-- Occasional gift rewards, granted from the admin panel.
--
-- A gift IS a reward grant — same catalog, same gallery, same vault — so it
-- reuses sadhna_reward_grants rather than introducing a parallel table that
-- every reader would then have to union in. What differs is only where it came
-- from, which `source` records.
--
-- `celebrated_at` already means "the devotee has seen this", which is exactly
-- the claim flag a gift needs: unclaimed gifts render blurred, and dismissing
-- the celebration is what clears them.
ALTER TABLE sadhna_reward_grants
    ADD COLUMN IF NOT EXISTS source VARCHAR(8) NOT NULL DEFAULT 'streak';

DO $$
BEGIN
    IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'sadhna_reward_grants_source_check') THEN
        ALTER TABLE sadhna_reward_grants
            ADD CONSTRAINT sadhna_reward_grants_source_check
            CHECK (source IN ('streak', 'gift'));
    END IF;
END $$;

-- A gift is not tied to a streak day, so it has no milestone.
ALTER TABLE sadhna_reward_grants ALTER COLUMN milestone DROP NOT NULL;

-- UNIQUE (user_id, milestone) was the streak rule: one reward per milestone.
-- It can't police gifts, which have no milestone — so it becomes a partial
-- index over streak rows, and gifts get their own rule: one of each reward
-- per person, so re-gifting is idempotent rather than a duplicate tile.
ALTER TABLE sadhna_reward_grants
    DROP CONSTRAINT IF EXISTS sadhna_reward_grants_user_id_milestone_key;

CREATE UNIQUE INDEX IF NOT EXISTS sadhna_reward_grants_streak_uniq
    ON sadhna_reward_grants (user_id, milestone) WHERE source = 'streak';

CREATE UNIQUE INDEX IF NOT EXISTS sadhna_reward_grants_gift_uniq
    ON sadhna_reward_grants (user_id, reward_id) WHERE source = 'gift';

-- "Which gifts is this devotee still to open?" — the blurred tiles.
CREATE INDEX IF NOT EXISTS sadhna_reward_grants_unopened_idx
    ON sadhna_reward_grants (user_id) WHERE celebrated_at IS NULL;