix.socket Unix.PF_INET Unix.SOCK_DGRAM 0
    in Unix.bind sock (Unix.ADDR_INET (Unix.inet_addr_any, 0));
       sock;
;;

let port_of_sockaddr sockaddr =
    match sockaddr with
    | Unix.ADDR_UNIX (_) -> 0
    | Unix.ADDR_INET (_, port) -> port
;;

let send_message message sock servaddr =
    Unix.sendto sock message 0 (String.length message) [] servaddr;
    print_string ("send " ^ (string_of_int (port_of_sockaddr servaddr)) ^ " : " ^ message);
    flush stdout
;;

(* receive_message sock *)

let receive_message =
    let buf = ref (String.create message_length) in
    let recv_msg sock = 
        let len, addr = Unix.recvfrom sock !buf 0 message_length [] in
        let answer = String.sub !buf 0 len
        in print_string ("recv " ^ (string_of_int (port_of_sockaddr addr)) ^ " : " ^ answer ^ "\n");
           flush stdout; (answer, addr)
    in recv_msg
;;

let select_loop sock sockaddr =
    let icfd = Unix.descr_of_in_channel stdin in
    let addr = ref sockaddr
    in while true do
           match Unix.select [icfd; sock] [] [] 1.0 with
           | [], [], [] -> ()
           | fdl, [], [] ->
               if List.mem sock fdl then (let _, newaddr = receive_message sock in addr := newaddr);
               if List.mem icfd fdl then send_message ((input_line stdin) ^ "\n") sock !addr;
           | _ -> ()
       done
;;

let message_loop sock servaddr =
    try
        select_loop sock servaddr
    with
    | End_of_file -> print_string "terminate"; print_newline ()
;;

let default_host = "localhost" ;;
let default_port = 6000 ;;

let main () =
    print_string "simple robocup client"; print_newline ();
    try
        let argc = Array.length Sys.argv in
        let host = if argc < 2 then default_host else Sys.argv.(1) in
        let port = if argc < 3 then default_port else int_of_string Sys.argv.(2) in
        let sockaddr = Unix.ADDR_INET (resolve_host host, port) in
        let sock = connect_soccerserver sockaddr
        in print_string ("Connecting to " ^ host ^ ":" ^ (string_of_int port));
           print_newline ();
           message_loop sock sockaddr;
           Unix.close sock
    with
    | Failure ("int_of_string") -> Printf.eprintf "%s: bad port number\n" Sys.argv.(2)
    | Not_found -> Printf.eprintf "%s: host not found\n" Sys.argv.(1)
;;

let _ = main () ;;