export module RandomEx {

    /**
     * 取得隨機布林值
     */
    export function GetBool() {
        return GetInt() >= 0;
    }
    /**
     * 取得隨機整數(回傳min ~ max - 1)
     * @param min
     * @param max
     */
    export function GetInt(min: number = Number.MIN_VALUE, max: number = Number.MAX_VALUE): number {
        return Math.floor(Math.random() * (max - min)) + min;
    }
    /**
     * 取得隨機小數
     * @param min 
     * @param max 
     */
    export function GetFloat(min: number = Number.MIN_VALUE, max: number = Number.MAX_VALUE): number {
        return Math.random() * (max - min) + min;
    }
    /**
     * 隨機取得複數個不重複回傳
     * @param num 取得數量
     * @param items 陣列 
     */
    export function GetMultiNoRepeat(num: number, items: any[]): any[] {
        let result: any[] = [];
        for (let i: number = 0; i < num; i++) {
            let ran: number = Math.floor(Math.random() * items.length);
            let item = items.splice(ran, 1)[0];
            if (result.indexOf(item) == -1) {
                result.push(item);
            }
        };
        return result;
    }

    /**
     * 根據權重取得複數個不重複回傳
     * @param prize 獎項
     * @param weights 機率
     * @param count 數量
     */
    export function GetMultiNoRepeatByWeight(prize: any[], weights: number[] = null, count: number = 1): any[] {
        if (weights === null) {
            weights = [];
            for (let i: number = 0; i < prize.length; i++) {
                weights.push(1);
            }
        }
        let target: any[] = [];
        for (let i: number = 0; i < count; i++) {
            let results: number[] = RandomEx.GetPrizeByWeight(prize, weights);
            prize.splice(results[0], 1);
            weights.splice(results[0], 1);
            target.push(results[1]);
        }
        return target;
    }


    /**
     * 根據權重隨機取值
     * @param prize 獎項
     * @param weights 機率
     */
    export function GetPrizeByWeight(prize: any[], weights: number[]): any[] {
        if (prize.length !== weights.length) {
            console.error(`GetWeight error -> prize.length:${prize.length} !== weights.length:${weights.length}`);
            return null;
        }
        let totalWeight: number = 0;
        for (let i: number = 0; i < weights.length; i++) {
            totalWeight += weights[i];
        }
        let random: number = RandomEx.GetInt(0, totalWeight) + 1;
        let nowWeight: number = weights[0];
        for (let i: number = 0; i < weights.length; i++) {
            if (nowWeight >= random) {
                return [i, prize[i]];
            }
            nowWeight += weights[i + 1];
        }
    }
}