import { Timeunit } from "../types";

export type TimeunitShorten = "y" | "mo" | "M" | "w" | "d" | "h" | "m" | "s" | "ms";
export type TimeunitSpecial = "quarter";

/**
 * A type represent a directed time duration as a set of values by timeunits.
 * The positive values mean the time duration into the future.
 */
export type Duration = { [c in Timeunit | TimeunitSpecial | TimeunitShorten]?: number };

/**
 * An explicit empty duration (not just empty duration object).
 * This is defined as zero day and second.
 */
export const EmptyDuration = {
    day: 0,
    second: 0,
    millisecond: 0,
};

/**
 * Returns the date after adding the given `duration` to `ref`.
 * @param ref
 * @param duration
 */
export function addDuration(ref: Date, duration: Duration): Date {
    let date = new Date(ref);

    // Replace short timeunit keys with full timeunit keys
    if (duration["y"]) {
        duration["year"] = duration["y"];
        delete duration["y"];
    }
    if (duration["mo"]) {
        duration["month"] = duration["mo"];
        delete duration["mo"];
    }
    if (duration["M"]) {
        duration["month"] = duration["M"];
        delete duration["M"];
    }
    if (duration["w"]) {
        duration["week"] = duration["w"];
        delete duration["w"];
    }
    if (duration["d"]) {
        duration["day"] = duration["d"];
        delete duration["d"];
    }
    if (duration["h"]) {
        duration["hour"] = duration["h"];
        delete duration["h"];
    }
    if (duration["m"]) {
        duration["minute"] = duration["m"];
        delete duration["m"];
    }
    if (duration["s"]) {
        duration["second"] = duration["s"];
        delete duration["s"];
    }
    if (duration["ms"]) {
        duration["millisecond"] = duration["ms"];
        delete duration["ms"];
    }

    if ("year" in duration) {
        const floor = Math.floor(duration["year"]);
        date.setFullYear(date.getFullYear() + floor);
        const remainingFraction = duration["year"] - floor;
        if (remainingFraction > 0) {
            duration.month = duration?.month ?? 0;
            duration.month += remainingFraction * 12;
        }
    }
    if ("quarter" in duration) {
        const floor = Math.floor(duration["quarter"]);
        date.setMonth(date.getMonth() + floor * 3);
    }
    if ("month" in duration) {
        const floor = Math.floor(duration["month"]);
        date.setMonth(date.getMonth() + floor);
        const remainingFraction = duration["month"] - floor;
        if (remainingFraction > 0) {
            duration.week = duration?.week ?? 0;
            duration.week += remainingFraction * 4;
        }
    }
    if ("week" in duration) {
        const floor = Math.floor(duration["week"]);
        date.setDate(date.getDate() + floor * 7);
        const remainingFraction = duration["week"] - floor;
        if (remainingFraction > 0) {
            duration.day = duration?.day ?? 0;
            duration.day += Math.round(remainingFraction * 7);
        }
    }
    if ("day" in duration) {
        const floor = Math.floor(duration["day"]);
        date.setDate(date.getDate() + floor);
        const remainingFraction = duration["day"] - floor;
        if (remainingFraction > 0) {
            duration.hour = duration?.hour ?? 0;
            duration.hour += Math.round(remainingFraction * 24);
        }
    }
    if ("hour" in duration) {
        const floor = Math.floor(duration["hour"]);
        date.setHours(date.getHours() + floor);
        const remainingFraction = duration["hour"] - floor;
        if (remainingFraction > 0) {
            duration.minute = duration?.minute ?? 0;
            duration.minute += Math.round(remainingFraction * 60);
        }
    }
    if ("minute" in duration) {
        const floor = Math.floor(duration["minute"]);
        date.setMinutes(date.getMinutes() + floor);
        const remainingFraction = duration["minute"] - floor;
        if (remainingFraction > 0) {
            duration.second = duration?.second ?? 0;
            duration.second += Math.round(remainingFraction * 60);
        }
    }
    if ("second" in duration) {
        const floor = Math.floor(duration["second"]);
        date.setSeconds(date.getSeconds() + floor);
        const remainingFraction = duration["second"] - floor;
        if (remainingFraction > 0) {
            duration.millisecond = duration?.millisecond ?? 0;
            duration.millisecond += Math.round(remainingFraction * 1000);
        }
    }
    if ("millisecond" in duration) {
        const floor = Math.floor(duration["millisecond"]);
        date.setMilliseconds(date.getMilliseconds() + floor);
    }
    return date;
}

/**
 * Return the reversed duration (e.g. back into the past, instead of future)
 * @param duration
 */
export function reverseDuration(duration: Duration): Duration {
    const reversed = {};
    for (const key in duration) {
        // noinspection JSUnfilteredForInLoop
        reversed[key] = -duration[key];
    }
    return reversed as Duration;
}