Show TLS certificate validity details

Include healthy TLS certificate validity in website check messages and show latest website check results in the UI.

worker/app/collectors/website.py

@@ -28,13 +28,22 @@ class WebsiteCheckResult:
     message: str
 
 
+@dataclass(frozen=True)
+class TlsExpiryResult:
+    status: str
+    response_time_ms: int
+    message: str
+
+
 async def run_website_check(config: WebsiteCheckConfig) -> WebsiteCheckResult:
     started = perf_counter()
+    tls_message: str | None = None
 
     if config.check_tls_expiry:
         tls_result = await check_tls_expiry(config.url, config.tls_warning_days, config.timeout_seconds)
-        if tls_result is not None:
+        if tls_result.status != "up":
             return tls_result
+        tls_message = tls_result.message
 
     try:
         async with httpx.AsyncClient(follow_redirects=True, timeout=config.timeout_seconds) as client:
@@ -61,38 +70,46 @@ async def run_website_check(config: WebsiteCheckConfig) -> WebsiteCheckResult:
             response_time_ms=response_time_ms,
             message="Unexpected text was present",
         )
-    return WebsiteCheckResult(status="up", response_time_ms=response_time_ms, message="Website check passed")
+    message = "Website check passed"
+    if tls_message:
+        message = f"{message}; {tls_message}"
+    return WebsiteCheckResult(status="up", response_time_ms=response_time_ms, message=message)
 
 
-async def check_tls_expiry(url: str, warning_days: int, timeout_seconds: float) -> WebsiteCheckResult | None:
+async def check_tls_expiry(url: str, warning_days: int, timeout_seconds: float) -> TlsExpiryResult:
     parsed_url = urlparse(url)
     if parsed_url.scheme != "https":
-        return None
+        return TlsExpiryResult(status="up", response_time_ms=0, message="TLS expiry check skipped for non-HTTPS target")
     if not parsed_url.hostname:
-        return WebsiteCheckResult(status="down", response_time_ms=None, message="TLS check could not determine the hostname")
+        return TlsExpiryResult(status="down", response_time_ms=0, message="TLS check could not determine the hostname")
 
     started = perf_counter()
     try:
         expires_at = await _get_certificate_expiry(parsed_url.hostname, parsed_url.port or 443, timeout_seconds)
     except (OSError, ssl.SSLError, ValueError) as exc:
-        return WebsiteCheckResult(status="down", response_time_ms=None, message=f"TLS certificate check failed: {exc}")
+        return TlsExpiryResult(status="down", response_time_ms=int((perf_counter() - started) * 1000), message=f"TLS certificate check failed: {exc}")
 
     response_time_ms = int((perf_counter() - started) * 1000)
     now = datetime.now(UTC)
     days_remaining = (expires_at - now).total_seconds() / 86400
+    days_remaining_text = str(max(0, int(days_remaining)))
     if days_remaining < 0:
-        return WebsiteCheckResult(
+        return TlsExpiryResult(
             status="down",
             response_time_ms=response_time_ms,
             message=f"TLS certificate expired on {expires_at.date().isoformat()}",
         )
     if days_remaining <= warning_days:
-        return WebsiteCheckResult(
+        return TlsExpiryResult(
             status="warning",
             response_time_ms=response_time_ms,
-            message=f"TLS certificate expires in {int(days_remaining)} days on {expires_at.date().isoformat()}",
+            message=f"TLS certificate expires in {days_remaining_text} days on {expires_at.date().isoformat()}",
         )
-    return None
+    return TlsExpiryResult(
+        status="up",
+        response_time_ms=response_time_ms,
+        message=f"TLS certificate valid for {days_remaining_text} days until {expires_at.date().isoformat()}",
+    )
 
 
 async def _get_certificate_expiry(hostname: str, port: int, timeout_seconds: float) -> datetime: