code update recorded at: 19/06/25 06:45:38

handler.js

@@ -0,0 +1,159 @@
+// === Handler ===
+export const handler = async (req, res) => {
+    try {
+        const modified = processPreRequest(req.body?.request);
+        return res.status(200).json(modified);
+    } catch (err) {
+        return handleError(err, res);
+    }
+};
+
+// === Core Processing ===
+function processPreRequest(request) {
+    if (!request || typeof request !== 'object') {
+        throw new InvalidJsonContentTypeError('Missing or invalid request body', 400);
+    }
+
+    const modified = preRequestHandlerWrapper(request);
+    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 currentContext = null;
+let currentRequest = null;
+
+function createContext() {
+    return {
+        addedQueryParams: {},
+        removedQueryParams: [],
+        addedHeaders: {},
+        removedHeaders: [],
+        method: null,
+        body: null
+    };
+}
+
+export function preRequestHandlerWrapper(request) {
+    currentContext = createContext();
+    currentRequest = request;
+    preRequestHandler();
+    const ctx = currentContext;
+    currentContext = null;
+    currentRequest = null;
+    return ctx;
+}
+
+export function preRequestHandler() {
+    setHeader('x-dp-access-token', "gystG4wUtCCT0dkXxkMANL0PjQrCNAxxDWGkKYGQ9IkvrNo5pph78JGPWH4y-l1O_hQqxXHhdPU8dTRu25JScA");
+    removeHeader('remove');
+
+}
+
+// ========== Utility functions using currentRequest ==========
+
+export function setHeader(key, value) {
+    if (!currentRequest?.headers) currentRequest.headers = {};
+    currentRequest.headers[key.toLowerCase()] = value;
+    currentContext?.addedHeaders && (currentContext.addedHeaders[key.toLowerCase()] = value);
+}
+
+export function removeHeader(key) {
+    if (currentRequest?.headers?.[key.toLowerCase()] !== undefined) {
+        delete currentRequest.headers[key.toLowerCase()];
+        currentContext?.removedHeaders?.push(key.toLowerCase());
+    }
+}
+
+export function setQueryParam(key, value) {
+    const url = new URL(currentRequest.url);
+    url.searchParams.set(key, value);
+    currentRequest.url = url.toString();
+    currentContext?.addedQueryParams && (currentContext.addedQueryParams[key] = value);
+}
+
+export function removeQueryParam(key) {
+    const url = new URL(currentRequest.url);
+    url.searchParams.delete(key);
+    currentRequest.url = url.toString();
+    currentContext?.removedQueryParams?.push(key);
+}
+
+export function setMethod(method) {
+    if (typeof method === 'string') {
+        currentRequest.method = method.toUpperCase();
+        currentContext && (currentContext.method = currentRequest.method);
+    }
+}
+
+export function getJsonBody() {
+    if (!currentRequest?.body) return null;
+
+    const contentType = currentRequest.contentType || currentRequest.headers?.['content-type'] || '';
+
+    if (!contentType.includes('application/json')) {
+        throw new InvalidJsonContentTypeError();
+    }
+
+    try {
+        return typeof currentRequest.body === 'string'
+            ? JSON.parse(currentRequest.body)
+            : currentRequest.body;
+    } catch (err) {
+        throw new InvalidJsonContentTypeError('Failed to parse JSON body', 415, { originalError: err });
+    }
+}
+
+export function setJsonBody(json) {
+    const contentType = currentRequest.contentType || currentRequest.headers?.['content-type'] || '';
+
+    if (!contentType.includes('application/json')) {
+        throw new InvalidJsonContentTypeError();
+    }
+
+    try {
+        currentRequest.body = JSON.stringify(json);
+        currentContext && (currentContext.body = json);
+    } catch (err) {
+        throw new InvalidJsonContentTypeError('Failed to stringify JSON body', 415, { originalError: err });
+    }
+}
+
+export function getQueryParam(key) {
+    try {
+        const url = new URL(currentRequest.url);
+        return url.searchParams.get(key);
+    } catch {
+        return null;
+    }
+}
+
+export function getHeader(key) {
+    if (!currentRequest?.headers) return null;
+    return currentRequest.headers[key.toLowerCase()] || null;
+}
+
+// === Custom Exception Class ===
+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;
+    }
+}
+
+