metapost = (metapost or {})

function metapost.report (a)
   print ("\n" .. a)
end

function metapost.finder (name, mode, ftype)
   return (mode=="w" and  name) or kpse.find_file(name, ftype)
end

function metapost.make(name, target, finder)
   local status = 2 -- higher numbers are errors
   finder = (finder or metapost.finder)
   local mpx = mplib.new ( {
                             hash_size = 100000,
                             main_memory = 2000000,
                             max_in_open = 50,
                             param_size = 100000,
                             ini_version = true,
                             find_file = finder,
                             job_name = target,
                          } )
   if mpx then
      local result = mpx:execute("input " .. name .. "; dump;")
      if result then status = result.status end
      mpx:finish()
   end
   if status < 2 then
      metapost.report('mp message: created mem file ' .. target )
   else 
      metapost.report('mp error: mem file generation failed')
   end
end

function metapost.load(name, finder)
   finder = (finder or metapost.finder)
   local memname = finder("mplib-" .. name,"r","mem")
   if not memname then
      memname = finder("mplib-" .. name, "w", "mem")
      metapost.make(name, memname, finder)
   end
   metapost.report('mp message: using mem file ' .. memname)
   local mpx = mplib.new ( {
                             ini_version = false,
                             mem_name = memname,
                             find_file = finder,
                          } )
   if not mpx then
      metapost.report('mp error: mem loading failed')
   end
   return mpx
end

function metapost.process(mpx, data)
    local result
    if mpx and data then
        result = mpx:execute(data)
        -- todo: error message
        if not result then
           metapost.report("mp error: no result object returned")
        elseif result.status > 0 then
           metapost.report("mp error:" .. (result.term or "no-term") .. "\n" .. (result.error or "no-error"))
        end
     end
     return result
end