package persistence

import (
	"encoding/json"
	"os"

	"github.com/StevanFreeborn/term-tier/internal/core"
)

type FileSystem interface {
	WriteFile(name string, data []byte, perm os.FileMode) error
	ReadFile(name string) ([]byte, error)
}

type osFileSystem struct{}

func (osFileSystem) WriteFile(name string, data []byte, perm os.FileMode) error {
	return os.WriteFile(name, data, perm)
}

func (osFileSystem) ReadFile(name string) ([]byte, error) {
	return os.ReadFile(name)
}

type fileSaver struct {
	fs FileSystem
}

func NewFileSaver() core.Saver {
	return &fileSaver{
		fs: osFileSystem{},
	}
}

func NewFileSaverWithFS(fs FileSystem) core.Saver {
	return &fileSaver{
		fs: fs,
	}
}

func (s *fileSaver) Save(filename string, state core.SaveState) error {
	data, err := json.MarshalIndent(state, "", "  ")
	if err != nil {
		return err
	}

	return s.fs.WriteFile(filename, data, 0644)
}

func (s *fileSaver) Load(filename string) (core.SaveState, error) {
	data, err := s.fs.ReadFile(filename)
	if err != nil {
		return core.SaveState{}, err
	}

	var state core.SaveState
	if err := json.Unmarshal(data, &state); err != nil {
		return core.SaveState{}, err
	}

	return state, nil
}