Automatic key import / export + Expected monad

Summary:
There are many things going on here (perhaps a bit much for a single patch):

- When an attachment is of mime type "application/pgp-keys", a button is added to import the key to GPG
- When sending a mail and crypto is enabled (encryption, signing or both), the public key of the first private key found is sent as an un-encrypted attachment (T6994)
- The `mailcrypto.{h,cpp}` was, for the most part, rewritten
- Introduction of the expected monad, inspired by what was proposed for C++ [here](https://isocpp.org/files/papers/n4015.pdf), but not at all a strict implementation of this specification. We may want to add some more features of this standard later.

The rationale for some of the choices:

- I found mailcrypto a bit hard to edit to add new features, and a great part was commented code to prepare for the support the SMIME crypto format, which would (in my current knowledge) not be used for sending emails.
- One thing I found that may be missing in the code base was a standardized way of handling errors in C++ code. Since exceptions are disabled I think that the functional way is the way to go. After some research I found the Expected monad / tagged union / sum type, which seemed to suit the problem particularly well.

In the long run, I hope we would move the entire code base to use `Expected` to indicate if a function might fail.

Of course every choice made here is to be considered as a proposition for doing things / RFC, critics wholeheartedly accepted.

Reviewers: cmollekopf

Tags: #kube

Maniphest Tasks: T6994, T8147, T6995

Differential Revision: https://phabricator.kde.org/D11158

1 files changed, 26 insertions, 8 deletions

diff --git a/framework/src/domain/mime/tests/mailtemplatetest.cpp b/framework/src/domain/mime/tests/mailtemplatetest.cpp
index 6338cd58..d5642bb6 100644
--- a/framework/src/domain/mime/tests/mailtemplatetest.cpp
+++ b/framework/src/domain/mime/tests/mailtemplatetest.cpp
@@ -31,16 +31,16 @@ static std::vector< GpgME::Key, std::allocator< GpgME::Key > > getKeys(bool smim
     if (smime) {
         const QGpgME::Protocol *const backend = QGpgME::smime();
         Q_ASSERT(backend);
-        job = backend->keyListJob(false);
+        job = backend->keyListJob(/* remote = */ false);
     } else {
         const QGpgME::Protocol *const backend = QGpgME::openpgp();
         Q_ASSERT(backend);
-        job = backend->keyListJob(false);
+        job = backend->keyListJob(/* remote = */ false);
     }
     Q_ASSERT(job);
 
     std::vector< GpgME::Key > keys;
-    GpgME::KeyListResult res = job->exec(QStringList(), true, keys);
+    GpgME::KeyListResult res = job->exec(QStringList(), /* secretOnly = */ true, keys);
 
     if (!smime) {
         Q_ASSERT(keys.size() == 3);
@@ -401,7 +401,7 @@ private slots:
 
         std::vector<GpgME::Key> keys = getKeys();
 
-        auto result = MailTemplates::createMessage({}, to, cc, bcc, from, subject, body, false, attachments, keys);
+        auto result = MailTemplates::createMessage({}, to, cc, bcc, from, subject, body, false, attachments, keys, {}, keys[0]);
 
         QVERIFY(result);
         // qWarning() << "---------------------------------";
@@ -409,9 +409,17 @@ private slots:
         // qWarning() << "---------------------------------";
         QCOMPARE(result->subject()->asUnicodeString(), subject);
         QVERIFY(result->date(false)->dateTime().isValid());
-        QVERIFY(result->contentType()->isMimeType("multipart/signed"));
 
-        const auto contents = result->contents();
+        QCOMPARE(result->contentType()->mimeType(), "multipart/mixed");
+        auto resultAttachments = result->attachments();
+        QCOMPARE(resultAttachments.size(), 1);
+        QCOMPARE(resultAttachments[0]->contentDisposition()->filename(), "0x8F246DE6.asc");
+
+        auto signedMessage = result->contents()[0];
+
+        QVERIFY(signedMessage->contentType()->isMimeType("multipart/signed"));
+
+        const auto contents = signedMessage->contents();
         QCOMPARE(contents.size(), 2);
         {
             auto c = contents.at(0);
@@ -441,9 +449,19 @@ private slots:
         QVERIFY(result);
         QCOMPARE(result->subject()->asUnicodeString(), subject);
         QVERIFY(result->date(false)->dateTime().isValid());
-        QVERIFY(result->contentType()->isMimeType("multipart/signed"));
 
-        const auto contents = result->contents();
+        QCOMPARE(result->contentType()->mimeType(), "multipart/mixed");
+        auto resultAttachments = result->attachments();
+        QCOMPARE(resultAttachments.size(), 3);
+        // It seems KMime searches for the attachments using depth-first
+        // search, so the public key is last
+        QCOMPARE(resultAttachments[2]->contentDisposition()->filename(), "0x8F246DE6.asc");
+
+        auto signedMessage = result->contents()[0];
+
+        QVERIFY(signedMessage->contentType()->isMimeType("multipart/signed"));
+
+        const auto contents = signedMessage->contents();
         QCOMPARE(contents.size(), 2);
         {
             auto c = contents.at(0);