add notifier package

1 files changed, 60 insertions, 0 deletions

diff --git a/internal/notifier/notifier.go b/internal/notifier/notifier.go
new file mode 100644
index 0000000..24447a9
--- /dev/null
+++ b/internal/notifier/notifier.go
@@ -0,0 +1,60 @@
+package notifier
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"codeberg.org/snonux/gorum/internal/config"
+)
+
+type Notifier struct{}
+
+func New() Notifier {
+	return Notifier{}
+}
+
+func (notifier Notifier) Start(ctx context.Context, conf config.Config, scoreCh <-chan string) {
+	go func() {
+		for scoresStr := range scoreCh {
+			if err := notifier.persist(conf, scoresStr); err != nil {
+				emailNotifyError(conf, err)
+			}
+		}
+	}()
+}
+
+func (notifier Notifier) persist(conf config.Config, scoresStr string) error {
+	if err := emailNotify(conf, "GORUM: Quorum changed", scoresStr); err != nil {
+		return err
+	}
+
+	if _, err := os.Stat(conf.StateDir); os.IsNotExist(err) {
+		if err := os.MkdirAll(conf.StateDir, 0755); err != nil {
+			return err
+		}
+	}
+
+	return writeFileViaTmp(fmt.Sprintf("%s/%s", conf.StateDir, conf.ScoreFile), scoresStr)
+}
+
+// Create tmp file first, and then, once written, rename it.
+func writeFileViaTmp(filePath, content string) error {
+	tmpFilePath := fmt.Sprintf("%s.tmp", filePath)
+
+	fd, err := os.Create(tmpFilePath)
+	if err != nil {
+		return err
+	}
+	defer fd.Close()
+
+	if _, err := fd.WriteString(content); err != nil {
+		return err
+	}
+
+	if err := fd.Sync(); err != nil {
+		return err
+	}
+
+	return os.Rename(tmpFilePath, filePath)
+}