#!/usr/bin/env texlua
-----------------------------------------------------------------------
--         FILE:  mkcharacters.lua
--        USAGE:  ./mkcharacters.lua 
--  DESCRIPTION:  import parts of char-def.lua
-- REQUIREMENTS:  lua, ConTeXt, the lualibs package
--       AUTHOR:  Philipp Gesang (Phg), <phg42.2a@gmail.com>
--      VERSION:  1.1
--      CREATED:  2013-05-17 12:41:39+0200
-----------------------------------------------------------------------
-- we create a stripped-down version of char-def.lua
-----------------------------------------------------------------------

-----------------------------------------------------------------------
--                              config
-----------------------------------------------------------------------
local charfile      = "./luaotfload-characters.lua"
local chardef       = "/home/phg/base/char-def.lua"

---  for every code point char-def.lua provides a set of fields. they
---  are:
---
---     * adobename
---     * category
---     * cjkwd
---     * comment
---     * contextname
---     * description
---     * direction
---     * lccode
---     * linebreak
---     * mathclass
---     * mathextensible
---     * mathfiller
---     * mathname
---     * mathspec
---     * mathstretch
---     * mathsymbol
---     * mirror
---     * shcode
---     * specials
---     * textclass
---     * uccode
---     * unicodeslot
---     * variants

local import = {
  "direction", "mirror", --> πολυγλωσσία/uax9
  "category",            --> https://gist.github.com/phi-gamma/5812290
  "textclass",           --> https://gist.github.com/phi-gamma/6488187 
}

-----------------------------------------------------------------------
--                             includes
-----------------------------------------------------------------------

kpse.set_program_name"luatex"

for _, lib in next, { "lualibs-lua.lua",
                      "lualibs-lpeg.lua",
                      "lualibs-table.lua", } do
  local found = assert(kpse.find_file(lib, "lua"),
                       "Could not locate " .. lib .. ".\n"
                       .. "Please install the lualibs package.")
  require(found)
end

if not (chardef and lfs.isfile(chardef)) then
  --- we could grab the file from contextgarden but as Context is part
  --- of TL it’s not worth bothering 
  chardef = assert(kpse.find_file("char-def.lua", "lua"),
                   "Could not find ConTeXt.")
end

-----------------------------------------------------------------------
--                           functionality
-----------------------------------------------------------------------

local get_characters = function ( )
  local data
  local inchan = io.open(chardef, "r")
  if not inchan then
    io.write("Could not open file for reading: "..chardef.."\n.")
    goto fail
  end
  data = inchan:read "*all"
  inchan:close()
  data = loadstring(data)
  if data then
    data() --> characters.data
    data = nil
    collectgarbage "collect"
    if characters.data and next(characters.data) then
      return characters.data
    end
    io.write "Character table empty.\n"
    goto fail
  end
  io.write(chardef .. " is not a valid Lua file.\n")
  ::fail::
  io.write "Emergency exit.\n"
  os.exit(1)
end

local extract_fields_indeed
extract_fields_indeed = function (data, acc, lastidx)
  local idx, char = next(data, lastidx)
  if idx then
    local imported = { }
    for i=1, #import do
      local field = import[i]
      imported[field] = char[field]
    end
    acc[idx] = imported
    return extract_fields_indeed(data, acc, idx)
  end
  return acc
end

local extract_fields = function (data)
  return extract_fields_indeed(data, {}, nil)
end

local writedata = function (data)
  local outchan = io.open(charfile, "w")
  if not outchan then
    io.write("Could not open "..charfile.." for writing.\n")
    return false
  end
  outchan:write(data)
  outchan:close()
  return true
end

do
  local chardata    = get_characters()
  local stripped    = extract_fields(chardata)
  local serialized  = table.serialize(stripped, true, {
    compact   = true,
    noquotes  = true,
    hexify    = true, --- for consistency with char-def
  })
  if writedata(serialized) then
    goto done
  end
  goto fail
end

::done::
  os.exit(0)

::fail::
  io.write "Emergency exit.\n"
  os.exit(1)