-- Migration: Extend scheduled_notifications for 9 push notification reminder types
-- Adds support for task-based, ISR-based, and pass-slip-based notifications alongside existing shift reminders.
-- Creates modular enqueue functions for each notification type, called by a master dispatcher.
-- Uses pg_cron + pg_net to fully automate enqueue and processing without external cron.

-- ============================================================================
-- 1. SCHEMA CHANGES
-- ============================================================================

-- 1a. Make schedule_id nullable (non-shift notifications don't reference a duty schedule)
ALTER TABLE public.scheduled_notifications ALTER COLUMN schedule_id DROP NOT NULL;

-- 1b. Add reference columns for tasks, IT service requests, and pass slips
ALTER TABLE public.scheduled_notifications
  ADD COLUMN IF NOT EXISTS task_id uuid REFERENCES public.tasks(id) ON DELETE CASCADE,
  ADD COLUMN IF NOT EXISTS it_service_request_id uuid REFERENCES public.it_service_requests(id) ON DELETE CASCADE,
  ADD COLUMN IF NOT EXISTS pass_slip_id uuid REFERENCES public.pass_slips(id) ON DELETE CASCADE;

-- 1c. Add epoch column for recurring notifications (hourly checkout, daily reminders)
ALTER TABLE public.scheduled_notifications
  ADD COLUMN IF NOT EXISTS epoch int NOT NULL DEFAULT 0;

-- 1d. Drop old unique constraint and create new one that supports all reference types + epoch
ALTER TABLE public.scheduled_notifications DROP CONSTRAINT IF EXISTS uniq_sched_user_type;

CREATE UNIQUE INDEX IF NOT EXISTS uniq_sched_notif ON public.scheduled_notifications (
  COALESCE(schedule_id, '00000000-0000-0000-0000-000000000000'),
  COALESCE(task_id, '00000000-0000-0000-0000-000000000000'),
  COALESCE(it_service_request_id, '00000000-0000-0000-0000-000000000000'),
  COALESCE(pass_slip_id, '00000000-0000-0000-0000-000000000000'),
  user_id,
  notify_type,
  epoch
);

-- 1e. CHECK: at least one reference must be non-null
DO $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM pg_constraint c
    JOIN pg_class t ON c.conrelid = t.oid
    WHERE c.conname = 'chk_at_least_one_ref' AND t.relname = 'scheduled_notifications'
  ) THEN
    ALTER TABLE public.scheduled_notifications
      ADD CONSTRAINT chk_at_least_one_ref
      CHECK (schedule_id IS NOT NULL OR task_id IS NOT NULL OR it_service_request_id IS NOT NULL OR pass_slip_id IS NOT NULL);
  END IF;
END$$;

-- 1f. Add indexes for new columns
CREATE INDEX IF NOT EXISTS idx_sched_notif_task ON public.scheduled_notifications(task_id) WHERE task_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_sched_notif_isr ON public.scheduled_notifications(it_service_request_id) WHERE it_service_request_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_sched_notif_pass_slip ON public.scheduled_notifications(pass_slip_id) WHERE pass_slip_id IS NOT NULL;

-- ============================================================================
-- 2. ENQUEUE FUNCTIONS
-- ============================================================================

-- ----------------------------------------------------------------------------
-- 2a. enqueue_due_shift_notifications() — REPLACE existing
--     Now handles: start_15, end, AND end_hourly (recurring hourly checkout)
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_due_shift_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
  v_hours_since_end int;
  v_latest_hourly timestamptz;
BEGIN
  -- 15-minute-before reminders (existing logic)
  FOR rec IN
    SELECT id AS schedule_id, user_id, start_time AS start_at
    FROM public.duty_schedules
    WHERE start_time BETWEEN now() + interval '15 minutes' - interval '90 seconds'
                         AND now() + interval '15 minutes' + interval '90 seconds'
      AND status = 'active'
  LOOP
    -- Skip if user already checked in for this duty
    IF EXISTS (
      SELECT 1 FROM public.attendance_logs al
      WHERE al.duty_schedule_id = rec.schedule_id AND al.check_in_at IS NOT NULL
    ) THEN
      CONTINUE;
    END IF;

    INSERT INTO public.scheduled_notifications (schedule_id, user_id, notify_type, scheduled_for)
    VALUES (rec.schedule_id, rec.user_id, 'start_15', rec.start_at)
    ON CONFLICT DO NOTHING;
  END LOOP;

  -- End-of-shift reminders at exact end time (existing logic)
  FOR rec IN
    SELECT id AS schedule_id, user_id, end_time AS end_at
    FROM public.duty_schedules
    WHERE end_time BETWEEN now() - interval '90 seconds' AND now() + interval '90 seconds'
      AND status IN ('arrival', 'late')
  LOOP
    INSERT INTO public.scheduled_notifications (schedule_id, user_id, notify_type, scheduled_for)
    VALUES (rec.schedule_id, rec.user_id, 'end', rec.end_at)
    ON CONFLICT DO NOTHING;
  END LOOP;

  -- Hourly checkout reminders: for users whose shift ended and have NOT checked out
  FOR rec IN
    SELECT ds.id AS schedule_id, ds.user_id, ds.end_time
    FROM public.duty_schedules ds
    JOIN public.attendance_logs al ON al.duty_schedule_id = ds.id AND al.user_id = ds.user_id
    WHERE ds.end_time < now()
      AND ds.status IN ('arrival', 'late')
      AND al.check_in_at IS NOT NULL
      AND al.check_out_at IS NULL
      AND ds.shift_type != 'overtime'
  LOOP
    v_hours_since_end := GREATEST(1, EXTRACT(EPOCH FROM (now() - rec.end_time))::int / 3600);

    -- Check if we already sent a notification for this hour
    SELECT MAX(scheduled_for) INTO v_latest_hourly
    FROM public.scheduled_notifications
    WHERE schedule_id = rec.schedule_id
      AND user_id = rec.user_id
      AND notify_type = 'end_hourly';

    -- Only enqueue if no hourly was sent, or the last one was >55 min ago
    IF v_latest_hourly IS NULL OR v_latest_hourly < now() - interval '55 minutes' THEN
      INSERT INTO public.scheduled_notifications
        (schedule_id, user_id, notify_type, scheduled_for, epoch)
      VALUES
        (rec.schedule_id, rec.user_id, 'end_hourly', now(), v_hours_since_end)
      ON CONFLICT DO NOTHING;
    END IF;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2b. enqueue_overtime_idle_notifications()
--     15 minutes into overtime without an active task or ISR
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_overtime_idle_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
BEGIN
  FOR rec IN
    SELECT ds.id AS schedule_id, ds.user_id
    FROM public.duty_schedules ds
    JOIN public.attendance_logs al ON al.duty_schedule_id = ds.id AND al.user_id = ds.user_id
    WHERE ds.shift_type = 'overtime'
      AND ds.status IN ('arrival', 'late')
      AND al.check_in_at IS NOT NULL
      AND al.check_out_at IS NULL
      AND al.check_in_at <= now() - interval '15 minutes'
      -- No in-progress task
      AND NOT EXISTS (
        SELECT 1 FROM public.task_assignments ta
        JOIN public.tasks t ON t.id = ta.task_id
        WHERE ta.user_id = ds.user_id AND t.status = 'in_progress'
      )
      -- No in-progress IT service request
      AND NOT EXISTS (
        SELECT 1 FROM public.it_service_request_assignments isra
        JOIN public.it_service_requests isr ON isr.id = isra.request_id
        WHERE isra.user_id = ds.user_id AND isr.status IN ('in_progress', 'in_progress_dry_run')
      )
  LOOP
    INSERT INTO public.scheduled_notifications
      (schedule_id, user_id, notify_type, scheduled_for)
    VALUES
      (rec.schedule_id, rec.user_id, 'overtime_idle_15', now())
    ON CONFLICT DO NOTHING;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2c. enqueue_overtime_checkout_notifications()
--     30 min after last task completion during overtime, no new task,
--     and at least 1 hour since overtime check-in
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_overtime_checkout_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
  v_last_completed timestamptz;
BEGIN
  FOR rec IN
    SELECT ds.id AS schedule_id, ds.user_id, al.check_in_at
    FROM public.duty_schedules ds
    JOIN public.attendance_logs al ON al.duty_schedule_id = ds.id AND al.user_id = ds.user_id
    WHERE ds.shift_type = 'overtime'
      AND ds.status IN ('arrival', 'late')
      AND al.check_in_at IS NOT NULL
      AND al.check_out_at IS NULL
      AND al.check_in_at <= now() - interval '1 hour'
      -- No in-progress tasks
      AND NOT EXISTS (
        SELECT 1 FROM public.task_assignments ta
        JOIN public.tasks t ON t.id = ta.task_id
        WHERE ta.user_id = ds.user_id AND t.status = 'in_progress'
      )
  LOOP
    -- Find most recently completed task for this user
    SELECT MAX(t.completed_at) INTO v_last_completed
    FROM public.task_assignments ta
    JOIN public.tasks t ON t.id = ta.task_id
    WHERE ta.user_id = rec.user_id
      AND t.status IN ('completed', 'closed')
      AND t.completed_at IS NOT NULL
      AND t.completed_at >= rec.check_in_at;  -- Only tasks completed during this overtime

    -- Only notify if a task was completed >=30 min ago
    IF v_last_completed IS NOT NULL AND v_last_completed <= now() - interval '30 minutes' THEN
      INSERT INTO public.scheduled_notifications
        (schedule_id, user_id, notify_type, scheduled_for)
      VALUES
        (rec.schedule_id, rec.user_id, 'overtime_checkout_30', now())
      ON CONFLICT DO NOTHING;
    END IF;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2d. enqueue_isr_event_notifications()
--     1 hour before IT service request event_date
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_isr_event_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
BEGIN
  FOR rec IN
    SELECT isr.id AS request_id, isr.event_date, isra.user_id
    FROM public.it_service_requests isr
    JOIN public.it_service_request_assignments isra ON isra.request_id = isr.id
    WHERE isr.status IN ('scheduled', 'in_progress_dry_run')
      AND isr.event_date IS NOT NULL
      AND isr.event_date BETWEEN now() + interval '60 minutes' - interval '90 seconds'
                              AND now() + interval '60 minutes' + interval '90 seconds'
  LOOP
    INSERT INTO public.scheduled_notifications
      (it_service_request_id, user_id, notify_type, scheduled_for)
    VALUES
      (rec.request_id, rec.user_id, 'isr_event_60', rec.event_date - interval '1 hour')
    ON CONFLICT DO NOTHING;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2e. enqueue_isr_evidence_notifications()
--     Daily reminder to assigned users who have NOT uploaded evidence or action
--     Only triggers after user has checked in today
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_isr_evidence_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
  v_today_doy int := EXTRACT(DOY FROM now())::int;
BEGIN
  FOR rec IN
    SELECT isr.id AS request_id, isra.user_id
    FROM public.it_service_requests isr
    JOIN public.it_service_request_assignments isra ON isra.request_id = isr.id
    WHERE isr.status IN ('completed', 'in_progress')
      AND (
        -- User has NOT uploaded evidence
        NOT EXISTS (
          SELECT 1 FROM public.it_service_request_evidence e
          WHERE e.request_id = isr.id AND e.user_id = isra.user_id
        )
        OR
        -- User has NOT submitted action taken
        NOT EXISTS (
          SELECT 1 FROM public.it_service_request_actions a
          WHERE a.request_id = isr.id AND a.user_id = isra.user_id
            AND a.action_taken IS NOT NULL AND TRIM(a.action_taken) != ''
        )
      )
      -- User must be checked in today
      AND EXISTS (
        SELECT 1 FROM public.attendance_logs al
        WHERE al.user_id = isra.user_id
          AND al.check_in_at::date = now()::date
      )
  LOOP
    INSERT INTO public.scheduled_notifications
      (it_service_request_id, user_id, notify_type, scheduled_for, epoch)
    VALUES
      (rec.request_id, rec.user_id, 'isr_evidence_daily', now(), v_today_doy)
    ON CONFLICT DO NOTHING;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2f. enqueue_paused_task_notifications()
--     Daily reminder for paused in-progress tasks after user checks in
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_paused_task_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
  v_today_doy int := EXTRACT(DOY FROM now())::int;
BEGIN
  FOR rec IN
    SELECT t.id AS task_id, ta.user_id
    FROM public.tasks t
    JOIN public.task_assignments ta ON ta.task_id = t.id
    WHERE t.status = 'in_progress'
      -- Latest activity log for this task is 'paused'
      AND EXISTS (
        SELECT 1 FROM public.task_activity_logs tal
        WHERE tal.task_id = t.id
          AND tal.action_type = 'paused'
          AND NOT EXISTS (
            SELECT 1 FROM public.task_activity_logs tal2
            WHERE tal2.task_id = t.id
              AND tal2.created_at > tal.created_at
              AND tal2.action_type IN ('resumed', 'completed', 'cancelled')
          )
      )
      -- User must be checked in today
      AND EXISTS (
        SELECT 1 FROM public.attendance_logs al
        WHERE al.user_id = ta.user_id
          AND al.check_in_at::date = now()::date
      )
  LOOP
    INSERT INTO public.scheduled_notifications
      (task_id, user_id, notify_type, scheduled_for, epoch)
    VALUES
      (rec.task_id, rec.user_id, 'task_paused_daily', now(), v_today_doy)
    ON CONFLICT DO NOTHING;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2g. enqueue_backlog_notifications()
--     15 min before shift end, users with pending tasks (queued/in_progress, not paused)
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_backlog_notifications()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  rec RECORD;
BEGIN
  FOR rec IN
    SELECT ds.id AS schedule_id, ds.user_id, ds.end_time
    FROM public.duty_schedules ds
    WHERE ds.end_time BETWEEN now() + interval '15 minutes' - interval '90 seconds'
                          AND now() + interval '15 minutes' + interval '90 seconds'
      AND ds.status IN ('arrival', 'late')
      -- User has pending (non-paused) tasks
      AND EXISTS (
        SELECT 1
        FROM public.task_assignments ta
        JOIN public.tasks t ON t.id = ta.task_id
        WHERE ta.user_id = ds.user_id
          AND t.status IN ('queued', 'in_progress')
          -- Exclude paused tasks
          AND NOT EXISTS (
            SELECT 1 FROM public.task_activity_logs tal
            WHERE tal.task_id = t.id
              AND tal.action_type = 'paused'
              AND NOT EXISTS (
                SELECT 1 FROM public.task_activity_logs tal2
                WHERE tal2.task_id = t.id
                  AND tal2.created_at > tal.created_at
                  AND tal2.action_type IN ('resumed', 'completed', 'cancelled')
              )
          )
      )
  LOOP
    INSERT INTO public.scheduled_notifications
      (schedule_id, user_id, notify_type, scheduled_for)
    VALUES
      (rec.schedule_id, rec.user_id, 'backlog_15', rec.end_time - interval '15 minutes')
    ON CONFLICT DO NOTHING;
  END LOOP;
END;
$$;

-- ----------------------------------------------------------------------------
-- 2h. enqueue_pass_slip_expiry_notifications()
--     15 min before pass slip reaches its 1-hour limit
-- ----------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.enqueue_pass_slip_expiry_notifications()
RETURNS void LANGUAGE plpgsql AS $$
BEGIN
  INSERT INTO public.scheduled_notifications (pass_slip_id, user_id, notify_type, scheduled_for)
  SELECT ps.id, ps.user_id, 'pass_slip_expiry_15', now()
  FROM public.pass_slips ps
  WHERE ps.status = 'approved'
    AND ps.slip_end IS NULL
    AND ps.slip_start IS NOT NULL
    AND ps.slip_start + interval '45 minutes'
        BETWEEN now() - interval '90 seconds' AND now() + interval '90 seconds'
  ON CONFLICT DO NOTHING;
END;
$$;

-- ============================================================================
-- 3. MASTER DISPATCHER
-- ============================================================================
CREATE OR REPLACE FUNCTION public.enqueue_all_notifications()
RETURNS void LANGUAGE plpgsql AS $$
BEGIN
  PERFORM public.enqueue_due_shift_notifications();
  PERFORM public.enqueue_overtime_idle_notifications();
  PERFORM public.enqueue_overtime_checkout_notifications();
  PERFORM public.enqueue_isr_event_notifications();
  PERFORM public.enqueue_isr_evidence_notifications();
  PERFORM public.enqueue_paused_task_notifications();
  PERFORM public.enqueue_backlog_notifications();
  PERFORM public.enqueue_pass_slip_expiry_notifications();
END;
$$;

-- ============================================================================
-- 4. PG_NET + PG_CRON SCHEDULING
-- ============================================================================
-- Uses pg_net to call the process_scheduled_notifications edge function
-- from within PostgreSQL, eliminating the need for external cron jobs.

CREATE EXTENSION IF NOT EXISTS pg_net;

-- Helper function: invokes the process_scheduled_notifications edge function via pg_net
CREATE OR REPLACE FUNCTION public.process_notification_queue()
RETURNS void LANGUAGE plpgsql AS $$
DECLARE
  v_base_url text;
  v_service_key text;
BEGIN
  -- Try Supabase vault first (standard in self-hosted Supabase)
  BEGIN
    SELECT decrypted_secret INTO v_service_key
    FROM vault.decrypted_secrets
    WHERE name = 'service_role_key'
    LIMIT 1;

    SELECT decrypted_secret INTO v_base_url
    FROM vault.decrypted_secrets
    WHERE name = 'supabase_url'
    LIMIT 1;
  EXCEPTION WHEN others THEN
    -- vault schema may not exist
    NULL;
  END;

  -- Fall back to app.settings GUC variables
  IF v_base_url IS NULL THEN
    v_base_url := current_setting('app.settings.supabase_url', true);
  END IF;
  IF v_service_key IS NULL THEN
    v_service_key := current_setting('app.settings.service_role_key', true);
  END IF;

  -- Guard: skip if config is missing
  IF v_base_url IS NULL OR v_service_key IS NULL THEN
    RAISE WARNING 'process_notification_queue: missing supabase_url or service_role_key config';
    RETURN;
  END IF;

  PERFORM net.http_post(
    url := v_base_url || '/functions/v1/process_scheduled_notifications',
    headers := jsonb_build_object(
      'Content-Type', 'application/json',
      'Authorization', 'Bearer ' || v_service_key
    ),
    body := '{}'::jsonb
  );
END;
$$;

-- Schedule pg_cron jobs (wrapped in exception block for safety)
DO $$
BEGIN
  -- Unschedule old jobs if they exist
  BEGIN
    PERFORM cron.unschedule('shift_reminders_every_min');
  EXCEPTION WHEN others THEN NULL;
  END;
  BEGIN
    PERFORM cron.unschedule('notification_reminders_every_min');
  EXCEPTION WHEN others THEN NULL;
  END;

  -- Job 1: Enqueue notifications every minute
  PERFORM cron.schedule(
    'notification_enqueue_every_min',
    '*/1 * * * *',
    'SELECT public.enqueue_all_notifications();'
  );

  -- Job 2: Process notification queue via pg_net every minute
  PERFORM cron.schedule(
    'notification_process_every_min',
    '*/1 * * * *',
    'SELECT public.process_notification_queue();'
  );

  -- Job 3: Daily cleanup of old processed notifications
  PERFORM cron.schedule(
    'cleanup_old_notifications',
    '0 3 * * *',
    'DELETE FROM scheduled_notifications WHERE processed = true AND processed_at < now() - interval ' || quote_literal('7 days') || '; DELETE FROM notification_pushes WHERE pushed_at < now() - interval ' || quote_literal('7 days') || ';'
  );

EXCEPTION WHEN others THEN
  RAISE NOTICE 'pg_cron/pg_net not available. After enabling them, run these manually:';
  RAISE NOTICE '  SELECT cron.schedule(%L, %L, %L);', 'notification_enqueue_every_min', '*/1 * * * *', 'SELECT public.enqueue_all_notifications();';
  RAISE NOTICE '  SELECT cron.schedule(%L, %L, %L);', 'notification_process_every_min', '*/1 * * * *', 'SELECT public.process_notification_queue();';
  RAISE NOTICE '  SELECT cron.schedule(%L, %L, %L);', 'cleanup_old_notifications', '0 3 * * *', 'DELETE FROM scheduled_notifications WHERE processed = true AND processed_at < now() - interval ' || quote_literal('7 days') || '; DELETE FROM notification_pushes WHERE pushed_at < now() - interval ' || quote_literal('7 days') || ';';
END $$;