feat: finish project basic structure and core functions

internal/template/template.go

@@ -0,0 +1,101 @@
+package template
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"nukumizu-backend/internal/node"
+)
+
+// Params holds all possible template parameters.
+type Params struct {
+	Time              string
+	ServerName        string
+	ServerUUID        string
+	UpStatus          string
+	Event             string
+	Message           string
+	Command           string
+	Result            string
+	OnlineServers     string // Pre-formatted multi-line list
+	OfflineServers    string // Pre-formatted multi-line list
+}
+
+// BuildParamsFromStatusChange creates template parameters from a status change event.
+func BuildParamsFromStatusChange(change node.StatusChange) Params {
+	return Params{
+		Time:       time.Now().Format("2006-01-02T15:04:05.000000000-07:00"),
+		ServerName: change.Name,
+		ServerUUID: change.UUID,
+		UpStatus:   change.Event,
+		Event:      change.Event,
+		Message:    change.Message,
+	}
+}
+
+// BuildParamsFromServerList creates template parameters for the server list.
+func BuildParamsFromServerList() Params {
+	tracker := node.GetTracker()
+	onlineServers := strings.Join(tracker.GetOnlineServers(), "\n")
+	offlineServers := strings.Join(tracker.GetOfflineServers(), "\n")
+
+	return Params{
+		Time:           time.Now().Format("2006-01-02T15:04:05.000000000-07:00"),
+		OnlineServers:  onlineServers,
+		OfflineServers: offlineServers,
+	}
+}
+
+// BuildParamsFromExecResult creates template parameters for a command execution result.
+func BuildParamsFromExecResult(serverName, serverUUID, command, result string) Params {
+	return Params{
+		Time:       time.Now().Format("2006-01-02T15:04:05.000000000-07:00"),
+		ServerName: serverName,
+		ServerUUID: serverUUID,
+		Command:    command,
+		Result:     result,
+	}
+}
+
+// Render substitutes {{ paramName }} placeholders in a template string.
+// Supported placeholders:
+//   - {{ time }} — current server time
+//   - {{ serverName }} — server name
+//   - {{ serverUUID }} — server UUID
+//   - {{ upStatus }} — "Online" or "Offline"
+//   - {{ event }} — "Online" or "Offline"
+//   - {{ message }} — event descriptive message
+//   - {{ command }} — executed command
+//   - {{ result }} — command execution result
+//   - {{ list.onlineServers }} — multi-line online server list
+//   - {{ list.offlineServers }} — multi-line offline server list
+func Render(tmpl string, params Params) string {
+	result := tmpl
+
+	result = strings.ReplaceAll(result, "{{ time }}", params.Time)
+	result = strings.ReplaceAll(result, "{{ serverName }}", params.ServerName)
+	result = strings.ReplaceAll(result, "{{ serverUUID }}", params.ServerUUID)
+	result = strings.ReplaceAll(result, "{{ upStatus }}", params.UpStatus)
+	result = strings.ReplaceAll(result, "{{ event }}", params.Event)
+	result = strings.ReplaceAll(result, "{{ message }}", params.Message)
+	result = strings.ReplaceAll(result, "{{ command }}", params.Command)
+	result = strings.ReplaceAll(result, "{{ result }}", params.Result)
+	result = strings.ReplaceAll(result, "{{ list.onlineServers }}", params.OnlineServers)
+	result = strings.ReplaceAll(result, "{{ list.offlineServers }}", params.OfflineServers)
+
+	return result
+}
+
+// FormatServerListEntry formats a single server entry for list display.
+func FormatServerListEntry(name, uuid string) string {
+	if name == "" {
+		return fmt.Sprintf("- %s", uuid)
+	}
+	return fmt.Sprintf("- %s (%s)", name, uuid)
+}
+
+// JoinServerListEntries joins formatted server entries with newlines.
+func JoinServerListEntries(entries []string) string {
+	return strings.Join(entries, "\n")
+}