add obsidian eslint plugin, solve major issues

packages/obsidian/src/utils/DateFormatter.ts

@@ -0,0 +1,73 @@
+import { moment } from 'obsidian';
+
+const momentFn = 'default' in moment ? moment.default : moment;
+
+export class DateFormatter {
+	private static readonly RFC2822_FORMAT = 'ddd, DD MMM YYYY HH:mm:ss ZZ';
+
+	toFormat: string;
+	locale: string;
+
+	constructor() {
+		this.toFormat = 'YYYY-MM-DD';
+		// get locale of this machine (e.g. en, en-gb, de, fr, etc.)
+		this.locale = new Intl.DateTimeFormat().resolvedOptions().locale;
+	}
+
+	setFormat(format: string): void {
+		this.toFormat = format;
+	}
+
+	getPreview(format?: string): string {
+		const today = momentFn();
+
+		format ??= this.toFormat;
+
+		return today.locale(this.locale).format(format);
+	}
+
+	/**
+	 * Tries to format a given date string with the currently set date format.
+	 * You can set a date format by calling `setFormat()`.
+	 *
+	 * @param dateString the date string to be formatted
+	 * @param dateFormat the current format of `dateString`. When this is `null` and the actual format of the
+	 * given date string is not `C2822` or `ISO` format, this function will try to guess the format by using the native `Date` module.
+	 * @param locale the locale of `dateString`. This is needed when `dateString` includes a month or day name and its locale format differs
+	 * from the locale of this machine.
+	 * @returns formatted date string or null if `dateString` is not a valid date
+	 */
+	format(dateString: string | null | undefined, dateFormat?: string, locale: string = 'en'): string | null {
+		if (!dateString) {
+			return null;
+		}
+
+		let date: moment.Moment;
+
+		if (!dateFormat) {
+			date = this.parseWithoutFormat(dateString);
+		} else {
+			date = momentFn(dateString, dateFormat, locale);
+		}
+
+		// format date (if it is valid)
+		return date.isValid() ? date.locale(this.locale).format(this.toFormat) : null;
+	}
+
+	private parseWithoutFormat(dateString: string): moment.Moment {
+		// reading date formats other than C2822 or ISO with moment is deprecated
+		// see https://momentjs.com/docs/#/parsing/string/
+		if (this.hasMomentFormat(dateString)) {
+			// expect C2822 or ISO format
+			return momentFn(dateString);
+		}
+
+		// fall back to native Date parsing for unknown formats
+		return momentFn(new Date(dateString));
+	}
+
+	private hasMomentFormat(dateString: string): boolean {
+		const date = momentFn(dateString, [moment.ISO_8601, DateFormatter.RFC2822_FORMAT], true); // strict mode
+		return date.isValid();
+	}
+}