Split front and back end.

1 files changed, 161 insertions, 0 deletions

diff --git a/FrontEnd/src/app/http/common.ts b/FrontEnd/src/app/http/common.ts
new file mode 100644
index 00000000..54203d1a
--- /dev/null
+++ b/FrontEnd/src/app/http/common.ts
@@ -0,0 +1,161 @@
+import { AxiosError, AxiosResponse } from "axios";
+
+export const apiBaseUrl = "/api";
+
+export function base64(blob: Blob): Promise<string> {
+  return new Promise<string>((resolve) => {
+    const reader = new FileReader();
+    reader.onload = function () {
+      resolve((reader.result as string).replace(/^data:.+;base64,/, ""));
+    };
+    reader.readAsDataURL(blob);
+  });
+}
+
+export function extractStatusCode(error: AxiosError): number | null {
+  if (error.isAxiosError) {
+    const code = error?.response?.status;
+    if (typeof code === "number") {
+      return code;
+    }
+  }
+  return null;
+}
+
+export interface CommonErrorResponse {
+  code: number;
+  message: string;
+}
+
+export function extractErrorCode(
+  error: AxiosError<CommonErrorResponse>
+): number | null {
+  if (error.isAxiosError) {
+    const code = error.response?.data?.code;
+    if (typeof code === "number") {
+      return code;
+    }
+  }
+  return null;
+}
+
+export class HttpNetworkError extends Error {
+  constructor(public innerError?: AxiosError) {
+    super();
+  }
+}
+
+export class HttpForbiddenError extends Error {
+  constructor(public innerError?: AxiosError) {
+    super();
+  }
+}
+
+export class NotModified {}
+
+export interface BlobWithEtag {
+  data: Blob;
+  etag: string;
+}
+
+export function extractResponseData<T>(res: AxiosResponse<T>): T {
+  return res.data;
+}
+
+export function catchIfStatusCodeIs<
+  TResult,
+  TErrorHandlerResult extends TResult | PromiseLike<TResult> | null | undefined
+>(
+  statusCode: number,
+  errorHandler: (error: AxiosError<CommonErrorResponse>) => TErrorHandlerResult
+): (error: AxiosError<CommonErrorResponse>) => TErrorHandlerResult {
+  return (error: AxiosError<CommonErrorResponse>) => {
+    if (extractStatusCode(error) == statusCode) {
+      return errorHandler(error);
+    } else {
+      throw error;
+    }
+  };
+}
+
+export function convertToIfStatusCodeIs<NewError>(
+  statusCode: number,
+  newErrorType: {
+    new (innerError: AxiosError): NewError;
+  }
+): (error: AxiosError<CommonErrorResponse>) => never {
+  return catchIfStatusCodeIs(statusCode, (error) => {
+    throw new newErrorType(error);
+  });
+}
+
+export function catchIfErrorCodeIs<
+  TResult,
+  TErrorHandlerResult extends TResult | PromiseLike<TResult> | null | undefined
+>(
+  errorCode: number,
+  errorHandler: (error: AxiosError<CommonErrorResponse>) => TErrorHandlerResult
+): (error: AxiosError<CommonErrorResponse>) => TErrorHandlerResult {
+  return (error: AxiosError<CommonErrorResponse>) => {
+    if (extractErrorCode(error) == errorCode) {
+      return errorHandler(error);
+    } else {
+      throw error;
+    }
+  };
+}
+export function convertToIfErrorCodeIs<NewError>(
+  errorCode: number,
+  newErrorType: {
+    new (innerError: AxiosError): NewError;
+  }
+): (error: AxiosError<CommonErrorResponse>) => never {
+  return catchIfErrorCodeIs(errorCode, (error) => {
+    throw new newErrorType(error);
+  });
+}
+
+export function convertToNetworkError(
+  error: AxiosError<CommonErrorResponse>
+): never {
+  if (error.isAxiosError && error.response == null) {
+    throw new HttpNetworkError(error);
+  } else {
+    throw error;
+  }
+}
+
+export function convertToForbiddenError(
+  error: AxiosError<CommonErrorResponse>
+): never {
+  if (
+    error.isAxiosError &&
+    error.response != null &&
+    (error.response.status == 401 || error.response.status == 403)
+  ) {
+    throw new HttpForbiddenError(error);
+  } else {
+    throw error;
+  }
+}
+
+export function convertToNotModified(
+  error: AxiosError<CommonErrorResponse>
+): NotModified {
+  if (
+    error.isAxiosError &&
+    error.response != null &&
+    error.response.status == 304
+  ) {
+    return new NotModified();
+  } else {
+    throw error;
+  }
+}
+
+export function convertToBlobWithEtag(res: AxiosResponse<Blob>): BlobWithEtag {
+  return {
+    data: res.data,
+    etag: (res.headers as Record<"etag", string>)["etag"],
+  };
+}