#!/usr/bin/env texlua
-------------------------------------------------------------------------------
--         FILE:  mkimport.lua
--        USAGE:  texlua ./mkimport.lua
--  DESCRIPTION:  check luaotfload imports against Context
-- REQUIREMENTS:  luatex, the lualibs package, Context MkIV
--       AUTHOR:  Philipp Gesang (Phg), <phg@phi-gamma.net>
-------------------------------------------------------------------------------
--

-------------------------------------------------------------------------------
--- PURPOSE
---
---  - Facilitate detecting changes in the fontloader source.
---  - Assist in updating source code and (partially) automate importing.
---
---  - Account for files in the plain fontloader distribution, alert in case of
---    additions or deletions.
---
---  - Fontloader packaging.
---
-------------------------------------------------------------------------------

local debug = false

kpse.set_program_name "luatex"

local lfs = require "lfs"
local md5 = require "md5"
local os  = require "os"

require "lualibs"
require "util-mrg"

assert (utilities and utilities.merger and utilities.merger.compact
        and type (utilities.merger.compact) == "function",
        "Whoa, util-mrg.lua is not accessible! How do you expect this to work‽")

local filedirname      = file.dirname
local fileiswritable   = file.is_writable
local ioloaddata       = io.loaddata
local iosavedata       = io.savedata
local iopopen          = io.popen
local iowrite          = io.write
local lfschdir         = lfs.chdir
local lfscurrentdir    = lfs.currentdir
local lfsisdir         = lfs.isdir
local lfsisfile        = lfs.isfile
local md5sumhexa       = md5.sumhexa
local osdate           = os.date
local osgettimeofday   = os.gettimeofday
local osrename         = os.rename
local stringformat     = string.format
local tableconcat      = table.concat

-------------------------------------------------------------------------------
-- config
-------------------------------------------------------------------------------

local parms               = { }
local our_prefix          = "fontloader"
local luatex_fonts_prefix = "luatex"
local fontloader_subdir   = "src/fontloader"

local origin_paths = {
  context    = { "tex/context/base/mkiv", "tex/context/base", },
  fontloader = "tex/generic/context/luatex",
}

local subdirs = {
  "runtime",
  "misc"
}

local searchdirs = {
  --- order is important!
  fontloader_subdir,
}

local prefixes = {
  context    = nil,
  fontloader = "luatex",
}

--[[doc--

    The output name is fixed so we have to deal with it but maybe we
    can get a patch to mtx-package upstreamed in the future. In any
    case, we are content with renaming the result for the time being.

    The target name is constructed on the fly from the current date.
    TODO It should be possible to supply a name and possibly
    destination path on the command line.

    Paths are relative to the base directory (``$PWD``).

--doc]]--

local loader_target_name = "fontloader-%s.lua"
local loader_orig_dir    = "/src/fontloader/"
local loader_target_dir  = "/build/"

-------------------------------------------------------------------------------
-- helpers
-------------------------------------------------------------------------------

local die = function (...)
  io.stderr:write "[\x1b[1;30;41mfatal error\x1b[0m] "
  io.stderr:write (stringformat (...))
  io.stderr:write "\naborting.\n"
  os.exit (1)
end

local uncertain = 0

local hmm = function (...)
  uncertain = uncertain + 1
  --[[ sorta like an error but non-fatal ]]
  io.stderr:write "[\x1b[1;31merror\x1b[0m] "
  io.stderr:write (stringformat (...))
  io.stderr:write "; continuing nontheless.\n"
end

local emphasis = function (txt)
  return stringformat("\x1b[1m%s\x1b[0m", txt)
end

local msg = function (...)
  iowrite (stringformat (...))
  iowrite "\n"
end

local separator_string = string.rep ("-", 79)
local separator = function ()
  iowrite (separator_string)
  iowrite "\n"
end

local good_tag   = stringformat("[\x1b[1;30;%dmgood\x1b[0m]   · ", 42)
local bad_tag    = stringformat("[\x1b[1;30;%dmBAD\x1b[0m]    · ", 41)
local alert_tag  = stringformat("[\x1b[1;%dmalert\x1b[0m]  · "   , 36)
local status_tag = stringformat("[\x1b[0;%dmstatus\x1b[0m] · "   , 36)

local good = function (...)
  local msg = (stringformat (...))
  iowrite (good_tag)
  iowrite (msg)
  iowrite "\n"
end

local bad = function (...)
  local msg = (stringformat (...))
  iowrite (bad_tag)
  iowrite (msg)
  iowrite "\n"
end

local attention = function (...)
  local msg = (stringformat (...))
  iowrite (alert_tag)
  iowrite (msg)
  iowrite "\n"
end

local status = function (...)
  local msg = (stringformat (...))
  iowrite (status_tag)
  iowrite (msg)
  iowrite "\n"
end

-------------------------------------------------------------------------------
-- definitions
-------------------------------------------------------------------------------

--- Accounting of upstream files. There are different categories:
---
---   · *essential*: Files required at runtime.
---   · *merged*:    Files merged into the fontloader package.
---   · *ignored*:   Lua files not merged, but part of the format.
---   · *tex*:       TeX code, i.e. format and examples.
---   · *lualibs*:   Files merged, but also provided by the Lualibs package.

local kind_essential = 0
local kind_merged    = 1
local kind_tex       = 2
local kind_ignored   = 3
local kind_lualibs   = 4

local kind_name = {
  [0] = "essential",
  [1] = "merged"   ,
  [2] = "tex"      ,
  [3] = "ignored"  ,
  [4] = "lualibs"  ,
}

local imports = {

  fontloader = {
    { name = "basics-gen"        , ours = nil          , kind = kind_essential },
    { name = "basics-nod"        , ours = nil          , kind = kind_merged    },
    { name = "basics"            , ours = nil          , kind = kind_tex       },
    { name = "fonts-demo-vf-1"   , ours = nil          , kind = kind_ignored   },
    { name = "fonts-enc"         , ours = nil          , kind = kind_merged    },
    { name = "fonts-ext"         , ours = nil          , kind = kind_merged    },
    { name = "fonts-merged"      , ours = "reference"  , kind = kind_essential },
    { name = "fonts"             , ours = nil          , kind = kind_merged    },
    { name = "fonts"             , ours = nil          , kind = kind_tex       },
    { name = "fonts-syn"         , ours = nil          , kind = kind_ignored   },
    { name = "languages"         , ours = nil          , kind = kind_ignored   },
    { name = "languages"         , ours = nil          , kind = kind_tex       },
    { name = "math"              , ours = nil          , kind = kind_ignored   },
    { name = "math"              , ours = nil          , kind = kind_tex       },
    { name = "mplib"             , ours = nil          , kind = kind_ignored   },
    { name = "mplib"             , ours = nil          , kind = kind_tex       },
    { name = "plain"             , ours = nil          , kind = kind_tex       },
    { name = "preprocessor"      , ours = nil          , kind = kind_ignored   },
    { name = "preprocessor"      , ours = nil          , kind = kind_tex       },
    { name = "preprocessor-test" , ours = nil          , kind = kind_tex       },
    { name = "swiglib"           , ours = nil          , kind = kind_ignored   },
    { name = "swiglib"           , ours = nil          , kind = kind_tex       },
    { name = "swiglib-test"      , ours = nil          , kind = kind_ignored   },
    { name = "swiglib-test"      , ours = nil          , kind = kind_tex       },
    { name = "test"              , ours = nil          , kind = kind_tex       },
  }, --[[ [fontloader] ]]

  context = { --=> all merged
    { name = "data-con"          , ours = "data-con"          , kind = kind_merged    },
    { name = "font-afk"          , ours = "font-afk"          , kind = kind_merged    },
    { name = "font-cff"          , ours = "font-cff"          , kind = kind_merged    },
    { name = "font-cid"          , ours = "font-cid"          , kind = kind_merged    },
    { name = "font-con"          , ours = "font-con"          , kind = kind_merged    },
    { name = "font-def"          , ours = "font-def"          , kind = kind_merged    },
    { name = "font-dsp"          , ours = "font-dsp"          , kind = kind_merged    },
    { name = "font-gbn"          , ours = "font-gbn"          , kind = kind_merged    },
    { name = "font-ini"          , ours = "font-ini"          , kind = kind_merged    },
    { name = "font-lua"          , ours = "font-lua"          , kind = kind_merged    },
    { name = "font-map"          , ours = "font-map"          , kind = kind_merged    },
    { name = "font-ocl"          , ours = "font-ocl"          , kind = kind_merged    },
    { name = "font-otc"          , ours = "font-otc"          , kind = kind_merged    },
    { name = "font-onr"          , ours = "font-onr"          , kind = kind_merged    },
    { name = "font-one"          , ours = "font-one"          , kind = kind_merged    },
    { name = "font-osd"          , ours = "font-osd"          , kind = kind_merged    },
    { name = "font-ota"          , ours = "font-ota"          , kind = kind_merged    },
    { name = "font-oti"          , ours = "font-oti"          , kind = kind_merged    },
    { name = "font-otj"          , ours = "font-otj"          , kind = kind_merged    },
    { name = "font-otl"          , ours = "font-otl"          , kind = kind_merged    },
    { name = "font-oto"          , ours = "font-oto"          , kind = kind_merged    },
    { name = "font-otr"          , ours = "font-otr"          , kind = kind_merged    },
    { name = "font-ots"          , ours = "font-ots"          , kind = kind_merged    },
    { name = "font-oup"          , ours = "font-oup"          , kind = kind_merged    },
    { name = "font-tfm"          , ours = "font-tfm"          , kind = kind_merged    },
    { name = "font-ttf"          , ours = "font-ttf"          , kind = kind_merged    },

    { name = "l-boolean"         , ours = "l-boolean"         , kind = kind_lualibs   },
    { name = "l-file"            , ours = "l-file"            , kind = kind_lualibs   },
    { name = "l-function"        , ours = "l-function"        , kind = kind_lualibs   },
    { name = "l-io"              , ours = "l-io"              , kind = kind_lualibs   },
    { name = "l-lpeg"            , ours = "l-lpeg"            , kind = kind_lualibs   },
    { name = "l-lua"             , ours = "l-lua"             , kind = kind_lualibs   },
    { name = "l-math"            , ours = "l-math"            , kind = kind_lualibs   },
    { name = "l-string"          , ours = "l-string"          , kind = kind_lualibs   },
    { name = "l-table"           , ours = "l-table"           , kind = kind_lualibs   },
    { name = "util-str"          , ours = "util-str"          , kind = kind_lualibs   },
    { name = "util-fil"          , ours = "util-fil"          , kind = kind_lualibs   },
  }, --[[ [context] ]]
} --[[ [imports] ]]

local package = {

  optional = { --- components not included in the default package

--- The original initialization sequence by Hans Hagen, see the file
--- luatex-fonts.lua for details:
---
---   [01] l-lua.lua
---   [02] l-lpeg.lua
---   [03] l-function.lua
---   [04] l-string.lua
---   [05] l-table.lua
---   [06] l-io.lua
---   [07] l-file.lua
---   [08] l-boolean.lua
---   [09] l-math.lua
---   [10] util-str.lua
---   [11] util-fil.lua
---   [12] luatex-basics-gen.lua
---   [13] data-con.lua
---   [14] luatex-basics-nod.lua
---   [15] luatex-basics-chr.lua
---   [16] font-ini.lua
---   [17] font-con.lua
---   [18] luatex-fonts-enc.lua
---   [19] font-cid.lua
---   [20] font-map.lua
---   [21] luatex-fonts-syn.lua
---   [23] font-oti.lua
---   [24] font-otr.lua
---   [25] font-cff.lua
---   [26] font-ttf.lua
---   [27] font-dsp.lua
---   [28] font-oup.lua
---   [29] font-otl.lua
---   [30] font-oto.lua
---   [31] font-otj.lua
---   [32] font-ota.lua
---   [33] font-ots.lua
---   [34] font-osd.lua
---   [35] font-ocl.lua
---   [36] font-otc.lua
---   [37] font-onr.lua
---   [38] font-one.lua
---   [39] font-afk.lua
---   [40] font-tfm.lua
---   [41] font-lua.lua
---   [42] font-def.lua
---   [43] font-xtx.lua
---   [44] luatex-fonts-ext.lua
---   [45] font-gbn.lua
---
--- Of these, nos. 01--11 are provided by the Lualibs. Keeping them
--- around in the Luaotfload fontloader is therefore unnecessary.
--- Packaging needs to account for this difference.

    "l-lua",
    "l-lpeg",
    "l-function",
    "l-string",
    "l-table",
    "l-io",
    "l-file",
    "l-boolean",
    "l-math",
    "util-str",
    "util-fil",

--- Another file containing auxiliary definitions must be present
--- prior to initialization of the configuration.

    "luatex-basics-gen",

--- We have a custom script for autogenerating data so we don’t use the
--- definitions from upstream.

    "basics-chr",

  }, --[[ [package.optional] ]]

--- The files below constitute the “fontloader proper”. Some of the
--- functionality like file resolvers is overloaded later by
--- Luaotfload. Consequently, the resulting package is pretty
--- bare-bones and not usable independently.

  required = {

    "data-con",
    "basics-nod",
    "font-ini",
    "font-con",
    "fonts-enc",
    "font-cid",
    "font-map",
    "font-oti",
    "font-otr",
    "font-cff",
    "font-ttf",
    "font-dsp",
    "font-oup",
    "font-otl",
    "font-oto",
    "font-otj",
    "font-ota",
    "font-ots",
    "font-osd",
    "font-ocl",
    "font-otc",
    "font-onr",
    "font-one",
    "font-afk",
    "font-tfm",
    "font-lua",
    "font-def",
    "fonts-ext",
    "font-gbn",

  }, --[[ [package.required] ]]

} --[[ [package] ]]

local hash_file = function (fname)
  if not lfsisfile (fname) then
    hmm ("cannot find %s", fname)
    return nil
  end
  local raw = ioloaddata (fname)
  if not raw then
    die ("cannot read from %s.", fname)
  end
  return md5sumhexa (raw)
end

local first_existing_subpath = function (pfx, subs)
  if not subs then return nil end
  local t_subs = type (subs)
  if t_subs == "table" then
    for i = 1, #subs do
      local sub = subs[i]
      local pth = file.join (pfx, sub)
      if lfsisdir (pth) then return pth end
    end
  elseif t_subs == "string" then
    local pth = file.join (pfx, subs)
    if lfsisdir (pth) then return pth end
  end
  return nil
end

local derive_category_path = function (cat)
  local location = first_existing_subpath (parms.context_root,
                                           origin_paths[cat])
  if not location then
    die ("invalid base path defined for category " .. cat)
  end
  return location
end

local derive_suffix = function (kind)
  if kind == kind_tex then return ".tex" end
  return ".lua"
end

local pfxlen = { }
local strip_prefix = function (fname, prefix)
  prefix = prefix or our_prefix
  if not pfxlen[prefix] then pfxlen[prefix] = #prefix end
  local len = pfxlen[prefix]
  if #fname <= len + 2 then
    --- too short to accomodate prefix + basename
    return
  end
  if string.sub (fname, 1, len) == prefix then
    return string.sub (fname, len + 2)
  end
end

local derive_fullname = function (cat, name, kind)
  local tmp = prefixes[cat]
  tmp = tmp and tmp .. "-" .. name or name
  return tmp .. derive_suffix (kind)
end

local derive_ourname = function (name, kind)
  local suffix = derive_suffix (kind)
  local subdir = kind == kind_essential and "runtime" or "misc"
  return subdir, our_prefix .. "-" .. name .. suffix
end

local format_file_definition = function (def)
  return stringformat ("name = \"%s\", kind = \"%s\"",
                       def.name,
                       kind_name[def.kind] or def.kind)
      .. (def.ours and (", ours = \"" .. def.ours .. "\"") or "")
end

local is_readable = function (f)
  local fh = io.open (f, "r")
  if fh then
    fh:close()
    return true
  end
  return false
end

local summarize_news = function (status)
  local ni = #status.import
  local nc = #status.create
  local ng = #status.good
  local nm = #status.missing

  separator ()
  msg ("Summary: Inspected %d files.", ni + nc + ng + nm)
  separator ()
  if ng > 0 then good      ("%d are up to date", ng) end
  if ni > 0 then attention ("%d changed"       , ni) end
  if nc > 0 then attention ("%d new"           , nc) end
  if nm > 0 then bad       ("%d missing"       , nm) end
  separator ()

  if nm == 0 and nc == 0 and ni == 0 then
    return 0
  end

  return -1
end

local news = function ()
  local status = {
    import  = { },
    good    = { },
    create  = { },
    missing = { },
  }

  for cat, entries in next, imports do
    local location = derive_category_path (cat)
    local nfiles = #entries

    for i = 1, nfiles do
      local def  = entries[i]
      local name = def.name
      local ours = def.ours
      local kind = def.kind
      local fullname = derive_fullname (cat, name, kind)
      local fullpath = file.join (location, fullname)
      local subdir, ourname  = derive_ourname (ours or name, kind)
      local ourpath  = file.join (fontloader_subdir, subdir, ourname) -- relative
      local imported = false

      if not is_readable (fullpath) then
        bad ("source for file %s not found at %s",
             emphasis (ourname),
             emphasis (fullpath))
        status.missing[#status.missing + 1] = ourname
      else
        --- Source file exists and is readable.
        if not lfsisdir (fontloader_subdir) then
          die ("path for fontloader tree ("
              .. fontloader_subdir .. ") is not a directory")
        end
        if is_readable (ourpath) then imported = true end
        local src_hash = hash_file (fullpath)
        if src_hash then
          local dst_hash = imported and hash_file (ourpath)
          local same     = src_hash == dst_hash -- same!
          if same then
            good ("file %s unchanged", emphasis (ourname))
            status.good[#status.good + 1] = ourname
          elseif not dst_hash then
            attention ("new file %s requires import from %s",
                      emphasis (ourname),
                      emphasis (fullpath))
            status.create[#status.create + 1] = ourname
          else --- src and dst exist but differ
            attention ("file %s requires import", emphasis (ourname))
            status.import[#status.import + 1] = ourname
          end
        end
      end

    end
  end

  return summarize_news (status)
end --[[ [local news = function ()] ]]

local get_file_definition = function (name, ourname, kind)
  kind = kind or "lua"
  for cat, defs in next, imports do
    local fullname = derive_fullname (cat, name, kind)
    local ndefs = #defs
    for i = 1, ndefs do
      local def = defs[i]
      local dname = def.name
      local dours = def.ours or def.name
      local dkind = def.kind

      --- test properties
      local subdir, derived = derive_ourname (dours, dkind)
      if                             derived == ourname  then return def, cat end
      if derive_fullname (cat, dname, dkind) == fullname then return def, cat end
      if                               dours == ourname  then return def, cat end
      if                               dname == fullname then return def, cat end
    end
  end
  --- search unsuccessful
end --[[ [local get_file_definition = function (name, ourname, kind)] ]]

local import_imported = 0
local import_skipped  = 1
local import_failed   = 2
local import_created  = 3

local import_status = {
  [import_imported] = "imported",
  [import_skipped ] = "skipped",
  [import_failed  ] = "failed",
  [import_created ] = "created",
}

local summarize_status = function (counters)
  local imported = counters[import_imported] or 0
  local skipped  = counters[import_skipped ] or 0
  local created  = counters[import_created ] or 0
  local failed   = counters[import_failed  ] or 0
  local sum = imported + skipped + created + failed
  if sum < 1 then die ("garbage total of imported files: %s", sum) end
  separator ()
  status (" RESULT: %d files processed, %d errors", sum, uncertain)
  separator ()
  if created  > 0 then status ("created:  %d (%d %%)", created , created  * 100 / sum) end
  if imported > 0 then status ("imported: %d (%d %%)", imported, imported * 100 / sum) end
  if skipped  > 0 then status ("skipped:  %d (%d %%)", skipped , skipped  * 100 / sum) end
  separator ()
end

local import_file = function (name, kind, def, cat)
  local expected_ourname = derive_ourname (name)
  if not def or not cat then
    def, cat = get_file_definition (name, expected_ourname, kind)
  end

  if not def then die ("unable to find a definition matching " .. name) end
  if not cat then die ("missing category for file " .. name .. " -- WTF‽") end

  local dname    = def.name
  local dours    = def.ours or dname
  local dkind    = def.kind
  local srcdir   = derive_category_path (cat)
  local fullname = derive_fullname (cat, dname, kind)
  local subdir, ourname = derive_ourname (dours, kind)
  local ourpath  = file.join (fontloader_subdir, subdir)
  local src      = file.join (srcdir, fullname)
  local dst      = file.join (ourpath, ourname)
  local new      = not lfsisfile (dst)
  if not new and hash_file (src) == hash_file (dst) then
    status ("file %s is unchanged, skipping", fullname)
    return import_skipped
  end
  if not (lfsisdir (ourpath) or not lfs.mkdirs (ourpath)) then
    die ("failed to create directory %s for file %s",
         ourpath, ourname)
  end
  status ("importing file %s", fullname)
  file.copy (src, dst)
  if hash_file (src) == hash_file (dst) then
    if new then return import_created end
    return import_imported end
  return import_failed
end --[[ [local import_file = function (name, kind)] ]]

local import = function (arg)
  --- Multiple files
  local statcount = { } -- import status codes -> size_t
  for cat, defs in next, imports do
    local ndefs = #defs
    for i = 1, ndefs do
      local def  = defs[i]
      local stat = import_file (def.name, def.kind, def, cat)
      if stat == import_failed then
        hmm (stringformat ("import failed at file %d of %d (%s)",
                           i, ndefs, def.name))
      end
      statcount[stat] = statcount[stat] or 0
      statcount[stat] = statcount[stat] + 1
    end
  end
  summarize_status (statcount)
  return uncertain == 0 and 0 or -42
end --[[ [local import = function (arg)] ]]

local find_in_path = function (root, subdir, target)
  local file = file.join (root, subdir, target)
  if lfsisfile (file) then
    return file
  end
end

local search_paths = function (target)
  for i = 1, #searchdirs do
    local root  = searchdirs[i]

    for j = 1, #subdirs do
      local found = find_in_path (root, subdirs[j], target)
      if found then return found end
    end

  end

  local found = find_in_path (parms.context_root, origin_paths.context, target)
  if found then return found end

  local found = find_in_path (parms.context_root, origin_paths.fontloader, target)
  if found then return found end
  return false
end

local search_defs = function (target)
  local variants = { target, --[[ unstripped ]] }
  local tmp
  tmp = strip_prefix (target)
  if tmp then variants[#variants + 1] = tmp end
  tmp = strip_prefix (target, luatex_fonts_prefix)
  if tmp then variants[#variants + 1] = tmp end

  local nvariants = #variants

  for cat, defs in next, imports do
    local ndefs = #defs
    for i = 1, ndefs do
      local def = defs[i]

      for i = 1, nvariants do
        local variant = variants[i]

        local dname = def.name
        if variant == dname then
          local found = search_paths (variant .. derive_suffix (def.kind))
          if found then return found end
        end

        local dkind = def.kind
        local dfull = derive_fullname (cat, dname, dkind)
        if derive_fullname (cat, variant, dkind) == dfull then
          local found = search_paths (dfull)
          if found then return found end
        end

        local dours = def.ours
        if dours then

          local _, ourname = derive_ourname (dours, dkind)
          if variant == dours then
            local found = search_paths (ourname)
            if found then return found end
          end

          if variant == ourname then
            local found = search_paths (ourname)
            if found then return found end
          end
        end

      end
    end
  end
  return false
end

local search = function (target)
  local look_for
  --- pick a file
  if lfsisfile (target) then --- absolute path given
    look_for = target
    goto found
  else

    --- search as file name in local tree
    look_for = search_paths (target)
    if look_for then goto found end

    --- seach the definitions
    look_for = search_defs (target)
    if look_for then goto found end

  end

::fail::
  if not look_for then return end

::found::
  return look_for
end

local find_matching_def = function (location)
  local basename = file.basename (location)
  if not basename then die ("corrupt path %s", location) end
  local barename = file.removesuffix (basename)
  local pfxless  = strip_prefix (barename)
  local kind     = file.suffix (pfxless) or "lua"
  for cat, defs in next, imports do
    for _, def in next, defs do
      local dname = def.name
      local dours = def.ours
      if dname == pfxless
      or dname == barename
      -- dname == basename -- can’t happen for lack of suffix
      or dours == pfxless
      or dours == barename
      then
        return cat, def
      end
    end
  end
  return false
end

local describe = function (target, location)
  --- Map files to import definitions
  separator ()
  status ("found file %s at %s", target, location)
  local cat, def = find_matching_def (location)
  if not cat or not def then
    die ("file %s not found in registry", location)
  end

  local dname           = def.name
  local dkind           = def.kind
  local subdir, ourname = derive_ourname (def.ours or dname, dkind)
  separator ()
  status ("category       %s", cat)
  status ("kind           %s", kind_name[dkind])
  status ("in Context     %s", derive_fullname (cat, dname, dkind))
  status ("in Luaotfload  %s", ourname)
  separator ()
  return 0
end

local tell = function (arg)
  local target = parms.target
  if not target then die "no filename given" end

  local location = search (target)
  if not location then
    die ("file %s not found in any of the search locations", target)
  end

  return describe (target, location)
end

local build_paths = function (argv)
  if not argv or type (argv) ~= "table" then die "build_paths" end

  local orig_dir    = lfscurrentdir ()
  local base_dir    = orig_dir .. loader_orig_dir
  local loader_name = stringformat (loader_target_name, os.date ("%F"))
  local target_name = orig_dir .. loader_target_dir .. loader_name

  if #argv >= 2 then
    local fname = argv[2]
    local dir   = filedirname (fname) .. "/"
    if not lfsisdir (dir) then
      die ("second argument must be point into existing directory, not “%s”",
           argv[2])
    end
    base_dir    = dir
    target_name  = fname
  end

  if #argv == 3 then
    --- also set the target name
    local fname = argv[3]
    local dir   = filedirname (fname)
    if not string.is_empty (dir) and not lfsisdir (dir) then
      die ("third argument must be point into writable directory, not “%s”",
           argv[3])
    end
    target_name = fname
  end

  local ret = {
    orig_dir    = orig_dir,
    base_dir    = base_dir,
    merge_name  = merge_name,
    target_name = target_name,
    loader_name = loader_name,
  }
  return ret
end

local luaotfload_header = [==[
--[[info-----------------------------------------------------------------------
  Luaotfload fontloader package
  build %s by %s@%s
-------------------------------------------------------------------------------

  © %s PRAGMA ADE / ConTeXt Development Team

  The code in this file is provided under the GPL v2.0 license. See the
  file COPYING in the Luaotfload repository for details.

  Report bugs to github.com/lualatex/luaotfload

  This file has been assembled from components taken from Context. See
  the Luaotfload documentation for details:

      $ texdoc luaotfload
      $ man 1 luaotfload-tool
      $ man 5 luaotfload.conf

  Included files:

%s

--info]]-----------------------------------------------------------------------

]==]

local make_header = function (files)
  local filelist = { }
  for i = 1, #files do
    local f = files[i]
    local _void, ourname = derive_ourname (f, kind_merged)
    filelist [#filelist + 1] = stringformat ("    · %s", ourname)
  end
  return stringformat (luaotfload_header,
                       os.date "%F %T",
                       os.getenv "USER" or "anon",
                       os.getenv "HOSTNAME" or "void",
                       os.date "%Y",
                       table.concat (filelist, "\n"))
end


local scope_start         = "\ndo  --- [luaotfload, %s scope for “%s” %s] ---\n\n"
local scope_stop          = "\nend --- [luaotfload, %s scope for “%s”] ---\n\n"
local luaotfload_modeline = "\n--- vim:ft=lua:sw=2:ts=8:et:tw=79\n"

local assemble_fontloader = function (tgt, dst)
  status ("packaging fontloader as “%s”.", emphasis (tgt))
  local required  = package.required
  local compact   = utilities.merger.compact
  local sequence  = { [1] = make_header (required) }
  for i = 1, #required do
    local cur = required [i]
    local subdir, ourname = derive_ourname (cur, kind_merged)
    local ourpath = file.join (fontloader_subdir, subdir, ourname)
    local data = ioloaddata (ourpath)
    if not data then
      bad ("file “%s” cannot be loaded from “%s”", ourname, ourpath)
      return false
    end
    sequence[#sequence + 1] = stringformat (scope_start, tgt, cur, md5sumhexa (data))
    sequence[#sequence + 1] = compact (data)
    sequence[#sequence + 1] = stringformat (scope_stop , tgt, cur)
  end
  sequence[#sequence + 1] = luaotfload_modeline
  local raw = table.concat (sequence)
  local _void, chunk, err = pcall (loadstring, raw)
  print(_void, chunk)
  if chunk == nil then
    bad ("packaging result not well-formed")
    bad ("error message: “%s”", err)
    bad ("dumping to fontloader-junk.lua")
    iosavedata ("fontloader-junk.lua", raw)
    return false
  end
  iosavedata (dst, raw)
  status ("amalgamated %d files, written to “%s”.",
          #required, dst)
  return dst
end

local package = function (argv)
  local t0    = osgettimeofday ()
  local paths = build_paths (argv)

  status ("assuming fontloader source in      %s", paths.base_dir)
  status ("reading merge instructions from    %s", paths.merge_name)
  status ("writing output to                  %s", paths.target_name)

  --- check preconditions

  if not lfsisdir (paths.base_dir)          then die ("directory %s does not exist", emphasis (paths.base_dir   )) end
  if not fileiswritable (paths.target_name) then die ("cannot write to %s",          emphasis (paths.target_name)) end
---- not lfschdir (paths.base_dir)          then die ("failed to cd into %s",        emphasis (paths.base_dir   )) end

  if lfsisfile (paths.target_name) then
    status ("output file already exists at “%s”, unlinking",
            paths.target_name)
    local ret, err = os.remove (paths.target_name)
    if ret == nil then
      if not lfschdir (paths.orig_dir) then
        status ("warning: failed to cd retour into %s",
                emphasis (paths.orig_dir))
      end
      die ("failed to remove existing merge package")
    end
  end
  --- perform merge

  local ret = assemble_fontloader (paths.loader_name, paths.target_name)

  if not ret then
    if not lfschdir (paths.orig_dir) then
      status ("warning: failed to cd retour into %s",
              emphasis (paths.orig_dir))
    end
    die ("merge failed; failed to invoke mtxrun")
  end

  --- clean up

  if not lfschdir (paths.orig_dir) then
    status ("warning: failed to cd retour into %s",
            emphasis (paths.orig_dir))
  end

  --- check postconditions

  if not lfsisfile (ret) then
    die ("merge failed; package not found at “%s”", paths.output_name)
  end

  --- at this point we know that mtxrun was invoked correctly and the
  --- result file has been created

  status ("merge complete; operation finished in %.0f ms",
          (osgettimeofday() - t0) * 1000)
  status ("a fresh fontloader at %s is ready to roll", paths.target_name)
end

local help = function ()
  iowrite "usage: mkimport  <command> [<args>]\n"
  iowrite "\n"
  iowrite "Where <command> is one of\n"
  iowrite "   help      Print this help message\n"
  iowrite "   tell      Display information about a file’s integration\n"
  iowrite "   news      Check Context for updated files\n"
  iowrite "   import    Update with files from Context\n"
  iowrite "   package   Invoke mtx-package on the current fontloader\n"
  iowrite "\n"
end

local job_kind = table.mirrored {
  help    = help,
  import  = import,
  news    = news,
  package = package,
  tell    = tell,
}

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

--- job_kind -> bool
local check_job = function (j)
  return job_kind[j] or die ("invalid job type “%s”.", j)
end

local parse_argv = function (argv)
  local job
  local tgt
  local pth

  local argc = #arg
  if argc < 1 or argc > 3 then return "help" end
  job = arg[1] or "help"
  if argc > 1 then
    tgt = arg[2]
    if argc == 3 then pth = arg[3] end
  end
  if not pth then pth = "~/context/tex/texmf-context" end
  parms.context_root = kpse.expand_path (pth)
  parms.target       = tgt
  searchdirs [#searchdirs + 1] = pth
  return job
end

-------------------------------------------------------------------------------
-- entry point
-------------------------------------------------------------------------------

local main = function ()
  local job = parse_argv (arg)
  local runner = check_job (job)
  return runner(arg)
end

os.exit (main ())

--- vim:ft=lua:ts=2:et:sw=2