feat: add background mail polling option for all workers

Check for new mail (recent, unseen, exists counts) with an external
command, or for imap with the STATUS command, at start or on
reconnection and every X time duration

IMAP:
The selected folder is skipped, per specification. Additional config
options are included for including/excluding folders explicitly.

Maildir/Notmuch:
An external command will be run in the background to check for new mail.
An optional timeout can be used with maildir/notmuch. Default is 10s

New account options:
check-mail
check-mail-cmd (maildir/notmuch only)
check-mail-timeout (maildir/notmuch only), default 10s
check-mail-include (IMAP only)
check-mail-exclude (IMAP only)

If unset, or set less than or equal to 0, check-mail will be ignored

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Tested-by: Moritz Poldrack <moritz@poldrack.dev>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 42 insertions, 11 deletions

diff --git a/worker/maildir/worker.go b/worker/maildir/worker.go
index 4a2a19b..d3de844 100644
--- a/worker/maildir/worker.go
+++ b/worker/maildir/worker.go
@@ -2,12 +2,14 @@ package maildir
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"net/url"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -60,17 +62,25 @@ func (w *Worker) Run() {
 
 func (w *Worker) handleAction(action types.WorkerMessage) {
 	msg := w.worker.ProcessAction(action)
-	if err := w.handleMessage(msg); err == errUnsupported {
-		w.worker.PostMessage(&types.Unsupported{
-			Message: types.RespondTo(msg),
-		}, nil)
-	} else if err != nil {
-		w.worker.PostMessage(&types.Error{
-			Message: types.RespondTo(msg),
-			Error:   err,
-		}, nil)
-	} else {
-		w.done(msg)
+	switch msg := msg.(type) {
+	// Explicitly handle all asynchronous actions. Async actions are
+	// responsible for posting their own Done message
+	case *types.CheckMail:
+		go w.handleCheckMail(msg)
+	default:
+		// Default handling, will be performed synchronously
+		if err := w.handleMessage(msg); err == errUnsupported {
+			w.worker.PostMessage(&types.Unsupported{
+				Message: types.RespondTo(msg),
+			}, nil)
+		} else if err != nil {
+			w.worker.PostMessage(&types.Error{
+				Message: types.RespondTo(msg),
+				Error:   err,
+			}, nil)
+		} else {
+			w.done(msg)
+		}
 	}
 }
 
@@ -672,3 +682,24 @@ func (w *Worker) msgInfoFromUid(uid uint32) (*models.MessageInfo, error) {
 	}
 	return info, nil
 }
+
+func (w *Worker) handleCheckMail(msg *types.CheckMail) {
+	ctx, cancel := context.WithTimeout(context.Background(), msg.Timeout)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, "sh", "-c", msg.Command)
+	ch := make(chan error)
+	go func() {
+		err := cmd.Run()
+		ch <- err
+	}()
+	select {
+	case <-ctx.Done():
+		w.err(msg, fmt.Errorf("checkmail: timed out"))
+	case err := <-ch:
+		if err != nil {
+			w.err(msg, fmt.Errorf("checkmail: error running command: %v", err))
+		} else {
+			w.done(msg)
+		}
+	}
+}