feat(details): rebuild the message details dialog as rows

A text box could not carry a per-value context menu without parsing displayed
text back into structure, and the user did not want a text box. Each row now
holds its own value, its message index and its query, built from the parsed
message.

Every value label states Qt::PlainText. The QPlainTextEdit this replaced was
plain by design rather than by style: header values come from strangers, and a
QLabel guesses the format under AutoText.

1 files changed, 153 insertions, 0 deletions

diff --git a/src/messagedetailsdialog.cpp b/src/messagedetailsdialog.cpp
new file mode 100644
index 0000000..058814b
--- /dev/null
+++ b/src/messagedetailsdialog.cpp
@@ -0,0 +1,153 @@
+/*
+ * qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "messagedetailsdialog.h"
+
+#include <QDialogButtonBox>
+#include <QFontDatabase>
+#include <QGridLayout>
+#include <QLabel>
+#include <QMenu>
+#include <QScrollArea>
+#include <QVBoxLayout>
+
+#include "mimeparser.h"
+#include "searchterm.h"
+
+MessageDetailsDialog::MessageDetailsDialog(const QList<ThreadRenderItem> &items,
+                                           QWidget *parent)
+    : QDialog(parent)
+{
+    setWindowTitle(tr("Message details"));
+    setObjectName(QStringLiteral("messageDetailsDialog"));
+
+    buildRows(items);
+
+    auto *layout = new QVBoxLayout(this);
+
+    // Scrollable: a long thread has many rows, and the dialog must not grow
+    // past the screen to show them.
+    auto *scroll = new QScrollArea(this);
+    scroll->setWidgetResizable(true);
+    auto *content = new QWidget(scroll);
+    auto *grid = new QGridLayout(content);
+
+    // A monospaced value keeps a long id or address readable as the record it
+    // is, which is what the text box did well and is worth carrying over.
+    const QFont fixed = QFontDatabase::systemFont(QFontDatabase::FixedFont);
+
+    int gridRow = 0;
+    int lastMessage = -1;
+    for (const HeaderRow &row : std::as_const(m_rows)) {
+        if (items.size() > 1 && row.messageIndex != lastMessage) {
+            lastMessage = row.messageIndex;
+            auto *heading = new QLabel(
+                tr("Message %1 of %2").arg(row.messageIndex + 1)
+                    .arg(items.size()),
+                content);
+            heading->setTextFormat(Qt::PlainText);
+            QFont headingFont = heading->font();
+            headingFont.setBold(true);
+            heading->setFont(headingFont);
+            grid->addWidget(heading, gridRow, 0, 1, 2);
+            ++gridRow;
+        }
+
+        auto *label = new QLabel(row.label, content);
+        label->setTextFormat(Qt::PlainText);
+        label->setAlignment(Qt::AlignTop | Qt::AlignLeft);
+        grid->addWidget(label, gridRow, 0);
+
+        // PlainText stated, not inferred. A QLabel guesses under AutoText, and
+        // this value came from a stranger.
+        auto *value = new QLabel(row.value, content);
+        value->setTextFormat(Qt::PlainText);
+        value->setFont(fixed);
+        value->setWordWrap(true);
+        value->setTextInteractionFlags(Qt::TextSelectableByMouse);
+
+        if (!row.query.isEmpty()) {
+            value->setContextMenuPolicy(Qt::CustomContextMenu);
+            connect(value, &QWidget::customContextMenuRequested, this,
+                    [this, value, row](const QPoint &pos) {
+                        QMenu menu(this);
+                        auto *replace = menu.addAction(tr("Search for this"));
+                        connect(replace, &QAction::triggered, this,
+                                [this, row]() { requestSearch(row, false); });
+                        auto *narrow = menu.addAction(tr("Add to search"));
+                        connect(narrow, &QAction::triggered, this,
+                                [this, row]() { requestSearch(row, true); });
+                        menu.exec(value->mapToGlobal(pos));
+                    });
+        }
+
+        grid->addWidget(value, gridRow, 1);
+        ++gridRow;
+    }
+
+    grid->setColumnStretch(1, 1);
+    grid->setRowStretch(gridRow, 1);
+    scroll->setWidget(content);
+    layout->addWidget(scroll);
+
+    auto *buttons = new QDialogButtonBox(QDialogButtonBox::Close, this);
+    connect(buttons, &QDialogButtonBox::rejected, this, &QDialog::reject);
+    layout->addWidget(buttons);
+
+    resize(700, 400);
+}
+
+void MessageDetailsDialog::buildRows(const QList<ThreadRenderItem> &items)
+{
+    for (int i = 0; i < items.size(); ++i) {
+        const ParsedMessage &message = items.at(i).message;
+
+        auto add = [this, i](const QString &field, const QString &label,
+                             const QString &value, const QString &query) {
+            if (value.isEmpty())
+                return;   // An empty row reads as a rendering fault.
+            m_rows.append({ field, label, value, query, i });
+        };
+
+        add(QStringLiteral("subject"), tr("Subject:"), message.subject,
+            SearchTerm::field(QStringLiteral("subject"), message.subject));
+        add(QStringLiteral("from"), tr("From:"), message.from,
+            SearchTerm::field(QStringLiteral("from"), message.from));
+        add(QStringLiteral("to"), tr("To:"), message.to,
+            SearchTerm::field(QStringLiteral("to"), message.to));
+        add(QStringLiteral("cc"), tr("Cc:"), message.cc,
+            SearchTerm::field(QStringLiteral("cc"), message.cc));
+
+        // The raw header is shown, but the query is a one-day range: a text
+        // match on an RFC 2822 string would match almost nothing.
+        const QDateTime sent = MimeParser::parseDate(message.date);
+        add(QStringLiteral("date"), tr("Date:"), message.date,
+            sent.isValid() ? SearchTerm::onDate(sent.date()) : QString());
+
+        // Shown but not searchable: an id names one message, and the thread
+        // holding it is already on screen.
+        add(QString(), tr("Message-Id:"), message.messageId, QString());
+    }
+}
+
+void MessageDetailsDialog::requestSearch(const HeaderRow &row, bool extend)
+{
+    if (row.query.isEmpty())
+        return;
+    emit searchRequested(row.query, extend);
+}