From ff74bec6e42aa9eede09f9361410f8bd14755027 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Fri, 9 Jun 2023 21:00:03 -0700
Subject: [PATCH 3/5] [5.6] Simplify logic for inserting ERC prompt input

* lisp/erc/erc.el (erc--current-line-input-split): New variable bound
to the current `erc--input-split' object, post review, for the extent
of display processing, so that "slash" commands can access it.
(erc-cmd-SAY): Defer to `erc--send-message'.
(erc--send-message): New implementation.  When called internally and
the variable `erc--current-line-input-split' is non-nil, treat input
as an outgoing message to ensure "send" hooks run and invariants for
prompt markers are preserved.  For example, this means noncommands,
like /SV will have `erc-input-face' applied, which is correct because
this message is sent to an actual target on the server.
(erc--make-input-split): New function.
(erc-send-current-line): Bind `erc--current-line-input-split' when
dispatching prompt-input handlers.  Use helper
`erc--make-input-split'.
(erc--run-send-hooks): Honor existing `refoldp' slot from
`erc--input-split' object.
---
 lisp/erc/erc.el | 50 +++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index a885038411d..4828319727e 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -3659,6 +3659,12 @@ erc--called-as-input-p
   "Non-nil when a user types a \"/slash\" command.
 Remains bound until `erc-cmd-SLASH' returns.")
 
+(defvar erc--current-line-input-split nil
+  "Current `erc--input-split' instance when processing user input.
+This is for special cases in which a \"slash\" command needs
+details about the input it's handling or needs to detect whether
+it's been dispatched by `erc-send-current-line'.")
+
 (defvar-local erc-send-input-line-function #'erc-send-input-line
   "Function for sending lines lacking a leading \"slash\" command.
 When prompt input starts with a \"slash\" command, like \"/MSG\",
@@ -3795,9 +3801,7 @@ erc-cmd-SAY
   (if (string-match "^\\s-*$" line)
       nil
     (string-match "^ ?\\(.*\\)" line)
-    (let ((msg (match-string 1 line)))
-      (erc-display-msg msg)
-      (erc-process-input-line msg nil t))))
+    (erc--send-message (match-string 1 line) nil)))
 (put 'erc-cmd-SAY 'do-not-parse-args t)
 
 (defun erc-cmd-SET (line)
@@ -4507,6 +4511,27 @@ erc--send-message
   ;; FIXME - treat multiline, run hooks, or remove me?
   t)
 
+;; When running inside insert and send hooks, take more care in
+;; dealing with the prompt.
+(cl-defmethod erc--send-message
+  (input-line force &context (erc--current-line-input-split erc--input-split))
+  "Process non-command INPUT-LINE almost as if it's normal chat input.
+Expect INPUT-LINE to differ from the `string' slot of the calling
+context's `erc--current-line-input-split' object because the
+latter is likely a slash command invocation whose handler
+generated INPUT-LINE.  Before inserting INPUT-LINE, split it and
+run `erc-send-modify-hook' and `erc-send-post-hook' on each
+actual outgoing line.  Forgo input validation because this isn't
+interactive input, and skip `erc-send-completed-hook' because it
+will run just before the outer `erc-send-current-line' call
+returns."
+  (let* ((erc-flood-protect (not force))
+         (lines-obj (erc--make-input-split input-line)))
+    (setf (erc--input-split-refoldp lines-obj) t
+          (erc--input-split-cmdp lines-obj) nil)
+    (erc--send-input-lines (erc--run-send-hooks lines-obj)))
+  t)
+
 (defun erc-cmd-MODE (line)
   "Change or display the mode value of a channel or user.
 The first word specifies the target.  The rest is the mode string
@@ -6880,6 +6905,14 @@ erc--inhibit-slash-cmd-insertion
   (when (erc--input-split-cmdp state)
     (setf (erc--input-split-insertp state) nil)))
 
+(defun erc--make-input-split (string)
+  (make-erc--input-split
+   :string string
+   :insertp erc-insert-this
+   :sendp erc-send-this
+   :lines (split-string string erc--input-line-delim-regexp)
+   :cmdp (string-match erc-command-regexp string)))
+
 (defun erc-send-current-line ()
   "Parse current line and send it to IRC."
   (interactive)
@@ -6894,16 +6927,11 @@ erc-send-current-line
             (expand-abbrev))
           (widen)
           (let* ((str (erc-user-input))
-                 (state (make-erc--input-split
-                         :string str
-                         :insertp erc-insert-this
-                         :sendp erc-send-this
-                         :lines (split-string
-                                 str erc--input-line-delim-regexp)
-                         :cmdp (string-match erc-command-regexp str))))
+                 (state (erc--make-input-split str)))
             (run-hook-with-args 'erc--input-review-functions state)
             (when-let (((not (erc--input-split-abortp state)))
                        (inhibit-read-only t)
+                       (erc--current-line-input-split state)
                        (old-buf (current-buffer)))
               (let ((erc--msg-prop-overrides `((erc-msg . msg)
                                                ,@erc--msg-prop-overrides)))
@@ -6969,6 +6997,8 @@ erc--run-send-hooks
                       (run-hook-with-args 'erc-send-pre-hook str)
                       (make-erc-input :string str
                                       :insertp erc-insert-this
+                                      :refoldp (erc--input-split-refoldp
+                                                lines-obj)
                                       :sendp erc-send-this))))
         (run-hook-with-args 'erc-pre-send-functions state)
         (setf (erc--input-split-sendp lines-obj) (erc-input-sendp state)
-- 
2.41.0