-- Per-user notifications + persisted @mentions.
-- Created by card chat messages (card_messages).
--
-- Kinds:
--   mention       — user mentioned via @username in body
--   assigned_chat — user is the card's assignee and someone else commented
--   reply         — user previously commented on this card (or is requester)
-- A row is created per (recipient_user, message). The kind chosen is the
-- highest priority among those that apply: mention > assigned_chat > reply.

CREATE TABLE IF NOT EXISTS notifications (
    id          TEXT PRIMARY KEY,
    user_id     TEXT NOT NULL,
    card_id     TEXT NOT NULL,
    message_id  TEXT NOT NULL,
    kind        TEXT NOT NULL,
    actor_id    TEXT NOT NULL,
    created_at  TEXT NOT NULL,
    read_at     TEXT,
    FOREIGN KEY (card_id)    REFERENCES cards(id)         ON DELETE CASCADE,
    FOREIGN KEY (message_id) REFERENCES card_messages(id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_notifications_user_unread
    ON notifications(user_id, read_at, created_at DESC);

CREATE INDEX IF NOT EXISTS idx_notifications_user_created
    ON notifications(user_id, created_at DESC);

CREATE TABLE IF NOT EXISTS card_mentions (
    id          TEXT PRIMARY KEY,
    card_id     TEXT NOT NULL,
    message_id  TEXT NOT NULL,
    user_id     TEXT NOT NULL,
    created_at  TEXT NOT NULL,
    FOREIGN KEY (card_id)    REFERENCES cards(id)         ON DELETE CASCADE,
    FOREIGN KEY (message_id) REFERENCES card_messages(id) ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_card_mentions_user    ON card_mentions(user_id, created_at DESC);
CREATE INDEX IF NOT EXISTS idx_card_mentions_card    ON card_mentions(card_id);
CREATE INDEX IF NOT EXISTS idx_card_mentions_message ON card_mentions(message_id);