Add user command support for sending private messages.

Can send to either the currently selected user (the %[userSID] keyword
substitution) or a given SID. To make the latter useful (e.g, for
commands sent to a bot) support for static SIDs is needed.

src/core/plugincallback.c

@@ -200,6 +200,7 @@ void plugin_register_callback_functions(struct plugin_handle* handle)
 	handle->hub.set_description = cbfunc_set_hub_description;
 	handle->hub.ucmd_create = cbfunc_ucmd_create;
 	handle->hub.ucmd_add_chat = cbfunc_ucmd_add_chat;
+	handle->hub.ucmd_add_pm = cbfunc_ucmd_add_pm;
 	handle->hub.ucmd_send = cbfunc_ucmd_send;
 	handle->hub.ucmd_free = cbfunc_ucmd_free;
 }

src/core/pluginucmd.c

@@ -145,6 +145,59 @@ int cbfunc_ucmd_add_chat(struct plugin_handle* plugin, struct plugin_ucmd* ucmd,
 	return 1;
 }
 
+int cbfunc_ucmd_add_pm(struct plugin_handle* plugin, struct plugin_ucmd* ucmd, const char* to, const char* message, int echo)
+{
+	/* Double-escape the message - once for when the client sends it back, and
+	 * then again to insert it into the user command message we send to them. */
+	char* temp = adc_msg_escape(message);
+	char* escmsg = adc_msg_escape(temp);
+	free(temp);
+	size_t msglen = strlen(escmsg);
+
+	/* If no target SID is given, use the keyword expansion %[userSID] for the
+	 * client to fill in with the currently selected user. */
+	size_t tolen = (to == NULL) ? 10 : 4;
+
+	/* Format of an echoed PM: "EMSG\s%[mySID]\s<target SID>\s<double-escaped message>\sPM%[mySID]\n".
+	 * Format of a non-echoed PM: "DMSG\s%[mySID]\s<target SID>\s<double-escaped message>\sPM%[mySID]\n". */
+	size_t required = 32 + tolen + msglen;
+	if(required > (ucmd->capacity - ucmd->length))
+	{
+		if(ucmd_expand_tt(ucmd, ucmd->capacity + required) == 0)
+		{
+			plugin->error_msg = "Could not expand memory to store private message.";
+			free(escmsg);
+			return 0;
+		}
+	}
+
+	/* Start with the appropriate ADC command plus the client SID placeholder. */
+	if(echo) strncpy(ucmd->tt + ucmd->length, "EMSG\\s%[mySID]\\s", 16);
+	else strncpy(ucmd->tt + ucmd->length, "DMSG\\s%[mySID]\\s", 16);
+	ucmd->length += 16;
+
+	/* Copy the target ID. */
+	if(to != NULL) strncpy(ucmd->tt + ucmd->length, to, tolen);
+	else strncpy(ucmd->tt + ucmd->length, "%[userSID]", tolen);
+	ucmd->length += tolen;
+
+	/* Space between target and message. */
+	ucmd->tt[ucmd->length++] = '\\';
+	ucmd->tt[ucmd->length++] = 's';
+
+	/* Message. */
+	strncpy(ucmd->tt + ucmd->length, escmsg, msglen);
+	ucmd->length += msglen;
+	free(escmsg);
+
+	/* Add the PM flag and final line break. */
+	strncpy(ucmd->tt + ucmd->length, "\\sPM%[mySID]\\n", 14);
+	ucmd->length += 14;
+
+	/* Done. */
+	return 1;
+}
+
 int cbfunc_ucmd_send(struct plugin_handle* plugin, struct plugin_user* user, struct plugin_ucmd* ucmd)
 {
 	/* Make sure we have a command. */

src/core/pluginucmd.h

@@ -38,6 +38,16 @@ extern struct plugin_ucmd* cbfunc_ucmd_create(struct plugin_handle* plugin, cons
  */
 extern int cbfunc_ucmd_add_chat(struct plugin_handle* plugin, struct plugin_ucmd* ucmd, const char* message, int me);
 
+/* Add a private message to be sent when the user command is clicked.
+ * To: The SID of the user to send the message to. Leave it blank to send to
+ *     the user that was right-clicked in the user list (i.e., a context-based
+ *     message - only effective if the user command is in the user category).
+ * Echo: If true, the message is also echoed to the sending user as in a normal
+ *       PM. If false, it is only sent to the target user and the sending user
+ *       will only see any response.
+ */
+extern int cbfunc_ucmd_add_pm(struct plugin_handle* plugin, struct plugin_ucmd* ucmd, const char* to, const char* message, int echo);
+
 /* Send the user command to a user. */
 extern int cbfunc_ucmd_send(struct plugin_handle* plugin, struct plugin_user* user, struct plugin_ucmd* ucmd);
 

src/plugin_api/handle.h

@@ -125,6 +125,7 @@ typedef void  (*hfunc_set_hub_description)(struct plugin_handle*, const char*);
 
 typedef struct plugin_ucmd* (*hfunc_ucmd_create)(struct plugin_handle*, const char*, size_t);
 typedef int                 (*hfunc_ucmd_add_chat)(struct plugin_handle*, struct plugin_ucmd*, const char*, int);
+typedef int                 (*hfunc_ucmd_add_pm)(struct plugin_handle*, struct plugin_ucmd*, const char*, const char*, int);
 typedef int                 (*hfunc_ucmd_send)(struct plugin_handle*, struct plugin_user*, struct plugin_ucmd*);
 typedef void                (*hfunc_ucmd_free)(struct plugin_handle*, struct plugin_ucmd*);
 
@@ -147,6 +148,7 @@ struct plugin_hub_funcs
 	hfunc_set_hub_description set_description;
 	hfunc_ucmd_create ucmd_create;
 	hfunc_ucmd_add_chat ucmd_add_chat;
+	hfunc_ucmd_add_pm ucmd_add_pm;
 	hfunc_ucmd_send ucmd_send;
 	hfunc_ucmd_free ucmd_free;
 };