Add ability to include files and images in custom latex templates

@Role
public interface LaTeXResourceConverter
{
    /**
     * @param currentReference the current document reference, used to resolve references to absolute references
     * @param outputStream the stream to which copied resources should be written to
     */
    void initialize(EntityReference currentReference, OutputStream outputStream);

    /**
     * Convert a {@link ResourceReference}'s reference so that it has the right reference when serialized into the
     * LaTeX output. For example this can mean converting the reference of an image attachment reference into a
     * filesystem file reference (by copying the image located into an attachment of a wiki page to the file system).
     *
     * @param reference the resource reference to convert (a link reference or an image reference)
     * @param baseResourceReference the base reference of the current XDOM block, used to resolve the resource
     *        reference into an absolute reference. Can be relative, in which case the current reference is used to
     *        make it absolute. Can be null in which was the current reference is used.
     * @param forceDownload if true, then convert external references (like URL references) into local references. For
     *        examples image reference by URLs can be downloaded locally and the reference swapped for a local
     *        filesystem reference.
     * @return the converted reference
     */
    ResourceReference convert(ResourceReference reference, String baseResourceReference, boolean forceDownload);

    /**
     * Convert a {@link ResourceReference}'s reference so that it has the right reference when serialized into the
     * LaTeX output. For example this can mean converting the reference of an image attachment reference into a
     * filesystem file reference (by copying the image located into an attachment of a wiki page to the file system).
     *
     * @param reference the resource reference to convert (a link reference or an image reference)
     * @param forceDownload if true, then convert external references (like URL references) into local references. For
     *        examples image reference by URLs can be downloaded locally and the reference swapped for a local
     *        filesystem reference.
     * @return the converted reference
     */
    ResourceReference convert(ResourceReference reference, boolean forceDownload);

    /**
     * @param linkBlock the link resource to convert. The closest base reference from the passed link block will be
     *        used to resolve local references
     * @return the converted reference
     */
    ResourceReference convert(LinkBlock linkBlock);

    /**
     * @param imageBlock the image resource to convert. The closest base reference from the passed image block will be
     *        used to resolve local references
     * @return the converted reference
     */
    ResourceReference convert(ImageBlock imageBlock);
}

#set ($linkBlock = $latex.block)
## Convert the image to a local image to embed it in the result
#set ($resourceReference = $latex.resourceConverter.convert($linkBlock))
#set ($type = $resourceReference.type.scheme)
## Consider that we're on a local link when the reference is empty and anchor is not empty
#set ($reference = $resourceReference.reference)
#set ($anchor = $latex.block.reference.getParameter('anchor'))
#if ($type == 'doc')
  #if ("$!reference" == '' && "$!anchor" != '')
    #if ($latex.block.getChildren().isEmpty())
      \ref{${anchor}}##
    #else
      \hyperref[${anchor}]{${latex.processor.process($latex.block.getChildren())}}##
    #end
  #else
    ## Ignore links that are not local, just display the label if there's one or the reference otherwise
    #if ($latex.block.getChildren().isEmpty())
      $latex.tool.escape($reference)##
    #else
      ${latex.processor.process($latex.block.getChildren())}##
    #end
  #end
#elseif ($type == 'url' || $type == 'path')
  #if ($latex.block.getChildren().isEmpty())
    \url{${reference}}##
  #else
    \href{${reference}}{${latex.processor.process($latex.block.getChildren())}}##
  #end
#elseif ($type == 'mailto')
  #if ($latex.block.getChildren().isEmpty())
    \href{mailto:${reference}}{$latex.tool.escape($reference)}##
  #else
    \href{mailto:${reference}}{${latex.processor.process($latex.block.getChildren())}}##
  #end
#elseif ($type == 'attach')
  #set ($escapedReference = $latex.tool.escape($reference))
  #if ($latex.block.getChildren().isEmpty())
    ## Use a default icon when no label is provided. Another option would be to use the filename as text.
    \attachfile{$latex.tool.escape($reference)}##
  #else
    \textattachfile{$latex.tool.escape($reference)}{${latex.processor.process($latex.block.getChildren())}}##
  #end
#end

\documentclass{$latex.properties.documentClass}
\usepackage{standalone}

## Commands that can be overridden by users in a custom Preamble
\newcommand{\xwikidate}[1]{
  ${SP}${SP}\date{\DTMdate{#1}}}
\newcommand{\xwikititle}[1]{
  ${SP}${SP}\title{#1}}
\newcommand{\xwikiauthor}[1]{
  ${SP}${SP}\author{#1}}

$latex.processor.render('Preamble')

## Needs to be put after the babel package
#if ("$!latex.properties.date" != '' && $latex.properties.coverPage)
  % Used to format the date for the cover page
  \usepackage[useregional]{datetime2}

#end
\begin{document}

#set ($shouldClearPage = false)
## Display numbers in TOC and list of tables/figures using the roman style
#if ($latex.properties.pageNumbering && $latex.properties.coverPage && $latex.properties.toc || $latex.properties.listOfFigures || $latex.properties.listOfTables)
  \pagenumbering{Roman}
#elseif (!$latex.properties.pageNumbering)
  \pagenumbering{gobble}
#end
#if ($latex.properties.coverPage && "$!latex.properties.title" != '')
  #if ("$!latex.properties.title" != '')
    #if ("$!latex.properties.subtitle" != '')
      \xwikititle{%
        ${SP}${SP}$latex.tool.escape($latex.properties.title)\\
        ${SP}${SP}\large ${latex.properties.subtitle}}
    #else
      \xwikititle{$latex.tool.escape($latex.properties.title)}
    #end
  #end
  #if ("$!latex.properties.author" != '')
    \xwikiauthor{$latex.tool.escape($latex.properties.author)}
  #end
  #if ("$!latex.properties.date" != '')
    \xwikidate{$latex.tool.escape($datetool.format('yyyy-MM-dd', $latex.properties.date))}
  #end
  #if ("$!latex.properties.coverPageImage" != '')
    \begin{center}
    \includegraphics{$latex.tool.escape($latex.resourceConverter.convert($latex.properties.coverPageImage, true).reference)}
    \end{center}
  #end
  \maketitle
#end
#if ($latex.properties.toc)
  \setcounter{tocdepth}{3}
  \tableofcontents
  ## Make sure no page numbers are printed in the TOC
  #if (!$latex.properties.pageNumbering)
    \addtocontents{toc}{\protect\thispagestyle{empty}}
  #end
  #set ($shouldClearPage = true)
#end
#if ($latex.properties.listOfFigures)
  \listoffigures
  #set ($shouldClearPage = true)
#end
#if ($latex.properties.listOfTables)
  \listoftables
  #set ($shouldClearPage = true)
#end
#if ($shouldClearPage)
  \clearpage
#end
## Reset page counter so that first page of the doc starts at 1
#if ($latex.properties.pageNumbering && $latex.properties.coverPage && $latex.properties.toc || $latex.properties.listOfFigures || $latex.properties.listOfTables)
  \setcounter{page}{0}
  ## Display numbers on pages using the arabic style
  \pagenumbering{arabic}
#end
#if ("$!latex.includes" != '')

  #foreach ($latexPageInclude in $latex.includes)
    ## Don't escape the page since LaTeX doesn't support escapes in paths and the path has already been cleaned.
    \include{$latexPageInclude}
  #end
#end

\end{document}