const db = getDb("cache.sqlite");
db.table(
  "asset_refs",
  /* SQL */ `
  create table if not exists asset_refs (
    id integer primary key autoincrement,
    key text not null UNIQUE,
    refs integer not null
  );
  create table if not exists asset_ref_files (
    file text not null,
    id integer not null,
    foreign key (id) references asset_refs(id) ON DELETE CASCADE
  );
  create index asset_ref_files_id on asset_ref_files(id);
`,
);

/**
 * Uncompressed files are read directly from the media store root. Derivied
 * assets like compressed files, optimized images, and streamable video are
 * stored in the `derived` folder. After scanning, the derived assets are
 * uploaded into the store (storage1/clofi-derived dataset on NAS). Since
 * multiple files can share the same hash, the number of references is
 * tracked, and the derived content is only produced once. This means if a
 * file is deleted, it should only decrement a reference count; deleting it
 * once all references are removed.
 */
export class AssetRef {
  /** Key which aws referenced */
  id!: number;
  key!: string;
  refs!: number;

  unref() {
    decrementQuery.run(this.key);
    deleteUnreferencedQuery.run().changes > 0;
  }

  addFiles(files: string[]) {
    for (const file of files) {
      addFileQuery.run({ id: this.id, file });
    }
  }

  static get(key: string) {
    return getQuery.get(key);
  }

  static putOrIncrement(key: string) {
    putOrIncrementQuery.get(key);
    return UNWRAP(AssetRef.get(key));
  }
}

const getQuery = db.prepare<[key: string]>(/* SQL */ `
  select * from asset_refs where key = ?;
`).as(AssetRef);
const putOrIncrementQuery = db.prepare<[key: string]>(/* SQL */ `
  insert into asset_refs (key, refs) values (?, 1)
  on conflict(key) do update set refs = refs + 1;
`);
const decrementQuery = db.prepare<[key: string]>(/* SQL */ `
  update asset_refs set refs = refs - 1 where key = ? and refs > 0;
`);
const deleteUnreferencedQuery = db.prepare(/* SQL */ `
  delete from asset_refs where refs <= 0;
`);
const addFileQuery = db.prepare<[{ id: number; file: string }]>(/* SQL */ `
  insert into asset_ref_files (id, file) values ($id, $file);
`);

import { getDb } from "#sitegen/sqlite";