--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/x/jb2_webserver.py	Sat Oct 05 23:58:05 2024 +0000
@@ -0,0 +1,187 @@
+#!/usr/bin/env python3
+# spec: simplest python web server with range support and multithreading that takes root path,
+# port and bind address as command line arguments; by default uses the current dir as webroot,
+# port 8000 and bind address of 0.0.0.0
+# borrowed from https://github.com/danvk/RangeHTTPServer
+# and reborrowed from https://gist.github.com/glowinthedark/b99900abe935e4ab4857314d647a9068
+#
+# The Apache 2.0 license copy in this repository is distributed with this code in accordance with that licence.
+# https://www.apache.org/licenses/LICENSE-2.0.txt
+# This part is not MIT licenced like the other components.
+
+# APPENDIX: How to apply the Apache License to your work.
+
+# To apply the Apache License to your work, attach the following
+# boilerplate notice, with the fields enclosed by brackets "[]"
+# replaced with your own identifying information. (Don't include
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+# comment syntax for the file format. We also recommend that a
+# file or class name and description of purpose be included on the
+# same "printed page" as the copyright notice for easier
+# identification within third-party archives.
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import argparse
+import functools
+import os
+import re
+import socketserver
+import webbrowser
+from http.server import SimpleHTTPRequestHandler
+
+
+DEFAULT_PORT = 8081
+
+
+def copy_byte_range(infile, outfile, start=None, stop=None, bufsize=16 * 1024):
+    """Like shutil.copyfileobj, but only copy a range of the streams.
+
+    Both start and stop are inclusive.
+    """
+    if start is not None:
+        infile.seek(start)
+    while 1:
+        to_read = min(bufsize, stop + 1 - infile.tell() if stop else bufsize)
+        buf = infile.read(to_read)
+        if not buf:
+            break
+        outfile.write(buf)
+
+
+BYTE_RANGE_RE = re.compile(r"bytes=(\d+)-(\d+)?$")
+
+
+def parse_byte_range(byte_range):
+    """Returns the two numbers in 'bytes=123-456' or throws ValueError.
+
+    The last number or both numbers may be None.
+    """
+    if byte_range.strip() == "":
+        return None, None
+
+    m = BYTE_RANGE_RE.match(byte_range)
+    if not m:
+        raise ValueError("Invalid byte range %s" % byte_range)
+
+    first, last = [x and int(x) for x in m.groups()]
+    if last and last < first:
+        raise ValueError("Invalid byte range %s" % byte_range)
+    return first, last
+
+
+class RangeRequestHandler(SimpleHTTPRequestHandler):
+    """Adds support for HTTP 'Range' requests to SimpleHTTPRequestHandler
+
+    The approach is to:
+    - Override send_head to look for 'Range' and respond appropriately.
+    - Override copyfile to only transmit a range when requested.
+    """
+
+    def handle(self):
+        try:
+            SimpleHTTPRequestHandler.handle(self)
+        except Exception:
+            # ignored, thrown whenever the client aborts streaming (broken pipe)
+            pass
+
+    def send_head(self):
+        if "Range" not in self.headers:
+            self.range = None
+            return SimpleHTTPRequestHandler.send_head(self)
+        try:
+            self.range = parse_byte_range(self.headers["Range"])
+        except ValueError:
+            self.send_error(400, "Invalid byte range")
+            return None
+        first, last = self.range
+
+        # Mirroring SimpleHTTPServer.py here
+        path = self.translate_path(self.path)
+        f = None
+        ctype = self.guess_type(path)
+        try:
+            f = open(path, "rb")
+        except IOError:
+            self.send_error(404, "File not found")
+            return None
+
+        fs = os.fstat(f.fileno())
+        file_len = fs[6]
+        if first >= file_len:
+            self.send_error(416, "Requested Range Not Satisfiable")
+            return None
+
+        self.send_response(206)
+        self.send_header("Content-type", ctype)
+
+        if last is None or last >= file_len:
+            last = file_len - 1
+        response_length = last - first + 1
+
+        self.send_header("Content-Range", "bytes %s-%s/%s" % (first, last, file_len))
+        self.send_header("Content-Length", str(response_length))
+        self.send_header("Last-Modified", self.date_time_string(fs.st_mtime))
+        self.end_headers()
+        return f
+
+    def end_headers(self):
+        self.send_header("Accept-Ranges", "bytes")
+        return SimpleHTTPRequestHandler.end_headers(self)
+
+    def copyfile(self, source, outputfile):
+        if not self.range:
+            return SimpleHTTPRequestHandler.copyfile(self, source, outputfile)
+
+        # SimpleHTTPRequestHandler uses shutil.copyfileobj, which doesn't let
+        # you stop the copying before the end of the file.
+        start, stop = self.range  # set in send_head()
+        copy_byte_range(source, outputfile, start, stop)
+
+
+class ThreadedTCPServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
+    allow_reuse_address = True
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Tiny Python Web Server supporting range requests, for local viewing of unzipped Galaxy JBrowse2 configurations"
+    )
+    parser.add_argument(
+        "--root",
+        default=os.getcwd(),
+        help="Root path to serve files from (default: current working directory)",
+    )
+    parser.add_argument(
+        "--port",
+        type=int,
+        default=DEFAULT_PORT,
+        help=f"Port to listen on (default: {DEFAULT_PORT})",
+    )
+    parser.add_argument(
+        "--bind",
+        default="127.0.0.1",
+        help="IP address to bind to (default: 127.0.0.1 - use 0.0.0.0 to allow access on your network)",
+    )
+    args = parser.parse_args()
+
+    handler = functools.partial(RangeRequestHandler, directory=args.root)
+
+    webbrowser.open(f"http://{args.bind}:{args.port}")
+
+    with ThreadedTCPServer((args.bind, args.port), handler) as httpd:
+        print(
+            f"Serving HTTP on {args.bind} port {args.port} (http://{args.bind}:{args.port}/)"
+        )
+        httpd.serve_forever()