webdb.js

/**
 * @author Marcelo Silva Nascimento Mancini
 * @github https://github.com/MrcSnm/Love.js-Api-Player
 */

//This line is needed for retrieving data from .lua
//Please remember that this is not a flexible API, it should be used with consolewrapper.js + love.js
//This will activate the web database for using in conjunction to .lua + love.js
window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB; 
if(!window.indexedDB)
{
    alert("Please, update your browser to newer versions or you won't be able to save your game")
}

var __webDb = null;
var __webTunnel = ""
var __currRequest = null
async function __getWebDB(dbName)
{
    if(__webTunnel == "")
        __webTunnel = dbName;
    return new Promise(function(resolve, reject)
    {
        if(__webDb != null)
        {
            console.log("Already connected with WebDB")
            return resolve();
        }
        if(__currRequest != null)
        {
            let success = __currRequest.onsuccess
            __currRequest.onsuccess = function()
            {
                success()
                console.log("Request stack completed")
                return resolve();
            }
            let blocked = __currRequest.onblocked
            __currRequest.onblocked = function()
            {
                blocked()
                return reject();
            }
        }
        else
        {
            __currRequest = indexedDB.open(dbName);
            __currRequest.onerror = function()
            {
                console.error("Some error ocurred when trying to access web database '" + dbName + "'");
                reject();
            }
            //This webdb should not change version, so it will not add any field
            __currRequest.onupgradeneeded = function()
            {
                __webDb = __currRequest.result;
                __webDb.createObjectStore("FILE_DATA");
            }
            __currRequest.onblocked = function(ev)
            {
                console.error("Access to the web database were blocked, please refresh the page");
                reject();
            }
            __currRequest.onsuccess = function()
            {
                __webDb = __currRequest.result;
                console.log("Connected with WebDB '"+dbName+"'")
            }
        }
    })
}

/**
 * This function must not be called manually
 * @param {any} val 
 */
function ___convertToUint8Array(val)
{
    val = String(val);
    let content = new Uint8Array(val.length);
    for(i = 0, len = val.length; i < len; i++)
    {
        content[i] = (val[i]).charCodeAt(0);
    }
    return content;
}

/**
 * This function must not be called manually
 * @param {any} value 
 */
function ___getLoveJSCompatibleObject(value)
{
    value = ___convertToUint8Array(value); //Content must be Uint8Array

    return {
        timestamp: Date.now(),
        mode : 33152, //For some reason it is the mode used for when doing love.filesystem.write
        contents: value //Uint8Array
    }
}

async function __storeWebDB(value, objStore, where)
{
    await __getWebDB(__webTunnel);
    console.log("Storing value '" + value + "'")    
    let lovejsCompatibleObject = ___getLoveJSCompatibleObject(value)

    let transaction = __webDb.transaction(objStore, "readwrite");
    let store = transaction.objectStore(objStore);
    let request = store.put(lovejsCompatibleObject, where);
    request.onsuccess = function()
    {
        console.log("'" + value + "' were succesfully added to "+where);
    }
    request.onerror = function()
    {
        console.error("Could not add the value '" + value + "' to "+where +": " + request.error);
    }
}

function __unconvertFromUint8Array(arr)
{
    return String.fromCharCode(arr);
}

/**
 * Please use it only for debugging purposes
 * @param {String= "FILE_DATA"} objStore 
 */
async function __readWebDB(objStore, where)
{
    await __getWebDB(__webTunnel);
    objStore = (objStore == undefined) ? "FILE_DATA" : objStore;
    let transaction = __webDb.transaction(objStore, "readonly");
    let store = transaction.objectStore(objStore);
    let request = store.get(where);
    request.onsuccess = function()
    {
        console.log("Value gotten: " + __unconvertFromUint8Array(request.result.contents));
    }   
}

if(typeof FS === 'undefined')
{
    FS = {};
    FS.writeFile = function(where, content)
    {
        __storeWebDB(content, "FILE_DATA", where);
    }
}