users/cmd/server/user_db.go

package main

import "errors"

type User struct {
	ID       int64
	Email    string
	Password string
}

type UserDB interface {
	FindByID(id int64) (*User, error)
	FindByEmail(email string) (*User, error)
	Save(*User) error
}

type inMemoryUserDB struct {
	UserDB
	nextID int
	users  []*User
}

func newInMemoryUserDB() *inMemoryUserDB {
	return &inMemoryUserDB{
		nextID: 1,
		users:  make([]*User, 0),
	}
}

func (m *inMemoryUserDB) FindByID(id int64) (*User, error) {
	for _, u := range m.users {
		if u.ID == id {
			return u, nil
		}
	}

	return nil, errors.New("User not found.")
}

func (m *inMemoryUserDB) FindByEmail(email string) (*User, error) {
	for _, u := range m.users {
		if u.Email == email {
			return u, nil
		}
	}

	return nil, errors.New("User not found.")
}

func (m *inMemoryUserDB) Save(user *User) error {
	for i, u := range m.users {
		if u.ID == user.ID || u.Email == user.Email {
			m.users[i] = user
			return nil
		}
	}

	user.ID = m.nextID
	m.users = append(m.users, user)
	m.nextID++
	return nil
}