-- conclusions.lua
-- A Pandoc Lua filter to distinguish conclusions from the surrounding text.
-- Copyright 2024 Bastien Dumont (bastien.dumont [at] posteo.net)
-- This file is under the MIT License: see LICENSE for more details

local MAX_HEADER_LEVEL = 6

local config = {
  innermost_level_header = 2,
  innermost_level_space = 3,
  ccl_explicit_titles = {
    'Conclusion de la partie',
    'Conclusion du chapitre'
  }
}

local function check_validity(key, value)
  if key ~= 'ccl-explicit-titles'
    and (value == nil or value < 1 or value > MAX_HEADER_LEVEL)
  then
    error(key .. ' must be a numeric value ' ..
          'comprised between 1 and ' .. MAX_HEADER_LEVEL .. '.\n')
  end
end

local function get_config(meta)
  if meta.conclusions then
    for key, value in pairs(meta.conclusions) do
      if key ~= 'ccl-explicit-titles' then
        value = math.tointeger(value[1].text)
      end
      check_validity(key, value)
      config[string.gsub(key, '-', '_')] = value
    end
  end
end

local function set_raw_space()
  local raw_space
  if FORMAT == 'native' then
    FORMAT = pandoc.system.environment().TESTED_FORMAT
    set_raw_space()
  elseif FORMAT == 'context' then
    raw_space = pandoc.RawBlock('tex', '\\blank[big]')
  elseif FORMAT == 'docx' then
    raw_space = pandoc.RawBlock('openxml', '<w:p/>')
  elseif  FORMAT == 'latex' then
    raw_space = pandoc.RawBlock('tex', '\\bigskip')
  else
    error(FORMAT ..
          ' output not supported by complex-paragraphs.lua\n')
  end
  return raw_space
end

local raw_space = set_raw_space()

local function get_level(div)
  local level = MAX_HEADER_LEVEL + 1
  local set_value = div.attributes.level
  if set_value then
    set_value = math.tointeger(set_value)
    check_validity('level', set_value)
    level = set_value
  else
    io.stderr:write('level attribute missing to a div ' ..
                    'with class conclusion or ccl, nothing done.\n')
  end
  return level
end

local function get_separator_as_list(level)
  local separator = {}
  if level <= config.innermost_level_header then
    local header =
      pandoc.Header(level + 1, config.ccl_explicit_titles[level])
    table.insert(header.classes, 'unnumbered')
    separator = { header }
  elseif level <= config.innermost_level_space then
    separator = { raw_space }
  end
  return separator
end

function Div(div)
  local classes = div.classes
  if classes:includes('conclusion')
    or classes:includes('ccl')
  then
    local level = get_level(div)
    local formatted_conclusion = get_separator_as_list(level)
    table.insert(formatted_conclusion, div)
    return formatted_conclusion
  end
end

return {
  { Meta = get_config },
  { Div = Div }
}