feat: check for available updates

update.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"hamlog/internal/applog"
+)
+
+// updateCheckURL is the GitHub Releases "latest" endpoint for the public OpsLog
+// build (the exe lives there; source stays on Gitea). Adjust the repo if needed.
+const updateCheckURL = "https://api.github.com/repos/GregTroar/OpsLog/releases/latest"
+
+// UpdateInfo is the result of the startup version check.
+type UpdateInfo struct {
+	Current   string `json:"current"`   // this build's version (appVersion)
+	Latest    string `json:"latest"`    // newest published release, "" if unknown
+	Available bool   `json:"available"` // Latest > Current
+	URL       string `json:"url"`       // release page to open
+}
+
+// CheckForUpdate asks GitHub for the latest release and compares it to this
+// build. Best effort — on any failure it reports "no update" so the app never
+// nags about a check it couldn't complete.
+func (a *App) CheckForUpdate() UpdateInfo {
+	out := UpdateInfo{Current: appVersion}
+	client := &http.Client{Timeout: 8 * time.Second}
+	req, err := http.NewRequest(http.MethodGet, updateCheckURL, nil)
+	if err != nil {
+		return out
+	}
+	req.Header.Set("Accept", "application/vnd.github+json")
+	resp, err := client.Do(req)
+	if err != nil {
+		applog.Printf("update: check failed: %v", err)
+		return out
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return out // no release yet (404) or rate-limited — treat as up to date
+	}
+	var r struct {
+		TagName string `json:"tag_name"`
+		HTMLURL string `json:"html_url"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		return out
+	}
+	out.Latest = strings.TrimPrefix(strings.TrimSpace(r.TagName), "v")
+	out.URL = r.HTMLURL
+	out.Available = versionLess(appVersion, out.Latest)
+	if out.Available {
+		applog.Printf("update: newer version available — current=%s latest=%s", appVersion, out.Latest)
+	}
+	return out
+}
+
+// versionLess reports whether version a is older than b. Compares dot-separated
+// numeric parts ("0.9" < "0.10" < "1.0"); non-numeric junk in a part counts as 0.
+func versionLess(a, b string) bool {
+	pa := strings.Split(a, ".")
+	pb := strings.Split(b, ".")
+	n := len(pa)
+	if len(pb) > n {
+		n = len(pb)
+	}
+	for i := 0; i < n; i++ {
+		ai, bi := 0, 0
+		if i < len(pa) {
+			ai = leadingInt(pa[i])
+		}
+		if i < len(pb) {
+			bi = leadingInt(pb[i])
+		}
+		if ai != bi {
+			return ai < bi
+		}
+	}
+	return false
+}
+
+// leadingInt parses the leading digits of s (e.g. "2beta" → 2), 0 if none.
+func leadingInt(s string) int {
+	s = strings.TrimSpace(s)
+	end := 0
+	for end < len(s) && s[end] >= '0' && s[end] <= '9' {
+		end++
+	}
+	if end == 0 {
+		return 0
+	}
+	n, _ := strconv.Atoi(s[:end])
+	return n
+}