"""Deployment-only HTTP prefix adapter; modeling code remains unchanged."""
import http.client
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
import re
import subprocess
import sys
from urllib.parse import urlsplit

PREFIX = '/box-sample'
UPSTREAM_PORT = 8097
HOP = {'connection', 'transfer-encoding', 'keep-alive', 'upgrade',
       'proxy-authenticate', 'proxy-authorization', 'te', 'trailer'}
ROOT_URL = re.compile(rb'''(["'`])/(api/|src/|dxf_rasterizer\.html|model-report\.html)''')


def rewrite(payload):
    return ROOT_URL.sub(lambda m: m[1] + PREFIX.encode() + b'/' + m[2], payload)


class Gateway(BaseHTTPRequestHandler):
    def forward(self):
        parsed = urlsplit(self.path)
        if parsed.path == PREFIX:
            self.send_response(308)
            self.send_header('Location', PREFIX + '/' + ('?' + parsed.query if parsed.query else ''))
            self.send_header('Content-Length', '0')
            self.end_headers()
            return
        if not parsed.path.startswith(PREFIX + '/'):
            self.send_error(404)
            return
        if self.headers.get('Transfer-Encoding'):
            self.send_error(411, 'Content-Length required')
            return
        target = self.path[len(PREFIX):]
        connection = http.client.HTTPConnection('127.0.0.1', UPSTREAM_PORT, timeout=600)
        try:
            size = int(self.headers.get('Content-Length', '0'))
            if size < 0 or size > 512 * 1024 * 1024:
                self.send_error(413)
                return
            headers = {k: v for k, v in self.headers.items()
                       if k.lower() not in HOP | {'accept-encoding', 'host'}}
            headers['Host'] = '127.0.0.1:' + str(UPSTREAM_PORT)
            connection.request(self.command, target, self.rfile.read(size) if size else None, headers)
            response = connection.getresponse()
            content_type = response.getheader('Content-Type', '').lower()
            text = any(t in content_type for t in ('json', 'javascript', 'text/html', 'text/css'))
            body = rewrite(response.read()) if text and self.command != 'HEAD' else None
            self.send_response(response.status)
            for key, value in response.getheaders():
                if key.lower() in HOP | {'content-length', 'etag', 'content-md5'}:
                    continue
                if key.lower() == 'location' and value.startswith('/') and not value.startswith('//'):
                    value = PREFIX + value
                self.send_header(key, value)
            self.send_header('X-DMS-Deployment', 'box-sample')
            self.send_header('Cache-Control', 'no-store')
            if body is not None:
                self.send_header('Content-Length', str(len(body)))
            elif response.getheader('Content-Length') is not None:
                self.send_header('Content-Length', response.getheader('Content-Length'))
            self.end_headers()
            if self.command != 'HEAD':
                if body is not None:
                    self.wfile.write(body)
                else:
                    while chunk := response.read(65536):
                        self.wfile.write(chunk)
        except (ValueError, OSError, http.client.HTTPException):
            self.send_error(502, 'Application not ready')
        finally:
            connection.close()

    do_GET = do_POST = do_HEAD = do_PUT = do_DELETE = forward


if __name__ == '__main__':
    child = subprocess.Popen([sys.executable, 'src/backend/serve.py', '--host', '127.0.0.1', '--port', str(UPSTREAM_PORT)])
    try:
        ThreadingHTTPServer(('0.0.0.0', 8080), Gateway).serve_forever()
    finally:
        child.terminate()
        child.wait(timeout=15)