-- Follow-up to Phase 2C's final whole-branch review: booked_slots only
-- recorded (date, time), so availability checking only ever excluded an
-- exact time match. A 4-hour service booked at 9:00 AM did not block
-- 11:00 AM or 1:00 PM, even though the two would physically overlap. This
-- was inert while nothing persisted (Phase 2A/2B); Phase 2C is what makes
-- it reachable by real customers, so it's fixed before that branch merges
-- rather than shipped as a known gap.
--
-- Fix: booked_slots gains duration_minutes, populated from the booked
-- service's own duration_minutes at sync time. Availability computation
-- (client-side, src/data/availability.ts) changes from an exact-time-match
-- check to a real half-open-interval overlap check: a candidate slot
-- [candidateStart, candidateStart + requestedDuration) is unavailable if it
-- overlaps ANY existing booked slot's [bookedStart, bookedStart +
-- bookedDuration) interval. booked_slots keeps exactly one row per active
-- booking (not one row per slot-grid-interval it spans) -- the overlap math
-- lives entirely in the client's pure computation function, matching this
-- project's established preference for a thin client over new DB logic.

alter table public.booked_slots add column duration_minutes integer not null default 0;

-- The default above only exists so the column can be added without a
-- backfill value for any pre-existing rows; every row from this point
-- forward is written by sync_booked_slot() below, which always supplies a
-- real duration. Drop the default so a future direct insert can't silently
-- create a zero-duration (and therefore never-overlapping, i.e. bookable
-- over) row by omitting the column.
alter table public.booked_slots alter column duration_minutes drop default;

create or replace function public.sync_booked_slot()
returns trigger
language plpgsql
security definer
set search_path = ''
as $$
declare
  v_duration integer;
begin
  if tg_op = 'DELETE' then
    if old.status in ('confirmed', 'completed') then
      delete from public.booked_slots
      where date = old.date and time = old.time
        and not exists (
          select 1 from public.bookings b
          where b.date = old.date and b.time = old.time and b.status in ('confirmed', 'completed')
        );
    end if;
    return old;
  end if;

  if tg_op = 'UPDATE' then
    -- Covers both a status change away from 'confirmed'/'completed'
    -- (cancellation) and a reschedule of a still-occupying booking to a
    -- different (date, time): either way, the OLD slot may no longer have
    -- any confirmed/completed booking holding it and its mirror row needs
    -- to go.
    if old.status in ('confirmed', 'completed')
       and (old.date, old.time, old.status) is distinct from (new.date, new.time, new.status) then
      delete from public.booked_slots
      where date = old.date and time = old.time
        and not exists (
          select 1 from public.bookings b
          where b.date = old.date and b.time = old.time and b.status in ('confirmed', 'completed')
        );
    end if;
    if new.status in ('confirmed', 'completed') then
      select duration_minutes into v_duration from public.services where id = new.service_id;
      insert into public.booked_slots (date, time, duration_minutes)
      values (new.date, new.time, coalesce(v_duration, 0))
      on conflict (date, time) do update set duration_minutes = excluded.duration_minutes;
    end if;
    return new;
  end if;

  -- INSERT
  if new.status in ('confirmed', 'completed') then
    select duration_minutes into v_duration from public.services where id = new.service_id;
    insert into public.booked_slots (date, time, duration_minutes)
    values (new.date, new.time, coalesce(v_duration, 0))
    on conflict (date, time) do update set duration_minutes = excluded.duration_minutes;
  end if;
  return new;
end;
$$;