document <- (space? crlf)* doctype? tags? eof;

doctype <- space? 'doctype' space name:(!eol .)+ eol;

tag <- comment / verbatim_text / tag_item;
tag_item <- space? (embedded_engine / inline_html / code / slime_tag);

tags <- (tag crlf*)+;
nested_tags <- crlf+ indent tags dedent;

inline_html <- &'<' text_item+ nested_tags?;

slime_tag <- tag_shortcut tag_spaces space? tag_attributes_and_content;

% NOTE: tag content cannot begin with attribute wrappers if attributes are not present.
tag_attributes_and_content <- attributes space? tag_content
  / !('<%= attr_list_delims |> Map.keys |> Enum.join("' / '") %>') tag_content;

tag_content <- '/' / inline_tag / nested_tags / dynamic_content / inline_text / '';

inline_tag <- ':' space? slime_tag;

inline_text <- !eol text_block;

dynamic_content <- '=' '='? space? (!eol .)+;

code <- output:('=' '='? tag_spaces? / '-') space?
  code:code_lines children:nested_tags? optional_else:code_else_condition?;
code_else_condition <- crlf* space? '-' space? 'else' children:nested_tags?;
code_lines <- code_line / code_line_with_break crlf code_lines;
code_line <- (!(. eol) .)* !code_line_break . &eol;
code_line_with_break <- (!(. eol) .)* code_line_break &eol;
code_line_break <-  ',' / '\\';

tag_spaces <- leading:'<'? trailing:'>'?;

tag_shortcut <- tag:tag_name attrs:shortcuts / tag:tag_name / attrs:shortcuts;

shortcuts <- head:shortcut tail:(shortcut)*;

shortcut <- type:('.' / '#' / '@' / '$' / '%' / '^' / '&' / '+' / '!') value:tag_name;

attributes <- wrapped_attributes / plain_attributes;

wrapped_attributes <-
  <%=
    attr_list_delims
    |> Enum.flat_map(fn ({open, close}) -> [
        "'#{open}' crlf+ indent wrapped_attribute+ (eol / space)+ '#{close}'",
        "'#{open}' wrapped_attribute+ '#{close}'"
      ]
    end)
    |> Enum.join(" / ")
  %>;

wrapped_attribute <- (space / eol)* (attribute:attribute / attribute_name:tag_name);

plain_attributes <- head:attribute tail:(space attribute)*;

attribute <- attribute_name '=' '='? attribute_value;

attribute_value <- simple:string / dynamic:(string_with_interpolation / attribute_code);

string <- '"' ('\\' . / !('"' / '#{') .)* '"';
string_with_interpolation <- '"' (elixir_interpolation / '\\' . / !'"' .)* '"';

attribute_code <- (parentheses / brackets / braces / !(space / eol / ')' / ']' / '}') .)+;

text_item <- static:text / dynamic:(safe:safe_interpolation / interpolation);
text <- ('\\' . / !('#{' / eol) .)+;
elixir_interpolation <- '#{' (string / string_with_interpolation / !'}' .)* '}';
interpolation <- '#{' (string / string_with_interpolation / !'}' .)* '}';
safe_interpolation <- '#{{' (string / string_with_interpolation / !'}}' .)* '}}';

parentheses <- '(' (parentheses / !')' .)* ')';
brackets <- '[' (brackets / !']' .)* ']';
braces <- '{' (braces / !'}' .)* '}';

comment <- html_comment / space? code_comment;

html_comment <- indent:space? type:'/!' content:text_block;

code_comment <- '/' text_block;

verbatim_text <- indent:space? type:[|'] content:text_block;

text_block <- indented_text_line (crlf
  indent lines:text_block_nested_lines dedent)?;
text_block_nested_lines <- indented_text_line (crlf (
  indent lines:text_block_nested_lines dedent / lines:text_block_nested_lines
))*;

embedded_engine <- tag_name ':' (crlf indent lines:embedded_engine_lines dedent);
embedded_engine_lines <- indented_text_line (crlf indented_text_line)*;

indented_text_line <- space? text_item*;

tag_name <- [a-zA-Z0-9_-]+;
attribute_name <- [a-zA-Z0-9_@:-]+;
space <- [ \t]+;
indent <- '\x{0E}';
dedent <- '\x{0F}';
crlf <- '\r'? '\n';
eof <- !.;
eol <- dedent / crlf / eof;