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.

2 files changed, 50 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;