feat: initial commit — uptime monitor (forked from go-upkeep)

Go-based uptime monitor with SQLite/Postgres storage, TUI dashboard,
SSH server, alerting, and clustering support.

internal/monitor/history.go

@@ -0,0 +1,70 @@
+package monitor
+
+import (
+	"sync"
+	"time"
+)
+
+const maxHistoryLen = 30
+
+type SiteHistory struct {
+	Latencies   []time.Duration
+	Statuses    []bool
+	TotalChecks int
+	UpChecks    int
+}
+
+var (
+	histories = make(map[int]*SiteHistory)
+	historyMu sync.RWMutex
+)
+
+func RecordCheck(siteID int, latency time.Duration, isUp bool) {
+	historyMu.Lock()
+	defer historyMu.Unlock()
+
+	h, ok := histories[siteID]
+	if !ok {
+		h = &SiteHistory{}
+		histories[siteID] = h
+	}
+
+	h.TotalChecks++
+	if isUp {
+		h.UpChecks++
+	}
+
+	h.Latencies = append(h.Latencies, latency)
+	if len(h.Latencies) > maxHistoryLen {
+		h.Latencies = h.Latencies[len(h.Latencies)-maxHistoryLen:]
+	}
+
+	h.Statuses = append(h.Statuses, isUp)
+	if len(h.Statuses) > maxHistoryLen {
+		h.Statuses = h.Statuses[len(h.Statuses)-maxHistoryLen:]
+	}
+}
+
+func GetHistory(siteID int) (SiteHistory, bool) {
+	historyMu.RLock()
+	defer historyMu.RUnlock()
+	h, ok := histories[siteID]
+	if !ok {
+		return SiteHistory{}, false
+	}
+	cp := SiteHistory{
+		TotalChecks: h.TotalChecks,
+		UpChecks:    h.UpChecks,
+		Latencies:   make([]time.Duration, len(h.Latencies)),
+		Statuses:    make([]bool, len(h.Statuses)),
+	}
+	copy(cp.Latencies, h.Latencies)
+	copy(cp.Statuses, h.Statuses)
+	return cp, true
+}
+
+func RemoveHistory(siteID int) {
+	historyMu.Lock()
+	defer historyMu.Unlock()
+	delete(histories, siteID)
+}