;;;; $Id$
;;;; $URL$

;;;; See the LICENSE file for licensing information.

(in-package :irc)

(defun find-reply-name (reply-number &key (reply-names *reply-names*))
  "Numeric replies in the IRC RFCs have more meaningful names.  Given
a numeric reply (`reply-number') this function will either return the
symbol representing the reply or raise a continuable error
(`no-such-reply') which gives you the opportunity to ignore the
situation."
  (let ((name (assoc reply-number reply-names)))
    (when name
      (cadr name))))

(defun return-source (string &key (start 0))
  "Assuming `string' is a valid IRC message this function returns the
source part of the message.  Returns nil if the source part is not
present."
  (cut-between string #\: '(#\! #\Space) :start start))

(defun return-user (string &key (start 0))
  "Assuming `string' is a valid IRC message this function returns the
user part of the message.  Returns nil if the user part is not
present."
  (cut-between string #\! '(#\@ #\Space) :start start))

(defun return-host (string &key (start 0))
  "Assuming `string' is a valid IRC message this function returns the
host part of the message.  Returns nil if the host part is not
present."
  (cut-between string #\@ '(#\Space) :start start))

(defun return-command (string &key (start 0))
  "Assuming `string' is a valid IRC message this function returns the
command part of the message.  Returns nil if the command part is not
present."
  (if (eql (char string start) #\Space)
      (cut-between string #\Space '(#\Space) :start start)
      (cut-between string nil '(#\Space) :start start :cut-extra nil)))

(defun return-arguments (string &key (start 0))
  "Assuming `string' is a valid IRC message this function returns the
arguments part of the message as a list.  Returns nil if the arguments
part is not present."
  (multiple-value-bind (end-position return-argument)
      (cut-before string " :" '(#\Return) :start start :cut-to-end t)
    (values end-position (tokenize-string return-argument
                                          :delimiters '(#\Space)))))

(defun return-trailing-argument (string &key (start 0))
  "Assuming `string' is a valid IRC message this function returns the
trailing-argument part of the message.  Returns nil if the
trailing-argument part is not present."
  (when (< start (length string))
    (cut-between string #\: '(#\Return) :start start :cut-to-end t)))

(defun combine-arguments-and-trailing (string &key (start 0))
  (multiple-value-bind
      (start return-string)
      (return-arguments string :start start)
    (multiple-value-bind
        (return-index trailing)
        (return-trailing-argument string :start start)
      (values return-index
              (append return-string (when (and trailing (string/= "" trailing))
                                      (list trailing)))))))

(defun parse-raw-message (string &key (start 0))
  "Assuming `string' is a valid IRC message, parse the message and
return the values in the following order:

  - source
  - user
  - host
  - command
  - arguments
  - trailing-argument

Any values not present will be represented as nil."
  (let ((index start)
        (returns nil))
    (dolist (function '(return-source
                        return-user
                        return-host
                        return-command
                        combine-arguments-and-trailing))
      (multiple-value-bind (return-index return-string)
          (funcall function string :start index)
        (setf index return-index)
        (push return-string returns)))
    (apply #'values (reverse returns))))

(defun irc-error-reply-p (string)
  "Returns t if `string' is a string-representation of an IRC error
reply message, nil otherwise."
  (unless (zerop (length string))
    (if (and (every #'digit-char-p string)
             (member (char string 0) '(#\4 #\5)))
        t
        nil)))

(defun numeric-reply-p (string)
  "Returns t if `string' is a string-representation of an IRC number
reply, nil otherwise."
  (every #'digit-char-p string))

(defun ctcp-type-p (string type)
  "Is the `string' actually a representation of the CTCP `type'?"
  (if (string-equal (substring string 1 (min (length string)
                                             (1+ (length (symbol-name type)))))
                    type)
      type
      nil))

(defun dcc-type-p (string type)
  "Is the `string' actually a representation of the DCC `type'?"
  (let* ((args (tokenize-string (string-trim (list +soh+) string)))
         (dcc (string-upcase (first args)))
         (sess-type (string-upcase (second args))))
    (when (string= dcc "DCC")
      (let ((r
             ;; the list below was found on Wikipedia and in kvirc docs
             (second (assoc sess-type '(("CHAT" :dcc-chat-request)
                                        ("SEND" :dcc-send-request)
                                        ("XMIT" :dcc-xmit-request)
                                        ("SCHAT" :dcc-schat-request)
                                        ("SSEND" :dcc-ssend-request)
                                        ("REVERSE" :dcc-reverse-request)
                                        ("RSEND" :dcc-rsend-request)
                                        ("TSEND" :dcc-tsend-request)
                                        ("STSEND" :dcc-stsend-request)
                                        ("TSSEND" :dcc-stsend-request)
                                        ("RESUME" :dcc-resume-request)
                                        ("ACCEPT" :dcc-accept-request)
                                        ;; GET
                                        ;; TGET
                                        ;; STGET
                                        ;; TSGET
                                        ;; RECV
                                        ;; SRECV
                                        ;; TRECV
                                        ;; STRECV
                                        ;; TSRECV
                                        ;; RSEND
                                        ;; SRSEND
                                        ;; TRSEND
                                        ;; STRSEND
                                        ;; TSRSEND
                                        ;; VOICE
                                        ) :test #'string=))))
        (when (eq r type)
          type)))))

(defun ctcp-message-type (string)
  "If `string' is a CTCP message, return the type of the message or
nil if this is a) not a CTCP message or b) a CTCP message we don't
know about."
  (if (or (not (stringp string))
          (zerop (length string))
          (not (eql (char string 0) +soh+)))
      nil
      (case (char string 1)
        (#\A (ctcp-type-p string :action))
        (#\C (ctcp-type-p string :clientinfo))
        (#\D
         (or (dcc-type-p string :dcc-chat-request)
             (dcc-type-p string :dcc-send-request)))
        (#\F (ctcp-type-p string :finger))
        (#\P (ctcp-type-p string :ping))
        (#\S (ctcp-type-p string :source))
        (#\T (ctcp-type-p string :time))
        (#\U (ctcp-type-p string :userinfo))
        (#\V (ctcp-type-p string :version))
        (otherwise nil))))

(defun create-irc-message (string)
  "If `string' is a valid IRC message parse it and return an object of
the correct type with its slots prefilled according to the information
in the message."
  (multiple-value-bind (source user host command arguments)
      (parse-raw-message string)
    (let* ((class 'irc-message)
           (trailing-argument (car (last arguments)))
           (ctcp (ctcp-message-type trailing-argument)))
      (when command
        (cond
          ;;((irc-error-reply-p command)
           ;; Disable for now, as it prevents adding hooks for some useful
           ;; error types
           ;;(progn
           ;;  (setf command (find-reply-name (parse-integer command)))
           ;;  (setf class 'irc-error-reply)))
          ((numeric-reply-p command)
           (let* ((reply-number (parse-integer command))
                  (reply-name (find-reply-name reply-number)))
             (unless reply-name
               (error "Ignore unknown reply."
                      'no-such-reply :reply-number reply-number))
             (setf command reply-name)
             (setf class (find-irc-message-class command))))
          (t
           (setf command (intern (string-upcase command)
                                 (find-package :keyword)))
           (setf class (find-irc-message-class command)))))
      (when ctcp
        (setf class (find-ctcp-message-class ctcp)))
      (let ((instance (make-instance class
                                     :source (or source "")
                                     :user (or user "")
                                     :host (or host "")
                                     :command (if command
                                                  (string command)
                                                  "")
                                     :arguments arguments
                                     :connection nil
                                     :received-time (get-universal-time)
                                     :raw-message-string (or string ""))))
        (when ctcp
          (setf (ctcp-command instance) ctcp))
        instance))))

(defun create-dcc-message (string)
  (let* ((class 'dcc-privmsg-message)
         (ctcp (ctcp-message-type string)))
    (when ctcp
      (setf class (find-dcc-ctcp-message-class ctcp)))
    (let ((instance (make-instance class
                                   :arguments (list string)
                                   :connection nil
                                   :received-time (get-universal-time)
                                   :raw-message-string string)))
      (when ctcp
        (setf (ctcp-command instance) ctcp))
      instance)))