-- Migration script: add_character_name_to_notification.sql
-- Fügt character_name und character_id zur falukant_log.notification Tabelle hinzu,
-- legt Index an, erzeugt die Helper-Funktion und den Trigger.
-- Idempotent und mit Down-Schritten zum Entfernen.

BEGIN;

-- 1) Spalten anlegen
ALTER TABLE IF EXISTS falukant_log.notification
  ADD COLUMN IF NOT EXISTS character_name text;

ALTER TABLE IF EXISTS falukant_log.notification
  ADD COLUMN IF NOT EXISTS character_id integer;

-- 2) Index (idempotent)
CREATE INDEX IF NOT EXISTS idx_notification_character_id
  ON falukant_log.notification (character_id);

-- 3) Trigger-Funktion anlegen (idempotent)
CREATE OR REPLACE FUNCTION falukant_log.populate_notification_character_name()
RETURNS TRIGGER AS $function$
DECLARE
  v_first_name TEXT;
  v_last_name  TEXT;
  v_char_id    INTEGER;
  v_column_exists BOOLEAN;
BEGIN
  -- prüfen, ob Zielspalte existiert
  SELECT EXISTS(
    SELECT 1 FROM information_schema.columns
    WHERE table_schema = 'falukant_log' AND table_name = 'notification' AND column_name = 'character_name'
  ) INTO v_column_exists;

  IF NOT v_column_exists THEN
    RETURN NEW;
  END IF;

  IF NEW.character_name IS NOT NULL THEN
    RETURN NEW;
  END IF;

  v_char_id := NEW.character_id;

  IF v_char_id IS NULL AND NEW.user_id IS NOT NULL THEN
    SELECT id INTO v_char_id
    FROM falukant_data.character
    WHERE user_id = NEW.user_id
    ORDER BY id DESC
    LIMIT 1;
  END IF;

  IF v_char_id IS NOT NULL THEN
    SELECT pf.name, pl.name
    INTO v_first_name, v_last_name
    FROM falukant_data.character c
    LEFT JOIN falukant_predefine.firstname pf ON pf.id = c.first_name
    LEFT JOIN falukant_predefine.lastname pl ON pl.id = c.last_name
    WHERE c.id = v_char_id;

    IF v_first_name IS NOT NULL OR v_last_name IS NOT NULL THEN
      NEW.character_name := COALESCE(v_first_name, '') || CASE WHEN v_first_name IS NOT NULL AND v_last_name IS NOT NULL THEN ' ' ELSE '' END || COALESCE(v_last_name, '');
    ELSE
      NEW.character_name := ('#' || v_char_id::text);
    END IF;
  ELSE
    IF NEW.user_id IS NOT NULL THEN
      NEW.character_name := ('#u' || NEW.user_id::text);
    END IF;
  END IF;

  RETURN NEW;
END;
$function$ LANGUAGE plpgsql;

-- 4) Trigger anlegen (BEFORE INSERT)
DROP TRIGGER IF EXISTS trg_populate_notification_character_name ON falukant_log.notification;
CREATE TRIGGER trg_populate_notification_character_name
BEFORE INSERT ON falukant_log.notification
FOR EACH ROW
EXECUTE FUNCTION falukant_log.populate_notification_character_name();

COMMIT;

-- Down / Rollback (falls benötigt):
-- Die folgenden Statements entfernen Trigger, Funktion, Index und Spalten.

-- Hinweis: Ausführbar separat; zur Anwendung einfach die folgenden Zeilen verwenden:
-- BEGIN; DROP TRIGGER IF EXISTS trg_populate_notification_character_name ON falukant_log.notification; DROP FUNCTION IF EXISTS falukant_log.populate_notification_character_name(); DROP INDEX IF EXISTS falukant_log.idx_notification_character_id; ALTER TABLE IF EXISTS falukant_log.notification DROP COLUMN IF EXISTS character_name; ALTER TABLE IF EXISTS falukant_log.notification DROP COLUMN IF EXISTS character_id; COMMIT;