package main

import (
	"encoding/json"
	"fmt"
	"os"
	"reflect"
)

type FileSystemUserStore struct {
	database *json.Encoder
	userList UserList
}

func NewFileSystemUserStore(file *os.File) (*FileSystemUserStore, error) {
	err := initialiseUserDBFile(file)
	if err != nil {
		fmt.Errorf("problem initializing user db file, %v", err)
	}

	userList, err := NewUserList(file)

	if err != nil {
		return nil, fmt.Errorf("problem loading user list from file %s, %v", file.Name(), err)
	}

	return &FileSystemUserStore{
		database: json.NewEncoder(&Tape{file}),
		userList: userList,
	}, nil
}

func initialiseUserDBFile(file *os.File) error {
	file.Seek(0, 0)

	info, err := file.Stat()

	if err != nil {
		return fmt.Errorf("problem getting file info from file %s, %v", file.Name(), err)
	}

	if info.Size() == 0 {
		file.Write([]byte("[]"))
		file.Seek(0, 0)
	}

	return nil
}

// todo add interface

func (f *FileSystemUserStore) AddUserToUserList(user User) {
	f.userList = append(f.userList, user)
}

func (f *FileSystemUserStore) DeleteUserFromUserList(user User) {
	var userList []User
	for _, u := range f.userList {
		if !reflect.DeepEqual(u, user) {
			userList = append(userList, u)
		}
	}
	f.userList = userList
}

func (f *FileSystemUserStore) GetUsers() UserList {
	return f.userList
}

func (f *FileSystemUserStore) UpdateUserFromUserList(toUpdate, newState User) {
	user := f.userList.Find(toUpdate.Username)
	*user = newState
}