-- Stickers in chat.
--
-- A sticker IS a sādhana reward — same catalog, same artwork — so there is no
-- separate sticker table. What's new is a second way to come by one: someone
-- sends you theirs and you keep it.
--
-- saved_stickers records only that second route. A reward you earned is
-- already yours through sadhna_reward_grants, and duplicating it here would
-- give two answers to "do I own this?".
CREATE TABLE IF NOT EXISTS saved_stickers (
    user_id    UUID        NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    reward_id  UUID        NOT NULL REFERENCES sadhna_rewards(id) ON DELETE CASCADE,
    -- Who sent it. Kept for provenance, and SET NULL rather than CASCADE so
    -- deleting an account doesn't take away stickers other people saved.
    saved_from UUID        REFERENCES users(id) ON DELETE SET NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
    PRIMARY KEY (user_id, reward_id)
);

-- "What's in my sticker drawer?" — the whole reason this table exists.
CREATE INDEX IF NOT EXISTS saved_stickers_user_idx
    ON saved_stickers (user_id, created_at DESC);

-- A sticker message: kind 'sticker', with the artwork denormalized onto the
-- attachment's existing image_url/title columns.
--
-- Denormalized rather than resolved per read, unlike a shared post: the
-- catalog is static art with no viewer-dependent visibility, so there is
-- nothing to re-check and a join on every message would buy nothing.
ALTER TABLE message_attachments DROP CONSTRAINT IF EXISTS message_attachments_kind_check;

ALTER TABLE message_attachments
    ADD CONSTRAINT message_attachments_kind_check
    CHECK (kind IN ('image', 'video', 'audio', 'file', 'link', 'entity', 'quote', 'sticker'));

-- entity_id carries the reward key on a sticker attachment, so a recipient can
-- save it without the client having to trust a URL it was handed.
ALTER TABLE message_attachments DROP CONSTRAINT IF EXISTS message_attachments_entity_type_check;

ALTER TABLE message_attachments
    ADD CONSTRAINT message_attachments_entity_type_check
    CHECK (entity_type IS NULL OR
           entity_type IN ('post', 'comment', 'profile', 'collection', 'sticker'));