"""Serve the sampler locally with HTTP Range support (plain `python -m http.server` can't seek videos).

    python serve.py [port]        then open http://localhost:8000/
"""
import os
import re
import sys
from functools import partial
from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer

SITE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "site")


class RangeHandler(SimpleHTTPRequestHandler):
    extensions_map = {**SimpleHTTPRequestHandler.extensions_map, ".js": "text/javascript", ".mp4": "video/mp4"}

    def end_headers(self):
        self.send_header("Accept-Ranges", "bytes")
        self.send_header("Cache-Control", "no-cache")
        super().end_headers()

    def send_head(self):
        rng = self.headers.get("Range")
        path = self.translate_path(self.path)
        if not rng or not os.path.isfile(path):
            return super().send_head()
        m = re.match(r"bytes=(\d*)-(\d*)", rng)
        size = os.path.getsize(path)
        if not m:
            return super().send_head()
        a = int(m.group(1)) if m.group(1) else max(0, size - int(m.group(2) or 0))
        b = int(m.group(2)) if m.group(1) and m.group(2) else size - 1
        b = min(b, size - 1)
        if a > b:
            self.send_error(416)
            return None
        f = open(path, "rb")
        f.seek(a)
        self.send_response(206)
        self.send_header("Content-Type", self.guess_type(path))
        self.send_header("Content-Range", f"bytes {a}-{b}/{size}")
        self.send_header("Content-Length", str(b - a + 1))
        self.end_headers()
        self._remaining = b - a + 1
        return f

    def copyfile(self, src, dst):
        n = getattr(self, "_remaining", None)
        if n is None:
            return super().copyfile(src, dst)
        try:
            while n > 0:
                buf = src.read(min(1 << 16, n))
                if not buf:
                    break
                dst.write(buf)
                n -= len(buf)
        except (ConnectionResetError, BrokenPipeError, ConnectionAbortedError):
            pass

    def log_message(self, *a):
        pass


if __name__ == "__main__":
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 8000
    print(f"Starpilot Sampler -> http://localhost:{port}/")
    ThreadingHTTPServer(("127.0.0.1", port), partial(RangeHandler, directory=SITE)).serve_forever()