package main

import "encoding/hex"
import "encoding/json"
import "fmt"
import "os"
import "path/filepath"

type Store struct {
  root string
}

func NewStore(root string) *Store {
  return &Store{
    root: root,
  }
}

func (s *Store) Write(obj Object) error {
  dir := filepath.Join(s.root, obj.GetType())
  filename := hex.EncodeToString([]byte(obj.GetId()))

  err := os.MkdirAll(dir, 0700)
  if err != nil {
    return err
  }

  tmp, err := os.CreateTemp(dir, fmt.Sprintf("%s.*", filename))
  if err != nil {
    return err
  }
  defer tmp.Close()

  enc := json.NewEncoder(tmp)
  enc.SetEscapeHTML(false)

  err = enc.Encode(obj)
  if err != nil {
    return err
  }

  err = tmp.Close()
  if err != nil {
    return err
  }

  err = os.Rename(tmp.Name(), filepath.Join(dir, filename))
  if err != nil {
    return err
  }

  return nil
}

func (s *Store) Read(obj Object) error {
  dir := filepath.Join(s.root, obj.GetType())
  filename := hex.EncodeToString([]byte(obj.GetId()))

  fh, err := os.Open(filepath.Join(dir, filename))
  if err != nil {
    return err
  }
  defer fh.Close()

  dec := json.NewDecoder(fh)
  dec.DisallowUnknownFields()

  err = dec.Decode(obj)
  if err != nil {
    return err
  }

  return nil
}