import { ifNoneMatchBlocks, strongEtagMatches } from "@/worker/dav/etag";
import { ifHeaderMatchesStateAndEtags, type ParsedIfHeader } from "@/worker/dav/if-header";

export interface DavConditionalInput {
  ifMatch: string | null;
  ifNoneMatch: string | null;
  ifHeader: ParsedIfHeader;
  targetHref: string;
  targetEtag: string | null;
  getEtag: (href: string) => string | null;
  getStateToken: (href: string) => string | null;
}

export function davConditionalFailure(input: DavConditionalInput): string | null {
  if (input.ifMatch && !strongEtagMatches(input.ifMatch, input.targetEtag)) {
    return "If-Match precondition failed";
  }
  if (input.ifNoneMatch && input.targetEtag !== null && ifNoneMatchBlocks(input.ifNoneMatch, input.targetEtag)) {
    return "If-None-Match precondition failed";
  }
  if (
    !ifHeaderMatchesStateAndEtags({
      header: input.ifHeader,
      targetHref: input.targetHref,
      targetEtag: input.targetEtag,
      getEtag: input.getEtag,
      getStateToken: input.getStateToken,
    })
  ) {
    return "If precondition failed";
  }
  return null;
}