Add APIError class with HTTP error parsing (#13)

* Add APIError class with HTTP error parsing

* update

* add a todo

Author: parthban-db

packages/databricks/src/apierror/apierror.ts

@@ -0,0 +1,253 @@
+import {z} from 'zod';
+
+import {Code, codeFromString} from './codes';
+import type {ErrorDetails} from './details';
+import {parseErrorDetails} from './details';
+
+// Reusable schema fragment for nullish string fields.
+const nullishString = z
+  .string()
+  .nullish()
+  .transform(v => v ?? '');
+
+// Zod schema for parsing the JSON error response body. The schema is lenient
+// to handle the various Databricks API error formats (standard, legacy, SCIM).
+const errorResponseSchema = z.object({
+  message: nullishString,
+  details: z
+    .array(z.unknown())
+    .nullish()
+    .transform(v => v ?? []),
+  // Some Databricks APIs incorrectly return the HTTP status code as an
+  // integer rather than the actual error code as a string.
+  error_code: z.unknown().optional(),
+  // Legacy Databricks APIs (e.g. version 1.2 and earlier) used "error"
+  // instead of "message".
+  error: nullishString,
+  // SCIM error fields (RFC7644 section 3.7.3).
+  // The "status" field is intentionally omitted; it duplicates HTTP status.
+  detail: nullishString,
+  scimType: nullishString,
+});
+
+// Constructor options for APIError.
+interface APIErrorOptions {
+  code: Code;
+  message: string;
+  details: ErrorDetails;
+  httpStatusCode?: number;
+  httpHeader?: Headers;
+  httpBody?: Uint8Array;
+  cause?: unknown;
+}
+
+/** APIError is a transport-agnostic error representing a Databricks API error. */
+export class APIError extends Error {
+  /** The canonical error code of the error. */
+  readonly code: Code;
+
+  /**
+   * The structured error details of the error. This is left empty if the
+   * error response is not a standard Databricks API error.
+   */
+  readonly details: ErrorDetails;
+
+  // The raw HTTP error details, undefined if this is not an HTTP error.
+  private readonly httpErr?: {
+    readonly statusCode: number;
+    readonly header: Headers | undefined;
+    readonly body: Uint8Array | undefined;
+  };
+
+  /**
+   * Do not use this constructor directly. Use {@link APIError.fromHttpError}
+   * instead. This constructor is only meant for internal and testing use.
+   * TODO: Make this constructor private.
+   *
+   * @private
+   */
+  constructor(options: APIErrorOptions) {
+    super(options.message, {cause: options.cause});
+    this.name = 'APIError';
+    this.code = options.code;
+    this.details = options.details;
+    if (options.httpStatusCode !== undefined) {
+      this.httpErr = {
+        statusCode: options.httpStatusCode,
+        header: options.httpHeader,
+        body: options.httpBody,
+      };
+    }
+  }
+
+  /**
+   * HTTPStatusCode returns the APIError's HTTP status code. If the APIError
+   * is not an HTTP error, it returns -1.
+   */
+  get httpStatusCode(): number {
+    if (this.httpErr === undefined) {
+      return -1;
+    }
+    return this.httpErr.statusCode;
+  }
+
+  /**
+   * HTTPHeader returns the APIError's HTTP headers. If the APIError is not
+   * an HTTP error, it returns undefined.
+   */
+  get httpHeader(): Headers | undefined {
+    if (this.httpErr === undefined) {
+      return undefined;
+    }
+    return this.httpErr.header;
+  }
+
+  /**
+   * HTTPBody returns the APIError's HTTP body. If the APIError is not an HTTP
+   * error, it returns undefined.
+   */
+  get httpBody(): Uint8Array | undefined {
+    if (this.httpErr === undefined) {
+      return undefined;
+    }
+    return this.httpErr.body;
+  }
+
+  /**
+   * Parses an HTTP error response into an APIError. Returns undefined if the
+   * status code is 2xx.
+   */
+  static fromHttpError(
+    statusCode: number,
+    header: Headers | undefined,
+    body: Uint8Array | undefined
+  ): APIError | undefined {
+    if (statusCode >= 200 && statusCode < 300) {
+      return undefined;
+    }
+
+    const emptyDetails: ErrorDetails = {unknownDetails: []};
+
+    if (body === undefined || body.length === 0) {
+      return new APIError({
+        code: toCode(statusCode),
+        message: '',
+        details: emptyDetails,
+        httpStatusCode: statusCode,
+        httpHeader: header,
+        httpBody: body,
+      });
+    }
+
+    // Decode the body to a string for JSON parsing.
+    let parsed: unknown;
+    try {
+      parsed = JSON.parse(new TextDecoder().decode(body));
+    } catch (e: unknown) {
+      // The JSON error is simply swallowed, this typically happens when the
+      // error does not come directly from a Databricks API. A typical example
+      // is when the error is returned by a proxy.
+      return new APIError({
+        code: toCode(statusCode),
+        message: '',
+        details: emptyDetails,
+        httpStatusCode: statusCode,
+        httpHeader: header,
+        httpBody: body,
+        cause: e instanceof Error ? e : undefined,
+      });
+    }
+
+    const result = errorResponseSchema.safeParse(parsed);
+    if (!result.success) {
+      return new APIError({
+        code: toCode(statusCode),
+        message: '',
+        details: emptyDetails,
+        httpStatusCode: statusCode,
+        httpHeader: header,
+        httpBody: body,
+        cause: result.error,
+      });
+    }
+
+    const errResp = result.data;
+
+    // Error codes may be missing or be an integer (legacy APIs). In such
+    // cases, defer to the HTTP status code to infer the closest canonical
+    // error code.
+    let errorCode: Code;
+    if (typeof errResp.error_code === 'string') {
+      errorCode = codeFromString(errResp.error_code);
+    } else {
+      errorCode = toCode(statusCode);
+    }
+
+    // Determine the error message from available fields.
+    let errorMessage = '';
+    if (errResp.message !== '') {
+      errorMessage = errResp.message;
+    } else if (errResp.error !== '') {
+      errorMessage = errResp.error;
+    } else if (errResp.detail !== '') {
+      errorMessage = errResp.detail;
+    } else if (errResp.scimType !== '') {
+      errorMessage = errResp.scimType;
+    }
+
+    return new APIError({
+      code: errorCode,
+      message: errorMessage,
+      details: parseErrorDetails(errResp.details),
+      httpStatusCode: statusCode,
+      httpHeader: header,
+      httpBody: body,
+    });
+  }
+}
+
+// Maps an HTTP status code to the closest canonical error code.
+export function toCode(httpCode: number): Code {
+  // Canonical mappings.
+  switch (httpCode) {
+    case 200:
+      return Code.OK;
+    case 400:
+      return Code.INVALID_ARGUMENT;
+    case 401:
+      return Code.UNAUTHENTICATED;
+    case 403:
+      return Code.PERMISSION_DENIED;
+    case 404:
+      return Code.NOT_FOUND;
+    case 409:
+      return Code.ABORTED;
+    case 416:
+      return Code.OUT_OF_RANGE;
+    case 429:
+      return Code.RESOURCE_EXHAUSTED;
+    case 501:
+      return Code.UNIMPLEMENTED;
+    case 503:
+      return Code.UNAVAILABLE;
+    case 504:
+      return Code.DEADLINE_EXCEEDED;
+    default:
+      break;
+  }
+
+  // Fallback for status codes without a direct canonical mapping.
+  if (httpCode >= 200 && httpCode < 300) {
+    return Code.OK;
+  }
+  if (httpCode >= 400 && httpCode < 500) {
+    // Most non-canonical 4xx status codes are state related and map
+    // to the definition of FailedPrecondition.
+    return Code.FAILED_PRECONDITION;
+  }
+  if (httpCode >= 500 && httpCode < 600) {
+    return Code.INTERNAL;
+  }
+
+  return Code.UNKNOWN;
+}

packages/databricks/src/apierror/index.ts

@@ -4,6 +4,8 @@
  * @packageDocumentation
  */
 
+export {APIError} from './apierror';
+
 export type {
   ErrorDetails,
   ErrorInfo,