-- Per-user delivery state for direct and broadcast bottom-bar messages.
CREATE TABLE IF NOT EXISTS bottom_bar_message_receipts (
    message_id INTEGER NOT NULL REFERENCES bottom_bar_messages(id) ON DELETE CASCADE,
    user_id INTEGER NOT NULL REFERENCES users(user_id) ON DELETE CASCADE,
    read_at TIMESTAMP NULL,
    acknowledged_at TIMESTAMP NULL,
    PRIMARY KEY (message_id, user_id)
);

CREATE INDEX IF NOT EXISTS idx_bottom_bar_message_receipts_user_unread
    ON bottom_bar_message_receipts (user_id, read_at, message_id);

-- Preserve the state of existing direct messages. Broadcast read_at cannot be
-- migrated safely because the old schema stored one shared value for everyone.
INSERT INTO bottom_bar_message_receipts (message_id, user_id, read_at, acknowledged_at)
SELECT id,
       recipient_user_id,
       read_at,
       CASE WHEN requires_manual_ack THEN read_at ELSE NULL END
FROM bottom_bar_messages
WHERE recipient_user_id IS NOT NULL
ON CONFLICT (message_id, user_id) DO NOTHING;