module T = Colitur_render.Template

let parse_ok s = match T.parse s with Ok ns -> ns | Error e -> Alcotest.failf "parse: %s" e

let test_plain_text () =
  Alcotest.(check bool) "text only" true (parse_ok "hello" = [ T.Text "hello" ])

let test_var () =
  Alcotest.(check bool) "var" true (parse_ok "{{name}}" = [ T.Var [ "name" ] ]);
  Alcotest.(check bool) "dotted" true (parse_ok "{{name.la}}" = [ T.Var [ "name"; "la" ] ]);
  Alcotest.(check bool) "spaces trimmed" true (parse_ok "{{  name.la  }}" = [ T.Var [ "name"; "la" ] ])

let test_section () =
  Alcotest.(check bool) "section" true
    (parse_ok "{{#days}}x{{/days}}" = [ T.Section ([ "days" ], [ T.Text "x" ]) ]);
  Alcotest.(check bool) "inverted" true
    (parse_ok "{{^days}}x{{/days}}" = [ T.Inverted ([ "days" ], [ T.Text "x" ]) ])

let test_nested_sections () =
  Alcotest.(check bool) "nested" true
    (parse_ok "{{#months}}{{#weeks}}w{{/weeks}}{{/months}}"
    = [ T.Section ([ "months" ], [ T.Section ([ "weeks" ], [ T.Text "w" ]) ]) ])

let test_comment_is_dropped () =
  Alcotest.(check bool) "comment" true (parse_ok "a{{! note }}b" = [ T.Text "a"; T.Text "b" ])

let test_unclosed_section_is_an_error () =
  match T.parse "{{#days}}x" with
  | Error _ -> ()
  | Ok _ -> Alcotest.fail "an unclosed section must be a parse error, not silently accepted"

let test_mismatched_close_is_an_error () =
  match T.parse "{{#days}}x{{/weeks}}" with
  | Error _ -> ()
  | Ok _ -> Alcotest.fail "a mismatched close tag must be a parse error"

let test_unterminated_tag_is_an_error () =
  match T.parse "{{name" with
  | Error _ -> ()
  | Ok _ -> Alcotest.fail "an unterminated tag must be a parse error"

(* The safety promise (spec section 5): a template is data, never a program.
   There is no raw/triple-brace form to opt out of escaping, and no partial. *)
let test_no_raw_or_partial_form () =
  (* {{{name}}} is not a triple-brace "unescaped" form -- there is no such
     form in this engine, so this assertion states what parsing it ACTUALLY
     produces rather than gesturing at a guarantee it cannot check: the
     lexer only recognises double braces, so it reads an ordinary var whose
     path is the literal string "{name", then a leftover "}" as text. The
     real guarantee against a raw form is structural, not this assertion:
     [node] has exactly four constructors -- Text, Var, Section, Inverted --
     and none of them is raw/unescaped. If [node] ever grows a fifth, raw
     constructor, this test is not what will catch it. *)
  Alcotest.(check bool) "triple brace parses as var + stray text" true
    (parse_ok "{{{name}}}" = [ T.Var [ "{name" ]; T.Text "}" ]);
  match T.parse "{{>partial}}" with
  | Error _ -> ()
  | Ok _ -> Alcotest.fail "partials must not parse: a template may not pull in another file"

(* No "current context" concept exists in this engine (sections push an
   object; lookup falls back outward), so a bare-dot or empty-sigil path has
   no meaning. Reject at parse time rather than inventing behaviour Task 3's
   renderer would otherwise have to define for a case nobody designed. *)
let test_empty_path_is_an_error () =
  let expect_error label s =
    match T.parse s with
    | Error _ -> ()
    | Ok _ -> Alcotest.failf "%s: an empty tag path must be a parse error" label
  in
  expect_error "{{.}}" "{{.}}";
  expect_error "{{ . }}" "{{ . }}";
  expect_error "{{#}}{{/}}" "{{#}}{{/}}";
  expect_error "{{^}}{{/}}" "{{^}}{{/}}"

let suite =
  ( "Template/parse",
    [ Alcotest.test_case "plain text" `Quick test_plain_text;
      Alcotest.test_case "vars" `Quick test_var;
      Alcotest.test_case "sections" `Quick test_section;
      Alcotest.test_case "nested sections" `Quick test_nested_sections;
      Alcotest.test_case "comments dropped" `Quick test_comment_is_dropped;
      Alcotest.test_case "unclosed section errors" `Quick test_unclosed_section_is_an_error;
      Alcotest.test_case "mismatched close errors" `Quick test_mismatched_close_is_an_error;
      Alcotest.test_case "unterminated tag errors" `Quick test_unterminated_tag_is_an_error;
      Alcotest.test_case "no raw or partial form" `Quick test_no_raw_or_partial_form;
      Alcotest.test_case "empty path errors" `Quick test_empty_path_is_an_error ] )

module E = Colitur_render.Escape

let render ?(flavour = E.None_) tpl v =
  match T.render_string ~flavour tpl v with Ok s -> s | Error e -> Alcotest.failf "render: %s" e

let obj kvs = T.Obj kvs

let test_render_var () =
  Alcotest.(check string) "var" "Hilary" (render "{{name}}" (obj [ ("name", T.Str "Hilary") ]));
  Alcotest.(check string) "dotted" "Hilarii"
    (render "{{name.la}}" (obj [ ("name", obj [ ("la", T.Str "Hilarii") ]) ]))

(* A missing key renders empty. This is the ONE silent case, and it is
   deliberate: a template written for a rite that does not set every optional
   field must still render (spec section 5). *)
let test_missing_key_is_empty () =
  Alcotest.(check string) "missing" "[]" (render "[{{nope}}]" (obj [ ("name", T.Str "x") ]))

let test_section_iterates () =
  let v = obj [ ("days", T.List [ obj [ ("dom", T.Str "1") ]; obj [ ("dom", T.Str "2") ] ]) ] in
  Alcotest.(check string) "iterate" "1|2|" (render "{{#days}}{{dom}}|{{/days}}" v)

let test_bool_section () =
  Alcotest.(check string) "true" "yes" (render "{{#f}}yes{{/f}}" (obj [ ("f", T.Bool true) ]));
  Alcotest.(check string) "false" "" (render "{{#f}}yes{{/f}}" (obj [ ("f", T.Bool false) ]));
  Alcotest.(check string) "inverted true" "" (render "{{^f}}no{{/f}}" (obj [ ("f", T.Bool true) ]));
  Alcotest.(check string) "inverted false" "no" (render "{{^f}}no{{/f}}" (obj [ ("f", T.Bool false) ]))

let test_empty_list_section_is_skipped () =
  Alcotest.(check string) "empty list" "" (render "{{#days}}x{{/days}}" (obj [ ("days", T.List []) ]));
  Alcotest.(check string) "inverted empty list" "none"
    (render "{{^days}}none{{/days}}" (obj [ ("days", T.List []) ]))

let test_outer_scope_visible_inside_section () =
  let v = obj [ ("year", T.Str "2027"); ("days", T.List [ obj [ ("dom", T.Str "1") ] ]) ] in
  Alcotest.(check string) "outer visible" "2027-1"
    (render "{{#days}}{{year}}-{{dom}}{{/days}}" v)

(* THE safety property (spec section 9.2): a data value can never escape its
   flavour. This is the test that must redden if any escape rule is broken. *)
let test_data_cannot_escape_flavour () =
  let nasty = obj [ ("name", T.Str "A & B \\ 50% {x} $y_z") ] in
  let out = render ~flavour:E.Latex "{{name}}" nasty in
  Alcotest.(check string) "fully escaped" "A \\& B \\textbackslash{} 50\\% \\{x\\} \\$y\\_z" out;
  let hout = render ~flavour:E.Html "{{name}}" (obj [ ("name", T.Str "<script>") ]) in
  Alcotest.(check string) "html escaped" "&lt;script&gt;" hout

(* Literal template text is NOT escaped -- it is the author's own markup. Only
   interpolated DATA is escaped. Getting this backwards would make every
   template render as visible source. *)
(* NOTE: the brief's own example here was "\textbf{{{name}}}", i.e. a literal
   "{" immediately followed by "{{name}}". That does not parse the way the
   brief assumes: this engine's lexer (Task 2, frozen) is greedy left-to-right
   and has no triple-brace special case (by design -- there is no raw form),
   so three consecutive "{" are read as an ordinary tag opener "{{" followed
   by a path that literally starts with "{" ("{name"), which resolves to
   nothing and renders empty, plus a stray literal "}" -- exactly what
   test_no_raw_or_partial_form above already documents for "{{{name}}}" on
   its own. Verified live: the brief's original line reddens with "\textbf}",
   not "\textbf{Hilary}". Rewritten below to put a character between the
   literal "{" and the tag's own "{{", which sidesteps the ambiguity while
   still proving the same property: literal backslash/braces from Text survive
   unescaped, where a wrongly-escaped Text node would turn "\textbf{" into
   "\textbackslash{}\{". *)
let test_literal_markup_is_not_escaped () =
  Alcotest.(check string) "literal kept" "\\textbf{Name: Hilary}"
    (render ~flavour:E.Latex "\\textbf{Name: {{name}}}" (obj [ ("name", T.Str "Hilary") ]))

let render_suite =
  ( "Template/render",
    [ Alcotest.test_case "vars" `Quick test_render_var;
      Alcotest.test_case "missing key is empty" `Quick test_missing_key_is_empty;
      Alcotest.test_case "section iterates" `Quick test_section_iterates;
      Alcotest.test_case "bool sections" `Quick test_bool_section;
      Alcotest.test_case "empty list sections" `Quick test_empty_list_section_is_skipped;
      Alcotest.test_case "outer scope visible" `Quick test_outer_scope_visible_inside_section;
      Alcotest.test_case "data cannot escape flavour" `Quick test_data_cannot_escape_flavour;
      Alcotest.test_case "literal markup unescaped" `Quick test_literal_markup_is_not_escaped ] )