%%
%% Copyright (C) 2022-2024 by Jinwen XU
%% ------------------------------------
%%
%% This file may be distributed and/or modified under the conditions of
%% the LaTeX Project Public License, either version 1.3c of this license
%% or (at your option) any later version.  The latest version of this
%% license is in:
%%
%%    http://www.latex-project.org/lppl.txt
%%
\NeedsTeXFormat{LaTeX2e}[2022-06-01]
\ProvidesExplPackage
  {multifootnote}
  {2024/03/24} {}
  {Multiple numbers for the same footnote}

\msg_new:nnn { multifootnote }
  { non-compatible-package }
  { "multifootnote" ~ is ~ not ~ compatible ~ with ~ the ~ package ~ "#1". }

\hook_gput_code:nnn { begindocument/before } { multifootnote }
  {
    \@ifpackageloaded { footnotebackref }
      {
        \msg_warning:nnn { multifootnote } { non-compatible-package } { footnotebackref }
      } {}
  }

\dim_new:N \l_multifootnote_space_after_comma_dim
\dim_set:Nn \l_multifootnote_space_after_comma_dim { 0.2ex }

\bool_new:N  \l__multifootnote_left_indent_bool
\bool_set_false:N  \l__multifootnote_left_indent_bool
\dim_new:N \l__multifootnote_left_indent_dim

\keys_define:nn { multifootnote }
  {
    , backref       .bool_set:N = \l__multifootnote_backref_bool
    , backref       .initial:n  = { false }

    , left-align    .bool_set:N = \l__multifootnote_left_align_bool
    , left-align    .initial:n  = { false }
    , left~align    .bool_set:N = \l__multifootnote_left_align_bool
    , left align    .bool_set:N = \l__multifootnote_left_align_bool
    , left-indent   .code:n     = {
                                    \bool_set_true:N \l__multifootnote_left_indent_bool
                                    \dim_set:Nn \l__multifootnote_left_indent_dim { #1 }
                                  }
    , left-indent   .default:n  = { 1.5em }
    , left~indent   .code:n     = {
                                    \bool_set_true:N \l__multifootnote_left_indent_bool
                                    \dim_set:Nn \l__multifootnote_left_indent_dim { #1 }
                                  }
    , left~indent   .default:n  = { 1.5em }
    , left indent   .code:n     = {
                                    \bool_set_true:N \l__multifootnote_left_indent_bool
                                    \dim_set:Nn \l__multifootnote_left_indent_dim { #1 }
                                  }
    , left indent   .default:n  = { 1.5em }

    , manual        .bool_set:N = \l__multifootnote_manual_mode_bool
    , manual        .initial:n  = { false }
    , manual-mode   .bool_set:N = \l__multifootnote_manual_mode_bool
    , manual~mode   .bool_set:N = \l__multifootnote_manual_mode_bool
    , manual mode   .bool_set:N = \l__multifootnote_manual_mode_bool

    , unknown       .code:n     = {}
  }
\ProcessKeyOptions [ multifootnote ]

\bool_if:NT \l__multifootnote_backref_bool
  {
    \RequirePackage { hyperref }
  }

\RequirePackage { refcount }

\cs_new_protected:Nn \multifootnote_make_footnote_left_align:n
  {
    \renewcommand { \@makefntext } [1]
      {
        \skip_horizontal:n { #1 }
        \tl_if_blank:eF { \text_expand:n { \@thefnmark } }
          {
            \@makefnmark
            \nobreakspace
          }
        ##1
      }
  }

\bool_if:NT \l__multifootnote_left_align_bool
  {
    \multifootnote_make_footnote_left_align:n { 0pt }
  }
\bool_if:NT \l__multifootnote_left_indent_bool
  {
    \multifootnote_make_footnote_left_align:n { \l__multifootnote_left_indent_dim }
  }

\cs_generate_variant:Nn \iow_now:Nn { ce }
\cs_generate_variant:Nn \clist_put_right:Nn { ce }

\tl_new:N \l__multifootnote_tmp_tl
\seq_new:N \l__multifootnote_tmp_seq
\clist_new:N \l__multifootnote_tmp_clist

% get the total page number
\hook_gput_code:nnn { enddocument } { multifootnote }
  {
    \label{multifootnote_last-page}
  }
\int_new:N \g_multifootnote_total_page_int
\hook_gput_code:nnn { begindocument } { multifootnote }
  {
    \int_gset:Nn \g_multifootnote_total_page_int { \getpagerefnumber{multifootnote_last-page} }
  }

% First approach
\NewDocumentCommand \multifootnotemarkmanual { O{} }
  {
    \footnotemark
    \group_begin:
      \tl_if_blank:nF { #1 }
        {
          \addtocounter { footnote } { -1 }
          \refstepcounter { footnote }
          \label { multifootnote-mark-#1 }
          \@ifpackageloaded { hyperref }
            {
              \cs_gset_eq:NN \@currentHref \Hy@footnote@currentHref
            } {}
          \label { multifootnote-#1 }
        }
    \group_end:
  }
\NewCommandCopy \footnotenumbermanual \multifootnotemarkmanual

\NewDocumentCommand \multifootnotetextmanual { O{} m }
  {
    \group_begin:
      \tl_if_blank:nTF { #1 }
        {
          \footnotetext { #2 }
        }
        {
          \clist_clear:N \l_tmpa_clist
          \clist_clear:N \l_tmpb_clist
          \clist_map_inline:nn { #1 }
            {
              \@ifpackageloaded { hyperref }
                {
                  \bool_if:NTF \l__multifootnote_backref_bool
                    {
                      \clist_put_right:Nn \l_tmpa_clist
                        { \hyperref[multifootnote-mark-##1]{ \ref*{ multifootnote-##1 } } }
                    }
                    {
                      \clist_put_right:Nn \l_tmpa_clist
                        { \ref*{ multifootnote-##1 } }
                    }
                  \clist_put_right:Nn \l_tmpb_clist
                    { \Hy@raisedlink { \hypertarget { \getrefbykeydefault{multifootnote-##1}{anchor}{Doc-Start} } {} } }
                }
                {
                  \clist_put_right:Nn \l_tmpa_clist
                    { \ref { multifootnote-##1 } }
                }
            }
          \def \thefootnote { \clist_use:Nn \l_tmpa_clist { , \skip_horizontal:n { \l_multifootnote_space_after_comma_dim } } }
          \@ifpackageloaded { hyperref }
            {
              \xdef \Hy@footnote@currentHref { x\Hy@footnote@currentHref }
            } {}
          \footnotetext { \clist_use:Nn \l_tmpb_clist {} \ignorespaces #2 }
        }
    \group_end:
  }

\seq_new:N \g__multifootnote_mark_internal_seq
\cs_new:Nn \__multifootnote_process_per_page_mark:nnnN
  % #1 = labels
  % #2 = footnote text
  % #3 = actual page number
  % #4 = a macro to store the result
  {
    \tl_gclear:N #4
    \clist_clear:N \l_tmpa_clist
    \clist_map_inline:nn { #1 }
      {
        % only keep those labels that appear on the current page
        \str_if_eq:eeT { #3 } { \getpagerefnumber{multifootnote-mark-##1} }
          {
            \clist_put_right:Nn \l_tmpa_clist { ##1 }
          }
      }
    \clist_if_empty:NF \l_tmpa_clist
      {
        \tl_gput_right:No #4 { \exp_after:wN { \l_tmpa_clist } }
        \tl_gput_right:Nn #4 { { #2 } }
      }
  }
\hook_gput_code:nnn { begindocument } { multifootnote/mark }
  {
    \int_step_inline:nn { \int_eval:n { \g_multifootnote_total_page_int } }
      {
        % generate the per page mark-footnotetext sequences
        % \tl_show:n { g__multifootnote_mark_internal_page_ #1 _seq }
        \seq_new:c { g__multifootnote_mark_internal_page_ #1 _seq }
        \seq_new:c { g__multifootnote_mark_internal_page_ #1 _recorded_seq }
        % keep only those labels appeared on the current page
        \seq_clear:N \l__multifootnote_tmp_seq
        \seq_map_inline:cn { g__multifootnote_mark_internal_seq }
          {
            % \tl_show:n { TEST:~##1 }
            \__multifootnote_process_per_page_mark:nnnN ##1 { #1 } \l__multifootnote_tmp_tl
            \tl_if_empty:NF \l__multifootnote_tmp_tl
              {
                \seq_put_right:No \l__multifootnote_tmp_seq { \l__multifootnote_tmp_tl }
              }
          }
        \seq_gset_eq:cN { g__multifootnote_mark_internal_page_ #1 _seq } \l__multifootnote_tmp_seq
        % \seq_show:c { g__multifootnote_mark_internal_page_ #1 _seq }
      }
  }

\NewDocumentCommand \multifootnotemark { O{} }
  {
    % print the footnote mark
    \footnotemark
    \group_begin:
      \tl_if_blank:nF { #1 }
        {
          \addtocounter { footnote } { -1 }
          \refstepcounter { footnote }
          \label { multifootnote-mark-#1 }
          \@ifpackageloaded { hyperref }
            {
              \cs_gset_eq:NN \@currentHref \Hy@footnote@currentHref
            } {}
          \label { multifootnote-#1 }
        }
    \group_end:
    % print the corresponding footnote text
    \tl_if_blank:nF { #1 }
      {
        \tl_set:Ne \l__multifootnote_tmp_tl { \getpagerefnumber{multifootnote-mark-#1} }
        % \tl_show:N \l__multifootnote_tmp_tl
        % \seq_show:c { g__multifootnote_mark_internal_page_ \l__multifootnote_tmp_tl _seq }
        \seq_map_inline:cn { g__multifootnote_mark_internal_page_ \l__multifootnote_tmp_tl _seq }
          {
            % \tl_show:n { TEST:~ { #1 } ##1 }
            \seq_if_in:cnF { g__multifootnote_mark_internal_page_ \l__multifootnote_tmp_tl _recorded_seq } { ##1 }
              {
                % \tl_show:n { TEST:~ { #1 } ##1 }
                \__multifootnote_print_footnotetext:nnnnn { #1 } ##1
                  {
                    % record the current item
                    \seq_gput_right:cn { g__multifootnote_mark_internal_page_ \l__multifootnote_tmp_tl _recorded_seq } { ##1 }
                    % \seq_show:c { g__multifootnote_mark_internal_page_ \l__multifootnote_tmp_tl _recorded_seq }
                  } {}
                  {} {} % the two extra empty groups are added for safety
              }
          }
      }
  }
\cs_new:Nn \__multifootnote_print_footnotetext:nnnnn
  % #1 = a given label
  % #2 = labels
  % #3 = footnote text
  % #4 = code when the footnote text is indeed printed
  % #5 = fallback code when the footnote text does not get printed
  {
    % \tl_show:n { TEST:~ { #1 } { #2 } { #3 } }
    % \clist_if_in:nnTF { #2 } { #1 } { \tl_show:n { TEST:~ {#1}~is~in~{#2}. } } { \tl_show:n { TEST:~ {#1}~is~NOT~in~{#2}. } }
    \clist_if_in:nnTF { #2 } { #1 }
      {
        \clist_clear:N \l_tmpa_clist
        \clist_clear:N \l_tmpb_clist
        % \clist_show:n { #2 }
        \clist_map_inline:nn { #2 }
          {
            \@ifpackageloaded { hyperref }
              {
                \bool_if:NTF \l__multifootnote_backref_bool
                  {
                    \clist_put_right:Nn \l_tmpa_clist
                      { \hyperref[multifootnote-mark-##1]{ \ref*{ multifootnote-##1 } } }
                  }
                  {
                    \clist_put_right:Nn \l_tmpa_clist
                      { \ref*{ multifootnote-##1 } }
                  }
                \clist_put_right:Nn \l_tmpb_clist
                  { \Hy@raisedlink { \hypertarget { \getrefbykeydefault{multifootnote-##1}{anchor}{Doc-Start} } {} } }
              }
              {
                \clist_put_right:Nn \l_tmpa_clist
                  { \ref { multifootnote-##1 } }
              }
          }
        % \clist_show:N \l_tmpa_clist
        \group_begin:
          \def \thefootnote { \clist_use:Nn \l_tmpa_clist { , \skip_horizontal:n { \l_multifootnote_space_after_comma_dim } } }
          \@ifpackageloaded { hyperref }
            {
              \xdef \Hy@footnote@currentHref { x\Hy@footnote@currentHref }
            } {}
          \footnotetext { \clist_use:Nn \l_tmpb_clist {} \ignorespaces #3 }
        \group_end:
        #4
      }
      {
        #5
      }
  }
\NewCommandCopy \footnotenumber \multifootnotemark

\NewDocumentCommand \multifootnotetext { O{} m }
  {
    \tl_if_blank:nTF { #1 }
      {
        \footnotetext { #2 }
      }
      {
        \iow_now:cn { @auxout }
          {
            \@multifootnote@add@to@mark@text@list { #1 } { #2 }
          }
      }
  }
\NewDocumentCommand \@multifootnote@add@to@mark@text@list { m m }
  {
    \seq_gput_right:Nn \g__multifootnote_mark_internal_seq { { #1 } { #2 } }
  }

% Second approach
\int_new:N \g__multifootnote_tag_footnotemark_counter_int

\NewDocumentCommand \multifootnotetagmanual { m }
  {
    \footnotemark
    \@ifpackageloaded { hyperref }
      {
        \int_gdecr:N \g__multifootnote_tag_footnotemark_counter_int
        \addtocounter { footnote } { -1 }
        \refstepcounter { footnote }
        \label { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } }
        \cs_gset_eq:NN \@currentHref \Hy@footnote@currentHref
        \label { multifootnote-tag-footnote- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } }
        \clist_map_inline:nn { #1 }
          {
            % generate hypertargets for footnote marks so that they can jump correctly to the corresponding footnotes
            \clist_if_exist:cF { multifootnote-tag-hypertarget- ##1 }
              { \clist_new:c { multifootnote-tag-hypertarget- ##1 } }
            \clist_put_right:ce { multifootnote-tag-hypertarget- ##1 }
              { \exp_not:N \Hy@raisedlink { \exp_not:N \hypertarget { \exp_not:N \getrefbykeydefault{ multifootnote-tag-footnote- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int  } }{anchor}{Doc-Start} } {} } }
          }
      } {}
    \clist_map_inline:nn { #1 }
      {
        % generate list of marks in the footnote
        \bool_if:NTF \l__multifootnote_backref_bool
          {
            \cs_if_exist:cTF { multifootnote-tag-list- ##1 }
              {
                \tl_gput_right:ce { multifootnote-tag-list- ##1 } { , \skip_horizontal:n { \l_multifootnote_space_after_comma_dim } \ref { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int  } } }
              }
              {
                \cs_gset:cpx { multifootnote-tag-list- ##1 } { \ref { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int  } } }
              }
          }
          {
            \cs_if_exist:cTF { multifootnote-tag-list- ##1 }
              {
                \tl_gput_right:ce { multifootnote-tag-list- ##1 } { , \skip_horizontal:n { \l_multifootnote_space_after_comma_dim } \thefootnote }
              }
              {
                \cs_gset:cpx { multifootnote-tag-list- ##1 } { \thefootnote }
              }
          }
      }
  }
\NewCommandCopy \footnotetagmanual \multifootnotetagmanual

\NewDocumentCommand \multifootnotetagtextmanual { O{} m }
  {
    \group_begin:
      \tl_if_blank:nTF { #1 }
        {
          \def \thefootnote { }
        }
        {
          \def \thefootnote { \use:c { multifootnote-tag-list- #1 } }
        }
      \@ifpackageloaded { hyperref }
        {
          \xdef \Hy@footnote@currentHref { x\Hy@footnote@currentHref }
          \footnotetext { \clist_use:cn { multifootnote-tag-hypertarget- #1 } {} \ignorespaces #2 }
        }
        {
          \footnotetext { #2 }
        }
    \group_end:
  }

\prop_new:N \g__multifootnote_tag_internal_prop
\NewDocumentCommand \multifootnotetag { m }
  {
    \footnotemark
    \int_gdecr:N \g__multifootnote_tag_footnotemark_counter_int
    \addtocounter { footnote } { -1 }
    \refstepcounter { footnote }
    \label { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } }
    % add the current label number to the clist of the given tag on the current page
    \clist_map_inline:nn { #1 }
      {
        \iow_now:ce { @auxout }
          {
            \@multifootnote@add@to@tag@label@list
              { ##1 }
              { \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } }
              { \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } }
          }
      }
    \@ifpackageloaded { hyperref }
      {
        \cs_gset_eq:NN \@currentHref \Hy@footnote@currentHref
        \label { multifootnote-tag-footnote- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } }
      } {}
    \clist_map_inline:nn { #1 }
      {
        \clist_if_exist:cF { g__multifootnote_tag_page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _recorded_clist }
          {
            \clist_new:c { g__multifootnote_tag_page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _recorded_clist }
          }
        \clist_if_in:cnF { g__multifootnote_tag_page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _recorded_clist } { ##1 }
          {
            \clist_gput_right:cn { g__multifootnote_tag_page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _recorded_clist } { ##1 }
            \group_begin:
              % \clist_show:c { g__multifootnote_tag_ ##1 _page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _clist }
              \clist_if_exist:cT { g__multifootnote_tag_ ##1 _page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _clist }
                { % skip the following code on the first run
                  \clist_clear:N \l__multifootnote_tmp_clist
                  \clist_map_inline:cn { g__multifootnote_tag_ ##1 _page_ \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } _clist }
                    {
                      % generate list of marks in the footnote
                      \clist_put_right:Nn \l__multifootnote_tmp_clist
                        {
                          % \tl_show:n { ####1 }
                          \bool_if:NTF \l__multifootnote_backref_bool
                            {
                              \ref { multifootnote-tag-mark- ####1 }
                            }
                            {
                              \@ifpackageloaded { hyperref }
                                {
                                  \ref*{ multifootnote-tag-mark- ####1 }
                                }
                                {
                                  \ref { multifootnote-tag-mark- ####1 }
                                }
                            }
                        }
                      \@ifpackageloaded { hyperref }
                        {
                          % generate hypertargets for footnote marks so that they can jump correctly to the corresponding footnotes
                          \clist_if_exist:cF { multifootnote-tag-hypertarget- ##1 -page- \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } }
                            { \clist_new:c { multifootnote-tag-hypertarget- ##1 -page- \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } } }
                          \clist_put_right:ce { multifootnote-tag-hypertarget- ##1 -page- \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } }
                            { \exp_not:N \Hy@raisedlink { \exp_not:N \hypertarget { \exp_not:N \getrefbykeydefault{ multifootnote-tag-footnote- ####1 }{anchor}{Doc-Start} } {} } }
                        } {}
                    }
                  % \clist_show:N \l__multifootnote_tmp_clist
                  \def \thefootnote { \clist_use:Nn \l__multifootnote_tmp_clist { , \skip_horizontal:n { \l_multifootnote_space_after_comma_dim } } }
                  \@ifpackageloaded { hyperref }
                    {
                      \xdef \Hy@footnote@currentHref { x\Hy@footnote@currentHref }
                      \footnotetext
                        {
                          \clist_use:cn { multifootnote-tag-hypertarget- ##1 -page- \getpagerefnumber { multifootnote-tag-mark- \int_eval:n { \g__multifootnote_tag_footnotemark_counter_int } } } {} \ignorespaces
                          \prop_item:Nn \g__multifootnote_tag_internal_prop { ##1 }
                        }
                    }
                    {
                      \footnotetext { \prop_item:Nn \g__multifootnote_tag_internal_prop { ##1 } }
                    }
                }
            \group_end:
          }
      }
  }
\NewCommandCopy \footnotetag \multifootnotetag
\NewDocumentCommand \@multifootnote@add@to@tag@label@list { m m m }
  % #1 = tag
  % #2 = label number
  % #3 = page number
  {
    \clist_if_exist:cF { g__multifootnote_tag_ #1 _page_ #3 _clist }
      {
        \clist_new:c { g__multifootnote_tag_ #1 _page_ #3 _clist }
      }
    \clist_gput_right:cn { g__multifootnote_tag_ #1 _page_ #3 _clist } { #2 }
    % \clist_show:c { g__multifootnote_tag_ #1 _page_ #3 _clist }
  }

\NewDocumentCommand \multifootnotetagtext { O{} m }
  {
    \tl_if_blank:nTF { #1 }
      {
        \footnotetext { #2 }
      }
      {
        \iow_now:cn { @auxout }
          {
            \@multifootnote@add@to@tag@text@list { #1 } { #2 }
          }
      }
  }
\NewDocumentCommand \@multifootnote@add@to@tag@text@list { m m }
  {
    \prop_gput:Nnn \g__multifootnote_tag_internal_prop { #1 } { #2 }
  }

% The combined interface for producing footnote text
\NewDocumentCommand \multifootnotemanual { O{} m }
  {
    \str_if_in:nnTF { #1 } { , }
      {
        \multifootnotetextmanual [ #1 ] { #2 }
      }
      {
        \multifootnotetagtextmanual [ #1 ] { #2 }
      }
  }
\NewDocumentCommand \multifootnote { O{} m }
  {
    \str_if_in:nnTF { #1 } { , }
      {
        \multifootnotetext [ #1 ] { #2 }
      }
      {
        \multifootnotetagtext [ #1 ] { #2 }
      }
  }

\bool_if:NT \l__multifootnote_manual_mode_bool
  {
    \RenewCommandCopy \multifootnotemark    \multifootnotemarkmanual
    \RenewCommandCopy \multifootnotetext    \multifootnotetextmanual
    \RenewCommandCopy \multifootnotetag     \multifootnotetagmanual
    \RenewCommandCopy \multifootnotetagtext \multifootnotetagtextmanual
    \RenewCommandCopy \multifootnote        \multifootnotemanual
    \RenewCommandCopy \footnotenumber       \footnotenumbermanual
    \RenewCommandCopy \footnotetag          \footnotetagmanual
  }

\endinput
%%
%% End of file `multifootnote.sty'.