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import {assertArray, assertNumber, assertObject, assertString} from './asserts';import {httpRequest} from './http-request';import {assertJSONValue, JSONValue, ReadonlyJSONValue} from './json';import type {HTTPRequestInfo} from './http-request-info';
export type PullerResult = {  response?: PullResponse;  httpRequestInfo: HTTPRequestInfo;};
/** * Puller is the function type used to do the fetch part of a pull. The request * is a POST request where the body is JSON with the type [[PullRequest]]. */export type Puller = (request: Request) => Promise<PullerResult>;
/** * The shape of a pull response under normal circumstances. */export type PullResponseOK = {  cookie?: ReadonlyJSONValue;  lastMutationID: number;  patch: PatchOperation[];};
/** * In certain scenarios the server can signal that it does not know about the * client. For example, the server might have deleted the client. */export type ClientStateNotFoundResponse = {  error: 'ClientStateNotFound';};
/** * PullResponse defines the shape and type of the response of a pull. This is * the JSON you should return from your pull server endpoint. */export type PullResponse = PullResponseOK | ClientStateNotFoundResponse;
export function isClientStateNotFoundResponse(  result: unknown,): result is ClientStateNotFoundResponse {  return (    typeof result === 'object' &&    result !== null &&    (result as Partial<ClientStateNotFoundResponse>).error ===      'ClientStateNotFound'  );}
export function assertPullResponse(v: unknown): asserts v is PullResponse {  if (typeof v !== 'object' || v === null) {    throw new Error('PullResponse must be an object');  }  if (isClientStateNotFoundResponse(v)) {    return;  }  const v2 = v as Partial<PullResponseOK>;  if (v2.cookie !== undefined) {    assertJSONValue(v2.cookie);  }  assertNumber(v2.lastMutationID);  assertPatchOperations(v2.patch);}
/** * This type describes the patch field in a [[PullResponse]] and it is used * to describe how to update the Replicache key-value store. */export type PatchOperation =  | {      op: 'put';      key: string;      value: JSONValue;    }  | {op: 'del'; key: string}  | {op: 'clear'};
export const defaultPuller: Puller = async request => {  const {httpRequestInfo, response} = await httpRequest(request);  if (httpRequestInfo.httpStatusCode !== 200) {    return {      httpRequestInfo,    };  }  return {    response: await response.json(),    httpRequestInfo,  };};
export function assertPatchOperations(  p: unknown,): asserts p is PatchOperation[] {  assertArray(p);  for (const item of p) {    assertPatchOperation(item);  }}
function assertPatchOperation(p: unknown): asserts p is PatchOperation {  assertObject(p);  switch (p.op) {    case 'put':      assertString(p.key);      assertJSONValue(p.value);      break;    case 'del':      assertString(p.key);      break;    case 'clear':      break;    default:      throw new Error(        `unknown patch op \`${p.op}\`, expected one of \`put\`, \`del\`, \`clear\``,      );  }}
/** * This error is thrown when the puller fails for any reason. */export class PullError extends Error {  name = 'PullError';  // causedBy is used instead of cause, because while cause has been proposed as a  // JavaScript language standard for this purpose (see  // https://github.com/tc39/proposal-error-cause) current browser behavior is  // inconsistent.  causedBy?: Error;  constructor(causedBy?: Error) {    super('Failed to pull');    this.causedBy = causedBy;  }}