xp.js

const fs = require('fs');

class XP {

    constructor(xpFile) {
        this.xpFile = xpFile;
    }

    ready() {
        this.checkIfXpFileExists();
        console.log("XP segment up and running.");
    }

    //check if the file with JSON data exists
    checkIfXpFileExists() {
        try {
            if (!fs.existsSync(this.xpFile)) {
                const xpData = { "xpData": [] };
                const data = JSON.stringify(xpData);
                fs.writeFileSync(this.xpFile, data);
            }
        }
        catch (err) {
            console.log("Unable to create XP File");
            console.error(err);
        }
    }

    //Check if a user wrote the message as opposed to a bot or discord itself
    checkIfMessageValid(message, botUserId) {
        if (!message.guild) return false;
        if (message.author.bot) return false;
        if (message.system) return false;
        if (message.toString().charAt(0) === '!') return false;
        if (message.author.id == botUserId) return false;
        return true;
    }

    lookUpAndIncrementXpData(data, message) {
        for (var index in data.xpData) {
            //we found the user data in the JSON file
            if (data.xpData[index].id === message.author.id) {
                let levelInfo = data.xpData[index].level;
                let levelUp = false;
                // increment messages
                data.xpData[index].numMessages = data.xpData[index].numMessages + 1;
                //if we've hit a new level
                if (data.xpData[index].numMessages >= data.xpData[index].messagesRequiredToNextLevel) {
                    levelInfo = levelInfo + 1;
                    levelUp = true;
                    //increment level data
                    data.xpData[index].level = data.xpData[index].level + 1;
                    if (levelInfo < 150) {
                        // determines messages to the next level
                        data.xpData[index].messagesRequiredToNextLevel = data.xpData[index].messagesRequiredToNextLevel * (2 * Math.exp(-1 * ((levelInfo - 1.7) / 4)) + 1.02);
                    }
                    else {
                        //past rank 150, flat 100 message increase to next level
                        data.xpData[index].messagesRequiredToNextLevel = data.xpData[index].messagesRequiredToNextLevel + 100;
                    }
                }
                return {
                    result: true,
                    level: levelInfo,
                    levelup: levelUp,
                    data: data
                }
            }
        }
        return {
            result: false,
            level: 1,
            levelUp: false,
            data: data
        }
    }
    //Create new data for users who are new to the server
    createXpData(message, data) {
        const xpInformation = {
            id: message.author.id,
            username: message.author.username,
            level: 1,
            numMessages: 1,
            messagesRequiredToNextLevel: 2
        };
        data.xpData.push(xpInformation);
        return data;
    }

    //looks up user data and updates it accordingly on new message events
    //returns true if level up
    updateXpData(message, botUserId, _callback) {
        if (this.checkIfMessageValid(message, botUserId)) {
            this.checkIfXpFileExists();
            fs.readFile(this.xpFile, (err, data) => {
                if (err) {
                    console.log("Unable to read XP File.");
                    throw err;
                }
                let xpDataRead = JSON.parse(data);
                const lookup = this.lookUpAndIncrementXpData(xpDataRead, message);
                let xpWrite = lookup['data'];
                if (!lookup['result']) {
                    xpWrite = this.createXpData(message, xpDataRead);
                }
                if (xpDataRead) {
                    const data = JSON.stringify(xpWrite);
                    fs.writeFile(this.xpFile, data, (err) => {
                        if (err) {
                            console.log("Unable to write to XP File");
                            throw err;
                        }
                    });
                    if (lookup['levelup']) {
                        _callback(lookup['level']);
                    }

                }
            });
        }
    }
}

module.exports = XP;