init work of uptime

internal/alert/alerter.go

@@ -0,0 +1,94 @@
+package alert
+
+import (
+	"fmt"
+	"time"
+
+	"arclineit/arcline-uptime/internal/config"
+	"arclineit/arcline-uptime/internal/monitor"
+)
+
+// Alerter sends a notification with a subject and body.
+type Alerter interface {
+	Send(subject, body string) error
+}
+
+// NamedAlerter wraps an Alerter with its configured name for per-monitor routing.
+type NamedAlerter struct {
+	Name    string
+	Alerter Alerter
+}
+
+// BuildNamedAlerters constructs one NamedAlerter per AlertConfig entry.
+func BuildNamedAlerters(alerts []config.AlertConfig) ([]NamedAlerter, error) {
+	out := make([]NamedAlerter, 0, len(alerts))
+	for _, a := range alerts {
+		var al Alerter
+		switch a.Type {
+		case "discord", "slack":
+			al = NewDiscordAlerter(a.WebhookURL)
+		case "email":
+			al = NewEmailAlerter(a)
+		case "ntfy":
+			al = NewNtfyAlerter(a.URL, a.Token)
+		case "gotify":
+			al = NewGotifyAlerter(a.URL, a.Token, a.Priority)
+		default:
+			return nil, fmt.Errorf("unknown alerter type %q", a.Type)
+		}
+		out = append(out, NamedAlerter{Name: a.Name, Alerter: al})
+	}
+	return out, nil
+}
+
+// BuildAlerters is a convenience shim for callers that don't need routing.
+func BuildAlerters(alerts []config.AlertConfig) ([]Alerter, error) {
+	named, err := BuildNamedAlerters(alerts)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]Alerter, len(named))
+	for i, na := range named {
+		out[i] = na.Alerter
+	}
+	return out, nil
+}
+
+// FormatDownMessage returns the subject and body for a failed check.
+func FormatDownMessage(r monitor.Result) (subject, body string) {
+	subject = fmt.Sprintf("[DOWN] %s", r.MonitorName)
+	body = subject + "\n"
+	if r.Error != "" {
+		body += r.Error + "\n"
+	}
+	if r.StatusCode != 0 {
+		body += fmt.Sprintf("Status code: %d\n", r.StatusCode)
+	}
+	body += fmt.Sprintf("Checked at %s UTC\n", r.CheckedAt.UTC().Format("2006-01-02 15:04:05"))
+	body += fmt.Sprintf("Response time: %dms", r.ResponseTime.Milliseconds())
+	return
+}
+
+// FormatUpMessage returns the subject and body for a recovery alert.
+// downSince is the time the last DOWN alert was sent.
+func FormatUpMessage(r monitor.Result, downSince time.Time) (subject, body string) {
+	subject = fmt.Sprintf("[UP] %s is back up", r.MonitorName)
+	body = subject + "\n"
+	body += fmt.Sprintf("Was down for %s\n", FormatDuration(time.Since(downSince)))
+	body += fmt.Sprintf("Recovered at %s UTC", r.CheckedAt.UTC().Format("2006-01-02 15:04:05"))
+	return
+}
+
+// FormatDuration renders a duration as human-readable text, omitting leading zero units.
+func FormatDuration(d time.Duration) string {
+	h := int(d.Hours())
+	m := int(d.Minutes()) % 60
+	s := int(d.Seconds()) % 60
+	if h > 0 {
+		return fmt.Sprintf("%dh %dm %ds", h, m, s)
+	}
+	if m > 0 {
+		return fmt.Sprintf("%dm %ds", m, s)
+	}
+	return fmt.Sprintf("%ds", s)
+}