Initial implementation of native mail sending

I'm felling comfortable that "b4 ty" is sufficiently mature at this
point to implement sending thank-yous directly. This is only the initial
implementation that covers only the very basic parts of git's sendemail
configuration options, but this should actually cover 90% of cases if
not more.

One important caveat -- I moved the "b4 ty -s" flag to be "b4 ty -t" in
order to disambiguate it from the capital -S (that actually does the
sending). Since "b4 ty" is still marked as an experimental feature, I
feel we can do this without much impact.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>

3 files changed, 125 insertions, 30 deletions

diff --git a/b4/__init__.py b/b4/__init__.py
index f8766d5..adbcf7d 100644
--- a/b4/__init__.py
+++ b/b4/__init__.py
@@ -130,6 +130,8 @@ DEFAULT_CONFIG = {
     # git-config for gpg.program, and if that's not set,
     # we'll use "gpg" and hope for the better
     'gpgbin': None,
+    # When sending mail, use this sendemail identity configuration
+    'sendemail-identity': None,
 }
 
 # This is where we store actual config
@@ -2480,3 +2482,54 @@ def read_template(tptfile):
                 continue
             tpt += line
     return tpt
+
+
+def get_smtp(identity: Optional[str] = None):
+    import smtplib
+    if identity:
+        sconfig = get_config_from_git(rf'sendemail\.{identity}\..*')
+        sectname = f'sendemail.{identity}'
+    else:
+        sconfig = get_config_from_git(rf'sendemail\..*')
+        sectname = 'sendemail'
+    if not len(sconfig):
+        raise smtplib.SMTPException('Unable to find %s settings in any applicable git config' % sectname)
+
+    # Limited support for smtp settings to begin with, but should cover the vast majority of cases
+    fromaddr = sconfig.get('from')
+    server = sconfig.get('smtpserver', 'localhost')
+    port = sconfig.get('smtpserverport', 0)
+    try:
+        port = int(port)
+    except ValueError:
+        raise smtplib.SMTPException('Invalid smtpport entry in %s' % sectname)
+
+    encryption = sconfig.get('smtpencryption')
+    # We only authenticate if we have encryption
+    if encryption:
+        if encryption in ('tls', 'starttls'):
+            # We do startssl
+            smtp = smtplib.SMTP(server, port)
+            # Introduce ourselves
+            smtp.ehlo()
+            # Start encryption
+            smtp.starttls()
+            # Introduce ourselves again to get new criteria
+            smtp.ehlo()
+        elif encryption in ('ssl', 'smtps'):
+            # We do TLS from the get-go
+            smtp = smtplib.SMTP_SSL(server, port)
+        else:
+            raise smtplib.SMTPException('Unclear what to do with smtpencryption=%s' % encryption)
+
+        # If we got to this point, we should do authentication.
+        auser = sconfig.get('smtpuser')
+        apass = sconfig.get('smtppass')
+        if auser and apass:
+            # Let any exceptions bubble up
+            smtp.login(auser, apass)
+    else:
+        # We assume you know what you're doing if you don't need encryption
+        smtp = smtplib.SMTP(server, port)
+
+    return smtp, fromaddr
diff --git a/b4/command.py b/b4/command.py
index 199d0c2..9d364dd 100644
--- a/b4/command.py
+++ b/b4/command.py
@@ -199,7 +199,7 @@ def cmd():
                        help='Write thanks files into this dir (default=.)')
     sp_ty.add_argument('-l', '--list', action='store_true', default=False,
                        help='List pull requests and patch series you have retrieved')
-    sp_ty.add_argument('-s', '--send', default=None,
+    sp_ty.add_argument('-t', '--thank-for', default=None,
                        help='Generate thankyous for specific entries from -l (e.g.: 1,3-5,7-; or "all")')
     sp_ty.add_argument('-d', '--discard', default=None,
                        help='Discard specific messages from -l (e.g.: 1,3-5,7-; or "all")')
@@ -209,6 +209,10 @@ def cmd():
                        help='The branch to check against, instead of current')
     sp_ty.add_argument('--since', default='1.week',
                        help='The --since option to use when auto-matching patches (default=1.week)')
+    sp_ty.add_argument('-S', '--send-email', action='store_true', dest='sendemail', default=False,
+                       help='Send email instead of writing out .thanks files')
+    sp_ty.add_argument('--dry-run', action='store_true', dest='dryrun', default=False,
+                       help='Print out emails instead of sending them')
     sp_ty.set_defaults(func=cmd_ty)
 
     # b4 diff
diff --git a/b4/ty.py b/b4/ty.py
index fbae20c..b790007 100644
--- a/b4/ty.py
+++ b/b4/ty.py
@@ -374,19 +374,30 @@ def auto_thankanator(cmdargs):
         sys.exit(0)
 
     logger.info('---')
-    send_messages(applied, cmdargs.gitdir, cmdargs.outdir, wantbranch, since=cmdargs.since)
+    send_messages(applied, wantbranch, cmdargs)
     sys.exit(0)
 
 
-def send_messages(listing, gitdir, outdir, branch, since='1.week'):
-    # Not really sending, but writing them out to be sent on your own
-    # We'll probably gain ability to send these once the feature is
-    # more mature and we're less likely to mess things up
-    datadir = b4.get_data_dir()
+def send_messages(listing, branch, cmdargs):
     logger.info('Generating %s thank-you letters', len(listing))
-    # Check if the outdir exists and if it has any .thanks files in it
-    if not os.path.exists(outdir):
-        os.mkdir(outdir)
+    gitdir = cmdargs.gitdir
+    datadir = b4.get_data_dir()
+    fromaddr = None
+    if cmdargs.sendemail:
+        # See if we have sendemail-identity set
+        config = b4.get_main_config()
+        identity = config.get('sendemail-identity')
+        try:
+            smtp, fromaddr = b4.get_smtp(identity)
+        except Exception as ex:  # noqa
+            logger.critical('Failed to configure the smtp connection:')
+            logger.critical(ex)
+            sys.exit(1)
+    else:
+        # We write .thanks notes
+        # Check if the outdir exists and if it has any .thanks files in it
+        if not os.path.exists(cmdargs.outdir):
+            os.mkdir(cmdargs.outdir)
 
     usercfg = b4.get_user_config()
     # Do we have a .signature file?
@@ -399,10 +410,6 @@ def send_messages(listing, gitdir, outdir, branch, since='1.week'):
 
     outgoing = 0
     for jsondata in listing:
-        slug_from = re.sub(r'\W', '_', jsondata['fromemail'])
-        slug_subj = re.sub(r'\W', '_', jsondata['subject'])
-        slug = '%s_%s' % (slug_from.lower(), slug_subj.lower())
-        slug = re.sub(r'_+', '_', slug)
         jsondata['myname'] = usercfg['name']
         jsondata['myemail'] = usercfg['email']
         jsondata['signature'] = signature
@@ -411,29 +418,60 @@ def send_messages(listing, gitdir, outdir, branch, since='1.week'):
             msg = generate_pr_thanks(gitdir, jsondata, branch)
         else:
             # This is a patch series
-            msg = generate_am_thanks(gitdir, jsondata, branch, since)
+            msg = generate_am_thanks(gitdir, jsondata, branch, cmdargs.since)
 
         if msg is None:
             continue
 
         outgoing += 1
-        outfile = os.path.join(outdir, '%s.thanks' % slug)
-        logger.info('  Writing: %s', outfile)
         msg.set_charset('utf-8')
         msg.replace_header('Content-Transfer-Encoding', '8bit')
-        with open(outfile, 'w') as fh:
-            fh.write(msg.as_string(policy=b4.emlpolicy))
-        logger.debug('Cleaning up: %s', jsondata['trackfile'])
-        fullpath = os.path.join(datadir, jsondata['trackfile'])
-        os.rename(fullpath, '%s.sent' % fullpath)
+        if cmdargs.sendemail:
+            if not fromaddr:
+                fromaddr = jsondata['myemail']
+            if cmdargs.dryrun:
+                logger.info('--- DRYRUN: message follows ---')
+                emldata = msg.as_string(policy=b4.emlpolicy)
+                logger.info('\t' + emldata.replace('\n', '\n\t'))
+                logger.info('--- DRYRUN: message ends ---')
+            else:
+                alldests = email.utils.getaddresses([str(x) for x in msg.get_all('to', [])])
+                alldests += email.utils.getaddresses([str(x) for x in msg.get_all('cc', [])])
+                sendto = {x[1] for x in alldests}
+                logger.info('Sending: %s', msg.get('subject'))
+                mypolicy = email.policy.EmailPolicy(utf8=True, cte_type='8bit')
+                smtp.sendmail(fromaddr, sendto, msg.as_string(policy=mypolicy))  # noqa
+        else:
+            slug_from = re.sub(r'\W', '_', jsondata['fromemail'])
+            slug_subj = re.sub(r'\W', '_', jsondata['subject'])
+            slug = '%s_%s' % (slug_from.lower(), slug_subj.lower())
+            slug = re.sub(r'_+', '_', slug)
+            outfile = os.path.join(cmdargs.outdir, '%s.thanks' % slug)
+            logger.info('  Writing: %s', outfile)
+            with open(outfile, 'w') as fh:
+                fh.write(msg.as_string(policy=b4.emlpolicy))
+        if cmdargs.dryrun:
+            logger.info('Dry run, preserving tracked series.')
+        else:
+            logger.debug('Cleaning up: %s', jsondata['trackfile'])
+            fullpath = os.path.join(datadir, jsondata['trackfile'])
+            os.rename(fullpath, '%s.sent' % fullpath)
+
     logger.info('---')
     if not outgoing:
         logger.info('No thanks necessary.')
         return
 
-    logger.debug('Wrote %s thank-you letters', outgoing)
-    logger.info('You can now run:')
-    logger.info('  git send-email %s/*.thanks', outdir)
+    if cmdargs.sendemail:
+        if cmdargs.dryrun:
+            logger.info('DRYRUN: generated %s thank-you letters', outgoing)
+        else:
+            logger.info('Sent %s thank-you letters', outgoing)
+        smtp.quit()
+    else:
+        logger.debug('Wrote %s thank-you letters', outgoing)
+        logger.info('You can now run:')
+        logger.info('  git send-email %s/*.thanks', cmdargs.outdir)
 
 
 def list_tracked():
@@ -465,7 +503,7 @@ def write_tracked(tracked):
         counter += 1
 
 
-def send_selected(cmdargs):
+def thank_selected(cmdargs):
     tracked = list_tracked()
     if not len(tracked):
         logger.info('Nothing to do')
@@ -494,7 +532,7 @@ def send_selected(cmdargs):
         sys.exit(0)
 
     wantbranch = get_wanted_branch(cmdargs)
-    send_messages(listing, cmdargs.gitdir, cmdargs.outdir, wantbranch, cmdargs.since)
+    send_messages(listing, wantbranch, cmdargs)
     sys.exit(0)
 
 
@@ -621,9 +659,9 @@ def main(cmdargs):
     if cmdargs.auto:
         check_stale_thanks(cmdargs.outdir)
         auto_thankanator(cmdargs)
-    elif cmdargs.send:
+    elif cmdargs.thank:
         check_stale_thanks(cmdargs.outdir)
-        send_selected(cmdargs)
+        thank_selected(cmdargs)
     elif cmdargs.discard:
         discard_selected(cmdargs)
     else:
@@ -634,4 +672,4 @@ def main(cmdargs):
         write_tracked(tracked)
         logger.info('---')
         logger.info('You can send them using number ranges, e.g:')
-        logger.info('  b4 ty -s 1-3,5,7-')
+        logger.info('  b4 ty -t 1-3,5,7-')