// (C) Copyright 2015 Moodle Pty Ltd.
//
// 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 { Translate } from '@singletons';
import { CoreConstants } from '../constants';

/**
 * Singleton with helper functions for time operations.
 */
export class CoreTime {

    /**
     * Returns years, months, days, hours, minutes and seconds in a human readable format.
     *
     * @param seconds A number of seconds
     * @param precision Number of elements to have in precision.
     * @return Seconds in a human readable format.
     */
    static formatTime(seconds: number, precision = 2): string {
        precision = precision || 5; // Use max precision if 0 is passed.

        const totalSecs = Math.abs(seconds);
        if (!totalSecs) {
            return Translate.instant('core.now');
        }

        const years = Math.floor(totalSecs / CoreConstants.SECONDS_YEAR);
        let remainder = totalSecs - (years * CoreConstants.SECONDS_YEAR);
        const days = Math.floor(remainder / CoreConstants.SECONDS_DAY);

        remainder = remainder - (days * CoreConstants.SECONDS_DAY);

        const hours = Math.floor(remainder / CoreConstants.SECONDS_HOUR);
        remainder = remainder - (hours * CoreConstants.SECONDS_HOUR);

        const mins = Math.floor(remainder / CoreConstants.SECONDS_MINUTE);
        const secs = remainder - (mins * CoreConstants.SECONDS_MINUTE);

        const secondsUnit = Translate.instant('core.' + (secs === 1 ? 'sec' : 'secs'));
        const minutesUnit = Translate.instant('core.' + (mins === 1 ? 'min' : 'mins'));
        const hoursUnit = Translate.instant('core.' + (hours === 1 ? 'hour' : 'hours'));
        const daysUnit = Translate.instant('core.' + (days === 1 ? 'day' : 'days'));
        const yearsUnit = Translate.instant('core.' + (years === 1 ? 'year' : 'years'));
        const parts: string[] = [];

        if (precision && years) {
            parts.push(`${years} ${yearsUnit}`);
            precision--;
        }
        if (precision && days) {
            parts.push(`${days} ${daysUnit}`);
            precision--;
        }
        if (precision && hours) {
            parts.push(`${hours} ${hoursUnit}`);
            precision--;
        }
        if (precision && mins) {
            parts.push(`${mins} ${minutesUnit}`);
            precision--;
        }
        if (precision && secs) {
            parts.push(`${secs} ${secondsUnit}`);
            precision--;
        }

        return parts.join(' ');
    }

    /**
     * Converts a number of seconds into a short human readable format: minutes and seconds, in fromat: 3' 27''.
     *
     * @param duration Duration in seconds.
     * @return Short human readable text.
     */
    static formatTimeShort(duration: number): string {
        const minutes = Math.floor(duration / 60);
        const seconds = duration - minutes * 60;
        const durations = <string[]>[];

        if (minutes > 0) {
            durations.push(minutes + '\'');
        }

        if (seconds > 0 || minutes === 0) {
            durations.push(seconds + '\'\'');
        }

        return durations.join(' ');
    }

    /**
     * Wrap a function so that it is called only once.
     *
     * @param fn Function.
     * @return Wrapper that will call the underlying function only once.
     */
    static once<T extends unknown[]>(fn: (...args: T) => unknown): (...args: T) => void {
        let called = false;

        return (...args: T) => {
            if (called) {
                return;
            }

            called = true;
            fn.apply(null, args);
        };
    }

}