% Copyright 2026 Open-Guji (https://github.com/open-guji)
%
% Licensed under the Apache License, Version 2.0 (the "License");
% you may not use this file except in compliance with the License.
% You may obtain a copy of the License at
%
%     http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS,
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
% See the License for the specific language governing permissions and
% limitations under the License.
% luatex-cn-banxin.sty
% 古籍版心与鱼尾功能支持
% 这是 luatex_cn 的子包
%
\RequirePackage{expl3}
\RequirePackage{xparse}
\ProvidesExplPackage {banxin/luatex-cn-banxin} {2026/08/07} {0.4.1} {Ancient Book Banxin Support}

\lua_now:e {
  package.loaded["banxin.luatex-cn-banxin-main"]~=~nil;
  banxin~=~require("banxin.luatex-cn-banxin-main");
}

% =============================================================================
% Variable Declarations
% =============================================================================

% Pre-rendered section boxes (global, survives groups)
\box_new:N \g__luatexcn_banxin_upper_box
\box_new:N \g__luatexcn_banxin_middle_box
\box_new:N \g__luatexcn_banxin_lower_box

% Banxin on/off
\bool_new:N \l__luatexcn_banxin_on_bool

% Banxin layout ratios
\tl_new:N \l__luatexcn_banxin_upper_ratio_tl
\tl_new:N \l__luatexcn_banxin_middle_ratio_tl

% Banxin divider
\bool_new:N \l__luatexcn_banxin_divider_bool

% Yuwei
\bool_new:N \l__luatexcn_banxin_upper_yuwei_bool
\bool_new:N \l__luatexcn_banxin_lower_yuwei_bool

% Upper section variables (版心上部)
\tl_new:N \l__luatexcn_banxin_upper_section_text_tl
\tl_new:N \l__luatexcn_banxin_upper_section_font_size_tl
\tl_new:N \l__luatexcn_banxin_upper_section_grid_height_tl
\tl_new:N \l__luatexcn_banxin_upper_section_align_tl
\tl_new:N \l__luatexcn_banxin_upper_section_top_padding_tl
\tl_new:N \l__luatexcn_banxin_upper_section_bottom_padding_tl
\tl_new:N \l__luatexcn_banxin_upper_section_bg_color_tl
\tl_new:N \l__luatexcn_banxin_upper_section_font_color_tl

% Middle section variables (版心中部)
\tl_new:N \l__luatexcn_banxin_middle_section_text_tl
\tl_new:N \l__luatexcn_banxin_middle_section_font_size_tl
\tl_new:N \l__luatexcn_banxin_middle_section_grid_height_tl
\tl_new:N \l__luatexcn_banxin_middle_section_top_margin_tl
\int_new:N \l__luatexcn_banxin_middle_section_cols_int
\tl_new:N \l__luatexcn_banxin_middle_section_align_tl
\tl_new:N \l__luatexcn_banxin_middle_section_bg_color_tl
\tl_new:N \l__luatexcn_banxin_middle_section_font_color_tl

% Page number variables
\bool_new:N \l__luatexcn_banxin_page_number_show_bool
\tl_new:N \l__luatexcn_banxin_page_number_font_size_tl
\tl_new:N \l__luatexcn_banxin_page_number_grid_height_tl
\tl_new:N \l__luatexcn_banxin_page_number_align_tl
\tl_new:N \l__luatexcn_banxin_page_number_bottom_padding_tl

% Lower section variables (版心下部)
\tl_new:N \l__luatexcn_banxin_lower_section_text_tl
\tl_new:N \l__luatexcn_banxin_lower_section_font_size_tl
\tl_new:N \l__luatexcn_banxin_lower_section_grid_height_tl
\tl_new:N \l__luatexcn_banxin_lower_section_bottom_margin_tl
\tl_new:N \l__luatexcn_banxin_lower_section_top_padding_tl
\tl_new:N \l__luatexcn_banxin_lower_section_bottom_padding_tl
\tl_new:N \l__luatexcn_banxin_lower_section_align_tl
\tl_new:N \l__luatexcn_banxin_lower_section_bg_color_tl
\tl_new:N \l__luatexcn_banxin_lower_section_font_color_tl

% Banxin-level style overrides (forwarded from unknown handler)
\tl_new:N \l__luatexcn_banxin_style_font_size_tl
\tl_new:N \l__luatexcn_banxin_style_font_color_tl
\tl_new:N \l__luatexcn_banxin_style_font_tl
\tl_new:N \l__luatexcn_banxin_style_grid_height_tl
\tl_new:N \l__luatexcn_banxin_style_grid_width_tl

% =============================================================================
% Sub-Namespace Definitions
% =============================================================================

% upper-section sub-namespace (版心上部)
\keys_define:nn { luatexcn / banxin / upper-section }
  {
    font-size .tl_set:N = \l__luatexcn_banxin_upper_section_font_size_tl,
    font-size .initial:n = {},
    grid-height .tl_set:N = \l__luatexcn_banxin_upper_section_grid_height_tl,
    grid-height .initial:n = {},
    align .tl_set:N = \l__luatexcn_banxin_upper_section_align_tl,
    align .initial:n = {center},
    top-padding .tl_set:N = \l__luatexcn_banxin_upper_section_top_padding_tl,
    top-padding .initial:n = {2pt},
    bottom-padding .tl_set:N = \l__luatexcn_banxin_upper_section_bottom_padding_tl,
    bottom-padding .initial:n = {10pt},
    background-color .tl_set:N = \l__luatexcn_banxin_upper_section_bg_color_tl,
    background-color .initial:n = {},
    font-color .tl_set:N = \l__luatexcn_banxin_upper_section_font_color_tl,
    font-color .initial:n = {},
  }

% middle-section sub-namespace (版心中部)
\keys_define:nn { luatexcn / banxin / middle-section }
  {
    font-size .tl_set:N = \l__luatexcn_banxin_middle_section_font_size_tl,
    font-size .initial:n = {},
    grid-height .tl_set:N = \l__luatexcn_banxin_middle_section_grid_height_tl,
    grid-height .initial:n = {},
    top-margin .tl_set:N = \l__luatexcn_banxin_middle_section_top_margin_tl,
    top-margin .initial:n = {20pt},
    cols .int_set:N = \l__luatexcn_banxin_middle_section_cols_int,
    cols .initial:n = 1,
    align .tl_set:N = \l__luatexcn_banxin_middle_section_align_tl,
    align .initial:n = {center},
    background-color .tl_set:N = \l__luatexcn_banxin_middle_section_bg_color_tl,
    background-color .initial:n = {},
    font-color .tl_set:N = \l__luatexcn_banxin_middle_section_font_color_tl,
    font-color .initial:n = {},
  }

% page-number sub-namespace
\keys_define:nn { luatexcn / banxin / page-number }
  {
    show .bool_set:N = \l__luatexcn_banxin_page_number_show_bool,
    show .initial:n = true,
    font-size .tl_set:N = \l__luatexcn_banxin_page_number_font_size_tl,
    font-size .initial:n = {14pt},
    grid-height .tl_set:N = \l__luatexcn_banxin_page_number_grid_height_tl,
    grid-height .initial:n = {},
    align .tl_set:N = \l__luatexcn_banxin_page_number_align_tl,
    align .initial:n = {right-bottom},
    bottom-padding .tl_set:N = \l__luatexcn_banxin_page_number_bottom_padding_tl,
    bottom-padding .initial:n = {10pt},
  }

% lower-section sub-namespace (版心下部)
\keys_define:nn { luatexcn / banxin / lower-section }
  {
    font-size .tl_set:N = \l__luatexcn_banxin_lower_section_font_size_tl,
    font-size .initial:n = {10pt},
    grid-height .tl_set:N = \l__luatexcn_banxin_lower_section_grid_height_tl,
    grid-height .initial:n = {},
    align .tl_set:N = \l__luatexcn_banxin_lower_section_align_tl,
    align .initial:n = {right},
    bottom-margin .tl_set:N = \l__luatexcn_banxin_lower_section_bottom_margin_tl,
    bottom-margin .initial:n = {5pt},
    top-padding .tl_set:N = \l__luatexcn_banxin_lower_section_top_padding_tl,
    top-padding .initial:n = {2pt},
    bottom-padding .tl_set:N = \l__luatexcn_banxin_lower_section_bottom_padding_tl,
    bottom-padding .initial:n = {10pt},
    background-color .tl_set:N = \l__luatexcn_banxin_lower_section_bg_color_tl,
    background-color .initial:n = {},
    font-color .tl_set:N = \l__luatexcn_banxin_lower_section_font_color_tl,
    font-color .initial:n = {},
  }

% =============================================================================
% Main Banxin Key Definitions
% =============================================================================
\keys_define:nn { luatexcn / banxin }
  {
    % Banxin on/off
    banxin .bool_set:N = \l__luatexcn_banxin_on_bool,
    banxin .initial:n = false,

    % Banxin layout ratios
    banxin-upper-ratio .tl_set:N = \l__luatexcn_banxin_upper_ratio_tl,
    banxin-upper-ratio .initial:n = {0.28},

    banxin-middle-ratio .tl_set:N = \l__luatexcn_banxin_middle_ratio_tl,
    banxin-middle-ratio .initial:n = {0.56},

    % Banxin divider
    banxin-divider .bool_set:N = \l__luatexcn_banxin_divider_bool,
    banxin-divider .initial:n = true,

    % Yuwei
    upper-yuwei .bool_set:N = \l__luatexcn_banxin_upper_yuwei_bool,
    upper-yuwei .initial:n = true,

    lower-yuwei .bool_set:N = \l__luatexcn_banxin_lower_yuwei_bool,
    lower-yuwei .initial:n = true,

    % Middle section text content (used by \chapter command)
    middle-section-text .tl_set:N = \l__luatexcn_banxin_middle_section_text_tl,
    middle-section-text .initial:n = {},

    % Nested key handlers - detect text vs key-value pairs
    upper-section .code:n = {
      \tl_if_in:nnTF { #1 } { = }
        { \keys_set:nn { luatexcn / banxin / upper-section } { #1 } }
        { \tl_set:Nn \l__luatexcn_banxin_upper_section_text_tl { #1 } }
    },

    middle-section .code:n = {
      \keys_set:nn { luatexcn / banxin / middle-section } { #1 }
    },

    page-number .code:n = {
      \keys_set:nn { luatexcn / banxin / page-number } { #1 }
    },

    lower-section .code:n = {
      \tl_if_in:nnTF { #1 } { = }
        { \keys_set:nn { luatexcn / banxin / lower-section } { #1 } }
        { \tl_set:Nn \l__luatexcn_banxin_lower_section_text_tl { #1 } }
    },
    % Forward unknown keys: try settings first, then style
    unknown .code:n =
      {
        \exp_args:Nnx \keys_if_exist:nnTF { luatexcn / settings } { \l_keys_key_str }
          { \keys_set:nx { luatexcn / settings } { \l_keys_key_str = { \exp_not:n {#1} } } }
          {
            \exp_args:Nnx \keys_if_exist:nnTF { luatexcn / style } { \l_keys_key_str }
              { \keys_set:nx { luatexcn / style } { \l_keys_key_str = { \exp_not:n {#1} } } }
              { }
          }
      },
  }

% =============================================================================
% Setup Command
% =============================================================================
\NewDocumentCommand{\banxinSetup}{ m }
  {
    % Clear style scratch variables before parsing (unknown keys forward to style)
    \__luatexcn_style_init_and_parse:n {}
    \keys_set:nn { luatexcn / banxin } { #1 }
    % Save any style overrides into banxin-specific variables
    \tl_if_empty:NF \l__luatexcn_style_size_tl
      { \tl_set_eq:NN \l__luatexcn_banxin_style_font_size_tl \l__luatexcn_style_size_tl }
    \tl_if_empty:NF \l__luatexcn_style_color_tl
      { \tl_set_eq:NN \l__luatexcn_banxin_style_font_color_tl \l__luatexcn_style_color_tl }
    \tl_if_empty:NF \l__luatexcn_style_font_tl
      { \tl_set_eq:NN \l__luatexcn_banxin_style_font_tl \l__luatexcn_style_font_tl }
    \tl_if_empty:NF \l__luatexcn_style_grid_height_tl
      { \tl_set_eq:NN \l__luatexcn_banxin_style_grid_height_tl \l__luatexcn_style_grid_height_tl }
    \tl_if_empty:NF \l__luatexcn_style_grid_width_tl
      { \tl_set_eq:NN \l__luatexcn_banxin_style_grid_width_tl \l__luatexcn_style_grid_width_tl }
    % Update _G.banxin.enabled for early access by content.setup
    \lua_now:e {
      _G.banxin.setup({
        enabled~=~\bool_if:NTF~\l__luatexcn_banxin_on_bool~{true}~{false}
      })
    }
  }

% =============================================================================
% Title / Chapter Synchronization
% =============================================================================

% 1. Title → upper section text
\cs_if_exist:NTF \title
  {
    \NewCommandCopy \__luatexcn_banxin_orig_title \title
    \RenewDocumentCommand \title { m }
      {
        \__luatexcn_banxin_orig_title { #1 }
        \tl_set:Nn \l__luatexcn_banxin_upper_section_text_tl { #1 }
      }
  }
  {
    \NewDocumentCommand \title { m }
      {
        \gdef\@title{#1}
        \tl_set:Nn \l__luatexcn_banxin_upper_section_text_tl { #1 }
      }
  }

% 2. Chapter → middle section text
\cs_if_exist:NTF \chapter
  {
    \NewCommandCopy \__luatexcn_banxin_orig_chapter \chapter
    \RenewDocumentCommand \chapter { s o m }
      {
        \IfBooleanTF {#1}
          {
            \IfValueTF {#2}
              { \__luatexcn_banxin_orig_chapter* [#2] {#3} }
              { \__luatexcn_banxin_orig_chapter* {#3} }
          }
          {
            \IfValueTF {#2}
              { \__luatexcn_banxin_orig_chapter [#2] {#3} }
              { \__luatexcn_banxin_orig_chapter {#3} }
          }
        \IfValueTF {#2}
          { \tl_set:Nn \l__luatexcn_banxin_middle_section_text_tl { #2 } }
          { \tl_set:Nn \l__luatexcn_banxin_middle_section_text_tl { #3 } }
      }
  }
  {
    \DeclareDocumentCommand \chapter { s o m }
      {
        \IfValueTF {#2}
          { \tl_set:Nn \l__luatexcn_banxin_middle_section_text_tl { #2 } }
          { \tl_set:Nn \l__luatexcn_banxin_middle_section_text_tl { #3 } }
      }
  }

% ============================================================================
% CJK Key Aliases (中文键值别名)
% ============================================================================

% --- upper-section sub-namespace ---
\keys_define:nn { luatexcn / banxin / upper-section }
  {
    字号 .tl_set:N = \l__luatexcn_banxin_upper_section_font_size_tl,
    格高 .tl_set:N = \l__luatexcn_banxin_upper_section_grid_height_tl,
    对齐 .tl_set:N = \l__luatexcn_banxin_upper_section_align_tl,
    底色 .tl_set:N = \l__luatexcn_banxin_upper_section_bg_color_tl,
    字体颜色 .tl_set:N = \l__luatexcn_banxin_upper_section_font_color_tl,
  }

% --- middle-section sub-namespace ---
\keys_define:nn { luatexcn / banxin / middle-section }
  {
    字号 .tl_set:N = \l__luatexcn_banxin_middle_section_font_size_tl,
    格高 .tl_set:N = \l__luatexcn_banxin_middle_section_grid_height_tl,
    上留白 .tl_set:N = \l__luatexcn_banxin_middle_section_top_margin_tl,
    列数 .int_set:N = \l__luatexcn_banxin_middle_section_cols_int,
    列數 .int_set:N = \l__luatexcn_banxin_middle_section_cols_int,
    对齐 .tl_set:N = \l__luatexcn_banxin_middle_section_align_tl,
    對齊 .tl_set:N = \l__luatexcn_banxin_middle_section_align_tl,
    底色 .tl_set:N = \l__luatexcn_banxin_middle_section_bg_color_tl,
    字体颜色 .tl_set:N = \l__luatexcn_banxin_middle_section_font_color_tl,
  }

% --- page-number sub-namespace ---
\keys_define:nn { luatexcn / banxin / page-number }
  {
    显示 .bool_set:N = \l__luatexcn_banxin_page_number_show_bool,
    顯示 .bool_set:N = \l__luatexcn_banxin_page_number_show_bool,
    字号 .tl_set:N = \l__luatexcn_banxin_page_number_font_size_tl,
    格高 .tl_set:N = \l__luatexcn_banxin_page_number_grid_height_tl,
    对齐 .tl_set:N = \l__luatexcn_banxin_page_number_align_tl,
  }

% --- lower-section sub-namespace ---
\keys_define:nn { luatexcn / banxin / lower-section }
  {
    字号 .tl_set:N = \l__luatexcn_banxin_lower_section_font_size_tl,
    格高 .tl_set:N = \l__luatexcn_banxin_lower_section_grid_height_tl,
    对齐 .tl_set:N = \l__luatexcn_banxin_lower_section_align_tl,
    下留白 .tl_set:N = \l__luatexcn_banxin_lower_section_bottom_margin_tl,
    底色 .tl_set:N = \l__luatexcn_banxin_lower_section_bg_color_tl,
    字体颜色 .tl_set:N = \l__luatexcn_banxin_lower_section_font_color_tl,
  }

% --- main banxin namespace ---
\keys_define:nn { luatexcn / banxin }
  {
    版心 .bool_set:N = \l__luatexcn_banxin_on_bool,
    版心上比 .tl_set:N = \l__luatexcn_banxin_upper_ratio_tl,
    版心中比 .tl_set:N = \l__luatexcn_banxin_middle_ratio_tl,
    版心分隔线 .bool_set:N = \l__luatexcn_banxin_divider_bool,
    版心分隔線 .bool_set:N = \l__luatexcn_banxin_divider_bool,
    上鱼尾 .bool_set:N = \l__luatexcn_banxin_upper_yuwei_bool,
    上魚尾 .bool_set:N = \l__luatexcn_banxin_upper_yuwei_bool,
    下鱼尾 .bool_set:N = \l__luatexcn_banxin_lower_yuwei_bool,
    下魚尾 .bool_set:N = \l__luatexcn_banxin_lower_yuwei_bool,
    中部文字 .tl_set:N = \l__luatexcn_banxin_middle_section_text_tl,
    上部 .meta:n = { upper-section = {#1} },
    中部 .meta:n = { middle-section = {#1} },
    下部 .meta:n = { lower-section = {#1} },
    页码 .meta:n = { page-number = {#1} },
    頁碼 .meta:n = { page-number = {#1} },
  }

% ============================================================================
% Pre-render upper section as box (called from \end{BodyText})
% ============================================================================
% Typesets upper-section content into a global box for use in banxin render.
% Must be called after content sync (fonts loaded, _G.content available).
\cs_new_protected:Nn \__luatexcn_banxin_typeset_sections:
  {
    \bool_if:NT \l__luatexcn_banxin_on_bool
      {
        \tl_if_empty:NTF \l__luatexcn_banxin_upper_section_text_tl
          {
            \box_gclear:N \g__luatexcn_banxin_upper_box
          }
          {
            % Calculate banxin dimensions from Lua globals
            % (available after content sync in \end{BodyText})
            % Height = upper_region - border (padding handled inside TextBox)
            \tl_set:Ne \l_tmpa_tl
              {
                \lua_now:e
                  {
                    local~c~=~_G.content~or~{}
                    local~ratio~=~tonumber(token.get_macro("l__luatexcn_banxin_upper_ratio_tl"))~or~0.28~
                    local~region_h~=~(c.content_height~or~0)~*~ratio~
                    local~border_t~=~c.border_on~and~(c.border_thickness~or~0)~or~0~
                    local~h~=~region_h~-~border_t~
                    if~h~<~0~then~h~=~region_h~end~
                    tex.print(tostring(math.floor(h~+~0.5))~..~"sp")
                  }
              }
            \tl_set:Ne \l_tmpb_tl
              {
                \lua_now:e
                  {
                    local~c~=~_G.content~or~{}
                    tex.print(tostring(c.banxin_width~or~655360)~..~"sp")
                  }
              }
            % Build TextBox options (border=false to avoid inheriting global border)
            % top-padding / bottom-padding are passed as distribute-padding
            % (affects fill distribution range, NOT per-cell padding)
            \tl_set:Nn \l__luatexcn_banxin_tb_opts_tl
              {
                height = \l_tmpa_tl ,
                grid-width = \l_tmpb_tl ,
                border = false ,
                box-align = fill ,
                fill-padding-top = \l__luatexcn_banxin_upper_section_top_padding_tl ,
                fill-padding-bottom = \l__luatexcn_banxin_upper_section_bottom_padding_tl
              }
            \tl_if_empty:NF \l__luatexcn_banxin_upper_section_font_size_tl
              {
                \tl_put_right:Ne \l__luatexcn_banxin_tb_opts_tl
                  { ,~ font-size = \l__luatexcn_banxin_upper_section_font_size_tl }
              }
            \tl_if_empty:NF \l__luatexcn_banxin_upper_section_grid_height_tl
              {
                \tl_put_right:Ne \l__luatexcn_banxin_tb_opts_tl
                  { ,~ grid-height = \l__luatexcn_banxin_upper_section_grid_height_tl }
              }
            % Typeset into global box using TextBox pipeline
            % If user text already contains \TextBox / \文本框, use it directly
            \vbox_gset:Nn \g__luatexcn_banxin_upper_box
              {
                \__luatexcn_banxin_typeset_content:NnN
                  \l__luatexcn_banxin_upper_section_text_tl
                  { \l__luatexcn_banxin_tb_opts_tl }
                  \l__luatexcn_banxin_upper_section_text_tl
              }
            % Store box in Lua for render stage
            \lua_now:e {
              _G.banxin~=~_G.banxin~or~{}
              _G.banxin.store_upper_section_box(
                \int_value:w \g__luatexcn_banxin_upper_box
              )
            }
          }
        % --- Middle section pre-render ---
        \tl_if_empty:NTF \l__luatexcn_banxin_middle_section_text_tl
          {
            \box_gclear:N \g__luatexcn_banxin_middle_box
          }
          {
            % Height = middle available height (middle region - yuwei - top_margin)
            \tl_set:Ne \l_tmpa_tl
              {
                \lua_now:e
                  {
                    local~layout~=~require("banxin.luatex-cn-banxin-layout")
                    local~c~=~_G.content~or~{}
                    local~upper_yw~=~token.get_macro("l__luatexcn_banxin_upper_yuwei_bool")
                    local~lower_yw~=~token.get_macro("l__luatexcn_banxin_lower_yuwei_bool")
                    local~top_margin_str~=~token.get_macro("l__luatexcn_banxin_middle_section_top_margin_tl")
                    local~constants~=~require("core.luatex-cn-constants")
                    local~top_margin~=~constants.resolve_dimen(top_margin_str,~655360)~or~0
                    local~h~=~layout.calc_middle_available_height({
                      content_height~=~c.content_height~or~0,
                      middle_ratio~=~tonumber(token.get_macro("l__luatexcn_banxin_middle_ratio_tl"))~or~0.56,
                      banxin_width~=~c.banxin_width~or~655360,
                      upper_yuwei~=~(upper_yw~==~"\\iftrue"),
                      lower_yuwei~=~(lower_yw~==~"\\iftrue"),
                      top_margin~=~top_margin,
                    })
                    tex.print(tostring(h)~..~"sp")
                  }
              }
            \tl_set:Ne \l_tmpb_tl
              {
                \lua_now:e
                  {
                    local~c~=~_G.content~or~{}
                    tex.print(tostring(c.banxin_width~or~655360)~..~"sp")
                  }
              }
            \tl_set:Nn \l__luatexcn_banxin_tb_opts_tl
              {
                height = \l_tmpa_tl ,
                grid-width = \l_tmpb_tl ,
                border = false
              }
            \tl_if_empty:NF \l__luatexcn_banxin_middle_section_font_size_tl
              {
                \tl_put_right:Ne \l__luatexcn_banxin_tb_opts_tl
                  { ,~ font-size = \l__luatexcn_banxin_middle_section_font_size_tl }
              }
            \tl_if_empty:NF \l__luatexcn_banxin_middle_section_grid_height_tl
              {
                \tl_put_right:Ne \l__luatexcn_banxin_tb_opts_tl
                  { ,~ grid-height = \l__luatexcn_banxin_middle_section_grid_height_tl }
              }
            \vbox_gset:Nn \g__luatexcn_banxin_middle_box
              {
                \__luatexcn_banxin_typeset_content:NnN
                  \l__luatexcn_banxin_middle_section_text_tl
                  { \l__luatexcn_banxin_tb_opts_tl }
                  \l__luatexcn_banxin_middle_section_text_tl
              }
            \lua_now:e {
              _G.banxin~=~_G.banxin~or~{}
              _G.banxin.store_middle_section_box(
                \int_value:w \g__luatexcn_banxin_middle_box
              )
            }
          }
        % --- Lower section pre-render ---
        \tl_if_empty:NTF \l__luatexcn_banxin_lower_section_text_tl
          {
            \box_gclear:N \g__luatexcn_banxin_lower_box
          }
          {
            % Height = lower_region - border
            \tl_set:Ne \l_tmpa_tl
              {
                \lua_now:e
                  {
                    local~c~=~_G.content~or~{}
                    local~ur~=~tonumber(token.get_macro("l__luatexcn_banxin_upper_ratio_tl"))~or~0.28~
                    local~mr~=~tonumber(token.get_macro("l__luatexcn_banxin_middle_ratio_tl"))~or~0.56~
                    local~lr~=~1~-~ur~-~mr~
                    local~region_h~=~(c.content_height~or~0)~*~lr~
                    local~border_t~=~c.border_on~and~(c.border_thickness~or~0)~or~0~
                    local~h~=~region_h~-~border_t~
                    if~h~<~0~then~h~=~region_h~end~
                    tex.print(tostring(math.floor(h~+~0.5))~..~"sp")
                  }
              }
            \tl_set:Ne \l_tmpb_tl
              {
                \lua_now:e
                  {
                    local~c~=~_G.content~or~{}
                    tex.print(tostring(c.banxin_width~or~655360)~..~"sp")
                  }
              }
            \tl_set:Nn \l__luatexcn_banxin_tb_opts_tl
              {
                height = \l_tmpa_tl ,
                grid-width = \l_tmpb_tl ,
                border = false ,
                box-align = fill ,
                fill-padding-top = \l__luatexcn_banxin_lower_section_top_padding_tl ,
                fill-padding-bottom = \l__luatexcn_banxin_lower_section_bottom_padding_tl
              }
            \tl_if_empty:NF \l__luatexcn_banxin_lower_section_font_size_tl
              {
                \tl_put_right:Ne \l__luatexcn_banxin_tb_opts_tl
                  { ,~ font-size = \l__luatexcn_banxin_lower_section_font_size_tl }
              }
            \tl_if_empty:NF \l__luatexcn_banxin_lower_section_grid_height_tl
              {
                \tl_put_right:Ne \l__luatexcn_banxin_tb_opts_tl
                  { ,~ grid-height = \l__luatexcn_banxin_lower_section_grid_height_tl }
              }
            \vbox_gset:Nn \g__luatexcn_banxin_lower_box
              {
                \__luatexcn_banxin_typeset_content:NnN
                  \l__luatexcn_banxin_lower_section_text_tl
                  { \l__luatexcn_banxin_tb_opts_tl }
                  \l__luatexcn_banxin_lower_section_text_tl
              }
            \lua_now:e {
              _G.banxin~=~_G.banxin~or~{}
              _G.banxin.store_lower_section_box(
                \int_value:w \g__luatexcn_banxin_lower_box
              )
            }
          }
      }
  }
\tl_new:N \l__luatexcn_banxin_tb_opts_tl

% Helper: typeset banxin section content
% Always wraps in \TextBox with the given options.
% User text may contain \TextBox / \文本框 — these become nested content
% processed through the TextBox pipeline with correct banxin dimensions.
% #1 = tl var (unused, kept for API compat)
% #2 = TextBox options tl
% #3 = tl var with the text content
\cs_new_protected:Nn \__luatexcn_banxin_typeset_content:NnN
  {
    \use:x
      {
        \exp_not:N \TextBox
          [ #2 ]
          { \exp_not:V #3 }
      }
  }

% ============================================================================
% CJK Aliases (中文别名)
% ============================================================================
% Simplified Chinese / 简体
\NewCommandCopy{\版心设置}{\banxinSetup}
% Traditional Chinese / 繁体
\NewCommandCopy{\版心設置}{\banxinSetup}

\ExplSyntaxOff%
%
\endinput%