Add PINECONE_DEBUG request middleware (#136)

## Problem

Sometimes it is helpful to see exactly what requests are being made
under the hood.

## Solution

Define new middleware functions that log out helpful information.

Set new env vars for extra output:

```sh
PINECONE_DEBUG=true
PINECONE_DEBUG_CURL=true
```

<img width="1496" alt="Screenshot 2023-10-06 at 5 32 44 PM"
src="https://github.com/pinecone-io/pinecone-ts-client/assets/1326365/4054f44e-6eb0-4216-8bad-ff5c8cfeffa3">

## Type of Change

- [x] None of the above: developer-oriented feature

## Test Plan

Describe specific steps for validating this change.

src/utils/middleware.ts

@@ -1,7 +1,78 @@
-import { ResponseError } from '../pinecone-generated-ts-fetch';
+import { Middleware, ResponseError } from '../pinecone-generated-ts-fetch';
 import { handleApiError } from '../errors';
 
+const debugMiddleware: Middleware[] = [];
+
+const chalk = (str, color) => {
+  const colors = {
+    blue: '\x1b[34m',
+    red: '\x1b[31m',
+    green: '\x1b[32m',
+    yellow: '\x1b[33m',
+  };
+
+  return colors[color] + str + '\x1b[39m';
+};
+
+/**
+ * Enable the `PINECONE_DEBUG` environment variable to print the request and
+ * response bodies for each request.
+ *
+ * Api-Key headers will be redacted.
+ */
+if (process && process.env && process.env.PINECONE_DEBUG) {
+  const debugLogMiddleware = {
+    pre: async (context) => {
+      console.debug(
+        chalk(`>>> Request: ${context.init.method} ${context.url}`, 'blue')
+      );
+
+      const headers = JSON.parse(JSON.stringify(context.init.headers));
+      headers['Api-Key'] = '***REDACTED***';
+      console.debug(chalk(`>>> Headers: ${JSON.stringify(headers)}`, 'blue'));
+
+      if (context.init.body) {
+        console.debug(chalk(`>>> Body: ${context.init.body}`, 'blue'));
+      }
+      console.debug('');
+    },
+
+    post: async (context) => {
+      console.debug(chalk(`<<< Status: ${context.response.status}`, 'green'));
+      console.debug(
+        chalk(`<<< Body: ${await context.response.text()}`, 'green')
+      );
+      console.debug('');
+    },
+  };
+
+  debugMiddleware.push(debugLogMiddleware);
+}
+
+/**
+ * Enable the `PINECONE_DEBUG_CURL` environment variable to print the equivalent
+ * curl commands for each request. These commands will include the API key and
+ * other sensitive information, so be careful when using this option.
+ */
+if (process && process.env && process.env.PINECONE_DEBUG_CURL) {
+  const debugCurlMiddleware = {
+    post: async (context) => {
+      let headers = `-H "Api-Key: ${(context.init.headers || {})['Api-Key']}"`;
+      if (context.init.headers && context.init.headers['Content-Type']) {
+        headers += ` -H "Content-Type: ${context.init.headers['Content-Type']}"`;
+      }
+      const cmd = `curl -X ${context.init.method} ${context.url} ${headers} ${
+        context.init.body ? `-d '${context.init.body}'` : ''
+      }`;
+      console.debug(chalk(cmd, 'red'));
+      console.debug('');
+    },
+  };
+  debugMiddleware.push(debugCurlMiddleware);
+}
+
 export const middleware = [
+  ...debugMiddleware,
   {
     onError: async (context) => {
       const err = await handleApiError(context.error);

src/utils/testHelper.ts

@@ -0,0 +1,11 @@
+import { ResponseError } from '../pinecone-generated-ts-fetch';
+
+export const responseError = (status: number, message: string) => {
+  return new ResponseError(
+    {
+      status,
+      text: async () => message,
+    } as Response,
+    'oops'
+  );
+};