package wisp

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

// EnsureDir ensures the .beads directory exists in the given root.
func EnsureDir(root string) (string, error) {
	dir := filepath.Join(root, WispDir)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return "", fmt.Errorf("create beads dir: %w", err)
	}
	return dir, nil
}

// WispPath returns the full path to a file in the beads directory.
func WispPath(root, filename string) string {
	return filepath.Join(root, WispDir, filename)
}

// writeJSON is a helper to write JSON files atomically.
func writeJSON(path string, v interface{}) error {
	data, err := json.MarshalIndent(v, "", "  ")
	if err != nil {
		return fmt.Errorf("marshal json: %w", err)
	}

	// Write to temp file then rename for atomicity
	tmp := path + ".tmp"
	if err := os.WriteFile(tmp, data, 0644); err != nil { //nolint:gosec // G306: wisp messages are non-sensitive operational data
		return fmt.Errorf("write temp: %w", err)
	}

	if err := os.Rename(tmp, path); err != nil {
		_ = os.Remove(tmp) // cleanup on failure
		return fmt.Errorf("rename: %w", err)
	}

	return nil
}