-- 观看进度与观看流水支持 deviceId 归属；登录时由账号事务合并。

ALTER TABLE watch_progress
    ADD COLUMN IF NOT EXISTS device_id VARCHAR(128) NOT NULL DEFAULT '';
ALTER TABLE watch_progress
    ALTER COLUMN user_id DROP NOT NULL;
DROP INDEX IF EXISTS uk_watch_progress;
CREATE UNIQUE INDEX IF NOT EXISTS uk_watch_progress_user
    ON watch_progress (user_id, drama_id)
    WHERE user_id IS NOT NULL;
CREATE UNIQUE INDEX IF NOT EXISTS uk_watch_progress_device
    ON watch_progress (device_id, drama_id)
    WHERE user_id IS NULL AND device_id <> '';
CREATE INDEX IF NOT EXISTS idx_watch_progress_device
    ON watch_progress (device_id, updated_at DESC)
    WHERE device_id <> '';

ALTER TABLE watch_history
    ADD COLUMN IF NOT EXISTS device_id VARCHAR(128) NOT NULL DEFAULT '';
ALTER TABLE watch_history
    ALTER COLUMN user_id DROP NOT NULL;
CREATE INDEX IF NOT EXISTS idx_watch_history_device
    ON watch_history (device_id, watched_at DESC)
    WHERE user_id IS NULL AND device_id <> '';