module E = Colitur_render.Escape

let check = Alcotest.(check string)

let test_latex () =
  check "ampersand" "\\&" (E.apply E.Latex "&");
  check "percent" "\\%" (E.apply E.Latex "%");
  check "underscore" "\\_" (E.apply E.Latex "_");
  check "braces" "\\{\\}" (E.apply E.Latex "{}");
  check "backslash first" "\\textbackslash{}" (E.apply E.Latex "\\");
  (* A real feast name that would otherwise break a .tex build. *)
  check "real name" "Ss.mi Nominis Iesu \\& Mari\xc3\xa6"
    (E.apply E.Latex "Ss.mi Nominis Iesu & Mari\xc3\xa6")

let test_groff () =
  check "backslash" "\\e" (E.apply E.Groff "\\");
  (* RG-irrelevant but groff-critical: a leading dot starts a request. *)
  check "leading dot" "\\&.Ss" (E.apply E.Groff ".Ss");
  check "leading quote" "\\&'tis" (E.apply E.Groff "'tis");
  check "interior dot untouched" "Ss.mi" (E.apply E.Groff "Ss.mi")

let test_html_xml () =
  check "amp first" "<" (E.apply E.Html "<");
  check "angles" "&lt;b&gt;" (E.apply E.Html "<b>");
  check "quote" "&quot;" (E.apply E.Html "\"");
  check "xml same" "&lt;b&gt;" (E.apply E.Xml "<b>")

let test_ics () =
  check "comma" "\\," (E.apply E.Ics ",");
  check "semicolon" "\\;" (E.apply E.Ics ";");
  check "backslash" "\\\\" (E.apply E.Ics "\\");
  check "newline" "\\n" (E.apply E.Ics "\n")

let test_none_is_identity () =
  check "none" "& < > \\ % {}" (E.apply E.None_ "& < > \\ % {}")

let test_flavour_names () =
  List.iter
    (fun f -> Alcotest.(check bool) "roundtrip" true (E.of_string (E.to_string f) = Some f))
    [ E.Latex; E.Groff; E.Html; E.Xml; E.Ics; E.None_ ];
  Alcotest.(check bool) "tex" true (E.of_extension ".tex" = Some E.Latex);
  Alcotest.(check bool) "ms" true (E.of_extension ".ms" = Some E.Groff);
  Alcotest.(check bool) "mom" true (E.of_extension ".mom" = Some E.Groff);
  Alcotest.(check bool) "html" true (E.of_extension ".html" = Some E.Html);
  Alcotest.(check bool) "md is none" true (E.of_extension ".md" = Some E.None_);
  Alcotest.(check bool) "adoc is none" true (E.of_extension ".adoc" = Some E.None_);
  Alcotest.(check bool) "txt is none" true (E.of_extension ".txt" = Some E.None_);
  (* Spec section 5: an unknown extension is an ERROR, never a silent fallback. *)
  Alcotest.(check bool) "unknown is None" true (E.of_extension ".wat" = None)

let test_fold_short_line_unchanged () =
  check "short" "SUMMARY:Feast\r\n" (E.fold_ics "SUMMARY:Feast")

let test_fold_long_line () =
  let long = "DESCRIPTION:" ^ String.make 200 'x' in
  let out = E.fold_ics long in
  let lines = String.split_on_char '\n' out in
  List.iter
    (fun l ->
      let l = if l <> "" && l.[String.length l - 1] = '\r' then String.sub l 0 (String.length l - 1) else l in
      if String.length l > 75 then Alcotest.failf "line of %d octets exceeds 75" (String.length l))
    (List.filter (fun l -> l <> "") lines);
  (* Continuation lines begin with exactly one space (RFC 5545 section 3.1). *)
  match lines with
  | _ :: second :: _ -> Alcotest.(check bool) "continuation starts with space" true (second.[0] = ' ')
  | _ -> Alcotest.fail "expected the line to fold"

(* RFC 5545 section 3.1 folds on OCTET boundaries; splitting mid-UTF-8 corrupts
   Polish and Latin names, which is the whole reason this is not a template job. *)
let test_fold_never_splits_utf8 () =
  let long = "SUMMARY:" ^ String.concat "" (List.init 40 (fun _ -> "\xc4\x99\xc5\x9b\xc4\x87")) in
  let out = E.fold_ics long in
  let chunks =
    List.filter_map
      (fun l ->
        let l = if l <> "" && l.[String.length l - 1] = '\r' then String.sub l 0 (String.length l - 1) else l in
        if l = "" then None else if l.[0] = ' ' then Some (String.sub l 1 (String.length l - 1)) else Some l)
      (String.split_on_char '\n' out)
  in
  (* The named property: no chunk may START with a UTF-8 continuation byte
     (0x80-0xBF) -- that would mean the previous fold cut mid-character.
     Unfolding losslessly (below) cannot detect this on its own: concatenation
     is insensitive to where the cuts fell, so a fold at ANY position still
     round-trips. *)
  List.iter
    (fun c ->
      if String.length c > 0 then
        Alcotest.(check bool) "chunk does not start mid-UTF-8" true (Char.code c.[0] land 0xC0 <> 0x80))
    chunks;
  let stripped = String.concat "" chunks in
  check "unfolds to the original" long stripped

(* B1 regression: 100 consecutive UTF-8 continuation bytes (0x80-0xBF) is not
   producible by valid UTF-8 (whose longest continuation run is 3), but
   fold_ics must stay TOTAL on arbitrary octet strings. A backoff loop with no
   hard-cut fallback backs `cut` all the way down to `pos`, yielding a
   zero-length chunk and recursing on the identical position forever. *)
let test_fold_pathological_input_terminates () =
  let pathological = String.make 100 '\x80' in
  let out = E.fold_ics pathological in
  let lines = String.split_on_char '\n' out in
  List.iter
    (fun l ->
      let l = if l <> "" && l.[String.length l - 1] = '\r' then String.sub l 0 (String.length l - 1) else l in
      if String.length l > 75 then Alcotest.failf "line of %d octets exceeds 75" (String.length l))
    (List.filter (fun l -> l <> "") lines)

let suite =
  ( "Escape",
    [ Alcotest.test_case "latex" `Quick test_latex;
      Alcotest.test_case "groff" `Quick test_groff;
      Alcotest.test_case "html/xml" `Quick test_html_xml;
      Alcotest.test_case "ics" `Quick test_ics;
      Alcotest.test_case "none is identity" `Quick test_none_is_identity;
      Alcotest.test_case "flavour names" `Quick test_flavour_names;
      Alcotest.test_case "fold: short unchanged" `Quick test_fold_short_line_unchanged;
      Alcotest.test_case "fold: long line" `Quick test_fold_long_line;
      Alcotest.test_case "fold: never splits utf8" `Quick test_fold_never_splits_utf8;
      Alcotest.test_case "fold: pathological input terminates" `Quick test_fold_pathological_input_terminates ] )