everywhere: add email notifications

api/email_notification.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"time"
+)
+
+type emailNotification struct {
+	Email         string
+	CommenterName string
+	Domain        string
+	Path          string
+	Title         string
+	CommentHex    string
+	Kind          string
+}
+
+var emailQueue map[string](chan emailNotification) = map[string](chan emailNotification){}
+
+func emailNotificationPendingResetAll() error {
+	statement := `
+		UPDATE emails
+		SET pendingEmails = 0;
+	`
+	_, err := db.Exec(statement)
+	if err != nil {
+		logger.Errorf("cannot reset pendingEmails: %v", err)
+		return err
+	}
+
+	return nil
+}
+
+func emailNotificationPendingIncrement(email string) error {
+	statement := `
+		UPDATE emails
+		SET pendingEmails = pendingEmails + 1
+		WHERE email = $1;
+	`
+	_, err := db.Exec(statement, email)
+	if err != nil {
+		logger.Errorf("cannot increment pendingEmails: %v", err)
+		return err
+	}
+
+	return nil
+}
+
+func emailNotificationPendingReset(email string) error {
+	statement := `
+		UPDATE emails
+		SET pendingEmails = 0, lastEmailNotificationDate = $2
+		WHERE email = $1;
+	`
+	_, err := db.Exec(statement, email, time.Now().UTC())
+	if err != nil {
+		logger.Errorf("cannot decrement pendingEmails: %v", err)
+		return err
+	}
+
+	return nil
+}
+
+func emailNotificationEnqueue(e emailNotification) error {
+	if err := emailNotificationPendingIncrement(e.Email); err != nil {
+		logger.Errorf("cannot increment pendingEmails when enqueueing: %v", err)
+		return err
+	}
+
+	if _, ok := emailQueue[e.Email]; !ok {
+		// don't enqueue more than 10 emails as we won't send more than 10 comments
+		// in one email anyway
+		emailQueue[e.Email] = make(chan emailNotification, 10)
+	}
+
+	select {
+	case emailQueue[e.Email] <- e:
+	default:
+	}
+
+	return nil
+}