Add user model

models/sql/users.sql

@@ -0,0 +1,5 @@
+CREATE TABLE users (
+  id SERIAL PRIMARY KEY,
+  email TEXT UNIQUE NOT NULL,
+  password_hash TEXT NOT NULL
+);

models/user.go

@@ -0,0 +1,43 @@
+package models
+
+import (
+	"database/sql"
+	"fmt"
+	"strings"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+type User struct {
+	ID           int
+	Email        string
+	PasswordHash string
+}
+
+type UserService struct {
+	DB *sql.DB
+}
+
+func (us *UserService) Create(email, password string) (*User, error) {
+	email = strings.ToLower(email)
+
+	hashedBytes, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return nil, fmt.Errorf("create user: %w", err)
+	}
+	passwordHash := string(hashedBytes)
+
+	user := User{
+		Email:        email,
+		PasswordHash: passwordHash,
+	}
+	row := us.DB.QueryRow(`
+    INSERT INTO users (email, password_hash)
+    VALUES ($1, $2) RETURNING id
+  `, email, passwordHash)
+	err = row.Scan(&user.ID)
+	if err != nil {
+		return nil, fmt.Errorf("create user: %w", err)
+	}
+	return &user, nil
+}