-- 379_asme_clause_kb.sql
-- ASME 절-지식베이스: 절 = 개별 documents 행(parent_id) + 절↔절 백링크 + 태깅 (additive, idempotent)
-- 검색 무접촉: 절 doc 은 embedding NULL(벡터 제외) + doc_kind='clause'(retrieval doc-leg 필터로 제외).

ALTER TABLE documents
  ADD COLUMN IF NOT EXISTS parent_id    bigint REFERENCES documents(id),
  ADD COLUMN IF NOT EXISTS doc_kind     text NOT NULL DEFAULT 'standard',
  ADD COLUMN IF NOT EXISTS clause_code  text,
  ADD COLUMN IF NOT EXISTS clause_part  text,
  ADD COLUMN IF NOT EXISTS clause_order int;

CREATE INDEX IF NOT EXISTS idx_documents_parent_id   ON documents(parent_id) WHERE parent_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_documents_doc_kind    ON documents(doc_kind);
CREATE INDEX IF NOT EXISTS idx_documents_clause_code ON documents(clause_code) WHERE clause_code IS NOT NULL;

-- 절↔절 백링크 (dangling 허용: dst_doc_id nullable)
CREATE TABLE IF NOT EXISTS clause_links (
  id          bigserial PRIMARY KEY,
  src_doc_id  bigint NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
  dst_code    text   NOT NULL,
  dst_doc_id  bigint REFERENCES documents(id) ON DELETE SET NULL,
  anchor      text,
  ctx         text,
  char_off    int
);
CREATE INDEX IF NOT EXISTS idx_clause_links_src     ON clause_links(src_doc_id);
CREATE INDEX IF NOT EXISTS idx_clause_links_dst     ON clause_links(dst_doc_id) WHERE dst_doc_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_clause_links_dstcode ON clause_links(dst_code);

-- 태깅 (Part 자동 + 주제)
CREATE TABLE IF NOT EXISTS document_tags (
  doc_id    bigint NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
  tag       text   NOT NULL,
  tag_kind  text   NOT NULL DEFAULT 'topic',
  PRIMARY KEY (doc_id, tag)
);
CREATE INDEX IF NOT EXISTS idx_document_tags_tag ON document_tags(tag);