class RandomGenerator{

    constructor( cache ){
        this.rng = new Uint8Array( cache  );
        this.index = cache-- ;
        this.generate();
    }

    generate(){
        window.crypto.getRandomValues(this.rng);
        this.index = this.rng.length - 2;
        return  this.rng.length - 1;
    }

    next(){
        return (this.index < 0)? this.generate() : this.index--;
    }

    rand(){
        return this.rng[ this.next() ]/256 ;
    }
    
    get( max, min ){
        min = ( typeof min === "number")? min : 0 ;
        return Math.round(this.rand() * (max - min) + min);
    }

    roll10( explode ){
        explode = ( typeof explode === "number")? differenceToArray( explode, 10 ) : [10];
        let dice = this.get( 10, 1 );
        return  ( explode.indexOf( dice ) >= 0 )? 10 + this.roll10( explode ) : dice ;
    }

    rk10( r, k, malus, explode ){
        let rolls = [];
        if((typeof r === "unsigned") || (typeof k === "unsigned"))
            return 0;
        malus = ( typeof malus === "unsigned")? 0 : malus ;
        for(let i = 0 ; i < r ; i++)
            rolls[i] = this.roll10( explode );
        sort( rolls );
        return rolls.slice( 0, k ).reduce((a, b) => a + b) - (malus || 0);
    }
}

function differenceToArray( min, max ) {
    let result = []
    for( let i = min; i <= max; i++)
        result.push(i) ; 
    return result;
}

function sort( array ){
    let temp = 0;
    var unsorted = true ;
    while(unsorted){
        unsorted = false;
        for(let i = 0; i < array.length -1 ; i++){
            if(array[ i ] < array[ i + 1 ]){
               temp = array[ i ];
               array[ i ] = array[ i + 1 ];
               array[ i + 1 ] = temp;
               unsorted =  true;
           }
       }
    }
}

function sortAssociative( array_arg ){
    let result = {};
    let array = array_arg;
    let higher = 1;
    while( !higher ){
        higher = 0;
        for(let i in array){
            higher = (higher)?
                (array[higher] < array[i])? i : higher : i ;
            if(array[ i ] < array[ i + 1 ]){
                temp = array[ i ];
                array[ i ] = array[ i + 1 ];
                array[ i + 1 ] = temp;
                unsorted =  true;
            }
        }
        if(higher){
            result.push(higher);
            delete array[ higher ];
            higher = 0;
        }
    }
    return result;
}


function random( max, min ){
    min = (typeof min == "undefined")? 0 : min;
    return Math.floor(Math.random() * (max - min + 1) + min);
}

function r_gender(){
    return (random(1))? "f": "m";
}

function arrayAt( index, array ){
    let i = 0;
    let result = {};
    for(let obj in array){
        if( index == ++i ){
            result[obj] = array[obj];
            return result;
        }
    }
}

function arrayAtWeight( index, array ){
    let i = 0;
    for(let obj in array){
        if(( i <= index ) && ( index <= (i + array[obj].occurence))){
            let rs = {};
            rs[ obj ] = array[obj];
            return rs;
        }
        i += array[obj].occurence ;
    }
    return null;
}

function arrayLength( array ){
    let i = 0;
    for(let obj in array){
        i++;
    };
    return i;
}

function arrayWeight( array ){
    let i = 0;
    for(let obj in array){
        i += array[obj].occurence;
    };
    return i;
}

function randomFromAssociative( array ){
    return arrayAt( random( arrayLength( array ), 1), array) ;
}

function randomFromArray( array ){
    return array[ random( arrayLength( array )) ] ;
}

function randomFromWeight( array ){
    return arrayAtWeight( random( arrayWeight( array )), array) ;
}