// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.
abstract class AbstractTextFormatter {
    private _regularExpression: RegExp;

    protected abstract internalFormat(lang: string | undefined, matches: RegExpExecArray): string;

    constructor(regularExpression: RegExp) {
        this._regularExpression = regularExpression;
    }

    format(lang: string | undefined, input: string | undefined): string | undefined {
        let matches;

        if (input) {
            let result = input;

            while ((matches = this._regularExpression.exec(input)) != null) {
                result = result.replace(matches[0], this.internalFormat(lang, matches));
            }

            return result;
        } else {
            return input;
        }
    }
}

class DateFormatter extends AbstractTextFormatter {
    protected internalFormat(lang: string | undefined, matches: RegExpExecArray): string {
        const date = new Date(Date.parse(matches[1]));
        const format = matches[2] !== undefined ? matches[2].toLowerCase() : "compact";

        if (format !== "compact") {
            return date.toLocaleDateString(lang, {
                day: "numeric",
                weekday: format,
                month: format,
                year: "numeric"
            } as Intl.DateTimeFormatOptions);
        } else {
            return date.toLocaleDateString();
        }
    }
}

class TimeFormatter extends AbstractTextFormatter {
    protected internalFormat(lang: string | undefined, matches: RegExpExecArray): string {
        const date = new Date(Date.parse(matches[1]));

        return date.toLocaleTimeString(lang, { hour: "numeric", minute: "2-digit" });
    }
}

export function formatText(lang: string | undefined, text: string | undefined): string | undefined {
    const formatters: AbstractTextFormatter[] = [
        new DateFormatter(
            /\{{2}DATE\((\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:Z|(?:(?:-|\+)\d{2}:\d{2})))(?:, ?(COMPACT|LONG|SHORT))?\)\}{2}/g
        ),
        new TimeFormatter(
            /\{{2}TIME\((\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:Z|(?:(?:-|\+)\d{2}:\d{2})))\)\}{2}/g
        )
    ];

    let result = text;

    for (const formatter of formatters) {
        result = formatter.format(lang, result);
    }

    return result;
}