import { ParsingComponents, ParsingResult } from "../results";
import { Meridiem } from "../types";
import { assignSimilarDate, implySimilarDate } from "../utils/dates";

export function mergeDateTimeResult(dateResult: ParsingResult, timeResult: ParsingResult): ParsingResult {
    const result = dateResult.clone();
    const beginDate = dateResult.start;
    const beginTime = timeResult.start;

    result.start = mergeDateTimeComponent(beginDate, beginTime);
    if (dateResult.end != null || timeResult.end != null) {
        const endDate = dateResult.end == null ? dateResult.start : dateResult.end;
        const endTime = timeResult.end == null ? timeResult.start : timeResult.end;
        const endDateTime = mergeDateTimeComponent(endDate, endTime);

        if (dateResult.end == null && endDateTime.date().getTime() < result.start.date().getTime()) {
            // For example,  "Tuesday 9pm - 1am" the ending should actually be 1am on the next day.
            // We need to add to ending by another day.
            const nextDay = new Date(endDateTime.date().getTime());
            nextDay.setDate(nextDay.getDate() + 1);
            if (endDateTime.isCertain("day")) {
                assignSimilarDate(endDateTime, nextDay);
            } else {
                implySimilarDate(endDateTime, nextDay);
            }
        }

        result.end = endDateTime;
    }

    return result;
}

export function mergeDateTimeComponent(
    dateComponent: ParsingComponents,
    timeComponent: ParsingComponents
): ParsingComponents {
    const dateTimeComponent = dateComponent.clone();

    if (timeComponent.isCertain("hour")) {
        dateTimeComponent.assign("hour", timeComponent.get("hour"));
        dateTimeComponent.assign("minute", timeComponent.get("minute"));

        if (timeComponent.isCertain("second")) {
            dateTimeComponent.assign("second", timeComponent.get("second"));

            if (timeComponent.isCertain("millisecond")) {
                dateTimeComponent.assign("millisecond", timeComponent.get("millisecond"));
            } else {
                dateTimeComponent.imply("millisecond", timeComponent.get("millisecond"));
            }
        } else {
            dateTimeComponent.imply("second", timeComponent.get("second"));
            dateTimeComponent.imply("millisecond", timeComponent.get("millisecond"));
        }
    } else {
        dateTimeComponent.imply("hour", timeComponent.get("hour"));
        dateTimeComponent.imply("minute", timeComponent.get("minute"));
        dateTimeComponent.imply("second", timeComponent.get("second"));
        dateTimeComponent.imply("millisecond", timeComponent.get("millisecond"));
    }

    if (timeComponent.isCertain("timezoneOffset")) {
        dateTimeComponent.assign("timezoneOffset", timeComponent.get("timezoneOffset"));
    }

    if (timeComponent.isCertain("meridiem")) {
        dateTimeComponent.assign("meridiem", timeComponent.get("meridiem"));
    } else if (timeComponent.get("meridiem") != null && dateTimeComponent.get("meridiem") == null) {
        dateTimeComponent.imply("meridiem", timeComponent.get("meridiem"));
    }

    if (dateTimeComponent.get("meridiem") == Meridiem.PM && dateTimeComponent.get("hour") < 12) {
        if (timeComponent.isCertain("hour")) {
            dateTimeComponent.assign("hour", dateTimeComponent.get("hour") + 12);
        } else {
            dateTimeComponent.imply("hour", dateTimeComponent.get("hour") + 12);
        }
    }

    dateTimeComponent.addTags(dateComponent.tags());
    dateTimeComponent.addTags(timeComponent.tags());
    return dateTimeComponent;
}