Introduce the concept of Contacts.Chunk

This commit introduces a new class `Contacts.Chunk`. Just like libfolks,
we see a contact as a collection of data, or to word it differently: a
collection built up from "chunks" of information.

The net result of adding this concept adds quite a bit of lines of code,
but it does have some major benefits:

* Rather than stuffing new properties into yet another if-else spread
  out over multiple places in contacts-utils (and quite a bit of other
  files), we can create a new subclass of `Contacts.Chunk`
* This also goes for property-specific logic, which we can consolidate
  within their appropriate classes/files.
* All of our logic is now unit-testable

In the future, this would allow for more cleanups/features:

* We can put the serialization code for each property inside the
  `Contacts.Chunk`
* We can extend ContactSheet to show a vCard's information, before
  actually importing it into a Folks.Individual.
* We can write unit tests on the set of chunks, rather than regularly
  having to deal with yet another regression in e.g. the birthday
  editor.

1 files changed, 60 insertions, 0 deletions

diff --git a/src/core/contacts-nickname-chunk.vala b/src/core/contacts-nickname-chunk.vala
new file mode 100644
index 0000000..ba505f0
--- /dev/null
+++ b/src/core/contacts-nickname-chunk.vala
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2022 Niels De Graef <nielsdegraef@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+using Folks;
+
+/**
+ * A {@link Chunk} that represents the nickname of a contact.
+ */
+public class Contacts.NicknameChunk : Chunk {
+
+  public string nickname {
+    get { return this._nickname; }
+    set {
+      if (this._nickname == value)
+        return;
+
+      bool was_empty = this.is_empty;
+      this._nickname = value;
+      notify_property ("nickname");
+      if (this.is_empty != was_empty)
+        notify_property ("is-empty");
+    }
+  }
+  private string _nickname = "";
+
+  public override string property_name { get { return "nickname"; } }
+
+  public override bool is_empty { get { return this._nickname.strip () == ""; } }
+
+  construct {
+    if (persona != null) {
+      return_if_fail (persona is NameDetails);
+      persona.bind_property ("nickname", this, "nickname", BindingFlags.SYNC_CREATE);
+    }
+  }
+
+  public override Value? to_value () {
+    return this.nickname;
+  }
+
+  public override async void save_to_persona () throws GLib.Error
+      requires (this.persona is NameDetails) {
+
+    yield ((NameDetails) this.persona).change_nickname (this.nickname);
+  }
+}