-- Multi-role support: user_roles junction table + backfill from users.role_id

CREATE TABLE IF NOT EXISTS user_roles (
  id         BIGSERIAL PRIMARY KEY,
  user_id    BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  role_id    BIGINT NOT NULL REFERENCES roles(id) ON DELETE RESTRICT,
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  UNIQUE (user_id, role_id)
);

CREATE INDEX IF NOT EXISTS idx_user_roles_user_id ON user_roles(user_id);
CREATE INDEX IF NOT EXISTS idx_user_roles_role_id ON user_roles(role_id);

INSERT INTO user_roles (user_id, role_id)
SELECT id, role_id
FROM users
WHERE role_id IS NOT NULL
  AND deleted_at IS NULL
ON CONFLICT (user_id, role_id) DO NOTHING;