"""Plex: make cast/crew names searchable

Revision ID: 0046_plex_people_search
Revises: 0045_plex_filter_meta
Create Date: 2026-07-06

Adds `people_text` (the item's cast + director names, space-joined) and folds it into the generated
`search_vector` at weight B — between the title (A) and the summary (C). So the top search box now
finds titles by an actor/director name and ranks those above films that merely mention the name in
their synopsis. A generated column's expression can't be altered in place, so we drop + recreate it
(and its GIN index). `people_text` is populated on the next Plex sync.
"""
from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op

revision: str = "0046_plex_people_search"
down_revision: Union[str, None] = "0045_plex_filter_meta"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None

_CFG = "public.unaccent_simple"
_NEW_VECTOR = (
    f"setweight(to_tsvector('{_CFG}', coalesce(title, '')), 'A') || "
    f"setweight(to_tsvector('{_CFG}', coalesce(people_text, '')), 'B') || "
    f"setweight(to_tsvector('{_CFG}', left(coalesce(summary, ''), 1000)), 'C')"
)
_OLD_VECTOR = (
    f"setweight(to_tsvector('{_CFG}', coalesce(title, '')), 'A') || "
    f"setweight(to_tsvector('{_CFG}', left(coalesce(summary, ''), 1000)), 'C')"
)


def _rebuild_vector(expr: str) -> None:
    op.execute("DROP INDEX IF EXISTS ix_plex_items_search_vector")
    op.execute("ALTER TABLE plex_items DROP COLUMN search_vector")
    op.execute(
        f"ALTER TABLE plex_items ADD COLUMN search_vector tsvector "
        f"GENERATED ALWAYS AS ({expr}) STORED"
    )
    op.execute("CREATE INDEX ix_plex_items_search_vector ON plex_items USING gin (search_vector)")


def upgrade() -> None:
    op.add_column("plex_items", sa.Column("people_text", sa.Text(), nullable=True))
    _rebuild_vector(_NEW_VECTOR)


def downgrade() -> None:
    _rebuild_vector(_OLD_VECTOR)
    op.drop_column("plex_items", "people_text")