"""Minimal internal OTLP/HTTP collector for the optional observer profile.

It accepts bounded trace batches, keeps only counters in memory, and exposes
Prometheus text metrics. It never logs request bodies or trace attributes.
"""

from __future__ import annotations

import json
from http import HTTPStatus
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from threading import Lock

MAX_BODY = 1024 * 1024
_lock = Lock()
_spans = 0
_batches = 0


class CollectorHandler(BaseHTTPRequestHandler):
    server_version = "ITWorxOTLPCollector/1.0"

    def do_GET(self) -> None:  # noqa: N802
        if self.path == "/healthz":
            self._write(
                HTTPStatus.OK,
                b'{"status":"ok","component":"observability-collector"}',
                "application/json",
            )
            return
        if self.path == "/metrics":
            with _lock:
                body = (
                    f"itworx_otel_batches_total {_batches}\\nitworx_otel_spans_total {_spans}\\n"
                ).encode()
            self._write(HTTPStatus.OK, body, "text/plain; version=0.0.4")
            return
        self.send_error(HTTPStatus.NOT_FOUND)

    def do_POST(self) -> None:  # noqa: N802
        global _batches, _spans
        if self.path != "/v1/traces":
            self.send_error(HTTPStatus.NOT_FOUND)
            return
        length = int(self.headers.get("Content-Length", "0"))
        if length <= 0 or length > MAX_BODY:
            self.send_error(HTTPStatus.REQUEST_ENTITY_TOO_LARGE)
            return
        try:
            document = json.loads(self.rfile.read(length))
            batches = document.get("resourceSpans", [])
            spans = sum(
                len(scope.get("spans", []))
                for batch in batches
                for scope in batch.get("scopeSpans", [])
            )
        except (ValueError, TypeError, AttributeError):
            self.send_error(HTTPStatus.BAD_REQUEST)
            return
        with _lock:
            _batches += 1
            _spans += spans
        self._write(HTTPStatus.ACCEPTED, b"", "text/plain")

    def _write(self, status: HTTPStatus, body: bytes, content_type: str) -> None:
        self.send_response(status)
        self.send_header("Content-Type", content_type)
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        if body:
            self.wfile.write(body)

    def log_message(self, _format: str, *_args: object) -> None:
        return


if __name__ == "__main__":
    ThreadingHTTPServer(("0.0.0.0", 4318), CollectorHandler).serve_forever()  # noqa: S104