#!/usr/bin/env node

const fs = require('fs');  
const readline = require('readline');  
  
function calculateEntropy(probabilities) {  
    let sum = 0;  
    for (let p of probabilities) {  
        if (p < 0) {  
            throw new Error('请输入大于0的数');  
        }else if(p > 1){
            throw new Error('请输入小于1的数');  
        }
        sum += p;  
    }  
  
    if (sum > 1) {  
        throw new Error('概率空间不封闭，概率和大于1');  
    }else if(sum <1){
        throw new Error('概率空间不封闭，概率和小于1');  
    }
  
    return -probabilities.reduce((acc, p) => acc + p * Math.log2(p), 0);  
}  
  
function parseProbabilities(input) {  
    const separators = [',', ' '];  
    let separator = null;  
    let trimmedInput = input.trim();  

    if (trimmedInput.includes(',') && trimmedInput.includes(' ')) {  
        throw new Error('请输入正确数字！');  
    } 
  
    // 查找分隔符  
    for (let sep of separators) {  
        if (trimmedInput.includes(sep)) {  
            separator = sep;  
            break;  
        }  
         
    }  
  
    // 使用找到的分隔符分割字符串，并尝试将每个部分转换为数字  
    const parts = trimmedInput.split(separator);  
    const probabilities = parts.map(p => {  
        const num = Number(p);  
        if (!Number.isFinite(num)) {  
            throw new Error('请输入有效的数字!');  
        }  
        return num;  
    });  

    if (!separator && trimmedInput !== '') {  
        throw new Error('命令行参数错误: 概率数据少于两个!');  
    } 
  
    // 如果没有找到分隔符但输入为空，返回空数组  
    if (!separator && trimmedInput === '') {  
        return [];  
    }  
  
    // 返回转换后的概率数组  
    return probabilities;  
}

function main() {  
    const args = process.argv.slice(2);  
    if (args.length === 0) {  
        // 交互输入  
        const rl = readline.createInterface({  
            input: process.stdin,  
            output: process.stdout  
        });  
  
        rl.question('请输入信源概率分布：（Ctrl+D退出输入） ', (input) => {  
             
                const probabilities = parseProbabilities(input);  
                const entropy = calculateEntropy(probabilities);  
                console.log(`Entropy: ${entropy.toFixed(4)} bits`);  
            }  
        );  
    } else {  
        try {  
            const probabilities = parseProbabilities(args.join(','));  
            const entropy = calculateEntropy(probabilities);  
            console.log(`Entropy: ${entropy.toFixed(4)} bits`);  
        } catch (error) {  
            console.error(error.message);  
        }  
    }  
}  
  
main();