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import { davConditionalFailure } from "@/worker/dav/conditional";
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import type { ParsedIfHeader } from "@/worker/dav/if-header";
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import { parseCollectionObjectPath } from "@/worker/dav/paths";
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export interface CollectionConditionalInput {
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  subjectId: string;
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  nowMs: number;
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  ifMatch: string | null;
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  ifNoneMatch: string | null;
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  ifHeader: ParsedIfHeader;
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}
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export interface CollectionPreconditionSpec<TDb, TCollection extends { id: string }, TError> {
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  basePath: string;
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  collectionHref: (collectionName: string) => string;
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  ensureCollection: (db: TDb, subjectId: string, nowMs: number, collectionName: string) => TCollection | null;
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  objectEtag: (db: TDb, collectionId: string, objectName: string) => string | null;
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  latestChangeSeq: (db: TDb) => number;
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  syncToken: (seq: number) => string;
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  preconditionFailed: (message: string) => TError;
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}
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export function collectionWritePrecondition<TDb, TCollection extends { id: string }, TError>(
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  db: TDb,
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  input: CollectionConditionalInput,
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  targetHref: string,
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  targetEtag: string | null,
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  spec: CollectionPreconditionSpec<TDb, TCollection, TError>,
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): TError | null {
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  const stateHref = collectionStateHrefForTarget(targetHref, spec.basePath, spec.collectionHref);
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  const failure = davConditionalFailure({
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    ifMatch: input.ifMatch,
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    ifNoneMatch: input.ifNoneMatch,
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    ifHeader: input.ifHeader,
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    targetHref,
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    targetEtag,
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    getEtag: (href) => collectionEtagForHref(db, input, href, spec),
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    getStateToken: (href) => (href === stateHref ? collectionStateTokenForHref(db, input, href, spec) : null),
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  });
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  return failure ? spec.preconditionFailed(failure) : null;
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}
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function collectionStateHrefForTarget(
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  targetHref: string,
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  basePath: string,
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  collectionHref: (collectionName: string) => string,
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): string | null {
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  const path = parseCollectionObjectPath(targetHref, basePath);
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  if (!path || path.kind === "home") return null;
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  return collectionHref(path.collectionName);
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}
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function collectionEtagForHref<TDb, TCollection extends { id: string }, TError>(
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  db: TDb,
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  input: CollectionConditionalInput,
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  href: string,
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  spec: CollectionPreconditionSpec<TDb, TCollection, TError>,
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): string | null {
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  const path = parseCollectionObjectPath(href, spec.basePath);
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  if (!path || path.kind !== "object") return null;
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  const collection = spec.ensureCollection(db, input.subjectId, input.nowMs, path.collectionName);
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  if (!collection) return null;
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  return spec.objectEtag(db, collection.id, path.objectName);
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}
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function collectionStateTokenForHref<TDb, TCollection extends { id: string }, TError>(
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  db: TDb,
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  input: CollectionConditionalInput,
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  href: string,
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  spec: CollectionPreconditionSpec<TDb, TCollection, TError>,
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): string | null {
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  const path = parseCollectionObjectPath(href, spec.basePath);
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  if (!path || path.kind !== "collection") return null;
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  const collection = spec.ensureCollection(db, input.subjectId, input.nowMs, path.collectionName);
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  return collection ? spec.syncToken(spec.latestChangeSeq(db)) : null;
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}