Reverse proxy support for custom server base path

scripts/server_with_rewrites.py

@@ -1,16 +1,28 @@
 from http.server import HTTPServer, SimpleHTTPRequestHandler
 import argparse
 
+class MyHTTPServer(HTTPServer):
+    def __init__(self, server_address, RequestHandlerClass,
+                 base_path='',
+                 bind_and_activate=True):
+        HTTPServer.__init__(self, server_address, RequestHandlerClass, bind_and_activate=bind_and_activate)
+        self.base_path = base_path
 
-class RequestHandler(SimpleHTTPRequestHandler):
 
+class RequestHandler(SimpleHTTPRequestHandler):
     # mimic firebase hosting's rewrite rules
-    def translate_path(self, path):
-        if path.startswith('/simplified') or path.startswith('/traditional') or path.startswith('/cantonese') or path.startswith('/hsk'):
+    def translate_path(self, request_path):
+        base_path = self.server.base_path if isinstance(self.server, MyHTTPServer) else ''
+        slashed_path = request_path.removeprefix(base_path)
+        crit_blank = slashed_path in ('/', '')
+        crit_specials = any([slashed_path.startswith(f"{candidate}") for candidate in (
+            '/simplified', '/traditional', '/cantonese', '/hsk'
+        )])
+        if crit_blank or crit_specials:
             return 'index.html'
-        # prepend . such that the frontend's use of /whatever results in ./whatever
-        # should maybe just strip the first character, tbh
-        return f".{path}"
+        # now turn the slashed path /foo/bar into ./foo/bar on disk
+        path = f".{slashed_path}"
+        return path
 
 
 if __name__ == '__main__':
@@ -20,9 +32,16 @@ def translate_path(self, path):
         description='Enable URL rewrites without relying on firebase hosting. Intended to be run from the public/ directory.')
     parser.add_argument(
         '--port', help='your choice of port; default 8000', nargs='?', default=8000, type=int)
+    parser.add_argument(
+        '--base-path', help='custom base path, e.g. /app/hanzi; useful for reverse proxy', default='')
     args = parser.parse_args()
     port = int(args.port)
-    myServer = HTTPServer(('0.0.0.0', port), RequestHandler)
+    base_path = args.base_path
+    if base_path:
+        assert base_path[0] == '/', '--base-path must start with /'
+        if base_path[-1] == '/':
+            base_path = base_path[:-1]
+    myServer = MyHTTPServer(('0.0.0.0', port), RequestHandler, base_path=base_path)
     print("HanziGraph started")
     try:
         myServer.serve_forever()