(*---------------------------------------------------------------------------
  Copyright (c) 2025 Anil Madhavapeddy <anil@recoil.org>. All rights reserved.
  SPDX-License-Identifier: ISC
 ---------------------------------------------------------------------------*)

(** Tests for Timing module - HTTP request timing metrics *)

module Timing = Requests.Timing

(** {1 Empty Timing} *)

let test_empty_total () =
  let t = Timing.empty in
  Alcotest.(check bool) "total is 0" true (Float.abs (Timing.total t) < 0.0001)

let test_empty_fields () =
  let t = Timing.empty in
  Alcotest.(check bool)
    "dns_lookup is None" true
    (Option.is_none (Timing.dns_lookup t));
  Alcotest.(check bool)
    "tcp_connect is None" true
    (Option.is_none (Timing.tcp_connect t));
  Alcotest.(check bool)
    "tls_handshake is None" true
    (Option.is_none (Timing.tls_handshake t));
  Alcotest.(check bool)
    "request_sent is None" true
    (Option.is_none (Timing.request_sent t));
  Alcotest.(check bool)
    "time_to_first_byte is None" true
    (Option.is_none (Timing.time_to_first_byte t));
  Alcotest.(check bool)
    "content_transfer is None" true
    (Option.is_none (Timing.content_transfer t))

(** {1 Make with Values} *)

let test_make_total () =
  let t = Timing.v ~total:1.5 () in
  Alcotest.(check bool)
    "total is 1.5" true
    (Float.abs (Timing.total t -. 1.5) < 0.0001)

let test_make_with_phases () =
  let t =
    Timing.v ~dns_lookup:0.01 ~tcp_connect:0.02 ~tls_handshake:0.05
      ~request_sent:0.001 ~time_to_first_byte:0.1 ~content_transfer:0.5
      ~total:0.681 ()
  in
  Alcotest.(check bool)
    "dns_lookup" true
    (match Timing.dns_lookup t with
    | Some v -> Float.abs (v -. 0.01) < 0.0001
    | None -> false);
  Alcotest.(check bool)
    "tcp_connect" true
    (match Timing.tcp_connect t with
    | Some v -> Float.abs (v -. 0.02) < 0.0001
    | None -> false);
  Alcotest.(check bool)
    "tls_handshake" true
    (match Timing.tls_handshake t with
    | Some v -> Float.abs (v -. 0.05) < 0.0001
    | None -> false);
  Alcotest.(check bool)
    "request_sent" true
    (match Timing.request_sent t with
    | Some v -> Float.abs (v -. 0.001) < 0.0001
    | None -> false);
  Alcotest.(check bool)
    "time_to_first_byte" true
    (match Timing.time_to_first_byte t with
    | Some v -> Float.abs (v -. 0.1) < 0.0001
    | None -> false);
  Alcotest.(check bool)
    "content_transfer" true
    (match Timing.content_transfer t with
    | Some v -> Float.abs (v -. 0.5) < 0.0001
    | None -> false)

(** {1 Computed Metrics} *)

let test_connection_time () =
  let t =
    Timing.v ~dns_lookup:0.01 ~tcp_connect:0.02 ~tls_handshake:0.05 ~total:0.5
      ()
  in
  match Timing.connection_time t with
  | Some ct ->
      (* connection_time = DNS + TCP + TLS = 0.01 + 0.02 + 0.05 = 0.08 *)
      Alcotest.(check bool)
        "connection_time" true
        (Float.abs (ct -. 0.08) < 0.001)
  | None -> Alcotest.fail "Expected Some connection_time"

let test_connection_time_no_tls () =
  let t = Timing.v ~dns_lookup:0.01 ~tcp_connect:0.02 ~total:0.5 () in
  (* Without TLS, connection_time may or may not be computed *)
  let _ = Timing.connection_time t in
  (* Just verify it doesn't crash *)
  ()

let test_server_time () =
  let t = Timing.v ~request_sent:0.001 ~time_to_first_byte:0.1 ~total:0.5 () in
  match Timing.server_time t with
  | Some st ->
      (* server_time = TTFB - request_sent = 0.1 - 0.001 = 0.099 *)
      Alcotest.(check bool) "server_time" true (Float.abs (st -. 0.099) < 0.001)
  | None -> Alcotest.fail "Expected Some server_time"

let test_server_time_none () =
  let t = Timing.empty in
  Alcotest.(check bool)
    "server_time is None" true
    (Option.is_none (Timing.server_time t))

(** {1 Timer} *)

let test_timer_basic () =
  let timer = Timing.start () in
  Timing.mark_dns timer;
  Timing.mark_connect timer;
  Timing.mark_send timer;
  Timing.mark_ttfb timer;
  Timing.mark_transfer_end timer;
  let t = Timing.finish timer in
  Alcotest.(check bool) "total >= 0" true (Timing.total t >= 0.0)

let test_timer_has_phases () =
  let timer = Timing.start () in
  Timing.mark_dns timer;
  Timing.mark_connect timer;
  Timing.mark_tls timer;
  Timing.mark_send timer;
  Timing.mark_ttfb timer;
  Timing.mark_transfer_end timer;
  let t = Timing.finish timer in
  Alcotest.(check bool)
    "dns_lookup is Some" true
    (Option.is_some (Timing.dns_lookup t));
  Alcotest.(check bool)
    "tcp_connect is Some" true
    (Option.is_some (Timing.tcp_connect t));
  Alcotest.(check bool)
    "tls_handshake is Some" true
    (Option.is_some (Timing.tls_handshake t))

(** {1 Test Suite} *)

let suite =
  ( "timing",
    [
      Alcotest.test_case "total is 0" `Quick test_empty_total;
      Alcotest.test_case "all fields None" `Quick test_empty_fields;
      Alcotest.test_case "total only" `Quick test_make_total;
      Alcotest.test_case "with all phases" `Quick test_make_with_phases;
      Alcotest.test_case "connection time" `Quick test_connection_time;
      Alcotest.test_case "connection time no TLS" `Quick
        test_connection_time_no_tls;
      Alcotest.test_case "server time" `Quick test_server_time;
      Alcotest.test_case "server time None" `Quick test_server_time_none;
      Alcotest.test_case "basic timer" `Quick test_timer_basic;
      Alcotest.test_case "timer has phases" `Quick test_timer_has_phases;
    ] )