-- Notification system — persistent, DB-backed nudges and vaccine alerts
-- Replaces the previous compute-only approach so read/unread syncs across devices.

CREATE TABLE IF NOT EXISTS notifications (
  id            UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
  family_id     UUID        NOT NULL REFERENCES families(id) ON DELETE CASCADE,
  child_id      UUID        REFERENCES children(id) ON DELETE CASCADE,

  -- Stable type codes:
  --   Vaccine alerts : "vaccine_BCG", "vaccine_OPV-0", etc.
  --   Daily nudges   : "log_nudge", "memory_nudge"
  --   Weekly nudge   : "garment_nudge"
  type          VARCHAR(80) NOT NULL,

  title         TEXT        NOT NULL,
  message       TEXT        NOT NULL,
  action_url    TEXT,
  is_read       BOOLEAN     NOT NULL DEFAULT false,

  -- IST date this notification belongs to.
  -- Nudges:   today's IST date  → ensures one per day per type
  -- Vaccines: the vaccine due date → ensures one per vaccine (due date is fixed)
  -- Garment:  Monday of current IST week → ensures one per week
  scheduled_for DATE        NOT NULL,

  -- Arbitrary extra data (e.g. { "vaccineName": "BCG" } for vaccine rows)
  metadata      JSONB,

  created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

-- One row per (family, child, type, date-slot) — prevents duplicate notifications
CREATE UNIQUE INDEX IF NOT EXISTS notifications_unique_slot
  ON notifications(family_id, child_id, type, scheduled_for);

-- Fast unread count + list query
CREATE INDEX IF NOT EXISTS notifications_family_child_idx
  ON notifications(family_id, child_id, is_read, created_at DESC);