Add erc-button helper for substituting command keys

* lisp/erc/erc-button.el (erc-button-mode, erc-button-enable): Warn if
`erc-button-alist' contains deprecated FORM field in `nicknames'
entry.
(erc-button-alist): Discourage arbitrary sexp form for third item of
entries and offer more useful bounds-modifying function in its place.
Mention that anything other than `erc-button-buttonize-nicks' is
deprecated as the FORM field in a `nicknames' entry.  Bump
package-version even though this doesn't introduce a visible change in
the default value.
(erc-button--maybe-warn-arbitrary-sexp): Add helper for validating
third `erc-button-alist' field.
(erc-button--check-nicknames-entry): Add helper to check for
deprecated items in `erc-button-alist'.
(erc-button--preserve-bounds): Add function to serve as default value
for `erc-button--modify-nick-function).
(erc-button--modify-nick-function): Add new variable to hold a
function that filters nickname bounds when buttonizing.
(erc-button--phantom-users, erc-button--add-phantom-speaker,
erc-button--phantom-users-mode): Add new internal minor mode for
treating unseen speakers of PRIVMSGs as known members of the server
for things like coloring nicks during buffer playback.
(erc-button--get-user-from-speaker-naive): Add temporary utility
function to scrape nick from speaker in narrowed buffer.  This will be
replaced by an account-aware version in next major ERC release.
(erc-button-add-nickname-buttons): Accommodate function variant for
"form" field of `erc-button-alist' entries.  Minor optimizations.
This function will likely become the primary juncture for applying
text properties that support nickname-related user-intelligence
features.
(erc-button-add-buttons-1): Show warning when arbitrary sexp for third
"form" field encountered.  Accommodate binary function instead.
(erc-button--substitute-command-keys-in-region): Add helper function
for applying key substitutions in ERC warning messages.
(erc-button--display-error-notice-with-keys): Add new helper function
for displaying ad hoc warnings that possibly require key substitution.
(erc-button--display-error-notice-with-keys-and-warn): Add variant of
`erc-button--display-error-notice-with-keys' that also emits warnings.
* lisp/erc/erc-networks.el (erc-networks--ensure-announced,
erc-networks--on-MOTD-end): Use new key-substitutions helper from
erc-button.
* test/lisp/erc/erc-tests.el
(erc-button--display-error-notice-with-keys): New test.
* test/lisp/erc/resources/base/assoc/bouncer-history/foonet.eld: Add
unknown speaker in channel for phantom store to handle.  Currently
requires manual intervention to leverage.  (Bug#60933.)

2 files changed, 62 insertions, 0 deletions

diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index 6e66de53edd..b155f85ab8a 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -1790,4 +1790,65 @@ connection."
                       (put 'erc-mname-enable 'definition-name 'mname)
                       (put 'erc-mname-disable 'definition-name 'mname))))))
 
+
+;; XXX move erc-button tests to new file if more added.
+(require 'erc-button)
+
+;; See also `erc-scenarios-networks-announced-missing' in
+;; erc-scenarios-misc.el for a more realistic example.
+(ert-deftest erc-button--display-error-notice-with-keys ()
+  (with-current-buffer (get-buffer-create "*fake*")
+    (let ((mode erc-button-mode)
+          (inhibit-message noninteractive)
+          erc-modules
+          erc-kill-channel-hook erc-kill-server-hook erc-kill-buffer-hook)
+      (erc-mode)
+      (erc-tests--set-fake-server-process "sleep" "1")
+      (erc--initialize-markers (point) nil)
+      (erc-button-mode +1)
+      (should (equal (erc-button--display-error-notice-with-keys
+                      "If \\[erc-bol] fails, "
+                      "see \\[erc-bug] or `erc-mode-map'.")
+                     "*** If C-a fails, see M-x erc-bug or `erc-mode-map'."))
+      (goto-char (point-min))
+
+      (ert-info ("Keymap substitution succeeds")
+        (erc-button-next)
+        (should (looking-at "C-a"))
+        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
+        (erc-button-press-button)
+        (with-current-buffer "*Help*"
+          (goto-char (point-min))
+          (should (search-forward "erc-bol" nil t)))
+        (erc-button-next)
+        (erc-button-previous) ; end of interval correct
+        (should (looking-at "a fails")))
+
+      (ert-info ("Extended command mapping succeeds")
+        (erc-button-next)
+        (should (looking-at "M-x erc-bug"))
+        (erc-button-press-button)
+        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
+        (with-current-buffer "*Help*"
+          (goto-char (point-min))
+          (should (search-forward "erc-bug" nil t))))
+
+      (ert-info ("Symbol-description face preserved") ; mutated by d-e-n-w-k
+        (erc-button-next)
+        (should (equal (get-text-property (point) 'font-lock-face)
+                       '(erc-button erc-error-face)))
+        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
+        (should (eq erc-button-face 'erc-button))) ; extent evaporates
+
+      (ert-info ("Format when trailing args include non-strings")
+        (should (equal (erc-button--display-error-notice-with-keys
+                        "abc" " %d def" " 45%s" 123 '\6)
+                       "*** abc 123 def 456")))
+
+      (when noninteractive
+        (unless mode
+          (erc-button-mode -1))
+        (kill-buffer "*Help*")
+        (kill-buffer)))))
+
 ;;; erc-tests.el ends here
diff --git a/test/lisp/erc/resources/base/assoc/bouncer-history/foonet.eld b/test/lisp/erc/resources/base/assoc/bouncer-history/foonet.eld
index 58df79e19fa..f34ae02f4e4 100644
--- a/test/lisp/erc/resources/base/assoc/bouncer-history/foonet.eld
+++ b/test/lisp/erc/resources/base/assoc/bouncer-history/foonet.eld
@@ -27,6 +27,7 @@
  (0 ":bob!~u@svpn88yjcdj42.irc PRIVMSG #chan :[07:04:02] alice: Here come the lovers, full of joy and mirth.")
  (0 ":alice!~u@svpn88yjcdj42.irc PRIVMSG #chan :[07:04:07] bob: According to the fool's bolt, sir, and such dulcet diseases.")
  (0 ":bob!~u@svpn88yjcdj42.irc PRIVMSG #chan :[07:04:10] alice: And hang himself. I pray you, do my greeting.")
+ (0 ":someone!~u@abcdefg.irc PRIVMSG #chan :[07:04:10] hi everyone.")
  (0 ":alice!~u@svpn88yjcdj42.irc PRIVMSG #chan :[07:04:18] bob: And you sat smiling at his cruel prey.")
  (0 ":bob!~u@svpn88yjcdj42.irc PRIVMSG #chan :[07:04:21] alice: Or never after look me in the face.")
  (0 ":alice!~u@svpn88yjcdj42.irc PRIVMSG #chan :[07:04:25] bob: If that may be, than all is well. Come, sit down, every mother's son, and rehearse your parts. Pyramus, you begin: when you have spoken your speech, enter into that brake; and so every one according to his cue.")