-- 0009_search_authors.sql — make credited people (authors, artists, directors)
-- searchable.
--
-- 0003 indexed only `title` and `path`, so typing an author's name found
-- nothing even though `people` and `item_people` already held the credits.
-- Rather than make the search query join the credit tables — which would mean a
-- second MATCH against a second index, or an unindexed LIKE over a join — the
-- names are denormalised into a real column on `media_items`. The existing
-- external-content FTS5 design then keeps working unchanged in spirit: the
-- index still stores no text of its own, and the media_items triggers that
-- already keep it in sync simply gain the new column.
--
-- `authors` is maintained by triggers on item_people/people, so a credit change
-- re-indexes the item no matter which code path writes it — the metadata
-- enricher today, anything else later.

ALTER TABLE media_items ADD COLUMN authors TEXT NOT NULL DEFAULT '';

-- Drop the old two-column index and its triggers before rebuilding.
-- Triggers first: dropping the virtual table does not drop triggers that
-- reference it, and a write landing between the two drops would fire a trigger
-- against a table that no longer exists.
DROP TRIGGER media_items_ai;
DROP TRIGGER media_items_ad;
DROP TRIGGER media_items_au;
DROP TABLE media_search;

CREATE VIRTUAL TABLE media_search USING fts5(
    title,
    path,
    authors,
    content='media_items',
    content_rowid='id',
    tokenize='unicode61 remove_diacritics 2'
);

-- Populate the fresh index from current content before the backfill below.
-- FTS5's external-content 'delete' command assumes the rowid is already in the
-- index; issuing it for an absent rowid raises "database disk image is
-- malformed". The backfill UPDATE fires media_items_au (a delete+insert) for
-- every existing row, so the index must first hold those rows. On a fresh
-- database this indexes nothing and is a no-op.
INSERT INTO media_search(media_search) VALUES ('rebuild');

-- Recreate the media_items triggers verbatim from 0003, with `authors` added,
-- so every direct write to an item keeps the index correct.
CREATE TRIGGER media_items_ai AFTER INSERT ON media_items BEGIN
    INSERT INTO media_search(rowid, title, path, authors)
    VALUES (new.id, new.title, new.path, new.authors);
END;

CREATE TRIGGER media_items_ad AFTER DELETE ON media_items BEGIN
    INSERT INTO media_search(media_search, rowid, title, path, authors)
    VALUES ('delete', old.id, old.title, old.path, old.authors);
END;

CREATE TRIGGER media_items_au AFTER UPDATE ON media_items BEGIN
    INSERT INTO media_search(media_search, rowid, title, path, authors)
    VALUES ('delete', old.id, old.title, old.path, old.authors);
    INSERT INTO media_search(rowid, title, path, authors)
    VALUES (new.id, new.title, new.path, new.authors);
END;

-- Credit triggers. Each recomputes media_items.authors for the affected item.
-- That UPDATE is itself on media_items, so media_items_au fires and rewrites
-- the FTS row — no FTS-specific code is needed here. (This is a single level of
-- trigger nesting, not recursion; and even with PRAGMA recursive_triggers=1 the
-- chain terminates because the FTS write targets the virtual table, not
-- media_items.)
CREATE TRIGGER item_people_ai AFTER INSERT ON item_people BEGIN
    UPDATE media_items SET authors = COALESCE((
        SELECT group_concat(p.name, ' ') FROM item_people ip
        JOIN people p ON p.id = ip.person_id
        WHERE ip.item_id = media_items.id), '')
    WHERE id = new.item_id;
END;

CREATE TRIGGER item_people_ad AFTER DELETE ON item_people BEGIN
    UPDATE media_items SET authors = COALESCE((
        SELECT group_concat(p.name, ' ') FROM item_people ip
        JOIN people p ON p.id = ip.person_id
        WHERE ip.item_id = media_items.id), '')
    WHERE id = old.item_id;
END;

-- An UPDATE can move a credit between items, so both ends are recomputed.
CREATE TRIGGER item_people_au AFTER UPDATE ON item_people BEGIN
    UPDATE media_items SET authors = COALESCE((
        SELECT group_concat(p.name, ' ') FROM item_people ip
        JOIN people p ON p.id = ip.person_id
        WHERE ip.item_id = media_items.id), '')
    WHERE id = old.item_id;
    UPDATE media_items SET authors = COALESCE((
        SELECT group_concat(p.name, ' ') FROM item_people ip
        JOIN people p ON p.id = ip.person_id
        WHERE ip.item_id = media_items.id), '')
    WHERE id = new.item_id;
END;

-- A rename must not leave the old spelling in the index: recompute every item
-- credited to this person. people.name is UNIQUE COLLATE NOCASE, so renames are
-- rare, but a stale denormalised column is exactly what a rename would expose.
CREATE TRIGGER people_au AFTER UPDATE ON people BEGIN
    UPDATE media_items SET authors = COALESCE((
        SELECT group_concat(p.name, ' ') FROM item_people ip
        JOIN people p ON p.id = ip.person_id
        WHERE ip.item_id = media_items.id), '')
    WHERE id IN (SELECT item_id FROM item_people WHERE person_id = old.id);
END;

-- Backfill: the triggers above only fire on future writes, so populate every
-- existing row once. The final rebuild re-derives the whole index from the
-- content table, which also normalises any transient FTS state left by the
-- per-row updates above.
UPDATE media_items SET authors = COALESCE((
    SELECT group_concat(p.name, ' ') FROM item_people ip
    JOIN people p ON p.id = ip.person_id
    WHERE ip.item_id = media_items.id), '');

INSERT INTO media_search(media_search) VALUES ('rebuild');