import {Pipe, PipeTransform} from '@angular/core';

@Pipe({ name: 'orderBy', pure: false })
export class OrderBy implements PipeTransform {

    static _orderByComparator(a: any, b: any): number {
       

        if (a != undefined && b == undefined) {
           
            return -1;
        }
        if (a == undefined && b != undefined) {

            return 1;
        }

        if (a == undefined && b == undefined) {

            return 0;
        }

        if ((isNaN(parseFloat(a)) || !isFinite(a)) || (isNaN(parseFloat(b)) || !isFinite(b))) {
            //Isn't a number so lowercase the string to properly compare
            if (a.toLowerCase() < b.toLowerCase()) return -1;
            if (a.toLowerCase() > b.toLowerCase()) return 1;
        }
        else {
            //Parse strings as numbers to compare properly
            if (parseFloat(a) < parseFloat(b)) return -1;
            if (parseFloat(a) > parseFloat(b)) return 1;
        }

        return 0; //equal each other
    }

    transform(input: any, [config = '+']): any {
        
        if (!Array.isArray(input)) return input;

        if (!Array.isArray(config) || (Array.isArray(config) && config.length == 1)) {
            var propertyToCheck: string = !Array.isArray(config) ? config : config[0];
            var desc = propertyToCheck.substr(0, 1) == '-';
            
            //Basic array
            if (!propertyToCheck || propertyToCheck == '-' || propertyToCheck == '+') {
                return !desc ? input.sort() : input.sort().reverse();
            }
            else {
                var property: string = propertyToCheck.substr(0, 1) == '+' || propertyToCheck.substr(0, 1) == '-'
                    ? propertyToCheck.substr(1)
                    : propertyToCheck;
                
                return input.sort(function (a: any, b: any) {
                    return !desc ?  OrderBy._orderByComparator(a[property], b[property])
                            : -OrderBy._orderByComparator(a[property], b[property]);
                });
            }
        }
        else {
            
            //Loop over property of the array in order and sort
            return input.sort(function (a: any, b: any) {
                for (var i: number = 0; i < config.length; i++) {
                    var desc = config[i].substr(0, 1) == '-';
                    var property = config[i].substr(0, 1) == '+' || config[i].substr(0, 1) == '-'
                        ? config[i].substr(1)
                        : config[i];

                    var comparison = !desc ?
                 OrderBy._orderByComparator(a[property], b[property])
                            : -OrderBy._orderByComparator(a[property], b[property]);
                    
                    //Don't return 0 yet in case of needing to sort by next property
                    if (comparison != 0) return comparison;
                }

                return 0; //equal each other
            });
        }
    }
}