#!/usr/bin/env python3
"""CASAN H6 — hosted AgentOps dashboard server (D3).

Serves the generated dashboard over HTTP with a stale-aware /healthz probe so
an external monitor (uptime check / load-balancer) can page when telemetry
stops flowing — not just when the process dies.

Routes:
  GET /            -> dashboard HTML (also /dashboard)
  GET /healthz     -> 200 {"status":"ok",...} while metrics are fresh,
                      503 {"status":"stale",...} when metrics are older than
                      CASAN_DASHBOARD_STALE_S (default 3600s) or missing.

Usage: dashboard-server.py <port>
"""
import json
import os
import pathlib
import sys
import time
from http.server import BaseHTTPRequestHandler, HTTPServer

ROOT = pathlib.Path(__file__).resolve().parents[3]
PORT = int(sys.argv[1]) if len(sys.argv) > 1 else 8787
DASH = pathlib.Path(os.environ.get(
    "CASAN_DASHBOARD_HTML", ROOT / "docs" / "output" / "casan" / "central-agentops-dashboard.html"))
METRICS = pathlib.Path(os.environ.get(
    "CASAN_DASHBOARD_METRICS", ROOT / ".specify" / "logs" / "cost" / "metrics.jsonl"))
ALERTS = pathlib.Path(os.environ.get(
    "CASAN_DASHBOARD_ALERTS", ROOT / ".specify" / "agentops" / "alerts.log"))
STALE_S = int(os.environ.get("CASAN_DASHBOARD_STALE_S", "3600"))


def count_lines(path: pathlib.Path) -> int:
    if not path.exists():
        return 0
    return sum(1 for line in path.read_text(encoding="utf-8").splitlines() if line.strip())


class Handler(BaseHTTPRequestHandler):
    def _send(self, code: int, ctype: str, body: str) -> None:
        data = body.encode("utf-8")
        self.send_response(code)
        self.send_header("Content-Type", ctype)
        self.send_header("Content-Length", str(len(data)))
        self.end_headers()
        self.wfile.write(data)

    def do_GET(self):  # noqa: N802 (http.server API)
        if self.path == "/healthz":
            if METRICS.exists():
                age = int(time.time() - METRICS.stat().st_mtime)
                stale = age > STALE_S
            else:
                age = -1
                stale = True
            body = json.dumps({
                "status": "stale" if stale else "ok",
                "metrics_age_s": age,
                "stale_after_s": STALE_S,
                "runs": count_lines(METRICS),
                "alerts": count_lines(ALERTS),
            })
            self._send(503 if stale else 200, "application/json", body)
        elif self.path in ("/", "/dashboard"):
            if DASH.exists():
                self._send(200, "text/html; charset=utf-8", DASH.read_text(encoding="utf-8"))
            else:
                self._send(404, "text/plain", "dashboard not generated")
        else:
            self._send(404, "text/plain", "not found")

    def log_message(self, *args):  # silence per-request stderr noise
        pass

BIND = os.environ.get("CASAN_DASHBOARD_BIND", "127.0.0.1")


if __name__ == "__main__":
    HTTPServer((BIND, PORT), Handler).serve_forever()