-- Per-user reading progress and uploader attribution.
--
-- Reading progress is the simplest shape that supports "jump to last
-- read chapter" — one row per (user, manga). The reader writes
-- through on chapter open and on page advance (debounced); the
-- history view shows them sorted by most-recently-touched.
--
-- Uploader attribution adds nullable `uploaded_by` columns to the two
-- upload sinks. Historical rows have NULL because the original
-- handlers didn't track this; new uploads stamp the current user.

CREATE TABLE read_progress (
    user_id     uuid NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    manga_id    uuid NOT NULL REFERENCES mangas(id) ON DELETE CASCADE,
    -- Chapter is nullable so a deleted chapter doesn't blow away
    -- the user's progress row entirely — they just see "(chapter
    -- removed)" in the history UI.
    chapter_id  uuid REFERENCES chapters(id) ON DELETE SET NULL,
    page        integer NOT NULL DEFAULT 1 CHECK (page >= 1),
    updated_at  timestamptz NOT NULL DEFAULT now(),
    PRIMARY KEY (user_id, manga_id)
);

-- Most queries on this table want "most recent first" per user; the
-- composite index makes both filter and sort index-only.
CREATE INDEX read_progress_user_idx
    ON read_progress (user_id, updated_at DESC);

ALTER TABLE mangas
    ADD COLUMN uploaded_by uuid REFERENCES users(id) ON DELETE SET NULL;
CREATE INDEX mangas_uploaded_by_idx
    ON mangas (uploaded_by, created_at DESC)
    WHERE uploaded_by IS NOT NULL;

ALTER TABLE chapters
    ADD COLUMN uploaded_by uuid REFERENCES users(id) ON DELETE SET NULL;
CREATE INDEX chapters_uploaded_by_idx
    ON chapters (uploaded_by, created_at DESC)
    WHERE uploaded_by IS NOT NULL;