-- Migration kept minimal because `swap_requests` & participants already exist in many deployments.
-- This migration ensures the RPCs are present and aligns behavior with the existing schema
-- (no `approved_by` column on `swap_requests`; approvals are tracked in `swap_request_participants`).

-- Ensure chat_thread_id column exists (no-op if already present)
ALTER TABLE public.swap_requests
  ADD COLUMN IF NOT EXISTS chat_thread_id uuid;

-- Idempotent RPC: request_shift_swap(shift_id, recipient_id) -> uuid
CREATE OR REPLACE FUNCTION public.request_shift_swap(p_shift_id uuid, p_recipient_id uuid)
RETURNS uuid LANGUAGE plpgsql AS $$
DECLARE
  v_shift_record RECORD;
  v_recipient RECORD;
  v_new_id uuid;
BEGIN
  -- shift must exist and be owned by caller
  SELECT * INTO v_shift_record FROM public.duty_schedules WHERE id = p_shift_id;
  IF NOT FOUND THEN
    RAISE EXCEPTION 'shift not found';
  END IF;
  IF v_shift_record.user_id <> auth.uid() THEN
    RAISE EXCEPTION 'permission denied: only shift owner may request swap';
  END IF;

  -- recipient must exist and be it_staff
  SELECT id, role INTO v_recipient FROM public.profiles WHERE id = p_recipient_id;
  IF NOT FOUND THEN
    RAISE EXCEPTION 'recipient not found';
  END IF;
  IF v_recipient.role <> 'it_staff' THEN
    RAISE EXCEPTION 'recipient must be it_staff';
  END IF;

  INSERT INTO public.swap_requests(requester_id, recipient_id, shift_id, status, created_at, updated_at)
  VALUES (auth.uid(), p_recipient_id, p_shift_id, 'pending', now(), now())
  RETURNING id INTO v_new_id;

  RETURN v_new_id;
END;
$$;

-- Idempotent RPC: respond_shift_swap(p_swap_id, p_action)
-- Updates status and records approver in swap_request_participants (no approved_by column required)
CREATE OR REPLACE FUNCTION public.respond_shift_swap(p_swap_id uuid, p_action text)
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  v_swap RECORD;
BEGIN
  SELECT * INTO v_swap FROM public.swap_requests WHERE id = p_swap_id;
  IF NOT FOUND THEN
    RAISE EXCEPTION 'swap request not found';
  END IF;

  IF p_action NOT IN ('accepted','rejected','admin_review') THEN
    RAISE EXCEPTION 'invalid action';
  END IF;

  IF p_action = 'accepted' THEN
    -- only recipient or admin/dispatcher can accept
    IF NOT (
      v_swap.recipient_id = auth.uid()
      OR EXISTS (SELECT 1 FROM public.profiles p WHERE p.id = auth.uid() AND p.role IN ('admin','dispatcher'))
    ) THEN
      RAISE EXCEPTION 'permission denied';
    END IF;

    -- ensure the shift is still owned by the requester before swapping
    UPDATE public.duty_schedules
    SET user_id = v_swap.recipient_id
    WHERE id = v_swap.shift_id AND user_id = v_swap.requester_id;
    IF NOT FOUND THEN
      RAISE EXCEPTION 'shift ownership changed, cannot accept swap';
    END IF;

    UPDATE public.swap_requests
    SET status = 'accepted', updated_at = now()
    WHERE id = p_swap_id;

    -- record approver/participant
    INSERT INTO public.swap_request_participants(swap_request_id, user_id, role)
    VALUES (p_swap_id, auth.uid(), 'approver')
    ON CONFLICT DO NOTHING;

  ELSIF p_action = 'rejected' THEN
    -- only recipient or admin/dispatcher can reject
    IF NOT (
      v_swap.recipient_id = auth.uid()
      OR EXISTS (SELECT 1 FROM public.profiles p WHERE p.id = auth.uid() AND p.role IN ('admin','dispatcher'))
    ) THEN
      RAISE EXCEPTION 'permission denied';
    END IF;

    UPDATE public.swap_requests
    SET status = 'rejected', updated_at = now()
    WHERE id = p_swap_id;

    INSERT INTO public.swap_request_participants(swap_request_id, user_id, role)
    VALUES (p_swap_id, auth.uid(), 'approver')
    ON CONFLICT DO NOTHING;

  ELSE -- admin_review
    -- only requester may escalate for admin review
    IF NOT (v_swap.requester_id = auth.uid()) THEN
      RAISE EXCEPTION 'permission denied';
    END IF;

    UPDATE public.swap_requests
    SET status = 'admin_review', updated_at = now()
    WHERE id = p_swap_id;
  END IF;
END;
$$;