elfeed, eww: Be stricter about the returned message ID

Using the second group in piem-link-re is not reliable because the
trailing part of the URL may be anything.  Instead get the inboxes
:url first and then generate a regular expression that has that value
as the prefix.

Message-Id: <20200828031920.7515-5-kyle@kyleam.com>

3 files changed, 24 insertions, 20 deletions

diff --git a/piem-elfeed.el b/piem-elfeed.el
index 5a6472b..b1e112b 100644
--- a/piem-elfeed.el
+++ b/piem-elfeed.el
@@ -43,10 +43,11 @@
 
 (defun piem-elfeed-get-mid ()
   "Return the message ID of an `elfeed-show-mode' buffer."
-  (when (derived-mode-p 'elfeed-show-mode)
-    (when-let ((link (elfeed-entry-link elfeed-show-entry)))
-      (and (string-match piem-link-re link)
-           (match-string 2 link)))))
+  (when-let ((inbox (piem-elfeed-get-inbox))
+             (inbox-url (piem-inbox-get :url inbox))
+             (link (elfeed-entry-link elfeed-show-entry)))
+    (and (string-match (piem-message-link-re inbox-url) link)
+         (match-string 1 link))))
 
 ;;;###autoload
 (define-minor-mode piem-elfeed-mode
diff --git a/piem-eww.el b/piem-eww.el
index 5fb629b..62b7166 100644
--- a/piem-eww.el
+++ b/piem-eww.el
@@ -42,10 +42,11 @@
 
 (defun piem-eww-get-mid ()
   "Return the message ID of an EWW buffer."
-  (when (derived-mode-p 'eww-mode)
-    (when-let ((link (plist-get eww-data :url)))
-      (and (string-match piem-link-re link)
-           (match-string 2 link)))))
+  (when-let ((inbox (piem-eww-get-inbox))
+             (inbox-url (piem-inbox-get :url inbox))
+             (url (plist-get eww-data :url)))
+    (and (string-match (piem-message-link-re inbox-url) url)
+         (match-string 1 url))))
 
 ;;;###autoload
 (define-minor-mode piem-eww-mode
diff --git a/piem.el b/piem.el
index 4b840cb..da1a693 100644
--- a/piem.el
+++ b/piem.el
@@ -255,18 +255,20 @@ Functions should accept one argument, the message ID given to
 (defun piem--ensure-trailing-slash (s)
   (if (string-match-p ".+/\\'" s) s (concat s "/")))
 
-(defvar piem-link-re
-  (rx "/" (group (one-or-more (not (any "/" "\n"))))
-      "/" (group (one-or-more (not (any "/" "\n"))))
-      "/" (group (zero-or-one
-                  (or "raw"
-                      "t.mbox.gz"
-                      (and (or "t" "T") "/#"
-                           (one-or-more (not (any "/" "\n")))))))
-      string-end)
-  "Regular expression matching public-inbox HTTP link.
-The first group is the inbox, the second is the message ID, and
-the rest is any trailing endpoint.")
+(defun piem-message-link-re (url &optional mid)
+  "Return a regular expression matching a public-inbox url.
+URL should be the top-level url for the inbox.  If MID is
+non-nil, make the match specific for that message."
+  (rx-to-string
+   `(and ,(piem--ensure-trailing-slash url)
+         (group ,(or mid
+                     '(one-or-more (not (any "/" "\n")))))
+         "/" (group (zero-or-one
+                     (or "raw"
+                         "t.mbox.gz"
+                         (and (or "t" "T") "/#"
+                              (one-or-more (not (any "/" "\n")))))))
+         string-end)))
 
 (defun piem-inbox-by-header-match ()
   "Return inbox based on matching message headers.