/*
 * Copyright (C) 2024 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {TIME_UNIT_TO_NANO} from './time_units';

export class UTCOffset {
  private valueNs: bigint | undefined;

  getValueNs(): bigint | undefined {
    return this.valueNs;
  }

  format(): string {
    if (this.valueNs === undefined) {
      return 'UTC+00:00';
    }
    const valueHours = Number(this.valueNs / BigInt(TIME_UNIT_TO_NANO.m)) / 60;
    const valueHoursAbs = Math.abs(valueHours);
    const hh = Math.floor(valueHoursAbs);
    const mm = (valueHoursAbs - hh) * 60;
    const timeDiff = `${hh}`.padStart(2, '0') + ':' + `${mm}`.padStart(2, '0');
    return `UTC${this.valueNs < 0 ? '-' : '+'}${timeDiff}`;
  }

  initialize(valueNs: bigint) {
    if (valueNs > BigInt(14 * TIME_UNIT_TO_NANO.h)) {
      console.warn('Failed to set timezone offset greater than UTC+14:00');
      return;
    }
    if (valueNs < BigInt(-12 * TIME_UNIT_TO_NANO.h)) {
      console.warn('Failed to set timezone offset greater than UTC-12:00');
      return;
    }
    this.valueNs = valueNs;
  }

  clear() {
    this.valueNs = undefined;
  }
}