"use strict";

module.exports = {
  async up(queryInterface, Sequelize) {
    // 1) Add character_name column to notification table
    await queryInterface.sequelize.query(`
      ALTER TABLE IF EXISTS falukant_log.notification
      ADD COLUMN IF NOT EXISTS character_name text;
    `);

    // 1b) Add character_id column so triggers and application can set a reference
    await queryInterface.sequelize.query(`
      ALTER TABLE IF EXISTS falukant_log.notification
      ADD COLUMN IF NOT EXISTS character_id integer;
    `);

    // Create an index on character_id to speed lookups (if not exists)
    await queryInterface.sequelize.query(`
      DO $$
      BEGIN
        IF NOT EXISTS (
          SELECT 1 FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace
          WHERE c.relkind = 'i' AND c.relname = 'idx_notification_character_id' AND n.nspname = 'falukant_log'
        ) THEN
          CREATE INDEX idx_notification_character_id ON falukant_log.notification (character_id);
        END IF;
      END$$;
    `);

    // 2) Create helper function to populate character_name from character_id or user_id
    //    - Resolve name via character_id if present
    //    - Fallback to a character for the same user_id when character_id is NULL
    //    - Only set NEW.character_name when the column exists and is NULL
    await queryInterface.sequelize.query(`
      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
        -- check if target column exists in the notification table
        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
          -- Nothing to do when target column absent
          RETURN NEW;
        END IF;

        -- only populate when column is NULL
        IF NEW.character_name IS NOT NULL THEN
          RETURN NEW;
        END IF;

        -- prefer explicit character_id
        v_char_id := NEW.character_id;

        -- when character_id is null, try to find a character for the user_id
        IF v_char_id IS NULL AND NEW.user_id IS NOT NULL THEN
          -- choose a representative character: the one with highest id for this user (change if different policy required)
          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
          -- last resort fallback: use user_id as identifier if present
          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;
    `);

    // 3) Create trigger that runs before insert to populate the column
    await queryInterface.sequelize.query(`
      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();
    `);
  },

  async down(queryInterface, Sequelize) {
    await queryInterface.sequelize.query(`
      DROP TRIGGER IF EXISTS trg_populate_notification_character_name ON falukant_log.notification;
    `);
    await queryInterface.sequelize.query(`
      DROP FUNCTION IF EXISTS falukant_log.populate_notification_character_name();
    `);
    await queryInterface.sequelize.query(`
      -- drop index if exists
      DO $$
      BEGIN
        IF EXISTS (
          SELECT 1 FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace
          WHERE c.relkind = 'i' AND c.relname = 'idx_notification_character_id' AND n.nspname = 'falukant_log'
        ) THEN
          EXECUTE 'DROP INDEX falukant_log.idx_notification_character_id';
        END IF;
      END$$;
    `);
    await queryInterface.sequelize.query(`
      ALTER TABLE IF EXISTS falukant_log.notification
      DROP COLUMN IF EXISTS character_name;
    `);
    await queryInterface.sequelize.query(`
      ALTER TABLE IF EXISTS falukant_log.notification
      DROP COLUMN IF EXISTS character_id;
    `);
  }
};