heygo/worker/lib/aliases.ts

export const ALIAS_MAX_LENGTH = 100;

const ALIAS_INVALID_ERROR = 'Alias may contain only letters, numbers, underscore, and hyphen';
const ALIAS_PATTERN = /^[a-z0-9][a-z0-9_-]{0,99}$/;

type AliasValidationSuccess = {
  ok: true;
  value: string;
};

type AliasValidationFailure = {
  ok: false;
  error: string;
};

export type ValidationResult = AliasValidationSuccess | AliasValidationFailure;

export function normalizeAlias(input: string): string {
  return input.trim().replace(/[A-Z]/g, (character) => character.toLowerCase());
}

export function validateAlias(input: string): ValidationResult {
  const value = normalizeAlias(input);

  if (value.length === 0) {
    return { ok: false, error: 'Alias is required' };
  }

  if (value.length > ALIAS_MAX_LENGTH) {
    return { ok: false, error: `Alias must be ${ALIAS_MAX_LENGTH} characters or fewer` };
  }

  if (!ALIAS_PATTERN.test(value)) {
    return { ok: false, error: ALIAS_INVALID_ERROR };
  }

  return { ok: true, value };
}