Add search support to the contact list

This searches everything in `PurplePerson` and all of it's contacts, but does not yet cover tags. I am planning on covering that in another review request.

Right now the matching is just using `strstr`, but will will update this as part of [PIDGIN-17737](https://issues.imfreedom.org/issue/PIDGIN-17737/).

I also tried to figure out how to get focus back to the list view, but didn't come up with any viable solutions.

Testing Done:
Ran the unit tests and did a bunch of searches in the contact list with the demo protocol plugin.

Bugs closed: PIDGIN-17717

Reviewed at https://reviews.imfreedom.org/r/2211/

6 files changed, 255 insertions, 1 deletions

diff --git a/libpurple/purplecontactinfo.c b/libpurple/purplecontactinfo.c
index 9f29f8a509..4d73ee3fd2 100644
--- a/libpurple/purplecontactinfo.c
+++ b/libpurple/purplecontactinfo.c
@@ -797,3 +797,43 @@ purple_contact_info_compare(PurpleContactInfo *a, PurpleContactInfo *b) {
 
 	return purple_utf8_strcasecmp(name_a, name_b);
 }
+
+gboolean
+purple_contact_info_matches(PurpleContactInfo *info, const char *needle) {
+	PurpleContactInfoPrivate *priv = NULL;
+
+	g_return_val_if_fail(PURPLE_IS_CONTACT_INFO(info), FALSE);
+
+	if(purple_strempty(needle)) {
+		return TRUE;
+	}
+
+	priv = purple_contact_info_get_instance_private(info);
+
+	if(!purple_strempty(priv->id)) {
+		if(strstr(priv->id, needle) != NULL) {
+			return TRUE;
+		}
+	}
+
+	if(!purple_strempty(priv->username)) {
+		if(strstr(priv->username, needle) != NULL) {
+			return TRUE;
+		}
+	}
+
+	if(!purple_strempty(priv->alias)) {
+		if(strstr(priv->alias, needle) != NULL) {
+			return TRUE;
+		}
+	}
+
+	if(!purple_strempty(priv->display_name)) {
+		if(strstr(priv->display_name, needle) != NULL) {
+			return TRUE;
+		}
+	}
+
+	/* Nothing matched, so return FALSE. */
+	return FALSE;
+}
diff --git a/libpurple/purplecontactinfo.h b/libpurple/purplecontactinfo.h
index f0ef858521..e1bfc3ea7d 100644
--- a/libpurple/purplecontactinfo.h
+++ b/libpurple/purplecontactinfo.h
@@ -355,6 +355,22 @@ const char *purple_contact_info_get_name_for_display(PurpleContactInfo *info);
  */
 int purple_contact_info_compare(PurpleContactInfo *a, PurpleContactInfo *b);
 
+/**
+ * purple_contact_info_matches:
+ * @info: The instance.
+ * @needle: (nullable): The string to match.
+ *
+ * This will determine if the alias, display name, or username matches @needle.
+ *
+ * If @needle is %NULL or empty string, %TRUE will be returned.
+ *
+ * Returns: %TRUE if @needle matches any of the above properties, otherwise
+ *          %FALSE.
+ *
+ * Since: 3.0.0
+ */
+gboolean purple_contact_info_matches(PurpleContactInfo *info, const char *needle);
+
 G_END_DECLS
 
 #endif /* PURPLE_CONTACT_INFO_H */
diff --git a/libpurple/purpleperson.c b/libpurple/purpleperson.c
index 14d4cb1885..8545d653e0 100644
--- a/libpurple/purpleperson.c
+++ b/libpurple/purpleperson.c
@@ -20,6 +20,8 @@
 
 #include "util.h"
 
+#include "util.h"
+
 struct _PurplePerson {
 	GObject parent;
 
@@ -122,6 +124,17 @@ purple_person_sort_contacts(PurplePerson *person) {
 	}
 }
 
+/* This function is used by purple_person_matches to determine if a contact info
+ * matches the needle.
+ */
+static gboolean
+purple_person_matches_find_func(gconstpointer a, gconstpointer b) {
+	PurpleContactInfo *info = (gpointer)a;
+	const char *needle = b;
+
+	return purple_contact_info_matches(info, needle);
+}
+
 /******************************************************************************
  * Callbacks
  *****************************************************************************/
@@ -569,3 +582,24 @@ purple_person_has_contacts(PurplePerson *person) {
 
 	return person->contacts->len > 0;
 }
+
+gboolean
+purple_person_matches(PurplePerson *person, const char *needle) {
+	g_return_val_if_fail(PURPLE_IS_PERSON(person), FALSE);
+
+	if(purple_strempty(needle)) {
+		return TRUE;
+	}
+
+	/* Check if the person's alias matches. */
+	if(!purple_strempty(person->alias)) {
+		if(strstr(person->alias, needle) != NULL) {
+			return TRUE;
+		}
+	}
+
+	/* See if any of the contact infos match. */
+	return g_ptr_array_find_with_equal_func(person->contacts, needle,
+	                                        purple_person_matches_find_func,
+	                                        NULL);
+}
diff --git a/libpurple/purpleperson.h b/libpurple/purpleperson.h
index a7a64bed73..5d7111a5e6 100644
--- a/libpurple/purpleperson.h
+++ b/libpurple/purpleperson.h
@@ -220,6 +220,23 @@ PurpleContactInfo *purple_person_get_priority_contact_info(PurplePerson *person)
  */
 gboolean purple_person_has_contacts(PurplePerson *person);
 
+/**
+ * purple_person_matches:
+ * @person: The instance.
+ * @needle: (nullable): The string to match on.
+ *
+ * Checks if the alias matches @needle. This also checks @needle against
+ * [method@Purple.ContactInfo.matches] for each [class@Purple.ContactInfo] that
+ * @person is tracking.
+ *
+ * If @needle is %NULL or empty string, %TRUE will be returned.
+ *
+ * Returns: %TRUE if @person matches @needle in any way.
+ *
+ * Since: 3.0.0
+ */
+gboolean purple_person_matches(PurplePerson *person, const char *needle);
+
 G_END_DECLS
 
 #endif /* PURPLE_PERSON_H */
diff --git a/libpurple/tests/test_contact_info.c b/libpurple/tests/test_contact_info.c
index cea1ed90e6..5584cf1e1f 100644
--- a/libpurple/tests/test_contact_info.c
+++ b/libpurple/tests/test_contact_info.c
@@ -315,6 +315,82 @@ test_purple_contact_info_compare_name__name(void) {
 }
 
 /******************************************************************************
+ * Matches
+ *****************************************************************************/
+static void
+test_purple_contact_info_matches_accepts_null(void) {
+	PurpleContactInfo *info = purple_contact_info_new(NULL);
+
+	g_assert_true(purple_contact_info_matches(info, NULL));
+
+	g_clear_object(&info);
+}
+
+static void
+test_purple_contact_info_matches_empty_string(void) {
+	PurpleContactInfo *info = purple_contact_info_new(NULL);
+
+	g_assert_true(purple_contact_info_matches(info, ""));
+
+	g_clear_object(&info);
+}
+
+static void
+test_purple_contact_info_matches_id(void) {
+	PurpleContactInfo *info = purple_contact_info_new("this is an id");
+
+	g_assert_true(purple_contact_info_matches(info, "an"));
+
+	g_clear_object(&info);
+}
+
+static void
+test_purple_contact_info_matches_username(void) {
+	PurpleContactInfo *info = purple_contact_info_new(NULL);
+
+	purple_contact_info_set_username(info, "username");
+
+	g_assert_true(purple_contact_info_matches(info, "name"));
+
+	g_clear_object(&info);
+}
+
+static void
+test_purple_contact_info_matches_alias(void) {
+	PurpleContactInfo *info = purple_contact_info_new(NULL);
+
+	purple_contact_info_set_alias(info, "alias");
+
+	g_assert_true(purple_contact_info_matches(info, "lia"));
+
+	g_clear_object(&info);
+}
+
+static void
+test_purple_contact_info_matches_display_name(void) {
+	PurpleContactInfo *info = purple_contact_info_new(NULL);
+
+	purple_contact_info_set_display_name(info, "display name");
+
+	g_assert_true(purple_contact_info_matches(info, "play"));
+
+	g_clear_object(&info);
+}
+
+static void
+test_purple_contact_info_matches_none(void) {
+	PurpleContactInfo *info = purple_contact_info_new("id");
+
+	purple_contact_info_set_username(info, "username");
+	purple_contact_info_set_alias(info, "alias");
+	purple_contact_info_set_display_name(info, "display name");
+
+	g_assert_false(purple_contact_info_matches(info, "nothing"));
+
+	g_clear_object(&info);
+}
+
+/******************************************************************************
  * Main
  *****************************************************************************/
 gint
@@ -352,5 +428,20 @@ main(gint argc, gchar *argv[]) {
 	g_test_add_func("/contact-info/compare/name__name",
 	                test_purple_contact_info_compare_name__name);
 
+	g_test_add_func("/contact-info/matches/accepts_null",
+	                test_purple_contact_info_matches_accepts_null);
+	g_test_add_func("/contact-info/matches/emptry_string",
+	                test_purple_contact_info_matches_empty_string);
+	g_test_add_func("/contact-info/matches/id",
+	                test_purple_contact_info_matches_id);
+	g_test_add_func("/contact-info/matches/username",
+	                test_purple_contact_info_matches_username);
+	g_test_add_func("/contact-info/matches/alias",
+	                test_purple_contact_info_matches_alias);
+	g_test_add_func("/contact-info/matches/display_name",
+	                test_purple_contact_info_matches_display_name);
+	g_test_add_func("/contact-info/matches/none",
+	                test_purple_contact_info_matches_none);
+
 	return g_test_run();
 }
diff --git a/libpurple/tests/test_person.c b/libpurple/tests/test_person.c
index f5e3cb3822..a47852b692 100644
--- a/libpurple/tests/test_person.c
+++ b/libpurple/tests/test_person.c
@@ -443,6 +443,53 @@ test_purple_person_priority_multiple_with_change(void) {
 }
 
 /******************************************************************************
+ * Matches tests
+ *****************************************************************************/
+static void
+test_purple_person_matches_accepts_null(void) {
+	PurplePerson *person = purple_person_new();
+
+	g_assert_true(purple_person_matches(person, NULL));
+
+	g_clear_object(&person);
+}
+
+static void
+test_purple_person_matches_empty_string(void) {
+	PurplePerson *person = purple_person_new();
+
+	g_assert_true(purple_person_matches(person, ""));
+
+	g_clear_object(&person);
+}
+
+static void
+test_purple_person_matches_alias(void) {
+	PurplePerson *person = purple_person_new();
+
+	purple_person_set_alias(person, "this is the alias");
+
+	g_assert_true(purple_person_matches(person, "the"));
+	g_assert_false(purple_person_matches(person, "what"));
+
+	g_clear_object(&person);
+}
+
+static void
+test_purple_person_matches_contact_info(void) {
+	PurplePerson *person = purple_person_new();
+	PurpleContactInfo *info = purple_contact_info_new(NULL);
+
+	purple_contact_info_set_username(info, "user1");
+	purple_person_add_contact_info(person, info);
+	g_clear_object(&info);
+
+	g_assert_true(purple_person_matches(person, "user1"));
+
+	g_clear_object(&person);
+}
+
+/******************************************************************************
  * Main
  *****************************************************************************/
 gint
@@ -476,5 +523,14 @@ main(gint argc, gchar *argv[]) {
 	g_test_add_func("/person/priority/multiple-with-change",
 	                test_purple_person_priority_multiple_with_change);
 
+	g_test_add_func("/person/matches/accepts_null",
+	                test_purple_person_matches_accepts_null);
+	g_test_add_func("/person/matches/empty_string",
+	                test_purple_person_matches_empty_string);
+	g_test_add_func("/person/matches/alias",
+	                test_purple_person_matches_alias);
+	g_test_add_func("/person/matches/contact_info",
+	                test_purple_person_matches_contact_info);
+
 	return g_test_run();
-}
\ No newline at end of file
+}