import { GemVersion, MaybeGemVersion, Ordering } from './ruby/gem-version';

export { gt, gte, lt, lte, eq, neq, cmp, compare, rcompare, diff };

function gt(v1: MaybeGemVersion, v2: MaybeGemVersion): boolean {
  return compare(v1, v2) > 0;
}

function gte(v1: MaybeGemVersion, v2: MaybeGemVersion): boolean {
  return compare(v1, v2) >= 0;
}

function lt(v1: MaybeGemVersion, v2: MaybeGemVersion): boolean {
  return compare(v1, v2) < 0;
}

function lte(v1: MaybeGemVersion, v2: MaybeGemVersion): boolean {
  return compare(v1, v2) <= 0;
}

function eq(v1: MaybeGemVersion, v2: MaybeGemVersion): boolean {
  return compare(v1, v2) === 0;
}

function neq(v1: MaybeGemVersion, v2: MaybeGemVersion): boolean {
  return !eq(v1, v2);
}

function _strictEq(v1, v2) {
  return GemVersion.create(v1).isIdentical(GemVersion.create(v2));
}

function _strictNeq(v1, v2) {
  return !_strictEq(v1, v2);
}

function cmp(
  v1: MaybeGemVersion,
  comparator: string,
  v2: MaybeGemVersion,
): boolean {
  switch (comparator) {
    case '>':
      return gt(v1, v2);
    case '>=':
      return gte(v1, v2);
    case '<':
      return lt(v1, v2);
    case '<=':
      return lte(v1, v2);
    case '==':
      return eq(v1, v2);
    case '!=':
      return neq(v1, v2);
    case '===':
      return _strictEq(v1, v2);
    case '!==':
      return _strictNeq(v1, v2);
    default:
      throw new Error(`Invalid comparator: ${comparator}`);
  }
}

function compare(
  v1: MaybeGemVersion,
  v2: MaybeGemVersion,
): Ordering | undefined {
  return GemVersion.create(v1).compare(GemVersion.create(v2));
}

function rcompare(
  v1: MaybeGemVersion,
  v2: MaybeGemVersion,
): Ordering | undefined {
  return GemVersion.create(v2).compare(GemVersion.create(v1));
}

function diff(v1: MaybeGemVersion, v2: MaybeGemVersion): string | null {
  if (eq(v1, v2)) {
    return null;
  }

  const version1 = GemVersion.create(v1);
  const version2 = GemVersion.create(v2);
  let hasPrerelease;

  const segments = [version1.getSegments(), version2.getSegments()]
    .map((seg) => {
      const prereleaseIndex = seg.findIndex((v) => String(v).match(/[a-zA-Z]/));
      if (prereleaseIndex === -1) {
        return seg;
      }

      hasPrerelease = true;
      return seg.slice(0, prereleaseIndex);
    })
    .sort((a, b) => b.length - a.length);

  const diffPosition = segments[0].findIndex((v, i) => v !== segments[1][i]);

  if (diffPosition === -1 && hasPrerelease) {
    return 'prerelease';
  }

  const diffType = ['major', 'minor'][diffPosition] || 'patch';
  return (hasPrerelease ? 'pre' : '') + diffType;
}