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 ] )