--
--  gcsd
--
--  gcsd the generic command sequencer daemon can be used to serialize
--  commands sent over various paralell communication channels to a
--  single command output. It can be seen as a multiplexer for any
--  kind of communication between a single resource and various clients
--  which want to submit commands to it or query information from it.
--  gcsd is written in C and Lua. The goal is to provide an easy to
--  understand high level API based on Lua which can be used to
--  implement the business logic of the so formed multiplexer daemon.
--
--
--  Copyright (C) 2009-2010 Markus Grueneis <gimpf@spreadspace.org>
--                          Christian Pointner <equinox@spreadspace.org>
--
--  This file is part of gcsd.
--
--  gcsd is free software: you can redistribute it and/or modify
--  it under the terms of the GNU General Public License as published by
--  the Free Software Foundation, either version 3 of the License, or
--  any later version.
--
--  gcsd is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--  GNU General Public License for more details.
--
--  You should have received a copy of the GNU General Public License
--  along with gcsd. If not, see <http://www.gnu.org/licenses/>.
--

module_list = {}

module_list.classes = {}
local mt = {}
function mt.__index(table, key)
   local value = rawget(table, key)
   if(value ~= nil) then return value end

   log.printf(log.DEBUG, "load module class: %s", key)

   local filename = defines.MODULES_PATH .. "/" .. key .. ".lua"
   local chunk, err = loadfile(filename)
   if (not chunk) then
      error("failed to load module: " .. err)
   end
   value = chunk()
   rawset(table, key, value)
   return value
end
setmetatable(module_list.classes, mt)

module_list.inputs = {}
module_list.output = nil

function module_list:new_instance(class_name, config, runtype)
   class = self.classes[class_name]
   if(class.__num_inst) then
      if(class.properties.max_instances >= 1 and
         class.__num_inst >= class.properties.max_instances) then
         error("max instances of " .. class_name .. " reached");
      end
      class.__num_inst = class.__num_inst + 1
   else
      class.__num_inst = 1
   end

   return class:new(config, runtype)
end

function module_list:init(opt)
   local class, config = self:parse_config(opt.cmd_out)
   if(not class) then return defines.KILL_DAEMON end
   if(self.classes[class].properties.type ~= defines.OUT_MODULE and
      self.classes[class].properties.type ~= defines.INOUT_MODULE) then
      log.printf(log.ERROR, "module class '%s' cannot be used as output module", class);
      return defines.KILL_DAEMON
   end
   log.printf(log.DEBUG, "output module class='%s'", class)
   for k, v in pairs(config) do
      log.printf(log.DEBUG, "              config['%s'] = '%s'", k, v)
   end
   self.output = self:new_instance(class, config, defines.OUT_MODULE)

   for idx, input in ipairs(opt.cmd_ins) do
      local class, config = self:parse_config(input)
      if(not class) then return defines.KILL_DAEMON end
      if(self.classes[class].properties.type ~= defines.IN_MODULE and
         self.classes[class].properties.type ~= defines.INOUT_MODULE and
         self.classes[class].properties.type ~= defines.MISC_MODULE) then
         log.printf(log.ERROR, "module class '%s' cannot be used as input module", class);
         return defines.KILL_DAEMON
      end

      log.printf(log.DEBUG, "input[%d] module class='%s'", idx, class)
      for k, v in pairs(config) do
         log.printf(log.DEBUG, "                config['%s'] = '%s'", k, v)
      end
      table.insert(self.inputs, self:new_instance(class, config, defines.IN_MODULE))
   end

   return defines.OK
end

function module_list:parse_config(module_config)
   local class, config_string = string.match(module_config, "^([%w-_]+):(.+)$")
   if(not class or not config_string) then
      log.printf(log.ERROR, "module config format error: '%s'", module_config)
      return nil
   end
   local config = {}
   for k, v in string.gmatch(config_string .. ",", "([^,=]+)=([^,=]+),") do
      config[k] = v
   end

   return class, config
end

function module_list:unregister(module)
   if(module == self.output) then
      log.printf(log.WARNING, "output module can't be removed safely, closing daemon")
      return defines.KILL_DAEMON
   end

   for i, m in ipairs(self.inputs) do
      if(m == module) then
         log.printf(log.INFO, "removing input module: " .. module.name)
         module:cleanup()
         table.remove(self.inputs, i)
         break
      end
   end

   return defines.OK
end

function module_list:unregister_by_class(class)
   local free_list = {}

   if(self.output.class == class) then
      log.printf(log.WARNING, "output module can't be removed safely, closing daemon")
      return defines.KILL_DAEMON
   end

   for i, m in ipairs(self.inputs) do
      if(m.class == class) then
         table.insert(free_list, 1, i)
      end
   end

   for _, i in ipairs(free_list) do
      log.printf(log.INFO, "removing input module: " .. self.inputs[i].name)
      self.inputs[i]:cleanup()
      table.remove(self.inputs, i)
   end

   return defines.OK
end

function module_list:cleanup()
   for _, module in ipairs(self.inputs) do
      log.printf(log.INFO, "removing input module: " .. module.name)
      module:cleanup()
   end
   if(self.output ~= nil) then
      log.printf(log.INFO, "removing output module: " .. self.output.name)
      self.output:cleanup()
   end
   self.inputs = {}
end