refactor: restructure in entirety

internal/database/user.go

@@ -0,0 +1,58 @@
+package database
+
+import (
+	"billit/internal/models"
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+// CreateUser creates a new user with hashed password
+func (s *service) CreateUser(email, passwordHash string) (*models.User, error) {
+	id := fmt.Sprintf("%d", time.Now().UnixNano())
+	_, err := s.db.Exec(`INSERT INTO users (id, email, password) VALUES (?, ?, ?)`, id, email, passwordHash)
+	if err != nil {
+		return nil, err
+	}
+	return s.GetUserByID(id)
+}
+
+// GetUserByEmail retrieves a user by email
+func (s *service) GetUserByEmail(email string) (*models.User, error) {
+	var u models.User
+	err := s.db.QueryRow(`SELECT id, email, password, COALESCE(company_details, ''), COALESCE(bank_details, ''), COALESCE(invoice_prefix, 'INV'), COALESCE(invoice_counter, 0), created_at FROM users WHERE email = ?`, email).
+		Scan(&u.ID, &u.Email, &u.Password, &u.CompanyDetails, &u.BankDetails, &u.InvoicePrefix, &u.InvoiceCounter, &u.CreatedAt)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &u, nil
+}
+
+// GetUserByID retrieves a user by ID
+func (s *service) GetUserByID(id string) (*models.User, error) {
+	var u models.User
+	err := s.db.QueryRow(`SELECT id, email, password, COALESCE(company_details, ''), COALESCE(bank_details, ''), COALESCE(invoice_prefix, 'INV'), COALESCE(invoice_counter, 0), created_at FROM users WHERE id = ?`, id).
+		Scan(&u.ID, &u.Email, &u.Password, &u.CompanyDetails, &u.BankDetails, &u.InvoicePrefix, &u.InvoiceCounter, &u.CreatedAt)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &u, nil
+}
+
+// UpdateUserPassword updates a user's password hash
+func (s *service) UpdateUserPassword(id string, passwordHash string) error {
+	_, err := s.db.Exec(`UPDATE users SET password = ? WHERE id = ?`, passwordHash, id)
+	return err
+}
+
+// UpdateUserDetails updates a user's company and bank details
+func (s *service) UpdateUserDetails(id string, companyDetails string, bankDetails string, invoicePrefix string) error {
+	_, err := s.db.Exec(`UPDATE users SET company_details = ?, bank_details = ?, invoice_prefix = ? WHERE id = ?`, companyDetails, bankDetails, invoicePrefix, id)
+	return err
+}