py_engine: add http python module

[Detail]
add http python module that requires urequests module

[Verified Cases]
Build Pass: <py_engine_demo>
Test Pass:  <py_engine_demo>

modules/http/http.py

+# -*- coding: UTF-8 -*-
+
+"""
+Wrapper for micropython's urequests module to provide HaaS Python http APIs.
+For detailed API description, please refer to:
+https://haas.iot.aliyun.com/haasapi/index.html?spm=a2cpu.b16145223.0.0.595660b1Vllyah#/Python/docs/zh-CN/haas_extended_api/http
+"""
+
+import urequests
+from _thread import start_new_thread
+import uio
+
+def request(data, cb):
+    """Make a http request (asynchronous)
+
+    Args:
+        data: A dictionary that contains the information of request.
+        cb: A function(data) that will be executed after this request complete.
+
+    Returns:
+        0: success, <0: error
+
+    Raises:
+        No
+    """
+    def request_thread(func_cb, method, url, http_headers, params):
+        resp = urequests.request(method, url, data=params, headers=http_headers)
+
+        request_header = {"method": method, "url": url, "headers": http_headers}
+        body = resp.text
+        func_cb_arg = {"header": request_header, "body": body }
+        func_cb(func_cb_arg)
+
+    if type(data) is not dict:
+        return -1
+
+    if not callable(cb):
+        return -2
+
+    if "method" not in data:
+        return -3
+
+    if "url" not in data:
+        return -4
+
+    method = data["method"]
+    url = data["url"]
+    if "headers" in data:
+        headers = data["headers"]
+    else:
+        headers = {"content-type": "application/json"}
+
+    # timeout not working now.
+    if "timeout" in data:
+        timeout = data["timeout"]
+
+    if "params" in data:
+        params = data["params"]
+    else:
+        params = None
+
+    start_new_thread(request_thread, (cb, method, url, headers, params))
+
+    return 0
+
+
+def download(data, cb):
+    """Download file to local from a http server (asynchronous)
+
+    Args:
+        data: A dictionary that contains the information of download, e.g.
+              data = {'url': 'http://httpbin.org/image/png', 'filepath': '/httpbin.dat'}
+        cb: A function that will be called as cb("success") or cb("fail") after this download complete.
+
+    Returns:
+        0: success, <0: error
+
+    Raises:
+        No
+    """
+
+    def download_thread(func_cb, url, filepath):
+        """A new thread entry to make a download http request"""
+
+        fd = None
+
+        try:
+            resp = urequests.get(url)
+            fd = uio.open(filepath, "w")
+            fd.write(resp.content)
+        except:
+            if (fd):
+                fd.close()
+            func_cb("fail")
+
+        if (fd):
+            fd.close()
+        func_cb("success")
+
+    if type(data) is not dict:
+        return -1
+
+    if not callable(cb):
+        return -2
+
+    if "url" not in data:
+        return -3
+
+    if "filepath" not in data:
+        return -4
+
+    start_new_thread(download_thread, (cb, data["url"], data["filepath"]))
+    return 0