// Package paths handles the resolution of configuration and runtime directories,
// providing a consistent way to locate profile and PID tracking files.
//
// Profile Storage:
// Profiles are stored as standard .conf files in ~/.config/wg-wrap/profiles/.
//
// PID Tracking:
// To manage namespace lifecycles and shared sessions, wg-wrap tracks active processes
// using PID files located in the runtime base directory:
// /run/user/$UID/wg-wrap/profiles/<profile-name>/pids/
package paths

import (
	"fmt"
	"os"
	"path/filepath"
)

// PathManager handles the resolution of configuration and runtime directories.
// By using a struct, we can instantiate different managers for parallel tests.
type PathManager struct {
	// ConfigDirOverride allows overriding the default config directory (usually XDG_CONFIG_HOME/wg-wrap/profiles).
	ConfigDirOverride string
	// RuntimeBaseOverride allows overriding the default runtime directory (usually XDG_RUNTIME_DIR).
	RuntimeBaseOverride string
}

// NewPathManager creates a PathManager with the given overrides.
func NewPathManager(configOverride, runtimeOverride string) *PathManager {
	return &PathManager{
		ConfigDirOverride:   configOverride,
		RuntimeBaseOverride: runtimeOverride,
	}
}

// ConfigDir returns the persistent storage path for .conf files.
func (pm *PathManager) ConfigDir() string {
	if pm.ConfigDirOverride != "" {
		return pm.ConfigDirOverride
	}

	configHome := os.Getenv("XDG_CONFIG_HOME")
	if configHome == "" {
		home, err := os.UserHomeDir()
		if err != nil {
			return "/etc/wg-wrap/profiles" // Fallback
		}
		configHome = filepath.Join(home, ".config")
	}
	return filepath.Join(configHome, "wg-wrap", "profiles")
}

// RuntimeBaseDir returns the base ephemeral path.
func (pm *PathManager) RuntimeBaseDir() string {
	if pm.RuntimeBaseOverride != "" {
		return pm.RuntimeBaseOverride
	}

	if envDir := os.Getenv("WG_WRAP_HOST_RUNTIME_BASE_DIR"); envDir != "" {
		return envDir
	}

	if envDir := os.Getenv("XDG_RUNTIME_DIR"); envDir != "" {
		return envDir
	}
	uid := os.Getuid()
	return fmt.Sprintf("/run/user/%d", uid)
}

// ProfileNamespacePath returns the specific path for a pinned namespace.
func (pm *PathManager) ProfileNamespacePath(profile string) string {
	return filepath.Join(pm.RuntimeBaseDir(), "profiles", profile+".ns")
}

// ProfilePidsDir returns the path for PID tracking.
func (pm *PathManager) ProfilePidsDir(profile string) string {
	return filepath.Join(pm.RuntimeBaseDir(), "profiles", profile, "pids")
}