lp.insPath {
  '?.lua',
  '?/init.lua',
}

local env = {
  name = lp.name,
  ver = lp.version,
  copy = lp.copyright,

  cache = '_c_',
  req = '_r_',
  mreq = '_m_', -- require by map
  mtemp = '  function($req) -- $file\n$src\n  end, -- $file\n',
  pre = '--[=[=]=]',
  regex = '([^\n]-)' .. 'require%s*%(?["\'](.-)["\']%)?%s*',
}

env.require = lp.strf('$req(%d)', env)

local base = lp.strf([[
$pre -- $name $ver
$pre -- $copy
$pre (function(m)
$pre   -- Module cache
$pre   local $cache = {}
%s$pre
$pre   -- Load main module
$pre   $require
$pre
$pre end) {
%s
$pre }
]], env)

local main = lp.strf([[
$pre
$pre   -- Require function
$pre   local function $req(i)
$pre     -- Check in cache
$pre     local c = $cache[i]
$pre     if not c then
$pre       -- Execute module function
$pre       c = m[i]($req)
$pre
$pre       -- And put it to cache
$pre       $cache[i] = c
$pre     end
$pre
$pre     -- Return cached returned value
$pre     return c
$pre   end
]], env)

local mreq = lp.strf([[
$pre
$pre   -- Require by map
$pre   local function $mreq(m, r)
$pre     -- Check if module exists
$pre     if not m[r]
$pre     then error('Cannot find module "'..r..'"')
$pre     end
$pre
$pre     -- Using default require
$pre     return $req(m[r])
$pre   end
]], env)

return function(op)
  return {
    name = 'Base Lua plugin',
    load = function(e, ext, oext)
      if ext == 'lua'
      then return true -- load every lua file
      end
    end,
    deps = function(e, opts)
      return e.src:gsub(env.regex, function(bef, name)
        name = name:gsub('%.', '/') -- lua.lua => lua/lua
        if bef:match '%-%-'
        then return '' end -- under comment
        local d = lp.get(name, e, opts)
        if d then
          return bef.. env.require:format(d.i)
        end
      end)
    end,
    transform = function(e, opts)
      if not e.entry then return end -- change only entry files
      if e.reqs > 0 then
        local m = ''
        for i = 1, #opts.ext do
          local v = opts.ext[opts.ext[i]] -- [i] => [file] => object
          m = m.. lp.strf(lp.strf(env.mtemp, env), v)
        end
        return base:format(main, opts.ext[e.file].i, m)
      end
    end,
    postbuild = function(e, opts)
      local f, err = load(e.src, 'lint')
      if err then
        print(e.src)
        error(err)
      end
    end,
  }
end