// https://stackoverflow.com/questions/70135031/how-to-sort-strings-in-javascript-by-code-point-values
// This is not exactly codepoint comparison, but, well. We take EN as "invariant culture" for now.
// This also means EOR collation is used.
// Iterating the codepoints through the string (ordinal / binary collation) in JS can be much slower.
//
// Note the difference between Ordinal/Invariant comparison

import { getInvariantLocale } from "../../globalization";
import { getCollator, invariantCollator, invariantIgnoreCaseCollator } from "./internal/collators";

export function compareStringInvariant(x: string | undefined, y: string | undefined): number {
  if (x == null) return y == null ? 0 : -1;
  if (y == null) return 1;
  return invariantCollator.compare(x, y);
}

export function compareStringInvariantIgnoreCase(x: string | undefined, y: string | undefined): number {
  if (x == null) return y == null ? 0 : -1;
  if (y == null) return 1;
  return invariantIgnoreCaseCollator.compare(x, y);
}

export interface StringComparisonOptions {
  /**
   * The locale used to compare the strings.
   * By default it uses the result of {@link getInvariantLocale}.
   */
  locale?: Intl.Locale | string | string[];
  ignoreCase?: boolean;
  /**
   * Indicates that the string comparison must ignore nonspacing combining characters, such as diacritics.
   * The Unicode Standard defines combining characters as characters that are combined with base characters to produce a new character.
   * Nonspacing combining characters do not occupy a spacing position by themselves when rendered.
   * 
   * @see https://learn.microsoft.com/en-us/dotnet/api/system.globalization.compareoptions
   */
  ignoreNonSpace?: boolean;
}

export function compareString(x: string | undefined, y: string | undefined, collator?: Intl.Collator): number;
export function compareString(x: string | undefined, y: string | undefined, collator?: StringComparisonOptions): number;
export function compareString(x: string | undefined, y: string | undefined, arg3?: Intl.Collator | StringComparisonOptions): number {
  if (x == null) return y == null ? 0 : -1;
  if (y == null) return 1;

  arg3 ??= invariantCollator;
  if (arg3 instanceof Intl.Collator) {
    return arg3.compare(x, y);
  }

  const collator = getCollator(arg3);
  return collator.compare(x, y);
}