persistence.js

var Persistence = function(table){
    this.table = table; //hold Tabulator object
    this.mode = "";
    this.id = "";
    // this.persistProps = ["field", "width", "visible"];
    this.defWatcherBlock = false;
    this.config = {};
    this.readFunc = false;
    this.writeFunc = false;
};

// Test for whether localStorage is available for use.
Persistence.prototype.localStorageTest = function() {
    var  testKey =  "_tabulator_test";

    try {
        window.localStorage.setItem( testKey, testKey);
        window.localStorage.removeItem( testKey );
        return true;
    } catch(e) {
        return false;
    }
};

//setup parameters
Persistence.prototype.initialize = function(){
    //determine persistent layout storage type

    var mode = this.table.options.persistenceMode,
    id = this.table.options.persistenceID,
    retreivedData;

    this.mode = mode !== true ?  mode : (this.localStorageTest() ? "local" : "cookie");

    if(this.table.options.persistenceReaderFunc){
        if(typeof this.table.options.persistenceReaderFunc === "function"){
            this.readFunc = this.table.options.persistenceReaderFunc;
        }else{
            if(this.readers[this.table.options.persistenceReaderFunc]){
                this.readFunc = this.readers[this.table.options.persistenceReaderFunc];
            }else{
                console.warn("Persistence Read Error - invalid reader set", this.table.options.persistenceReaderFunc);
            }
        }
    }else{
        if(this.readers[this.mode]){
            this.readFunc = this.readers[this.mode];
        }else{
            console.warn("Persistence Read Error - invalid reader set", this.mode);
        }
    }

    if(this.table.options.persistenceWriterFunc){
        if(typeof this.table.options.persistenceWriterFunc === "function"){
            this.writeFunc = this.table.options.persistenceWriterFunc;
        }else{
            if(this.readers[this.table.options.persistenceWriterFunc]){
                this.writeFunc = this.readers[this.table.options.persistenceWriterFunc];
            }else{
                console.warn("Persistence Write Error - invalid reader set", this.table.options.persistenceWriterFunc);
            }
        }
    }else{
        if(this.writers[this.mode]){
            this.writeFunc = this.writers[this.mode];
        }else{
            console.warn("Persistence Write Error - invalid writer set", this.mode);
        }
    }

    //set storage tag
    this.id = "tabulator-" + (id || (this.table.element.getAttribute("id") || ""));

    this.config = {
        sort:this.table.options.persistence === true || this.table.options.persistence.sort,
        filter:this.table.options.persistence === true || this.table.options.persistence.filter,
        group:this.table.options.persistence === true || this.table.options.persistence.group,
        page:this.table.options.persistence === true || this.table.options.persistence.page,
        columns:this.table.options.persistence === true ? ["title", "width", "visible"] : this.table.options.persistence.columns,
    };

    //load pagination data if needed
    if(this.config.page){
        retreivedData = this.retreiveData("page");

        if(retreivedData){
            if(typeof retreivedData.paginationSize !== "undefined" && (this.config.page === true || this.config.page.size)){
                this.table.options.paginationSize = retreivedData.paginationSize;
            }

            if(typeof retreivedData.paginationInitialPage !== "undefined" && (this.config.page === true || this.config.page.page)){
                this.table.options.paginationInitialPage = retreivedData.paginationInitialPage;
            }
        }
    }

    //load group data if needed
    if(this.config.group){
        retreivedData = this.retreiveData("group");

        if(retreivedData){
            if(typeof retreivedData.groupBy !== "undefined" && (this.config.group === true || this.config.group.groupBy)){
                this.table.options.groupBy = retreivedData.groupBy;
            }
            if(typeof retreivedData.groupStartOpen !== "undefined" && (this.config.group === true || this.config.group.groupStartOpen)){
                this.table.options.groupStartOpen = retreivedData.groupStartOpen;
            }
            if(typeof retreivedData.groupHeader !== "undefined" && (this.config.group === true || this.config.group.groupHeader)){
                this.table.options.groupHeader = retreivedData.groupHeader;
            }
        }
    }
};


Persistence.prototype.initializeColumn = function(column){
    var self = this,
    def, keys;

    if(this.config.columns){
        this.defWatcherBlock = true;

        def = column.getDefinition();

        keys = this.config.columns === true ? Object.keys(def) : this.config.columns;

        keys.forEach((key)=>{
            var props = Object.getOwnPropertyDescriptor(def, key);
            var value = def[key];
            if(props){
                Object.defineProperty(def, key, {
                    set: function(newValue){
                        value = newValue;

                        if(!self.defWatcherBlock){
                            self.save("columns");
                        }

                        if(props.set){
                            props.set(newValue);
                        }
                    },
                    get:function(){
                        if(props.get){
                            props.get();
                        }
                        return value;
                    }
                });
            }
        });

        this.defWatcherBlock = false;
    }

};

//load saved definitions
Persistence.prototype.load = function(type, current){
    var data = this.retreiveData(type);

    if(current){
        data = data ? this.mergeDefinition(current, data) : current;
    }

    return data;
};

//retreive data from memory
Persistence.prototype.retreiveData = function(type){
    return this.readFunc ? this.readFunc(this.id, type) : false;
};

//merge old and new column definitions
Persistence.prototype.mergeDefinition = function(oldCols, newCols){
    var self = this,
    output = [];

    // oldCols = oldCols || [];
    newCols = newCols || [];

    newCols.forEach(function(column, to){

        var from = self._findColumn(oldCols, column),
        keys;

        if(from){

            if(self.config.columns === true || self.config.columns == undefined){
                keys =  Object.keys(from);
                keys.push("width");
            }else{
                keys = self.config.columns;
            }

            keys.forEach((key)=>{
                if(typeof column[key] !== "undefined"){
                    from[key] = column[key];
                }
            });

            if(from.columns){
                from.columns = self.mergeDefinition(from.columns, column.columns);
            }


            output.push(from);
        }

    });

    oldCols.forEach(function (column, i) {
        var from = self._findColumn(newCols, column);
        if (!from) {
            if(output.length>i){
                output.splice(i, 0, column);
            }else{
                output.push(column);
            }
        }
    });

    return output;
};

//find matching columns
Persistence.prototype._findColumn = function(columns, subject){
    var type = subject.columns ? "group" : (subject.field ? "field" : "object");

    return columns.find(function(col){
        switch(type){
            case "group":
            return col.title === subject.title && col.columns.length === subject.columns.length;
            break;

            case "field":
            return col.field === subject.field;
            break;

            case "object":
            return col === subject;
            break;
        }
    });
};

//save data
Persistence.prototype.save = function(type){
    var data = {};


    switch(type){
        case "columns":
        data = this.parseColumns(this.table.columnManager.getColumns())
        break;

        case "filter":
        data = this.table.modules.filter.getFilters();
        break;

        case "sort":
        data = this.validateSorters(this.table.modules.sort.getSort());
        break;

        case "group":
        data = this.getGroupConfig();
        break;

        case "page":
        data = this.getPageConfig();
        break;
    }

    if(this.writeFunc){
        this.writeFunc(this.id, type, data);
    }

};

//ensure sorters contain no function data
Persistence.prototype.validateSorters = function(data){
    data.forEach(function(item){
        item.column = item.field;
        delete item.field;
    });

    return data;
};

Persistence.prototype.getGroupConfig = function(){
    if(this.config.group){
        if(this.config.group === true || this.config.group.groupBy){
            data.groupBy = this.table.options.groupBy;
        }

        if(this.config.group === true || this.config.group.groupStartOpen){
            data.groupStartOpen = this.table.options.groupStartOpen;
        }

        if(this.config.group === true || this.config.group.groupHeader){
            data.groupHeader = this.table.options.groupHeader;
        }
    }

    return data;
};

Persistence.prototype.getPageConfig = function(){
    var data = {};

    if(this.config.page){
        if(this.config.page === true || this.config.page.size){
            data.paginationSize = this.table.modules.page.getPageSize();
        }

        if(this.config.page === true || this.config.page.page){
            data.paginationInitialPage = this.table.modules.page.getPage();
        }
    }

    return data;
};


//parse columns for data to store
Persistence.prototype.parseColumns = function(columns){
    var self = this,
    definitions = [];

    columns.forEach(function(column){
        var defStore = {},
        colDef = column.getDefinition(),
        keys;

        if(column.isGroup){
            defStore.title = colDef.title;
            defStore.columns = self.parseColumns(column.getColumns());
        }else{
            defStore.field = column.getField();

            if(self.config.columns === true || self.config.columns == undefined){
                keys =  Object.keys(colDef);
                keys.push("width");
            }else{
                keys = self.config.columns;
            }

            keys.forEach((key)=>{

                switch(key){
                    case "width":
                    defStore.width = column.getWidth();
                    break;
                    case "visible":
                    defStore.visible = column.visible;
                    break;

                    default:
                    defStore[key] = colDef[key];
                }

            });
        }

        definitions.push(defStore);
    });

    return definitions;
};

// read peristence information from storage
Persistence.prototype.readers = {
    local:function(id, type){
        var data = localStorage.getItem(id + "-" + type);

        return data ? JSON.parse(data) : false;
    },
    cookie:function(id, type){
        var cookie = document.cookie,
        key = id + "-" + type,
        cookiePos = cookie.indexOf(key + "="),
        end;

        //if cookie exists, decode and load column data into tabulator
        if(cookiePos > -1){
            cookie = cookie.substr(cookiePos);

            end = cookie.indexOf(";");

            if(end > -1){
                cookie = cookie.substr(0, end);
            }

            data = cookie.replace(key + "=", "");
        }

        return data ? JSON.parse(data) : false;
    }
};

//write persistence information to storage
Persistence.prototype.writers = {
    local:function(id, type, data){
        localStorage.setItem(id + "-" + type, JSON.stringify(data));
    },
    cookie:function(id, type, data){
        var expireDate = new Date();

        expireDate.setDate(expireDate.getDate() + 10000);

        document.cookie = id + "_" + type + "=" + JSON.stringify(data) + "; expires=" + expireDate.toUTCString();
    }
};


Tabulator.prototype.registerModule("persistence", Persistence);