package storage

import (
	"encoding/json"
	"fmt"
	"io/fs"
)

type Data interface {
}

type Item struct {
	Version      int    `json:"version"`
	MinorVersion *int   `json:"minor_version,omitempty"`
	Key          string `json:"key"`
	Data         Data   `json:"data"`
}

type store struct {
	fs.FS
}

type Store interface {
	Get(key string, data interface{}) error
}

func (s *store) Get(key string, data interface{}) error {
	f, err := s.Open(key)
	if err != nil {
		return err
	}

	defer f.Close()

	item := Item{
		Data: data,
	}
	d := json.NewDecoder(f)
	err = d.Decode(&item)
	if err != nil {
		return err
	}

	if item.Key != key {
		return fmt.Errorf("key mismatch '%s' != '%s'", item.Key, key)
	}

	return nil
}

func Open(dir fs.FS) (*store, error) {
	stor, err := fs.Sub(dir, ".storage")
	if err != nil {
		return nil, err
	}

	return &store{stor}, nil
}