Pandoc (github Markdown -> Scrapbox). Using Custom template, indent does not work correctly. So, I swaped double and triple indented list to "--", before I use pandoc

scrapbox.lua

-- This is a sample custom writer for pandoc.
-- Scrapbox

-- Character escaping
local function escape(s, in_attribute)
  return s:gsub("[<>&\"']",
    function(x)
      if x == '<' then
        return '&lt;'
      elseif x == '>' then
        return '&gt;'
      elseif x == '&' then
        return '&amp;'
      elseif x == '"' then
        return '&quot;'
      elseif x == "'" then
        return '&#39;'
      else
        return x
      end
    end)
end

-- Helper function to convert an attributes table into
-- a string that can be put into HTML tags.
local function attributes(attr)
  local attr_table = {}
  for x,y in pairs(attr) do
    if y and y ~= "" then
      table.insert(attr_table, ' ' .. x .. '="' .. escape(y,true) .. '"')
    end
  end
  return table.concat(attr_table)
end

-- Run cmd on a temporary file containing inp and return result.
local function pipe(cmd, inp)
  local tmp = os.tmpname()
  local tmph = io.open(tmp, "w")
  tmph:write(inp)
  tmph:close()
  local outh = io.popen(cmd .. " " .. tmp,"r")
  local result = outh:read("*all")
  outh:close()
  os.remove(tmp)
  return result
end

-- remove Note

-- Blocksep is used to separate block elements.
function Blocksep()
  return "\n\n"
end

-- This function is called once for the whole document. Parameters:
-- body is a string, metadata is a table, variables is a table.
-- This gives you a fragment.  You could use the metadata table to
-- fill variables in a custom lua template.  Or, pass `--template=...`
-- to pandoc, and pandoc will add do the template processing as
-- usual.
function Doc(body, metadata, variables)
  local buffer = {}
  local function add(s)
    table.insert(buffer, s)
  end
  add(body)
  return table.concat(buffer,'\n')
end

-- The functions that follow render corresponding pandoc elements.
-- s is always a string, attr is always a table of attributes, and
-- items is always an array of strings (the items in a list).
-- Comments indicate the types of other variables.

function Str(s)
  return escape(s)
end

function Space()
  return " "
end

function SoftBreak()
  return "\n"
end

function LineBreak()
  return "\n"
end

function Emph(s)
  return "[/ " .. s .. "]"
end

function Strong(s)
  return "[[" .. s .. "]]"
end

-- remove Subscript
-- remove Superscript
-- remove SmallCaps

function Strikeout(s)
  return '[- ' .. s .. ']'
end

function Link(s, src, tit, attr)
  return "[" .. escape(s,true) .. " " .. escape(src,true) .. "]"
end

function Image(s, src, tit, attr)
  return "[" .. escape(s,true) .. " " .. escape(src,true) .. "]"
end

function Code(s, attr)
  return "`" .. escape(s) .. "`\n"
end

function InlineMath(s)
  return "[$ " .. escape(s) .. "]"
end

function DisplayMath(s)
  return "[$" .. escape(s) .. "]"
end

function Note(s)
  return "((" .. s .. "))"
end

function Span(s, attr)
  return attributes(attr) .. s
end

-- function RawInline(format, str)
--   if format == "html" then
--     return str
--   else
--     return ''
--   end
-- end

-- remove Cite

function Plain(s)
  return s
end

function Para(s)
  return s
end

-- lev is an integer, the header level.
function Header(lev, s, attr)
  local buffer = {}
  table.insert(buffer, "[")
  for i = 1, 5 do
    table.insert(buffer, "*")
  end
  for i = 1, lev do
    table.remove(buffer)
  end
  return table.concat(buffer, "") .. " " .. s .. "]"
end

function BlockQuote(s)
  local buffer = {}
  local lines = Split(s, "\n")
  for _, line in pairs(lines) do
    table.insert(buffer, "> " .. line .. "\n")
  end
  return table.concat(buffer, "")
end

-- remove HorizontalRule
-- remove LineBlock

-- add Split for CodeBlock
function Split(str, pat)
   local t = {}  -- NOTE: use {n = 0} in Lua-5.0
   local fpat = "(.-)" .. pat
   local last_end = 1
   local s, e, cap = str:find(fpat, 1)
   while s do
      if s ~= 1 or cap ~= "" then
         table.insert(t,cap)
      end
      last_end = e+1
      s, e, cap = str:find(fpat, last_end)
   end
   if last_end <= #str then
      cap = str:sub(last_end)
      table.insert(t, cap)
   end
   return t
end

function CodeBlock(s, attr)
  local buffer = {}
  local lines = Split(s, "\n")
  return "code:temp" .. table.concat(attr, "") .. "\n\t" ..
    table.concat(lines, "\n\t") .. "\n"
end 

function BulletList(items)
  local buffer = {}
  for _, item in pairs(items) do
    table.insert(buffer, "\t" .. item)
  end
  return table.concat(buffer, "\n")
end

function OrderedList(items)
  local buffer = {}
  for _, item in pairs(items) do
    table.insert(buffer, "\t" .. item)
  end
  return table.concat(buffer, "\n")
end

-- Revisit association list STackValue instance.
function DefinitionList(items)
  local buffer = {}
  for _,item in pairs(items) do
    for k, v in pairs(item) do
      table.insert(buffer, "\t" .. k .. "：" .. table.concat(v, "") .. "\n")
    end
  end
  return table.concat(buffer, "\n")
end

-- remove html Align

-- edit CaptionedImage
function CaptionedImage(src, tit, caption)
   return '[' .. escape(caption,true) .. " " .. escape(src,true) .. ']'
end

-- edit
-- Caption is a string, aligns is an array of strings,
-- widths is an array of floats, headers is an array of
-- strings, rows is an array of arrays of strings.
function Table(caption, aligns, widths, headers, rows)
  local buffer = {}
  table.insert(buffer, "table:temp")
  local function add(s)
    table.insert(buffer, s)
  end
  if caption ~= "" then
    add(caption)
  end
  local header_row = {}
  local empty_header = true
  for i, h in pairs(headers) do
    table.insert(header_row, h)
    empty_header = empty_header and h == ""
  end
  if empty_header then
    head = ""
  else
    head = "\t" .. table.concat(header_row, "\t")
  end
  add(head)
  for _, row in pairs(rows) do
    local rows = {}
    for i,c in pairs(row) do
      table.insert(rows, c)
    end
    add("\t" .. table.concat(rows, "\t"))
  end
  return table.concat(buffer,'\n')
end

function RawBlock(format, str)
  if format == "html" then
    return str
  else
    return ''
  end
end

function Div(s, attr)
  return s
end

-- The following code will produce runtime warnings when you haven't defined
-- all of the functions you need for the custom writer, so it's useful
-- to include when you're working on a writer.
local meta = {}
meta.__index =
  function(_, key)
    io.stderr:write(string.format("WARNING: Undefined function '%s'\n",key))
    return function() return "" end
  end
setmetatable(_G, meta)