code update recorded at: 17/06/25 09:51:25

handler.js

@@ -0,0 +1,133 @@
+// === Handler ===
+export const postHandler = async (req, res) => {
+    try {
+        const modified = processPostRequest(req.body?.response);
+        return res.status(200).json(modified);
+    } catch (err) {
+        return handleError(err, res);
+    }
+};
+
+// === Core Processing ===
+function processPostRequest(response) {
+    if (!response || typeof response !== 'object') {
+        throw new InvalidJsonContentTypeError('Missing or invalid response body', 400);
+    }
+
+    const modified = postRequestHandlerWrapper(response);
+    return modified;
+}
+
+// === Unified Error Handler ===
+function handleError(err, res) {
+    const isJsonTypeError = err instanceof InvalidJsonContentTypeError ||
+        err?.message?.includes('Body content-type is not valid JSON');
+
+    const status = isJsonTypeError ? err.statusCode || 415 : 500;
+
+    return res.status(status).json({
+        error: err.name || 'InternalServerError',
+        message: err.message || 'Unexpected error occurred',
+        ...(err.details && { details: err.details }),
+    });
+}
+let currentResponse = null;
+let postContext = null;
+
+function createPostContext() {
+    return {
+        addedHeaders: {},
+        removedHeaders: [],
+        modifiedBody: null,
+        modifiedStatus: null,
+    };
+}
+
+export function postRequestHandlerWrapper(response) {
+    postContext = createPostContext();
+    currentResponse = response;
+    postRequestHandler();
+    const ctx = postContext;
+    postContext = null;
+    currentResponse = null;
+    return ctx;
+}
+
+export function postRequestHandler() {
+    setHeader('x-post-transform', 'applied');
+    removeHeader('x-unwanted-header');
+
+    const body = getJsonBody();
+    if (body) {
+        body.modifiedAt = new Date().toISOString();
+        body.transformed = "transformed***********";
+        setJsonBody(body);
+    }
+
+    setStatus(202);
+}
+export function setHeader(key, value) {
+    if (!currentResponse?.headers) currentResponse.headers = {};
+    currentResponse.headers[key.toLowerCase()] = value;
+    postContext?.addedHeaders && (postContext.addedHeaders[key.toLowerCase()] = value);
+}
+
+export function removeHeader(key) {
+    if (currentResponse?.headers?.[key.toLowerCase()] !== undefined) {
+        delete currentResponse.headers[key.toLowerCase()];
+        postContext?.removedHeaders?.push(key.toLowerCase());
+    }
+}
+
+export function getHeader(key) {
+    if (!currentResponse?.headers) return null;
+    return currentResponse.headers[key.toLowerCase()] || null;
+}
+
+export function getJsonBody() {
+    if (!currentResponse?.body) return null;
+
+    const contentType = currentResponse.contentType || currentResponse.headers?.['content-type'] || '';
+
+    if (!contentType.includes('application/json')) {
+        throw new InvalidJsonContentTypeError();
+    }
+
+    try {
+        return typeof currentResponse.body === 'string'
+            ? JSON.parse(currentResponse.body)
+            : currentResponse.body;
+    } catch (err) {
+        throw new InvalidJsonContentTypeError('Failed to parse JSON body', 415, { originalError: err });
+    }
+}
+
+export function setJsonBody(json) {
+    const contentType = currentResponse.contentType || currentResponse.headers?.['content-type'] || '';
+
+    if (!contentType.includes('application/json')) {
+        throw new InvalidJsonContentTypeError();
+    }
+
+    try {
+        currentResponse.body = JSON.stringify(json);
+        postContext && (postContext.modifiedBody = json);
+    } catch (err) {
+        throw new InvalidJsonContentTypeError('Failed to stringify JSON body', 415, { originalError: err });
+    }
+}
+
+export function setStatus(statusCode) {
+    if (typeof statusCode === 'number') {
+        currentResponse.status = statusCode;
+        postContext && (postContext.modifiedStatus = statusCode);
+    }
+}
+export class InvalidJsonContentTypeError extends Error {
+    constructor(message = 'Body content-type is not valid JSON', statusCode = 415, details = {}) {
+        super(message);
+        this.name = 'InvalidJsonContentTypeError';
+        this.statusCode = statusCode;
+        this.details = details;
+    }
+}