aitest-reasonml-mon-fbk/lib/monitor.ml

(* Website monitoring logic *)

open Lwt.Infix
open Cohttp
open Cohttp_lwt_unix
open Database

(* Result of a website check *)
type check_result = {
  status_code: int;
  response_time: float; (* milliseconds *)
  error_message: string option;
  is_success: bool;
}

(* Check a single website *)
let check_website (website : Website.t) : check_result Lwt.t =
  let start_time = Unix.gettimeofday () in

  let uri =
    try Uri.of_string website.url
    with _ -> failwith (Printf.sprintf "Invalid URL: %s" website.url)
  in

  (* Create HTTP client with timeout *)
  let timeout = website.timeout in
  let client = Client.conns ~connection_timeout:(float_of_int timeout) () in

  (* Make HTTP request *)
  Client.get ~uri client
  >>= fun (response, body) ->
  let end_time = Unix.gettimeofday () in
  let response_time = (end_time -. start_time) *. 1000.0 in

  let status_code = Code.code_of_status (Cohttp.Response.status response) in

  let is_success =
    status_code = website.expected_status && Code.is_success status_code
  in

  let result = {
    status_code;
    response_time;
    error_message = None;
    is_success;
  } in

  (* Drain body to complete request *)
  Cohttp_lwt.Body.to_string body
  >>= fun _body ->
  Lwt.return result
  |> Lwt.catch
    (fun exn ->
      let error_message = Some (Printexc.to_string exn) in
      let result = {
        status_code = 0;
        response_time = (Unix.gettimeofday () -. start_time) *. 1000.0;
        error_message;
        is_success = false;
      } in
      Lwt.return result)

(* Check website and store result *)
let check_and_store_website (website : Website.t) : unit Lwt.t =
  Logs.app (fun m ->
    m "Checking website: %s (%s)" website.name website.url);

  check_website website
  >>= fun result ->
  let now = Ptime.v (Unix.gettimeofday ()) in

  (* Store check history *)
  let error_message =
    match result.error_message with
    | None -> None
    | Some msg -> Some msg
  in

  CheckHistories.create website.id result.status_code result.response_time error_message
  >>= fun () ->

  (* Update website status *)
  let last_status = Some result.status_code in
  let last_checked = now in

  Websites.update_status website.id last_checked last_status
  >>= fun () ->

  Logs.app (fun m ->
    m "Website %s check result: status=%d, time=%.2fms, success=%b"
      website.name result.status_code result.response_time result.is_success);

  (* Trigger alerts if needed *)
  Alert.trigger_alerts website result
  >>= fun () ->
  Lwt.return_unit
  |> Lwt.catch
    (fun exn ->
      Logs.err (fun m ->
        m "Error checking website %s: %s" website.name (Printexc.to_string exn));
      Lwt.return_unit)

(* Check all active websites *)
let check_all_active_websites () : unit Lwt.t =
  Websites.get_active ()
  >>= fun websites ->
  Lwt_list.iter_p check_and_store_website websites
  >>= fun () ->
  Logs.app (fun m -> m "Completed checking all active websites");
  Lwt.return_unit

(* Get current status summary for a website *)
let get_website_status (website_id : int64) : Yojson.Basic.t Lwt.t =
  Websites.get_by_id website_id
  >>= function
  | None -> Lwt.return Yojson.Basic.(`Null)
  | Some website ->
      CheckHistories.get_by_website_id website_id 10
      >>= fun histories ->
      let recent_checks =
        List.map
          (fun (h : CheckHistory.t) ->
            Yojson.Basic.(
              `Assoc
                [
                  ("id", `String (Int64.to_string h.id));
                  ("status_code", `Int h.status_code);
                  ("response_time", `Float h.response_time);
                  ("error_message",
                   (match h.error_message with
                    | None -> `Null
                    | Some msg -> `String msg));
                  ("checked_at", `String (Ptime.to_rfc3339 h.checked_at));
                ]))
          histories
      in

      let website_json =
        Yojson.Basic.(
          `Assoc
            [
              ("id", `String (Int64.to_string website.id));
              ("name", `String website.name);
              ("url", `String website.url);
              ("expected_status", `Int website.expected_status);
              ("active", `Bool website.active);
              ("last_checked",
               (match website.last_checked with
                | None -> `Null
                | Some t -> `String (Ptime.to_rfc3339 t)));
              ("last_status",
               (match website.last_status with
                | None -> `Null
                | Some s -> `Int s));
              ("recent_checks", `List recent_checks);
            ])
      in
      Lwt.return website_json