--[[
Copyright (c) 2012-2013 Kaarle Ritvanen
See LICENSE file for license details
--]]

module(..., package.seeall)

local loadmods = require('acf.loader').loadmods
local object = require('acf.object')
local pth = require('acf.path')
local util = require('acf.util')


DataStore = object.class(require('acf.transaction.backend').TransactionBackend)

function DataStore:init()
   object.super(self, DataStore):init()
   self.backends = util.map(
      function(m) return m.backend() end,
      loadmods('persistence/backends')
   )
end

function DataStore:split_path(path)
   local comps = pth.split(path)
   local backend = self.backends[comps[1]]
   assert(backend)
   table.remove(comps, 1)
   return backend, comps
end

function DataStore:get(path, t)
   local backend, comps = self:split_path(path)
   local res = backend:get(comps, t)

   if t ~= nil and res ~= nil then
      local atype = type(res)

      if t == 'table' then assert(atype == 'table')

      else
	 assert(atype ~= 'table')

	 if t == 'string' then res = tostring(res)
	 elseif t == 'number' then res = tonumber(res)
	 elseif t == 'boolean' then res = res and true or false
	 elseif t == 'reference' then assert(atype == 'string')
	 else assert(false) end
      end
   end

   return util.copy(res), self.mod_time[path] or 0
end

function DataStore:_set_multiple(mods)
   local bms = {}
   
   for _, mod in ipairs(mods) do
      local path, t, value = unpack(mod)
      local backend, comps = self:split_path(path)
      table.insert(util.setdefault(bms, backend, {}), {comps, t, value})
   end

   for backend, bm in pairs(bms) do backend:set(bm) end
end