-- Critical student alerts — spec section 6.
--
-- These are the red banners: custody limits, unauthorized pickups, severe
-- allergies, court-ordered communication restrictions. The spec requires that
-- every view and every acknowledgment be auditable, so both are recorded as
-- rows rather than as a boolean on the alert.
--
-- Visibility is an explicit role array rather than a single sensitivity level.
-- A severe-allergy alert must reach teachers and front-desk staff; a
-- court-order alert usually must not. One column expresses both.

CREATE TABLE IF NOT EXISTS public.student_alerts (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  student_id UUID NOT NULL REFERENCES public.students(id) ON DELETE CASCADE,

  alert_type TEXT NOT NULL,
  severity TEXT NOT NULL DEFAULT 'critical',
  title TEXT NOT NULL,
  description TEXT NOT NULL,

  effective_date DATE NOT NULL DEFAULT CURRENT_DATE,
  expiration_date DATE,

  document_path TEXT,
  parenting_plan_id UUID REFERENCES public.parenting_plans(id) ON DELETE SET NULL,

  -- Which staff roles see this alert. Org admins always see everything.
  visible_to_roles app_role[] NOT NULL
    DEFAULT ARRAY['admin','org_admin','super_admin','campus_admin','management','teacher','staff']::app_role[],

  requires_acknowledgment BOOLEAN NOT NULL DEFAULT TRUE,
  is_active BOOLEAN NOT NULL DEFAULT TRUE,

  created_by UUID REFERENCES auth.users(id),
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),

  CONSTRAINT sa_type_valid CHECK (alert_type IN (
    'parenting_plan','custody','unauthorized_pickup','medical','allergy',
    'court_order','safety','dismissal','other')),
  CONSTRAINT sa_severity_valid CHECK (severity IN ('critical','high','info')),
  CONSTRAINT sa_dates_ordered
    CHECK (expiration_date IS NULL OR effective_date <= expiration_date)
);

GRANT SELECT, INSERT, UPDATE, DELETE ON public.student_alerts TO authenticated;
GRANT ALL ON public.student_alerts TO service_role;
ALTER TABLE public.student_alerts ENABLE ROW LEVEL SECURITY;

CREATE INDEX IF NOT EXISTS sa_student_idx ON public.student_alerts (student_id);
-- The hot path: "show me this student's live alerts". Partial, because expired
-- and deactivated alerts are never on that screen.
CREATE INDEX IF NOT EXISTS sa_active_idx ON public.student_alerts (student_id, severity)
  WHERE is_active;
CREATE INDEX IF NOT EXISTS sa_plan_idx ON public.student_alerts (parenting_plan_id);

DROP TRIGGER IF EXISTS trg_sa_upd ON public.student_alerts;
CREATE TRIGGER trg_sa_upd BEFORE UPDATE ON public.student_alerts
  FOR EACH ROW EXECUTE FUNCTION public.set_updated_at();

-- ============================================================================
-- ACKNOWLEDGMENTS
-- ============================================================================
-- One row per staff member per alert. UNIQUE keeps it idempotent so a
-- double-click cannot fabricate two acknowledgment records.

CREATE TABLE IF NOT EXISTS public.student_alert_acknowledgments (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  alert_id UUID NOT NULL REFERENCES public.student_alerts(id) ON DELETE CASCADE,
  user_id UUID NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
  acknowledged_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  note TEXT,
  UNIQUE (alert_id, user_id)
);

GRANT SELECT, INSERT ON public.student_alert_acknowledgments TO authenticated;
GRANT ALL ON public.student_alert_acknowledgments TO service_role;
ALTER TABLE public.student_alert_acknowledgments ENABLE ROW LEVEL SECURITY;
CREATE INDEX IF NOT EXISTS saa_alert_idx ON public.student_alert_acknowledgments (alert_id);
CREATE INDEX IF NOT EXISTS saa_user_idx ON public.student_alert_acknowledgments (user_id);

-- ============================================================================
-- VIEW LOG
-- ============================================================================
-- Append-only. No UNIQUE constraint: the point is to record every occasion the
-- alert was displayed, not merely that it was seen once. Deliberately has no
-- UPDATE or DELETE grant for authenticated — it is evidence.

CREATE TABLE IF NOT EXISTS public.student_alert_views (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  alert_id UUID NOT NULL REFERENCES public.student_alerts(id) ON DELETE CASCADE,
  user_id UUID NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
  viewed_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

GRANT SELECT, INSERT ON public.student_alert_views TO authenticated;
GRANT ALL ON public.student_alert_views TO service_role;
ALTER TABLE public.student_alert_views ENABLE ROW LEVEL SECURITY;
CREATE INDEX IF NOT EXISTS sav_alert_idx ON public.student_alert_views (alert_id, viewed_at DESC);
CREATE INDEX IF NOT EXISTS sav_user_idx ON public.student_alert_views (user_id);

-- ============================================================================
-- HELPERS
-- ============================================================================

-- Currently-in-force alerts for a student that the caller is cleared to see.
CREATE OR REPLACE FUNCTION public.active_student_alerts(_student UUID)
RETURNS SETOF public.student_alerts
LANGUAGE SQL STABLE SECURITY DEFINER SET search_path = public
AS $$
  SELECT a.* FROM public.student_alerts a
  WHERE a.student_id = _student
    AND a.is_active
    AND a.effective_date <= CURRENT_DATE
    AND (a.expiration_date IS NULL OR a.expiration_date >= CURRENT_DATE)
    AND (public.is_org_admin() OR public.current_user_has_any_role(a.visible_to_roles))
  ORDER BY CASE a.severity WHEN 'critical' THEN 0 WHEN 'high' THEN 1 ELSE 2 END,
           a.effective_date DESC
$$;

-- Alerts still awaiting this user's acknowledgment.
CREATE OR REPLACE FUNCTION public.unacknowledged_alerts(_student UUID)
RETURNS SETOF public.student_alerts
LANGUAGE SQL STABLE SECURITY DEFINER SET search_path = public
AS $$
  SELECT a.* FROM public.active_student_alerts(_student) a
  WHERE a.requires_acknowledgment
    AND NOT EXISTS (
      SELECT 1 FROM public.student_alert_acknowledgments k
      WHERE k.alert_id = a.id AND k.user_id = (SELECT auth.uid())
    )
$$;

-- ============================================================================
-- POLICIES
-- ============================================================================

-- Staff see alerts targeted at their role; parents see their own child's
-- alerts only when the alert is not restricted away from them.
DROP POLICY IF EXISTS "alerts read" ON public.student_alerts;
CREATE POLICY "alerts read" ON public.student_alerts FOR SELECT TO authenticated
  USING (
    public.is_org_admin()
    OR public.is_auditor()
    OR (public.can_access_student(student_id)
        AND public.current_user_has_any_role(visible_to_roles))
    OR (public.is_parent_of(student_id) AND 'parent'::app_role = ANY(visible_to_roles))
  );

DROP POLICY IF EXISTS "alerts manage" ON public.student_alerts;
CREATE POLICY "alerts manage" ON public.student_alerts FOR ALL TO authenticated
  USING (public.can_manage_student(student_id))
  WITH CHECK (public.can_manage_student(student_id));

-- A user may only record their own acknowledgment, and never edit it after.
DROP POLICY IF EXISTS "alert ack read" ON public.student_alert_acknowledgments;
CREATE POLICY "alert ack read" ON public.student_alert_acknowledgments FOR SELECT TO authenticated
  USING (
    public.is_org_admin() OR public.is_auditor() OR user_id = (SELECT auth.uid())
    OR EXISTS (SELECT 1 FROM public.student_alerts a
               WHERE a.id = alert_id AND public.can_manage_student(a.student_id))
  );

DROP POLICY IF EXISTS "alert ack self insert" ON public.student_alert_acknowledgments;
CREATE POLICY "alert ack self insert" ON public.student_alert_acknowledgments FOR INSERT TO authenticated
  WITH CHECK (user_id = (SELECT auth.uid()));

DROP POLICY IF EXISTS "alert views read" ON public.student_alert_views;
CREATE POLICY "alert views read" ON public.student_alert_views FOR SELECT TO authenticated
  USING (
    public.is_org_admin() OR public.is_auditor() OR user_id = (SELECT auth.uid())
    OR EXISTS (SELECT 1 FROM public.student_alerts a
               WHERE a.id = alert_id AND public.can_manage_student(a.student_id))
  );

DROP POLICY IF EXISTS "alert views self insert" ON public.student_alert_views;
CREATE POLICY "alert views self insert" ON public.student_alert_views FOR INSERT TO authenticated
  WITH CHECK (user_id = (SELECT auth.uid()));