-- 79-class-markbook.sql
-- G2 running markbook / gradebook: teacher-editable per-class assessment columns and marks.

create table if not exists public.class_assessments (
    id uuid primary key default gen_random_uuid(),
    class_id uuid not null references public.classes(id) on delete cascade,
    tenant_id uuid not null references public.institutes(id) on delete cascade,
    title text not null check (length(btrim(title)) > 0),
    date date,
    max_marks numeric not null default 100 check (max_marks > 0),
    created_at timestamptz not null default now(),
    updated_at timestamptz not null default now()
);

create table if not exists public.assessment_marks (
    id uuid primary key default gen_random_uuid(),
    assessment_id uuid not null references public.class_assessments(id) on delete cascade,
    student_id uuid not null references public.profiles(id) on delete cascade,
    tenant_id uuid not null references public.institutes(id) on delete cascade,
    mark numeric check (mark is null or mark >= 0),
    updated_by uuid references public.profiles(id),
    updated_at timestamptz not null default now(),
    constraint assessment_marks_assessment_student_key unique (assessment_id, student_id)
);

create index if not exists idx_class_assessments_class on public.class_assessments(class_id);
create index if not exists idx_class_assessments_tenant on public.class_assessments(tenant_id);
create index if not exists idx_assessment_marks_assessment on public.assessment_marks(assessment_id);
create index if not exists idx_assessment_marks_student on public.assessment_marks(student_id);
create index if not exists idx_assessment_marks_tenant on public.assessment_marks(tenant_id);

create or replace function public.set_class_assessment_tenant()
returns trigger language plpgsql security definer set search_path = public as $$
begin
  select c.institute_id into new.tenant_id from public.classes c where c.id = new.class_id;
  if new.tenant_id is null then
    raise exception 'class % not found for assessment tenant', new.class_id;
  end if;
  new.updated_at = now();
  return new;
end;
$$;

drop trigger if exists trg_set_class_assessment_tenant on public.class_assessments;
create trigger trg_set_class_assessment_tenant
before insert or update of class_id, title, date, max_marks on public.class_assessments
for each row execute function public.set_class_assessment_tenant();

create or replace function public.set_assessment_mark_tenant_and_validate()
returns trigger language plpgsql security definer set search_path = public as $$
declare
  a record;
begin
  select ca.tenant_id, ca.max_marks, ca.class_id into a
  from public.class_assessments ca
  where ca.id = new.assessment_id;
  if a.tenant_id is null then
    raise exception 'assessment % not found for mark tenant', new.assessment_id;
  end if;
  if new.mark is not null and new.mark > a.max_marks then
    raise exception 'mark % exceeds assessment max %', new.mark, a.max_marks;
  end if;
  if not exists (
    select 1 from public.class_students cs
    where cs.class_id = a.class_id and cs.student_id = new.student_id and cs.status = 'active'
  ) then
    raise exception 'student % is not active in assessment class', new.student_id;
  end if;
  new.tenant_id = a.tenant_id;
  new.updated_at = now();
  return new;
end;
$$;

drop trigger if exists trg_set_assessment_mark_tenant_validate on public.assessment_marks;
create trigger trg_set_assessment_mark_tenant_validate
before insert or update of assessment_id, student_id, mark on public.assessment_marks
for each row execute function public.set_assessment_mark_tenant_and_validate();

alter table public.class_assessments enable row level security;
alter table public.assessment_marks enable row level security;

-- Assessment columns: class teachers/admins can read/write.
drop policy if exists class_assessments_service_role on public.class_assessments;
create policy class_assessments_service_role on public.class_assessments
  using (auth.role() = 'service_role')
  with check (auth.role() = 'service_role');

drop policy if exists class_assessments_class_staff_rw on public.class_assessments;
create policy class_assessments_class_staff_rw on public.class_assessments for all to authenticated
  using (public.is_class_teacher(class_id) or public.is_class_admin(class_id))
  with check (public.is_class_teacher(class_id) or public.is_class_admin(class_id));

-- Marks: staff can read/write; students can read their own rows.
drop policy if exists assessment_marks_service_role on public.assessment_marks;
create policy assessment_marks_service_role on public.assessment_marks
  using (auth.role() = 'service_role')
  with check (auth.role() = 'service_role');

drop policy if exists assessment_marks_class_staff_rw on public.assessment_marks;
create policy assessment_marks_class_staff_rw on public.assessment_marks for all to authenticated
  using (exists (
    select 1 from public.class_assessments ca
    where ca.id = assessment_marks.assessment_id
      and (public.is_class_teacher(ca.class_id) or public.is_class_admin(ca.class_id))
  ))
  with check (exists (
    select 1 from public.class_assessments ca
    where ca.id = assessment_marks.assessment_id
      and (public.is_class_teacher(ca.class_id) or public.is_class_admin(ca.class_id))
  ));

drop policy if exists assessment_marks_student_read on public.assessment_marks;
create policy assessment_marks_student_read on public.assessment_marks for select to authenticated
  using (student_id = auth.uid());