feat: add the contacts_dir config key

Adds Config::contactsDir(), the [general] key Task 5 will read to locate
the ContactStore. Empty means the feature is off.

The key is read WITHOUT the general/ prefix, like notmuch_config, because
QSettings' INI backend strips a section literally named [general]. Absent
or empty is silent; a set path that does not exist is reported through
addProblem(). A leading ~ is expanded by a local helper, since config.cpp
expands no other path and this is the first one to need it.

3 files changed, 150 insertions, 0 deletions

diff --git a/src/config.cpp b/src/config.cpp
index 184c756..3cd842b 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -94,6 +94,21 @@ bool generatorIsFlat(const QString &generator)
            || generator == QStringLiteral("drafts");
 }
 
+/// Expands a leading "~" to the home directory.
+///
+/// No other key in config.cpp expands one; contacts_dir is the first, and only
+/// because the README documents its usual value as
+/// "~/.local/share/vdirsyncer/contacts/". A shared helper would serve one
+/// caller, so this stays local until a second one exists.
+QString expandTilde(const QString &path)
+{
+    if (path == QLatin1String("~"))
+        return QDir::homePath();
+    if (path.startsWith(QLatin1String("~/")))
+        return QDir::homePath() + path.mid(1);
+    return path;
+}
+
 } // namespace
 
 QString Account::scopedQuery(const QString &query) const
@@ -236,6 +251,27 @@ void Config::load(const QString &path)
     m_notmuchConfig =
         settings.value(QStringLiteral("notmuch_config")).toString();
 
+    // [general], so no prefix, per the note above. Tilde is expanded for the
+    // README's documented value, "~/.local/share/vdirsyncer/contacts/", which
+    // would otherwise name a literal "~" directory that does not exist.
+    //
+    // Absent or empty is silent: the feature is simply off, which is an
+    // ordinary machine rather than a misconfiguration. A path that is set and
+    // missing is reported, because there the user asked for something and is
+    // not getting it. The value is KEPT rather than cleared: a vdirsyncer
+    // target may not exist until its first run, and ContactStore's walk treats
+    // a missing directory as empty anyway, so the warning is the whole report.
+    const QString contactsDir =
+        settings.value(QStringLiteral("contacts_dir")).toString().trimmed();
+    if (!contactsDir.isEmpty()) {
+        m_contactsDir = expandTilde(contactsDir);
+        if (!QFileInfo::exists(m_contactsDir)) {
+            addProblem(tr("Contacts directory '%1' does not exist; contact "
+                          "completion will find no contacts.")
+                           .arg(m_contactsDir));
+        }
+    }
+
     // Absent is fine and silent: the default is 1.0. Present but unparseable
     // is a problem, since the user asked for something and is not getting it.
     // The range is enforced by MessageView::clampZoom(), the one place that
diff --git a/src/config.h b/src/config.h
index 5a43d8c..c6f1cae 100644
--- a/src/config.h
+++ b/src/config.h
@@ -404,6 +404,19 @@ public:
     /// Optional alternate notmuch config file. Empty means "let notmuch decide".
     QString notmuchConfig() const { return m_notmuchConfig; }
 
+    /// The vdirsyncer contacts directory (vCard 3.0 files), or empty to turn
+    /// contact completion off.
+    ///
+    /// A [general] key, read WITHOUT the "general/" prefix like notmuch_config
+    /// above. There is no default: guessing a vdir would make the application
+    /// read a directory the user never named, and a machine with no address
+    /// book is an ordinary machine. A leading "~" is expanded, because the
+    /// README documents the usual value in that form. A set path that does not
+    /// exist is reported through addProblem(), because the user asked for
+    /// something and is not getting it; an absent key is silent, because that
+    /// is simply the feature being off rather than a misconfiguration.
+    QString contactsDir() const { return m_contactsDir; }
+
     /// Matches every configured account's sent mail, or empty when no account
     /// configures one.
     ///
@@ -578,6 +591,7 @@ private:
     QString m_syncStatus;
     int m_toolbarIconSize = 24;
     QString m_notmuchConfig;
+    QString m_contactsDir;
     QString m_dateFormat;
     QStringList m_forwardPrefixes;
     QString m_language;
diff --git a/tests/test_config.cpp b/tests/test_config.cpp
index 70e3705..05ddbee 100644
--- a/tests/test_config.cpp
+++ b/tests/test_config.cpp
@@ -144,6 +144,11 @@ private slots:
     void theSignatureKeysAreRead();
     void anAccountSignatureOverridesTheComposeDefault();
     void aMalformedSignaturePositionIsReportedAndFallsBack();
+    void contactsDirIsEmptyWithoutTheKey();
+    void contactsDirIsEmptyWhenBlank();
+    void contactsDirIsActuallyRead();
+    void contactsDirExpandsATilde();
+    void contactsDirThatDoesNotExistIsReported();
 };
 
 static QString writeIni(const QTemporaryDir &dir, const QString &body)
@@ -2761,5 +2766,100 @@ void TestConfig::aMalformedSignaturePositionIsReportedAndFallsBack()
              "an unrecognised signature_position was accepted silently");
 }
 
+void TestConfig::contactsDirIsEmptyWithoutTheKey()
+{
+    // Absent is the feature off, and silently so: a machine with no address
+    // book is an ordinary machine, not a misconfiguration. A modal on every
+    // launch about a key the user never wrote would train them to dismiss
+    // dialogs without reading them. Only problems() is asserted, not
+    // warnings(): a bare [general] also carries the "no sync command" notice.
+    QTemporaryDir dir;
+    Config config;
+    config.load(writeIni(dir, QStringLiteral("[general]\n")));
+
+    QVERIFY(config.contactsDir().isEmpty());
+    QVERIFY(config.problems().isEmpty());
+}
+
+void TestConfig::contactsDirIsEmptyWhenBlank()
+{
+    // A key written with no value is the same "off" as an absent one, not a
+    // problem: the user named nothing, so nothing is missing. Trimmed too, so
+    // a stray space cannot become a path that does not exist and warn.
+    QTemporaryDir dir;
+    Config config;
+    config.load(writeIni(dir, QStringLiteral("[general]\n"
+                                             "contacts_dir = \n")));
+
+    QVERIFY(config.contactsDir().isEmpty());
+    QVERIFY(config.problems().isEmpty());
+}
+
+void TestConfig::contactsDirIsActuallyRead()
+{
+    // [general] keys are read WITHOUT the general/ prefix, per the note at the
+    // top of Config::load(). A "general/contacts_dir" lookup matches nothing
+    // and would leave the accessor empty, which looks exactly like the feature
+    // being off: the whole key would be silently inert.
+    QTemporaryDir dir;
+    Config config;
+    config.load(writeIni(dir, QStringLiteral("[general]\n"
+                                             "contacts_dir=%1\n")
+                                  .arg(dir.path())));
+
+    QCOMPARE(config.contactsDir(), dir.path());
+    QVERIFY(config.problems().isEmpty());
+}
+
+void TestConfig::contactsDirExpandsATilde()
+{
+    // The README documents the usual value as
+    // "~/.local/share/vdirsyncer/contacts/", so a leading "~" has to reach
+    // QDir::homePath() or the user gets a literal "~" directory that does not
+    // exist. config.cpp expands no other path key; this is the first, which is
+    // why the expansion lives here rather than in a shared helper nothing else
+    // calls.
+    QTemporaryDir dir;
+    Config config;
+    config.load(writeIni(dir, QStringLiteral("[general]\n"
+                                             "contacts_dir=~\n")));
+
+    QCOMPARE(config.contactsDir(), QDir::homePath());
+    QVERIFY(config.problems().isEmpty());
+
+    // Under a subpath, which is the form the README actually names. The
+    // directory deliberately does not exist, which also pins the missing-path
+    // decision: the value is KEPT, not cleared, and the warning is what
+    // reports it. A vdirsyncer target may not exist until its first run.
+    QTemporaryDir other;
+    Config nested;
+    const QString sub = QStringLiteral(".qtmaildir-test-no-such-contacts");
+    nested.load(writeIni(other, QStringLiteral("[general]\n"
+                                               "contacts_dir=~/%1\n")
+                                    .arg(sub)));
+    QCOMPARE(nested.contactsDir(),
+             QDir::homePath() + QLatin1Char('/') + sub);
+}
+
+void TestConfig::contactsDirThatDoesNotExistIsReported()
+{
+    // Present and not there is a problem, the same line message_zoom and
+    // forward_prefixes draw: the user asked for something and is not getting
+    // it. The value is kept so the accessor still says what was asked for.
+    QTemporaryDir dir;
+    const QString missing = dir.filePath(QStringLiteral("no-such-contacts"));
+    Config config;
+    config.load(writeIni(dir, QStringLiteral("[general]\n"
+                                             "contacts_dir=%1\n")
+                                  .arg(missing)));
+
+    QVERIFY2(!config.problems().isEmpty(),
+             "a configured but missing contacts directory must be reported");
+    const QString joined = config.problems().join(QLatin1Char('\n'));
+    QVERIFY2(joined.contains(missing),
+             "the warning must name the path the user wrote");
+    QCOMPARE(config.contactsDir(), missing);
+}
+
 QTEST_MAIN(TestConfig)
 #include "test_config.moc"