✨ feat(storage): 支持自定义数据目录与显式迁移

Fixes #242

internal/appdata/root.go

@@ -0,0 +1,112 @@
+package appdata
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const bootstrapFileName = "storage_root.json"
+
+type bootstrapConfig struct {
+	DataRoot string `json:"dataRoot"`
+}
+
+func DefaultRoot() string {
+	homeDir, err := os.UserHomeDir()
+	if err != nil || strings.TrimSpace(homeDir) == "" {
+		return "."
+	}
+	return filepath.Join(homeDir, ".gonavi")
+}
+
+func BootstrapPath() string {
+	return filepath.Join(DefaultRoot(), bootstrapFileName)
+}
+
+func normalizeRoot(root string) (string, error) {
+	trimmed := strings.TrimSpace(root)
+	if trimmed == "" {
+		trimmed = DefaultRoot()
+	}
+	abs, err := filepath.Abs(trimmed)
+	if err != nil {
+		return "", err
+	}
+	return abs, nil
+}
+
+func ResolveRoot(root string) (string, error) {
+	return normalizeRoot(root)
+}
+
+func ResolveActiveRoot() (string, error) {
+	defaultRoot, err := normalizeRoot(DefaultRoot())
+	if err != nil {
+		return "", err
+	}
+	data, err := os.ReadFile(BootstrapPath())
+	if err != nil {
+		if os.IsNotExist(err) {
+			return defaultRoot, nil
+		}
+		return "", err
+	}
+	var cfg bootstrapConfig
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return "", err
+	}
+	if strings.TrimSpace(cfg.DataRoot) == "" {
+		return defaultRoot, nil
+	}
+	return normalizeRoot(cfg.DataRoot)
+}
+
+func MustResolveActiveRoot() string {
+	root, err := ResolveActiveRoot()
+	if err != nil {
+		return DefaultRoot()
+	}
+	return root
+}
+
+func DriverRoot(activeRoot string) string {
+	root := strings.TrimSpace(activeRoot)
+	if root == "" {
+		root = MustResolveActiveRoot()
+	}
+	return filepath.Join(root, "drivers")
+}
+
+func SetActiveRoot(root string) (string, error) {
+	targetRoot, err := normalizeRoot(root)
+	if err != nil {
+		return "", err
+	}
+	defaultRoot, err := normalizeRoot(DefaultRoot())
+	if err != nil {
+		return "", err
+	}
+	if err := os.MkdirAll(targetRoot, 0o755); err != nil {
+		return "", fmt.Errorf("创建数据目录失败：%w", err)
+	}
+	if targetRoot == defaultRoot {
+		if err := os.Remove(BootstrapPath()); err != nil && !os.IsNotExist(err) {
+			return "", err
+		}
+		return defaultRoot, nil
+	}
+	if err := os.MkdirAll(defaultRoot, 0o755); err != nil {
+		return "", fmt.Errorf("创建默认引导目录失败：%w", err)
+	}
+	payload, err := json.MarshalIndent(bootstrapConfig{DataRoot: targetRoot}, "", "  ")
+	if err != nil {
+		return "", err
+	}
+	if err := os.WriteFile(BootstrapPath(), payload, 0o644); err != nil {
+		return "", err
+	}
+	return targetRoot, nil
+}