Add http-server for lesson 2

http-server

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+#/usr/bin/env python3
+
+from http import server
+from urllib import parse
+
+class SimpleHandler(server.BaseHTTPRequestHandler):
+
+    def do_GET(self):
+        self.send_response(200)
+        self.end_headers()
+
+        parsed = parse.urlparse(self.path)
+        path = parsed.path
+        query = parsed.query
+        query_components = parse.parse_qsl(query)
+
+        if path == "/":
+            self.return_get_components(path, query, query_components)
+        elif path == "/ying":
+            self.return_ying()
+        elif path == "/yang":
+            self.return_yang()
+        elif path == "/squares":
+            self.return_squares(query_components)
+        else:
+            msg = "Error 404"
+            self.wfile.write(msg.encode('utf-8'))
+
+    def return_squares(self, query_components):
+        if len(query_components) != 2:
+            msg = "Invalid number of Query Components! Two components needed."
+        else:
+            if query_components[0][0] != 'von' or query_components[1][0] != 'bis':
+                msg = "Invalid Query Components! First key has to be 'von', second key 'bis'."
+                self.wfile.write(msg.encode('utf-8'))
+            else:
+                try:
+                    von = int(query_components[0][1])
+                    bis = int(query_components[1][1])
+                except:
+                    msg = "One or both query values are not integer."
+                else:
+                    msg = "<table border='1'>"
+                    for i in range(von, bis+1):
+                        msg += f"<tr><td>{i}</td><td>{i**2}</td></tr>"
+                    msg += "</table>"
+        self.wfile.write(msg.encode('utf-8'))
+
+    
+    def return_ying(self):
+        msg = "<a href='/yang'>Ying</a>"
+        self.wfile.write(msg.encode('utf-8'))
+    
+    def return_yang(self):
+        msg = "<a href='/ying'>Yang</a>"
+        self.wfile.write(msg.encode('utf-8'))
+    
+    def return_get_components(self, path, query, query_components):
+        msg = f"Path: {path}\nQuery: {query}\nComponents: {str(query_components)}"
+
+        self.wfile.write(msg.encode('utf-8'))
+
+if __name__ == "__main__":
+    port = 60000
+    handler = SimpleHandler
+    address = ('', port)
+
+    server = server.HTTPServer(address, handler)
+    server.serve_forever()