Write initial settings-function

internal/config/settings.go

@@ -0,0 +1,150 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"sync"
+)
+
+// UISettings holds both the UI settings (like language) and
+// relevant Fail2ban jail/local config options.
+type UISettings struct {
+	// UI-specific
+	Language       string `json:"language"`
+	// Whether a reload is needed (e.g. user changed filter or jail settings).
+	ReloadNeeded   bool   `json:"reloadNeeded"`
+
+	// These mirror some Fail2ban [DEFAULT] section parameters from jail.local
+	BantimeIncrement bool   `json:"bantimeIncrement"`
+	IgnoreIP         string `json:"ignoreip"`
+	Bantime          string `json:"bantime"`
+	Findtime         string `json:"findtime"`
+	Maxretry         int    `json:"maxretry"`
+	Destemail        string `json:"destemail"`
+	Sender           string `json:"sender"`
+}
+
+// path to the JSON file (relative to where the app is started)
+const settingsFile = "fail2ban-ui-settings.json"
+
+// in-memory copy of settings
+var (
+	currentSettings UISettings
+	settingsLock    sync.RWMutex
+)
+
+func init() {
+	// Attempt to load existing file; if it doesn't exist, create with defaults.
+	if err := loadSettings(); err != nil {
+		fmt.Println("Error loading settings:", err)
+		fmt.Println("Creating a new settings file with defaults...")
+
+		// set defaults
+		setDefaults()
+
+		// save defaults to file
+		if err := saveSettings(); err != nil {
+			fmt.Println("Failed to save default settings:", err)
+		}
+	}
+}
+
+// setDefaults populates default values in currentSettings
+func setDefaults() {
+	settingsLock.Lock()
+	defer settingsLock.Unlock()
+
+	currentSettings = UISettings{
+		Language:       "en",
+		ReloadNeeded:   false,
+
+		BantimeIncrement: true,
+		IgnoreIP:         "127.0.0.1/8 ::1 172.16.10.1/24",
+		Bantime:          "48h",
+		Findtime:         "30m",
+		Maxretry:         3,
+		Destemail:        "admin@swissmakers.ch",
+		Sender:           "noreply@swissmakers.ch",
+	}
+}
+
+// loadSettings reads the file (if exists) into currentSettings
+func loadSettings() error {
+	data, err := os.ReadFile(settingsFile)
+	if os.IsNotExist(err) {
+		return err // triggers setDefaults + save
+	}
+	if err != nil {
+		return err
+	}
+
+	var s UISettings
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+
+	settingsLock.Lock()
+	defer settingsLock.Unlock()
+	currentSettings = s
+	return nil
+}
+
+// saveSettings writes currentSettings to JSON
+func saveSettings() error {
+	settingsLock.RLock()
+	defer settingsLock.RUnlock()
+
+	b, err := json.MarshalIndent(currentSettings, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(settingsFile, b, 0644)
+}
+
+// GetSettings returns a copy of the current settings
+func GetSettings() UISettings {
+	settingsLock.RLock()
+	defer settingsLock.RUnlock()
+	return currentSettings
+}
+
+// UpdateSettings modifies the in-memory settings, sets ReloadNeeded if required, then saves to disk.
+// Optionally, we can detect changes that require a reload vs. changes that don't.
+func UpdateSettings(new UISettings) (UISettings, error) {
+	settingsLock.Lock()
+	defer settingsLock.Unlock()
+
+	// If user changed certain fields that require a Fail2ban reload, set ReloadNeeded = true.
+	// For example, if any of these fields changed:
+	reloadNeededBefore := currentSettings.ReloadNeeded
+
+	if currentSettings.BantimeIncrement != new.BantimeIncrement ||
+		currentSettings.IgnoreIP != new.IgnoreIP ||
+		currentSettings.Bantime != new.Bantime ||
+		currentSettings.Findtime != new.Findtime ||
+		currentSettings.Maxretry != new.Maxretry ||
+		currentSettings.Destemail != new.Destemail ||
+		currentSettings.Sender != new.Sender {
+		new.ReloadNeeded = true
+	} else {
+		// preserve previous ReloadNeeded if it was already true
+		new.ReloadNeeded = new.ReloadNeeded || reloadNeededBefore
+	}
+
+	currentSettings = new
+
+	// persist to file
+	if err := saveSettings(); err != nil {
+		return currentSettings, err
+	}
+	return currentSettings, nil
+}
+
+// MarkReloadDone sets ReloadNeeded = false after the user reloaded fail2ban
+func MarkReloadDone() error {
+	settingsLock.Lock()
+	defer settingsLock.Unlock()
+	currentSettings.ReloadNeeded = false
+	return saveSettings()
+}