;;; TCP Chat Client — connects to the TCP chat server
;;;
;;; Usage:
;;;   mix clje.run --no-halt examples/tcp_chat_client.clje -- <username>
;;;
;;; The server must be running first:
;;;   mix clje.run --no-halt examples/tcp_chat_server.clje
;;;
;;; Commands:
;;;   Type a message and press Enter to send
;;;   /who   — list online users
;;;   /quit  — disconnect and exit

(ns TcpChatClient
  (:require [clje.core :refer :all]
            [IO] [String] [System] [erlang] [gen_tcp]))

;; ── Receiver process ──────────────────────────────────────────────
;; Listens for TCP messages from the server and prints them.

(defn receiver [socket parent]
  (receive
    [:tcp _sock data]
      (let [line (String/trim data)]
        (cond
          (String/starts-with? line "MSG:")
            (let [rest  (String/slice line 4 (String/length line))
                  parts (String/split rest ":" (list #el[:parts 2]))
                  from  (hd parts)
                  text  (hd (tl parts))]
              (IO/puts (str from "> " text))
              (TcpChatClient/receiver socket parent))

          (String/starts-with? line "SYS:")
            (do
              (IO/puts (str "* " (String/slice line 4 (String/length line))))
              (TcpChatClient/receiver socket parent))

          (String/starts-with? line "JOIN:")
            (do
              (IO/puts (str "* " (String/slice line 5 (String/length line)) " joined"))
              (TcpChatClient/receiver socket parent))

          (String/starts-with? line "QUIT:")
            (do
              (IO/puts (str "* " (String/slice line 5 (String/length line)) " left"))
              (TcpChatClient/receiver socket parent))

          :else
            (do
              (IO/puts line)
              (TcpChatClient/receiver socket parent))))

    [:tcp_closed _sock]
      (do
        (IO/puts "* Connection closed by server.")
        (System/halt 0))

    [:tcp_error _sock _reason]
      (do
        (IO/puts "* Connection error.")
        (System/halt 1))))

;; ── Input loop ────────────────────────────────────────────────────
;; Reads from stdin and sends to the server.

(defn send-line [socket line]
  (gen_tcp/send socket line))

(defn input-loop [socket]
  (let [line (IO/gets "")]
    (cond
      (== line :eof)
        (do
          (TcpChatClient/send-line socket "QUIT\n")
          (gen_tcp/close socket)
          (System/halt 0))

      :else
        (let [trimmed (String/trim line)]
          (cond
            (== trimmed "/quit")
              (do
                (TcpChatClient/send-line socket "QUIT\n")
                (gen_tcp/close socket)
                (IO/puts "Goodbye!")
                (System/halt 0))

            (== trimmed "")
              (TcpChatClient/input-loop socket)

            :else
              (do
                (TcpChatClient/send-line socket (str "MSG:" trimmed "\n"))
                (TcpChatClient/input-loop socket)))))))

;; ── Connect ───────────────────────────────────────────────────────

(defn start [username]
  (case (gen_tcp/connect (erlang/binary-to-list "127.0.0.1") 4040
          (list :binary #el[:active true] #el[:packet :line]))
    [:ok socket]
      (do
        ;; Send JOIN
        (TcpChatClient/send-line socket (str "JOIN:" username "\n"))

        ;; Spawn receiver and hand it the socket
        (let [me *self*
              recv-pid (spawn (fn [] (TcpChatClient/receiver socket me)))]
          (gen_tcp/controlling-process socket recv-pid)

          ;; Run input loop in the main process
          (IO/puts (str "Connected as " username ". Type a message or /quit to exit."))
          (TcpChatClient/input-loop socket)))

    [:error reason]
      (do
        (IO/puts (str "Could not connect: " reason))
        (IO/puts "Is the server running? Start it with:")
        (IO/puts "  mix clje.run --no-halt examples/tcp_chat_server.clje")
        (System/halt 1))))

;; ── Entry point ─────────────────────────────────────────────────────

(let [args (System/argv)]
  (if (== (count args) 0)
    (do
      (IO/puts "Usage: mix clje.run --no-halt examples/tcp_chat_client.clje -- <username>")
      (System/halt 1))
    (TcpChatClient/start (hd args))))