feat: complete contacts in the query bar

from: and to: now offer the vCard store's addresses, each quoted via
SearchTerm::quote() with the contact's name as the description. The store
is the enumerator libnotmuch does not expose, which is what the old
complete-nothing comment said was missing; it keeps that role for folder:,
subject:, attachment:, thread: and id:.

With no store configured the branch returns {} and the behaviour is
unchanged.

3 files changed, 153 insertions, 5 deletions

diff --git a/src/querycompleter.cpp b/src/querycompleter.cpp
index 9848faf..1b4c2fc 100644
--- a/src/querycompleter.cpp
+++ b/src/querycompleter.cpp
@@ -19,6 +19,7 @@
 #include "querycompleter.h"
 
 #include "config.h"
+#include "searchterm.h"
 
 #include <QCompleter>
 #include <QCoreApplication>
@@ -597,6 +598,11 @@ void QueryCompleter::setTags(const QStringList &tags)
     m_tags = tags;
 }
 
+void QueryCompleter::setContacts(const QList<Contact> &contacts)
+{
+    m_contacts = contacts;
+}
+
 QList<CompletionEntry> QueryCompleter::entriesFor(
     const CompletionContext &context) const
 {
@@ -649,10 +655,27 @@ QList<CompletionEntry> QueryCompleter::entriesFor(
         return entries;
     }
 
-    // from:, to:, folder:, subject:, attachment:, thread:, id: complete no
-    // values. Addresses need an enumerator libnotmuch does not expose;
-    // folder: matches a Maildir folder name that config cannot enumerate, and
-    // the rest are free text.
+    // The addresses live in the vCard store, which is the enumerator
+    // libnotmuch does not expose. The VALUE is the bare address because that
+    // is what notmuch matches on; the contact's name is the description, so
+    // the popup says who owns it.
+    if (context.prefix == QStringLiteral("from")
+        || context.prefix == QStringLiteral("to")) {
+        QList<CompletionEntry> entries;
+        entries.reserve(m_contacts.size());
+        for (const Contact &contact : m_contacts) {
+            const QString address = SearchTerm::quote(contact.email);
+            if (address.isEmpty())
+                continue;
+            entries.append({ address, contact.name });
+        }
+        return entries;
+    }
+
+    // folder:, subject:, attachment:, thread:, id: complete no values. folder:
+    // matches a Maildir folder name that config cannot enumerate, and the rest
+    // are free text. from: and to: no longer belong in this list: the vCards
+    // are the enumerator they lacked.
     return {};
 }
 
diff --git a/src/querycompleter.h b/src/querycompleter.h
index 27161bc..147909c 100644
--- a/src/querycompleter.h
+++ b/src/querycompleter.h
@@ -24,6 +24,7 @@
 #include <QStringList>
 
 #include "completionentry.h"
+#include "contactstore.h"
 
 class Config;
 class QCompleter;
@@ -98,6 +99,11 @@ public:
     /// Replaces the tag candidates. Called with the worker's allTagsReady.
     void setTags(const QStringList &tags);
 
+    /// Replaces the address candidates. Called by MainWindow after the vCard
+    /// store is read, and REPLACES rather than merges for the same reason
+    /// setTags does: the caller owns the list.
+    void setContacts(const QList<Contact> &contacts);
+
     /// The candidate values for a context, in the order they are offered.
     QStringList candidatesFor(const CompletionContext &context) const;
 
@@ -134,6 +140,7 @@ private:
     QLineEdit *m_edit = nullptr;
     const Config &m_config;
     QStringList m_tags;
+    QList<Contact> m_contacts;
 
     /// Set while the filter is redelivering a key to the popup. The filter is
     /// installed on the application and sendEvent re-runs application filters,
diff --git a/tests/test_querycompleter.cpp b/tests/test_querycompleter.cpp
index 4c1e866..ca08d7b 100644
--- a/tests/test_querycompleter.cpp
+++ b/tests/test_querycompleter.cpp
@@ -19,13 +19,19 @@
 #include <QtTest>
 #include <QTemporaryDir>
 
+#include <QHash>
 #include <QLineEdit>
 #include <QImage>
 #include <QListView>
 #include <QPixmap>
 
 #include "config.h"
+#include "contactstore.h"
 #include "querycompleter.h"
+#include "searchterm.h"
+
+// Defined further down, beside the popup tests that also need it.
+static QListView *findPopup();
 
 class TestQueryCompleter : public QObject
 {
@@ -51,6 +57,11 @@ private slots:
     void tagAndIsShareTheTagModel();
     void pathOffersAccountMaildirsBothForms();
     void folderOffersNothing();
+    void fromOffersQuotedAddressesWithNamesAsDescriptions();
+    void toOffersTheSameContactsAsFrom();
+    void anEmptyContactStoreOffersNoAddresses();
+    void anAddressValueIsTheBareAddressNotAName();
+    void addressesTakeTheValueBranchNotThePrefixVocabulary();
     void mimetypeAppendsConfiguredEntries();
     void rangeContextDropsRelativeDates();
     void acceptReplacesOnlyThePrefixToken();
@@ -294,7 +305,8 @@ void TestQueryCompleter::pathOffersAccountMaildirsBothForms()
 void TestQueryCompleter::folderOffersNothing()
 {
     // folder: matches a Maildir folder name, not a path, and its values are
-    // not enumerable from config. Prefix-only, like from: and to:.
+    // not enumerable from config. Prefix-only, unlike from: and to:, whose
+    // values come from the vCard store.
     Config config;
     QueryCompleter completer(nullptr, config);
     const QStringList candidates = completer.candidatesFor(
@@ -302,6 +314,112 @@ void TestQueryCompleter::folderOffersNothing()
     QVERIFY(candidates.isEmpty());
 }
 
+void TestQueryCompleter::fromOffersQuotedAddressesWithNamesAsDescriptions()
+{
+    // The popup shows who an address belongs to: the value is the address,
+    // the description is the contact's name. Read through the real popup model
+    // rather than candidatesFor(), which carries the values alone.
+    Config config;
+    QLineEdit edit;
+    edit.show();
+    QueryCompleter completer(&edit, config);
+    completer.setContacts({
+        { QStringLiteral("Alice Example"), QStringLiteral("alice@example.org") },
+        { QStringLiteral("Bob Example"), QStringLiteral("bob@example.org") },
+    });
+
+    QTest::keyClicks(&edit, QStringLiteral("from:"));
+    QListView *popup = findPopup();
+    QVERIFY(popup && popup->isVisible());
+
+    QStringList values;
+    QHash<QString, QString> namesByValue;
+    for (int row = 0; row < popup->model()->rowCount(); ++row) {
+        const QString value = popup->model()->index(row, 0).data().toString();
+        values << value;
+        namesByValue.insert(
+            value, popup->model()->index(row, 1).data().toString());
+    }
+
+    const QString alice = SearchTerm::quote(QStringLiteral("alice@example.org"));
+    QVERIFY(values.contains(alice));
+    QCOMPARE(namesByValue.value(alice), QStringLiteral("Alice Example"));
+    QCOMPARE(namesByValue.value(SearchTerm::quote(QStringLiteral("bob@example.org"))),
+             QStringLiteral("Bob Example"));
+}
+
+void TestQueryCompleter::toOffersTheSameContactsAsFrom()
+{
+    Config config;
+    QueryCompleter completer(nullptr, config);
+    completer.setContacts({
+        { QStringLiteral("Alice Example"), QStringLiteral("alice@example.org") },
+    });
+
+    const QStringList from = completer.candidatesFor(
+        completionContext(QStringLiteral("from:"), 5));
+    const QStringList to = completer.candidatesFor(
+        completionContext(QStringLiteral("to:"), 3));
+
+    QCOMPARE(to, from);
+    QCOMPARE(to, QStringList({ SearchTerm::quote(QStringLiteral("alice@example.org")) }));
+}
+
+void TestQueryCompleter::anEmptyContactStoreOffersNoAddresses()
+{
+    // No store configured is today's behaviour: from: and to: offer nothing,
+    // and the other addressless keywords are unchanged.
+    Config config;
+    QueryCompleter completer(nullptr, config);
+
+    QVERIFY(completer.candidatesFor(
+        completionContext(QStringLiteral("from:"), 5)).isEmpty());
+    QVERIFY(completer.candidatesFor(
+        completionContext(QStringLiteral("to:"), 3)).isEmpty());
+    QVERIFY(completer.candidatesFor(
+        completionContext(QStringLiteral("folder:"), 7)).isEmpty());
+}
+
+void TestQueryCompleter::anAddressValueIsTheBareAddressNotAName()
+{
+    // notmuch matches on the address, so "Name <addr>" would be one token that
+    // never matches. The display name is the description, never the value.
+    Config config;
+    QueryCompleter completer(nullptr, config);
+    completer.setContacts({
+        { QStringLiteral("Alice Example"), QStringLiteral("alice@example.org") },
+    });
+
+    const QStringList candidates = completer.candidatesFor(
+        completionContext(QStringLiteral("from:"), 5));
+
+    QCOMPARE(candidates,
+             QStringList({ SearchTerm::quote(QStringLiteral("alice@example.org")) }));
+    QVERIFY(!candidates.first().contains(QStringLiteral("Alice")));
+}
+
+void TestQueryCompleter::addressesTakeTheValueBranchNotThePrefixVocabulary()
+{
+    // A from: value is a Value context, resolved by the same branch that serves
+    // path: and tag:, never the prefix vocabulary. If the kind were misjudged
+    // the popup would offer "from:" itself back at the user.
+    const CompletionContext ctx =
+        completionContext(QStringLiteral("from:"), 5);
+    QCOMPARE(ctx.kind, CompletionContext::Value);
+    QCOMPARE(ctx.prefix, QStringLiteral("from"));
+
+    Config config;
+    QueryCompleter completer(nullptr, config);
+    completer.setContacts({
+        { QStringLiteral("Alice Example"), QStringLiteral("alice@example.org") },
+    });
+
+    const QStringList candidates = completer.candidatesFor(ctx);
+    QVERIFY(candidates.contains(
+        SearchTerm::quote(QStringLiteral("alice@example.org"))));
+    QVERIFY(!candidates.contains(QStringLiteral("tag:")));
+}
+
 void TestQueryCompleter::mimetypeAppendsConfiguredEntries()
 {
     QTemporaryDir dir;