From d35c949a134524395b20617855570e8d5f0867af Mon Sep 17 00:00:00 2001
From: default <nobody@localhost>
Date: Fri, 12 May 2023 11:56:17 +0200
Subject: [PATCH] Resolve (partially) the issue with mentions without server.

Mastodon (mainly from the API) usually include mentions without server,
which is just stupid. This patch tries to resolve these broken mentions in
process_tags() by looking for a user name starting with it in the already
pre-populated tag list. As of now, this only works if the message is an
inReplyTo and the broken mention is the one of the original
(attributedTo) poster.
---
 activitypub.c | 69 +++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 51 insertions(+), 18 deletions(-)

diff --git a/activitypub.c b/activitypub.c
index b322a40..51a2cfa 100644
--- a/activitypub.c
+++ b/activitypub.c
@@ -368,36 +368,69 @@ void process_tags(snac *snac, const char *content, xs_str **n_content, xs_list *
     xs_val *v;
     int n = 0;
 
-    split = xs_regex_split(content, "(@[A-Za-z0-9_]+@[A-Za-z0-9\\.-]+|&#[0-9]+;|#[^ ,\\.:;<]+)");
+    split = xs_regex_split(content, "(@[A-Za-z0-9_]+(@[A-Za-z0-9\\.-]+)?|&#[0-9]+;|#[^ ,\\.:;<]+)");
 
     p = split;
     while (xs_list_iter(&p, &v)) {
         if ((n & 0x1)) {
             if (*v == '@') {
-                /* query the webfinger about this fellow */
-                xs *v2    = xs_strip_chars_i(xs_dup(v), "@.");
-                xs *actor = NULL;
-                xs *uid   = NULL;
-                int status;
+                xs *link = NULL;
 
-                status = webfinger_request(v2, &actor, &uid);
+                if (strchr(v + 1, '@') == NULL) {
+                    /* only one @? it's a dumb Mastodon-like mention
+                       without server; check if there is anybody
+                       whose name starts with this in the tag list */
+                    xs_list *p2 = tl;
+                    xs_dict *v2;
+                    xs *pname = xs_fmt("%s@", v);
 
-                if (valid_status(status)) {
-                    xs *d = xs_dict_new();
-                    xs *n = xs_fmt("@%s", uid);
-                    xs *l = xs_fmt("<a href=\"%s\" class=\"u-url mention\">%s</a>", actor, n);
+                    while (xs_list_iter(&p2, &v2)) {
+                        const char *type = xs_dict_get(v2, "type");
 
-                    d = xs_dict_append(d, "type",   "Mention");
-                    d = xs_dict_append(d, "href",   actor);
-                    d = xs_dict_append(d, "name",   n);
+                        if (type && strcmp(type, "Mention") == 0) {
+                            const char *name = xs_dict_get(v2, "name");
+                            const char *href = xs_dict_get(v2, "href");
 
-                    tl = xs_list_append(tl, d);
+                            if (name && href && (xs_startswith(name, pname) ||
+                                                 xs_startswith(name, pname + 1))) {
+                                /* good enough :shrug2: */
+                                link = xs_fmt(
+                                    "<a href=\"%s\" class=\"u-url mention\">%s</a>", href, name);
 
-                    /* add the code */
-                    nc = xs_str_cat(nc, l);
+                                break;
+                            }
+                        }
+                    }
+
+                    snac_debug(snac, 2, xs_fmt(
+                        "mention without server '%s' (%s)", v, link ? link : "none"));
                 }
+                else {
+                    /* query the webfinger about this fellow */
+                    xs *v2    = xs_strip_chars_i(xs_dup(v), "@.");
+                    xs *actor = NULL;
+                    xs *uid   = NULL;
+                    int status;
+
+                    status = webfinger_request(v2, &actor, &uid);
+
+                    if (valid_status(status)) {
+                        xs *d = xs_dict_new();
+                        xs *n = xs_fmt("@%s", uid);
+
+                        d = xs_dict_append(d, "type",   "Mention");
+                        d = xs_dict_append(d, "href",   actor);
+                        d = xs_dict_append(d, "name",   n);
+
+                        tl = xs_list_append(tl, d);
+
+                        link = xs_fmt("<a href=\"%s\" class=\"u-url mention\">%s</a>", actor, n);
+                    }
+                }
+
+                if (!xs_is_null(link))
+                    nc = xs_str_cat(nc, link);
                 else
-                    /* store as is */
                     nc = xs_str_cat(nc, v);
             }
             else