Added data layer.

Initial structure for database clients. Exposes a user package with
SQLite and PostgreSQL implementations.

internal/data/user/user_sqlite.go

@@ -0,0 +1,89 @@
+package user
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"crawshaw.io/sqlite/sqlitex"
+)
+
+// SQLite provides methods for creating users in SQLite.
+type SQLite struct{ db *sqlitex.Pool }
+
+// NewSQLite creates a SQLite client.
+func NewSQLite(db *sqlitex.Pool) *SQLite {
+	return &SQLite{db: db}
+}
+
+// CreateUser creates a new user in the database.
+func (d *SQLite) CreateUser(ctx context.Context, username, email, password string) (*User, error) {
+	u, err := create(username, email, password)
+	if err != nil {
+		return nil, err
+	}
+
+	conn := d.db.Get(ctx)
+	if conn == nil {
+		return nil, context.Canceled
+	}
+	defer d.db.Put(conn)
+
+	stmt := conn.Prep(
+		`INSERT INTO users (
+			id, username, email, password, salt, confirmation_hash
+		) VALUES (
+			$id, $username, $email, $password, $salt, $confirmationHash);`)
+	stmt.SetText("$id", u.ID)
+	stmt.SetText("$username", u.Username)
+	stmt.SetText("$email", u.Email)
+	stmt.SetBytes("$password", u.Password)
+	stmt.SetBytes("$salt", u.Salt)
+	stmt.SetText("$confirmationHash", *u.ConfirmationHash)
+	if _, err := stmt.Step(); err != nil {
+		return nil, err
+	}
+
+	stmt = conn.Prep(`SELECT created_at, updated_at FROM users WHERE id = $id`)
+	stmt.SetText("$id", u.ID)
+	if _, err := stmt.Step(); err != nil {
+		return nil, err
+	}
+
+	u.CreatedAt, err = time.Parse("2006-01-02 15:04:05", stmt.GetText("created_at"))
+	if err != nil {
+		return nil, err
+	}
+
+	u.UpdatedAt, err = time.Parse("2006-01-02 15:04:05", stmt.GetText("updated_at"))
+	if err != nil {
+		return nil, err
+	}
+
+	return u, stmt.Reset()
+}
+
+func (d *SQLite) ConfirmUser(ctx context.Context, confirmation string) error {
+	conn := d.db.Get(ctx)
+	if conn == nil {
+		return context.Canceled
+	}
+	defer d.db.Put(conn)
+
+	stmt := conn.Prep(
+		`UPDATE users 
+		 SET confirmation_hash = NULL 
+		 WHERE confirmation_hash = $confirmationHash;`)
+
+	stmt.SetText("$confirmationHash", confirmation)
+	if _, err := stmt.Step(); err != nil {
+		return fmt.Errorf("set sqlite confirmation_hash to NULL: %w", err)
+	}
+
+	if conn.Changes() == 0 {
+		return errors.New("unknown confirmation_hash in sqlite")
+	}
+
+	return nil
+}