package goncfiles

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

// DefaultPathStore persists the Saved Default Working Folder path (User Files Root–relative).
type DefaultPathStore interface {
	// GetDefault returns the stored path, or empty when none is set yet.
	GetDefault() (string, error)
	// SetDefault writes a User Files Root–relative Working Folder path.
	SetDefault(rel string) error
}

// FileStore is the local-adapter settings JSON file.
type FileStore struct {
	Path string
}

type settingsFile struct {
	DefaultPath string `json:"defaultPath"`
}

// GetDefault reads the saved default; empty means the caller should use the product initial default.
func (s FileStore) GetDefault() (string, error) {
	body, err := os.ReadFile(s.Path)
	if err != nil {
		if os.IsNotExist(err) {
			return "", nil
		}
		return "", err
	}
	var sf settingsFile
	if err := json.Unmarshal(body, &sf); err != nil {
		return "", err
	}
	return strings.TrimSpace(sf.DefaultPath), nil
}

// SetDefault writes the saved Working Folder path.
func (s FileStore) SetDefault(rel string) error {
	body, err := json.MarshalIndent(settingsFile{DefaultPath: rel}, "", "  ")
	if err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(s.Path), 0o755); err != nil {
		return err
	}
	return os.WriteFile(s.Path, append(body, '\n'), 0o644)
}

// Memory is an in-memory DefaultPathStore for tests.
type Memory struct {
	Value string
}

// GetDefault returns the in-memory value.
func (m *Memory) GetDefault() (string, error) { return m.Value, nil }

// SetDefault stores the value in memory.
func (m *Memory) SetDefault(rel string) error {
	m.Value = rel
	return nil
}