\newcommand\markdownRendererJekyllDataBooleanPrototype[2]{#1}
\newcommand\markdownRendererJekyllDataEmptyPrototype[1]{#1}
\newcommand\markdownRendererJekyllDataNumberPrototype[2]{#1}
\newcommand\markdownRendererJekyllDataStringPrototype[2]{#1}
\newcommand\markdownRendererJekyllDataEnd[1]{#1}

\RequirePackage[%
	  contentBlocks,
%	  debugExtensions,
	  definitionLists,
	  fancy_lists,
	  fencedCode,
	  hashEnumerators,
	  inlineNotes,
	  jekyllData,
	  notes,
	  pipeTables,
	  rawAttribute,
	  smartEllipses,
	  strikeThrough,
	  subscripts,
	  superscripts,
	  tableCaptions,
	  taskLists,
	  citations,
	  tightLists=false,
	  html,
	  hybrid,
	  relativeReferences=true,
]{markdown}

\makeatletter

\ExplSyntaxOn

\iow_new:N \l_letter_csv_ior
\tl_new:N \l_letter_csv_header_tl
\seq_new:N \l_letter_tmp_seq
\tl_new:N \l_letter_tmp_tl

\newcommand{\LoadTemplate}[1]{
	\input{template-#1.tex}
}

\newcommand{\SetTemplatePreamble}[1]{%
	\gdef\TemplatePreamble{#1}
}
\newcommand{\SetTemplateBegin}[1]{%
	\gdef\TemplateBegin{#1}
}
\newcommand{\SetTemplateEnd}[1]{%
	\gdef\TemplateEnd{#1}
}

\newcommand*\insertcsvdata[1]{\use:c {insertCSV#1}}

\newcommand*{\processCSVletter}{
	\tl_if_empty:NF \l_letter_csv_tl {
		\ior_open:Nn \l_letter_csv_ior {\l_letter_csv_tl}
		\ior_get:NN \l_letter_csv_ior \l_letter_csv_tmp_tl
		\seq_set_split:NnV \l_letter_header_seq {;} \l_letter_csv_tmp_tl
		\ior_str_map_inline:Nn  \l_letter_csv_ior {
			\seq_set_split:Nnn \l_letter_tmp_seq {;} {##1}
			\int_step_variable:nNn {\seq_count:N \l_letter_tmp_seq} \l_tmpa_int {
				\cs_set:cpx {insertCSV\seq_item:Nn \l_letter_header_seq {\l_tmpa_int}} {\seq_item:Nn \l_letter_tmp_seq {\l_tmpa_int}}
			}
			\UseHook{markdownInput/begin}
			\tl_if_empty:NF \l_letter_csv_content_tl
				{\markdownInput{\l_letter_csv_content_tl}}
			\UseHook{markdownInput/end}
		}
		\ior_close:N \l_letter_csv_ior
	}
}

\keys_define:nn {Markdown/Template/jekyllData} {
	unknown .code:n = {\exp_args:Nc \gdef {insert\l_keys_key_tl} {#1}},
	letter-csv .tl_set:N = \l_letter_csv_tl,
	letter-csv .initial:n = ,
	letter-content .tl_set:N = \l_letter_csv_content_tl,
	letter-content .initial:n=,
	tableofcontents .bool_gset:N = \g__ptxcd_tableofcontents_bool,
	tableofcontents .initial:n = true,
}

\tl_new:N \l__markdown_sequence_tl

\markdownSetup{
	rendererPrototypes = {
		jekyllDataString = {\keys_set:nn {Markdown/Template/jekyllData}{{#1} = {#2}}},
		jekyllDataNumber = {\keys_set:nn {Markdown/Template/jekyllData}{{#1} = {#2}}},
		jekyllDataBoolean = {\keys_set:nn {Markdown/Template/jekyllData}{{#1} = {#2}}},
		jekyllDataEmpty = {\keys_set:nn {Markdown/Template/jekyllData}{{#1} = }},
		jekyllDataSequenceBegin = {
			\begingroup
			\renewcommand*{\markdownRendererJekyllDataString}[2]{
			\seq_if_exist:cF {g__ptxcd_#1_seq}  {\seq_new:c {g__ptxcd_#1_seq}}
			\seq_gput_right:cn {g__ptxcd_#1_seq} {##2}
		}},
		jekyllDataSequenceEnd = {
			\endgroup
		}
	}
}

\def\insertauthor{
	\bool_set_false:N \l_tmpa_bool
	\seq_map_inline:Nn \g__ptxcd_author_seq {
		\bool_if:NTF \l_tmpa_bool {,\space} {\bool_set_true:N \l_tmpa_bool}
		\tl_if_in:nnTF {##1} {=} {
			\__ptxcd_author_afil:w ##1 \q_stop
		} {##1}
	}
}


\def\insertshortauthor{
		\seq_map_inline:Nn \g__ptxcd_author_seq {
			\keyval_parse:nn {\use:n } {\use_i:nn} {##1}
		}
}

\cs_new:Npn	\__ptxcd_author_afil:w #1 = #2 \q_stop {
	\tl_trim_spaces:n{#1}\thanks{\tl_trim_spaces:n {#2}}
}

\renewcommand\markdownRendererJekyllDataBegin{\endgroup\markdownMakeOther}

\renewcommand\markdownRendererJekyllDataEnd{
	\LoadTemplate{\inserttemplate}
	\char_set_catcode_comment:N\%
		\TemplatePreamble
		\tl_if_empty:NT \l_letter_csv_tl  {
			\AddToHook{markdownInput/end}{\TemplateEnd}
			\AddToHook{markdownInput/begin}{\TemplateBegin}
		}
		\begin{document}
		\UseHook{markdownInput/begin}
		\begingroup
		\char_set_catcode_other:N\%
}

\NewMirroredHookPair{markdownInput/begin}{markdownInput/end}

\ExplSyntaxOff

\markdownInputPlainTeX{\MarkDownInputFile}%
\UseHook{markdownInput/end}%

\markdownSetup{rendererPrototypes={
		backslash = {\\},
}}

\AddToHook{markdownInput/end}{\TemplateEnd}
\AddToHook{markdownInput/begin}{\TemplateBegin}

\processCSVletter

\end{document}