-- Author: fruit.com.cn
-- 推荐榜：运营分类增加稳定语义、展示类型和版本，关联关系增加明确位置

ALTER TABLE drama_classification
  ADD COLUMN IF NOT EXISTS code VARCHAR(64),
  ADD COLUMN IF NOT EXISTS layout_type VARCHAR(16) NOT NULL DEFAULT 'GRID',
  ADD COLUMN IF NOT EXISTS revision BIGINT NOT NULL DEFAULT 1;

UPDATE drama_classification
SET code = 'CLASSIFICATION_' || id
WHERE code IS NULL OR BTRIM(code) = '';

UPDATE drama_classification
SET code = 'RECOMMEND_RANKING',
    layout_type = 'RANKING'
WHERE id = (
  SELECT id
  FROM drama_classification
  WHERE name IN ('推荐榜', '榜单')
  ORDER BY sort ASC, id ASC
  LIMIT 1
);

CREATE UNIQUE INDEX IF NOT EXISTS uk_drama_classification_code
  ON drama_classification (code);

ALTER TABLE drama_classification_drama
  ADD COLUMN IF NOT EXISTS position INTEGER NOT NULL DEFAULT 0;

WITH ranked AS (
  SELECT id,
         ROW_NUMBER() OVER (
           PARTITION BY classification_id
           ORDER BY created_at DESC, id DESC
         ) AS next_position
  FROM drama_classification_drama
)
UPDATE drama_classification_drama relation
SET position = ranked.next_position
FROM ranked
WHERE relation.id = ranked.id
  AND relation.position = 0;

CREATE INDEX IF NOT EXISTS idx_classification_drama_position
  ON drama_classification_drama (classification_id, position, id);

COMMENT ON COLUMN drama_classification.code IS '稳定语义码，不随多语言名称变化';
COMMENT ON COLUMN drama_classification.layout_type IS '客户端布局：GRID/RANKING';
COMMENT ON COLUMN drama_classification.revision IS '内容或顺序版本，变更后递增';
COMMENT ON COLUMN drama_classification_drama.position IS '分类内展示位置，从 1 开始';