-- 0054_user_profiles_username.sql
-- ----------------------------------------------------------------------------
-- Optional username as a sign-in alternative to email. Stored alongside the
-- canonical first/last name on user_profiles so the rest of the auth/profile
-- code keeps a single place to look. The Better-Auth `user` table stays the
-- source of truth for email + password; the username is a thin alias the
-- login form looks up to resolve to the matching email before delegating
-- to better-auth's email/password flow.
--
-- Constraints (enforced application-side AND in SQL):
--   - 2..30 characters
--   - lowercase letters, digits, dot, underscore, hyphen
--   - case-insensitive uniqueness per install (no per-port scoping -
--     reps move between ports and a global username keeps URLs stable)
--
-- The column is nullable; existing users keep email-only sign-in until they
-- pick one.

ALTER TABLE user_profiles
  ADD COLUMN IF NOT EXISTS username TEXT;

-- Shape check at the DB level catches anything that slipped past the API
-- (raw SQL inserts in tests, scripts, etc.).
ALTER TABLE user_profiles
  ADD CONSTRAINT chk_user_profiles_username_shape
    CHECK (username IS NULL OR username ~ '^[a-z0-9._-]{2,30}$');

-- Case-insensitive uniqueness. Partial so multiple NULLs are allowed.
CREATE UNIQUE INDEX IF NOT EXISTS idx_user_profiles_username_unique
  ON user_profiles (LOWER(username))
  WHERE username IS NOT NULL;
