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

module(..., package.seeall)

local pth = require('acf.path')
local util = require('acf.persistence.util')

require 'posix'
require 'stringy'


backend = require('acf.object').class()

-- TODO cache expiration
function backend:init() self.cache = {} end

function backend:get(path, tpe)
   local name = pth.join('/', unpack(path))

   if not self.cache[name] then
      local t = posix.stat(name, 'type')
      if not t then return end

      if t == 'regular' then
	 self.cache[name] = util.read_file(name)

      elseif t == 'link' then
	 -- TODO handle relative symlinks
	 local target = posix.readlink(name)
	 assert(target)
	 if not tpe then return target end

	 assert(stringy.startswith(tpe, 'reference/files/'))
	 local scope = string.sub(tpe, 16, -1)..'/'

	 local slen = string.len(scope)
	 assert(string.sub(target, 1, slen) == scope)
	 return string.sub(target, slen + 1, -1)

      elseif t == 'directory' then
	 local res = {}
	 for _, fname in ipairs(posix.dir(name)) do
	    if not ({['.']=true, ['..']=true})[fname] then
	       table.insert(res, pth.name(fname))
	    end
	 end
	 return res

      else error('Unsupported file type: '..name) end
   end

   return self.cache[name]
end

function backend:set(mods)
   for _, mod in pairs(mods) do
      local path, tpe, value = unpack(mod)
      local name = pth.join('/', unpack(path))

      if not tpe then
	 print('DEL', name)

	 local t = posix.stat(name, 'type')
	 if t == 'directory' then
	    assert(posix.rmdir(name))
	 elseif t then assert(os.remove(name)) end

	 self.cache[name] = nil

      elseif tpe == 'table' then
	 assert(posix.mkdir(name))

      elseif stringy.startswith(tpe, 'reference/files/') then
	 -- TODO use relative symlink
	 os.remove(name)
	 assert(
	    posix.link(
	       pth.to_absolute(value, string.sub(tpe, 16, -1)), name, true
	    )
	 )

      else
	 local file = util.open_file(name, 'w')
	 file:write(tostring(value))
	 file:close()

	 self.cache[name] = value
      end
   end
end