js.lua

--[[
    MIT License

    Copyright (c) 2020 Marcelo Silva Nascimento Mancini

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
]]

local __requestQueue={}
local _requestCount=0
local _Request={
    command="",
    currentTime=0,
    timeOut=2,
    id='0',
}
local __defaultErrorFunction=nil
local isDebugActive=false

local JS={}

function JS.callJS(funcToCall)
    print("callJavascriptFunction "..funcToCall)
end

--You can pass a set of commands here and, it is a syntactic sugar for executing many commands inside callJS, as it only calls a function
--If you pass arguments to the func beyond the string, it will perform automatically string.format
--Return statement is possible inside this structure
--This will return a string containing a function to be called by JS.callJS
function JS.stringFunc(str,...)
    str="(function(){"..str.."})()"
    if (#arg>0) then
        str=str:format(unpack(arg))
    end
    str=str:gsub("[\n\t]","")
    return str
end

--The call will store in the webDB the return value from the function passed it timeouts
local function retrieveJS(funcToCall,filename)
    --Used for retrieveData function
    JS.callJS(("FS.writeFile('%s/%s',%s);"):format(love.filesystem.getSaveDirectory(),filename,funcToCall))
end

--Call JS.newRequest instead
function _Request:new(isPromise,command,onDataLoaded,onError,timeout,id)
    local obj={}
    setmetatable(obj,self)
    obj.command=command
    obj.onError=onError or __defaultErrorFunction
    if not isPromise then
        retrieveJS(command,self.filename)
    else
        JS.callJS(command)
    end
    obj.onDataLoaded=onDataLoaded
    obj.timeOut=(timeout==nil) and obj.timeOut or timeout
    obj.id=id
    obj.filename="__temp"..id


    function obj:getData()
        --Try to read from webdb
        if love.filesystem.getInfo(self.filename) then
            return love.filesystem.read(self.filename)
        end
    end

    function obj:purgeData()
        --Data must be purged for not allowing old data to be retrieved
        love.filesystem.remove(self.filename)
    end

    function obj:update(dt)
        self.timeOut=self.timeOut-dt
        local retData=self:getData()

        if ((retData~=nil and retData~="nil") or self.timeOut<=0) then
            if (retData~=nil and retData:match("ERROR")==nil) then
                if isDebugActive then
                    print("Data has been retrieved "..retData)
                end
                self.onDataLoaded(retData)
            else
                self.onError(self.id,retData)
            end
            self:purgeData()
            return false
        else
            return true
        end
    end
    return obj
end

--Place this function on love.update and set it to return if it returns false (This API is synchronous)
function JS.retrieveData(dt)
    local isRetrieving=#__requestQueue~=0
    local deadRequests={}
    for i=1,#__requestQueue do
        local isUpdating=__requestQueue[i]:update(dt)
        if not isUpdating then
            table.insert(deadRequests,i)
        end
    end
    for i=1,#deadRequests do
        if (isDebugActive) then
            print("Request died: "..deadRequests[i])
        end
        table.remove(__requestQueue,deadRequests[i])
    end
    return isRetrieving
end

--May only be used for functions that don't return a promise
function JS.newRequest(funcToCall,onDataLoaded,onError,timeout,optionalId)
    table.insert(__requestQueue,_Request:new(false,funcToCall,onDataLoaded,onError,timeout or 5,optionalId or _requestCount))
end

--This function can be handled manually (in JS code)
--How to: add the function call when your events resolve: FS.writeFile("Put love.filesystem.getSaveDirectory here", "Pass a string here (NUMBER DONT WORK"))
--Or it can be handled by Lua, it auto sets your data if you write the following command:
-- _$_(yourStringOrFunctionHere)
function JS.newPromiseRequest(funcToCall,onDataLoaded,onError,timeout,optionalId)
    optionalId=optionalId or _requestCount
    funcToCall=funcToCall:gsub("_$_%(","FS.writeFile('"..love.filesystem.getSaveDirectory().."/__temp"..optionalId.."', ")
    table.insert(__requestQueue,_Request:new(true,funcToCall,onDataLoaded,onError,timeout or 5,optionalId))
end


--It receives the ID from ther request
--Don't try printing the request.command, as it will execute the javascript command
function JS.setDefaultErrorFunction(func)
    __defaultErrorFunction=func
end

JS.setDefaultErrorFunction(function(id,error)
    if (isDebugActive) then
        local msg="Data could not be loaded for id:'"..id.."'"
        if (error) then
            msg=msg.."\nError: "..error
        end
        print(msg)
    end
end)


JS.callJS(JS.stringFunc("__getWebDB('%s');","__LuaJSDB"))

return JS