-- Bidirectionele live klasinteractie. Sessies onthouden het laatste echte
-- voortgangsmoment en een eventuele pauze. Leerkrachtacties worden duurzaam
-- opgeslagen, zodat een korte netwerkonderbreking geen hint of aanmoediging
-- laat verdwijnen.
ALTER TABLE live_learning_sessions
  ADD COLUMN IF NOT EXISTS last_progress_at TIMESTAMPTZ,
  ADD COLUMN IF NOT EXISTS paused_at TIMESTAMPTZ;

CREATE TABLE IF NOT EXISTS teacher_pupil_actions (
  id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  class_id BIGINT NOT NULL REFERENCES classes(id) ON DELETE CASCADE,
  pupil_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  teacher_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  kind TEXT NOT NULL CHECK (kind IN ('hint', 'encourage', 'pause', 'resume', 'easier')),
  message TEXT,
  payload JSONB NOT NULL DEFAULT '{}'::jsonb,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  acknowledged_at TIMESTAMPTZ,
  CHECK (message IS NULL OR char_length(message) <= 160)
);

CREATE INDEX IF NOT EXISTS idx_teacher_pupil_actions_pending
  ON teacher_pupil_actions (pupil_id, acknowledged_at, created_at DESC);
CREATE INDEX IF NOT EXISTS idx_teacher_pupil_actions_class
  ON teacher_pupil_actions (class_id, created_at DESC);