-- migrate:up
CREATE EXTENSION pgcrypto;
CREATE EXTENSION pgjwt;

CREATE FUNCTION
internal.check_role_exists() RETURNS TRIGGER AS $$
BEGIN
  IF NOT EXISTS (SELECT 1 FROM pg_roles AS r WHERE r.rolname = NEW.role) THEN
    RAISE foreign_key_violation USING MESSAGE =
      'Unknown database role: ' || NEW.role;
    RETURN NULL;
  END IF;
  RETURN NEW;
END
$$ LANGUAGE plpgsql;

CREATE CONSTRAINT TRIGGER ensure_user_role_exists
AFTER INSERT OR UPDATE ON internal.user
FOR EACH ROW
EXECUTE FUNCTION internal.check_role_exists();


CREATE FUNCTION
internal.encrypt_pass() RETURNS TRIGGER AS $$
BEGIN
  IF TG_OP = 'INSERT' OR NEW.password_hash != OLD.password_hash THEN
    NEW.password_hash = crypt(NEW.password_hash, gen_salt('bf'));
  END IF;
  RETURN NEW;
END
$$ LANGUAGE plpgsql;

CREATE TRIGGER encrypt_pass
BEFORE INSERT OR UPDATE ON internal.user
FOR EACH ROW
EXECUTE FUNCTION internal.encrypt_pass();


CREATE FUNCTION
internal.user_role(username TEXT, password TEXT) RETURNS NAME AS $$
BEGIN
  RETURN (
    SELECT role FROM internal.user AS u
    WHERE u.username = user_role.username
    AND u.password_hash = crypt(user_role.password, u.password_hash)
  );
END;
$$ LANGUAGE plpgsql;


CREATE FUNCTION
api.register(username TEXT, password TEXT, OUT user_id UUID) AS $$
DECLARE
  _username_length_min CONSTANT INT := 3;
  _username_length_max CONSTANT INT := 16;
  _password_length_min CONSTANT INT := 12;
  _password_length_max CONSTANT INT := 128;
BEGIN
  IF LENGTH(register.username) NOT BETWEEN _username_length_min AND _username_length_max THEN
    RAISE string_data_length_mismatch USING MESSAGE = format('Username must be between %s and %s characters long', _username_length_min, _username_length_max);
  END IF;

  IF EXISTS (SELECT 1 FROM internal.user AS u WHERE u.username = register.username) THEN
    RAISE unique_violation USING MESSAGE = 'Username is already taken';
  END IF;

  IF LENGTH(register.password) NOT BETWEEN _password_length_min AND _password_length_max THEN
    RAISE string_data_length_mismatch USING MESSAGE = format('Password must be between %s and %s characters long', _password_length_min, _password_length_max);
  END IF;

  IF register.password !~ '[a-z]' THEN
    RAISE invalid_parameter_value USING MESSAGE = 'Password must contain at least one lowercase letter';
  END IF;

  IF register.password !~ '[A-Z]' THEN
    RAISE invalid_parameter_value USING MESSAGE = 'Password must contain at least one uppercase letter';
  END IF;

  IF register.password !~ '[0-9]' THEN
    RAISE invalid_parameter_value USING MESSAGE = 'Password must contain at least one number';
  END IF;

  IF register.password !~ '[!@#$%^&*(),.?":{}|<>]' THEN
    RAISE invalid_parameter_value USING MESSAGE = 'Password must contain at least one special character';
  END IF;

  INSERT INTO internal.user (username, password_hash)
  VALUES (register.username, register.password)
  RETURNING id INTO user_id;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;


CREATE FUNCTION
api.login(username TEXT, password TEXT, OUT token TEXT) AS $$
DECLARE
  _role NAME;
  _user_id UUID;
  _exp INTEGER;
BEGIN
  SELECT internal.user_role(login.username, login.password) INTO _role;
  IF _role IS NULL THEN
    RAISE invalid_password USING MESSAGE = 'Invalid username or password';
  END IF;

  SELECT id INTO _user_id
  FROM internal.user AS u
  WHERE u.username = login.username;

  _exp := extract(EPOCH FROM CLOCK_TIMESTAMP())::INTEGER + 86400;

  SELECT sign(
    json_build_object(
      'role', _role,
      'user_id', _user_id,
      'username', login.username,
      'exp', _exp
    ),
    current_setting('app.jwt_secret')
  ) INTO token;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;


CREATE FUNCTION
api.delete_account(password TEXT, OUT was_deleted BOOLEAN) AS $$
DECLARE
  _username TEXT := current_setting('request.jwt.claims', true)::json->>'username';
  _role NAME;
BEGIN
  SELECT internal.user_role(_username, delete_account.password) INTO _role;
  IF _role IS NULL THEN
    RAISE invalid_password USING MESSAGE = 'Invalid password';
  END IF;

  DELETE FROM internal.user AS u
  WHERE u.username = _username;

  was_deleted := TRUE;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;


GRANT EXECUTE ON FUNCTION api.register(TEXT, TEXT) TO anon;
GRANT EXECUTE ON FUNCTION api.login(TEXT, TEXT) TO anon;

-- migrate:down
DROP FUNCTION api.register(TEXT, TEXT);
DROP FUNCTION api.login(TEXT, TEXT);
DROP FUNCTION api.delete_account(TEXT);

DROP FUNCTION internal.user_role(TEXT, TEXT);

DROP TRIGGER encrypt_pass ON internal.user;
DROP FUNCTION internal.encrypt_pass();

DROP TRIGGER ensure_user_role_exists ON internal.user;
DROP FUNCTION internal.check_role_exists();

DROP EXTENSION pgjwt;
DROP EXTENSION pgcrypto;