feat(brain): add single-stream visual prototype (T-017)

Brain/yovision_brain/server.py

@@ -0,0 +1,141 @@
+from __future__ import annotations
+
+import hmac
+import json
+import secrets
+from http import HTTPStatus
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from pathlib import Path
+from typing import Any
+from urllib.parse import urlsplit
+
+from .domain import Zone
+
+
+MAX_BODY_BYTES = 64 * 1024
+
+
+def parse_bind(value: str) -> tuple[str, int]:
+    parsed = urlsplit(f"//{value}")
+    host = parsed.hostname
+    try:
+        port = parsed.port
+    except ValueError as exc:
+        raise ValueError("invalid demo bind address") from exc
+    if host not in {"127.0.0.1", "localhost", "::1"} or port is None or not 1 <= port <= 65535:
+        raise ValueError("Brain demo must bind to an explicit loopback address and valid port")
+    return host, port
+
+
+def index_path() -> Path:
+    return Path(__file__).resolve().parents[2] / "docs" / "design" / "brain" / "index.html"
+
+
+class DemoHTTPServer(ThreadingHTTPServer):
+    daemon_threads = True
+
+    def __init__(self, address: tuple[str, int], engine: Any, token: str, html: str) -> None:
+        self.engine = engine
+        self.demo_token = token
+        self.html = html
+        super().__init__(address, DemoHandler)
+
+
+class DemoHandler(BaseHTTPRequestHandler):
+    server: DemoHTTPServer
+
+    def log_message(self, _format: str, *_args: object) -> None:
+        # Do not echo request paths or headers; URL credentials never reach HTTP paths.
+        return
+
+    def _security_headers(self) -> None:
+        self.send_header("X-Content-Type-Options", "nosniff")
+        self.send_header("X-Frame-Options", "DENY")
+        self.send_header("Referrer-Policy", "no-referrer")
+        self.send_header("Cache-Control", "no-store")
+        self.send_header(
+            "Content-Security-Policy",
+            "default-src 'self'; style-src 'unsafe-inline'; script-src 'unsafe-inline'; "
+            "img-src 'self' data: blob:; connect-src 'self'; base-uri 'none'; frame-ancestors 'none'",
+        )
+
+    def _send_bytes(self, status: int, content_type: str, body: bytes) -> None:
+        self.send_response(status)
+        self.send_header("Content-Type", content_type)
+        self.send_header("Content-Length", str(len(body)))
+        self._security_headers()
+        self.end_headers()
+        self.wfile.write(body)
+
+    def _send_json(self, status: int, payload: object) -> None:
+        body = json.dumps(payload, ensure_ascii=False, separators=(",", ":")).encode("utf-8")
+        self._send_bytes(status, "application/json; charset=utf-8", body)
+
+    def do_GET(self) -> None:  # noqa: N802
+        path = urlsplit(self.path).path
+        if path in {"/", "/brain-demo"}:
+            body = self.server.html.replace("__BRAIN_DEMO_TOKEN__", self.server.demo_token).encode("utf-8")
+            self._send_bytes(HTTPStatus.OK, "text/html; charset=utf-8", body)
+            return
+        if path == "/healthz":
+            self._send_json(HTTPStatus.OK, {"status": "ok"})
+            return
+        if path == "/api/v1/state":
+            self._send_json(HTTPStatus.OK, self.server.engine.state())
+            return
+        if path == "/api/v1/frame.jpg":
+            frame = self.server.engine.frame_jpeg()
+            if frame is None:
+                self._send_json(HTTPStatus.SERVICE_UNAVAILABLE, {"code": "frame_not_ready"})
+                return
+            self._send_bytes(HTTPStatus.OK, "image/jpeg", frame)
+            return
+        self._send_json(HTTPStatus.NOT_FOUND, {"code": "not_found"})
+
+    def do_PUT(self) -> None:  # noqa: N802
+        if urlsplit(self.path).path != "/api/v1/zones/active":
+            self._send_json(HTTPStatus.NOT_FOUND, {"code": "not_found"})
+            return
+        raw_length = self.headers.get("Content-Length")
+        try:
+            length = int(raw_length or "-1")
+        except ValueError:
+            length = -1
+        if length < 0 or length > MAX_BODY_BYTES:
+            self._send_json(HTTPStatus.REQUEST_ENTITY_TOO_LARGE, {"code": "body_too_large"})
+            return
+        body = self.rfile.read(length)
+        supplied = self.headers.get("X-Brain-Demo-Token", "")
+        if not hmac.compare_digest(supplied, self.server.demo_token):
+            self._send_json(HTTPStatus.FORBIDDEN, {"code": "forbidden"})
+            return
+        try:
+            payload = json.loads(body.decode("utf-8"))
+            zone: Zone = self.server.engine.update_zone(payload)
+        except (UnicodeError, json.JSONDecodeError, ValueError):
+            self._send_json(HTTPStatus.BAD_REQUEST, {"code": "invalid_zone"})
+            return
+        self._send_json(
+            HTTPStatus.OK,
+            {
+                "id": zone.zone_id,
+                "name": zone.name,
+                "version": zone.version,
+                "points": [{"x": point.x, "y": point.y} for point in zone.points],
+            },
+        )
+
+
+def build_server(engine: Any, bind: str = "127.0.0.1:8090", token: str | None = None) -> DemoHTTPServer:
+    html = index_path().read_text(encoding="utf-8")
+    return DemoHTTPServer(parse_bind(bind), engine, token or secrets.token_urlsafe(32), html)
+
+
+def serve(engine: Any, bind: str) -> None:
+    server = build_server(engine, bind)
+    engine.start()
+    try:
+        server.serve_forever(poll_interval=0.25)
+    finally:
+        server.server_close()
+        engine.stop()