open Space_wire

let encode codec v =
  let ws = Wire.Codec.wire_size codec in
  let buf = Bytes.create ws in
  Wire.Codec.encode codec v buf 0;
  Bytes.unsafe_to_string buf

let decode codec s = Wire.Codec.decode codec (Bytes.of_string s) 0

let test_error_roundtrip () =
  let err =
    Error_payload.v Unknown_type ~offending_type:0xFF ~offending_apid:0x42
      ~offending_pay_len:248
  in
  let encoded = encode Error_payload.codec err in
  Alcotest.(check int) "error size" 8 (String.length encoded);
  let decoded = decode Error_payload.codec encoded in
  Alcotest.(check bool) "roundtrip" true (Error_payload.equal err decoded)

let test_error_layout () =
  let err =
    Error_payload.v Host_busy ~offending_type:0x07 ~offending_apid:0x100
      ~offending_pay_len:0x1234
  in
  let encoded = encode Error_payload.codec err in
  Alcotest.(check int) "error_code" 0x05 (Char.code encoded.[0]);
  Alcotest.(check int) "offending_type" 0x07 (Char.code encoded.[1]);
  (* apid 0x0100 big-endian *)
  Alcotest.(check int) "apid high" 0x01 (Char.code encoded.[2]);
  Alcotest.(check int) "apid low" 0x00 (Char.code encoded.[3]);
  (* pay_len 0x1234 big-endian at offset 4-5 *)
  Alcotest.(check int) "pay_len high" 0x12 (Char.code encoded.[4]);
  Alcotest.(check int) "pay_len low" 0x34 (Char.code encoded.[5]);
  (* reserved = 0 at offset 6-7 *)
  Alcotest.(check int) "reserved high" 0x00 (Char.code encoded.[6]);
  Alcotest.(check int) "reserved low" 0x00 (Char.code encoded.[7])

let suite =
  ( "error_payload",
    [
      Alcotest.test_case "roundtrip" `Quick test_error_roundtrip;
      Alcotest.test_case "layout" `Quick test_error_layout;
    ] )