loadsave functions

local _ = {}
local json = require("Json")
local DefaultLocation = system.DocumentsDirectory
local RealDefaultLocation = DefaultLocation
local ValidLocations = {
   [system.DocumentsDirectory] = true,
   [system.CachesDirectory] = true,
   [system.TemporaryDirectory] = true
}

function _.saveTable(t, filename, location)
    if location and (not ValidLocations[location]) then
     error("Attempted to save a table to an invalid location", 2)
    elseif not location then
      location = DefaultLocation
    end

    local path = system.pathForFile( filename, location)
    local file = io.open(path, "w")
    if file then
        local contents = json.encode(t)
        file:write( contents )
        io.close( file )
        return true
    else
        return false
    end
end

function _.loadTable(filename, location)
    if location and (not ValidLocations[location]) then
     error("Attempted to load a table from an invalid location", 2)
    elseif not location then
      location = DefaultLocation
    end
    local path = system.pathForFile( filename, location)
    local contents = ""
    local myTable = {}
    local file = io.open( path, "r" )
    if file then
        -- read all contents of file into a string
        local contents = file:read( "*a" )
        myTable = json.decode(contents);
        io.close( file )
        return myTable
    end
    return nil
end

function _.changeDefault(location)
    if location and (not location) then
        error("Attempted to change the default location to an invalid location", 2)
    elseif not location then
        location = RealDefaultLocation
    end
    DefaultLocation = location
    return true
end

return _