index.js

/**
 * Automatically detects new posts made on Reddit that match the specified 
 * queries and are in the specified subreddits, and sends them to Discord.
 * @author @eric-lu-VT (Eric Lu)
 */

require('dotenv').config();

const mongoose = require('mongoose');
const RedditPost = require('./schema/redditPost');
const ServerPost = require('./schema/serverPost');
var snoowrap = require('snoowrap');

const { Client, Intents, MessageEmbed } = require('discord.js');
const { REST } = require('@discordjs/rest');
const { Routes } = require('discord-api-types/v9');
const { commands } = require('./deploy-commands.js');

// Connect to MongoDB
mongoose.connect(process.env.MONGOURI, { useNewUrlParser: true, useUnifiedTopology: true })
    .then((result) => console.log('Connected to MongoDB'))
    .catch((err) => console.log(err));

// Connect to Reddit API
const reddit = new snoowrap({
    userAgent: process.env.USERAGENT,
    clientId: process.env.REDDITBOTID,
    clientSecret: process.env.REDDITBOTSECRET,
    username: process.env.REDDITUSERUSERNAME,
    password: process.env.REDDITUSERPASSWORD
});

// Connect to Discord API
const client = new Client({ intents: [Intents.FLAGS.GUILDS] });
var handle = null;

/**
 * For each Discord server Bot is in, search for the queries attributed to the Discord server,
 * and post the results to the Discord server.
 * @param {Array.<String>} guilds list of all guild ids found in database
 */
function searchReddit(guilds) {
    guilds.forEach((guildId) => {
        ServerPost.findOne({ _id: guildId}, ['channels', 'queries']).then((resdoc) => {        
            resdoc.queries.forEach(q => {
                reddit.getSubreddit(q.subreddit).search({query: q.query, time: 'hour', sort: 'new'}).then(data => {
                    data.forEach(listing => {
                        RedditPost.exists({postid: listing.name, guildId: guildId}).then((result) => {
                            if(result) {
                                // ("entry already exists");
                            }
                            else {
                                // Send Reddit search information to database
                                new RedditPost({
                                    postid: listing.name,
                                    subreddit: (listing.subreddit_name_prefixed),
                                    url: ("https://www.reddit.com" + listing.permalink),
                                    date: listing.created_utc,
                                    guildId: guildId
                                }).save();
                                // console.log("Made an entry to DB");
                                
                                var title = (listing.title);
                                if(title.length > 253) {  // For Reddit posts, max character length = 256
                                    title = title.substring(0, 253) + "...";
                                }
                                         
                                // For each elligible channel in the Discord server, send query results
                                resdoc.channels.forEach(channelId => {
                                    client.channels.cache.get(channelId).send({embeds : [new MessageEmbed()
                                        .setColor([255, 165, 0])
                                        .setAuthor(listing.author.name, "", encodeURI("https://www.reddit.com/u/" + listing.author.name))
                                        .setTitle(title)
                                        .setDescription(listing.score + " votes and " + listing.num_comments + " comments so far")
                                        .setFooter("On " + listing.subreddit_name_prefixed)
                                        .setTimestamp(listing.created * 1000)
                                        .setURL("https://www.reddit.com" + listing.permalink)]});
                                });
                            }
                        });
                    });
                });
            });
        });
    });
}

/**
 * Initializes slash commands for servers and begins search timer.
 * Run this command each time bot first turns on.
 */
function registerCommands() {
    var guilds = [];
    
    ServerPost.find({}, ['_id']).then((doc) => {
        const rest = new REST({ version: '9' }).setToken(process.env.DISCORDBOTTOKEN);
        doc.forEach(res => {
            guilds.push(res._id);
            rest.put(Routes.applicationGuildCommands(process.env.DISCORDID, res._id), { body: commands })
                .then().catch(console.error);
            });
    });

    handle = setInterval(() => searchReddit(guilds), 30000);  // run every 30 seconds
}

/**
 * Processes to run when bot first connects to Discord.
 * @listens 'ready' 
 */
client.once('ready', () => {
	registerCommands();
    console.log('Connected to Discord');
});

/**
 * Processes to run when a slash command is received.
 * @listens 'interactionCreate' 
 */
client.on('interactionCreate', async interaction => {
	if (!interaction.isCommand()) return; // only process slash commands

	const { commandName } = interaction;

	if (commandName === 'ping') {
		await interaction.reply('Pong!');
    } 
    else if(commandName === 'addchannel') {
        // Add channel to corresponding Discord server in the database
        ServerPost.findOneAndUpdate({_id: interaction.guildId}, 
                                    { $push : { 'channels': interaction.channelId}}, 
                                    {upsert: true}).then(data => {});
            
        // Display add results to Discord server
        var embd = new MessageEmbed()
            .setColor([46, 204, 113])
            .setTitle("Added channel!")
            .setDescription("Added the following channel:")
            .addField("Channel", String(interaction.channelId))
            .addField("Server", String(interaction.guildId))
            .setAuthor(interaction.user.username, 
                `https://cdn.discordapp.com/avatars/${interaction.user.id}/${interaction.user.avatar}.png?size=256`)
            .setTimestamp();    
        await interaction.reply({embeds : [embd]});
    } 
    else if (commandName === 'removechannel') {
        // Remove channel from the corresponding server in the database
        ServerPost.findOneAndUpdate({_id: interaction.guildId}, 
            { $pull : { 'channels': interaction.channelId}}).then(data => {});

        // Display remove results to Discord server
        var embd = new MessageEmbed()
            .setColor([46, 204, 113])
            .setTitle("Removed channel!")
            .setDescription("Removed the following channel:")
            .addField("Channel", String(interaction.channelId))
            .addField("Server", String(interaction.guildId))
            .setAuthor(interaction.user.username, 
                `https://cdn.discordapp.com/avatars/${interaction.user.id}/${interaction.user.avatar}.png?size=256`)
            .setTimestamp();
        await interaction.reply({embeds : [embd]});
    }
    else if (commandName === 'addquery') {
        // Process which search term and subreddit to look for
        query = interaction.options.getString("input").split(" ");
        var queryStr = "";
        var subredditStr = "";
        if(query.length > 1) {
            if(query.length == 1) {
                queryStr = query[0];
                subredditStr = "All";
            }
            else {
                for(var i = 0; i < query.length - 1; i++) {
                    queryStr += query[i];
                }
                subredditStr = query[query.length - 1];
            }
        }
        queryStr = queryStr.toLowerCase();
        subredditStr = subredditStr.toLowerCase();

        // If query does not exist in database, send this:
        var embd = new MessageEmbed()
            .setColor([231, 76, 60])
            .setTitle("Failed to add query...")
            .setDescription("The following query already exists:")
            .addField("Query", String(queryStr))
            .addField("Subreddit", String(subredditStr))
            .setAuthor(interaction.user.username, 
                `https://cdn.discordapp.com/avatars/${interaction.user.id}/${interaction.user.avatar}.png?size=256`)
            .setTimestamp();

        // If query does exist in the database, handle as follows
        ServerPost.exists({_id: interaction.guildId, queries: {$elemMatch: {query: queryStr, subreddit: subredditStr}}})
        .then((result) => {
            if(!result) {
                ServerPost.findOneAndUpdate({_id: interaction.guildId}, 
                    { $push : { 'queries': {
                        query: queryStr,
                        subreddit: subredditStr
                    }}}, 
                    {upsert: true}).then(data => {});
                embd.setColor([46, 204, 113]);
                embd.setTitle("Added query!");
                embd.setDescription("Added the following query:");
            }
            interaction.reply({embeds : [embd]});
        });
    } 
    else if (commandName === 'removequery') {
        // Process which search term and subreddit to look for
        query = interaction.options.getString("input").split(" ");
        var queryStr = "";
        var subredditStr = "";
        if(query.length > 1) {
            if(query.length == 1) {
                queryStr = query[0];
                subredditStr = "All";
            }
            else {
                for(var i = 0; i < query.length - 1; i++) {
                    queryStr += query[i];
                }
                subredditStr = query[query.length - 1];
            }
        }
        queryStr = queryStr.toLowerCase();
        subredditStr =subredditStr.toLowerCase();

        // If query does not exist in database, send this:
        var embd = new MessageEmbed()
            .setColor([231, 76, 60])
            .setTitle("Failed to remove query...")
            .setDescription("The following query does not exist in the database:")
            .addField("Query", String(queryStr))
            .addField("Subreddit", String(subredditStr))
            .setAuthor(interaction.user.username, 
                `https://cdn.discordapp.com/avatars/${interaction.user.id}/${interaction.user.avatar}.png?size=256`)
            .setTimestamp();

        // If query does exist in the database, handle as follows
        ServerPost.exists({_id: interaction.guildId, queries: {$elemMatch: { query: queryStr, subreddit: subredditStr}}})
        .then((result) => {
            if(result) {
                ServerPost.findOneAndUpdate({_id: interaction.guildId}, 
                    { $pull : { 'queries': {
                        query: queryStr,
                        subreddit: subredditStr
                    }}}).then(data => {});
                embd.setColor([46, 204, 113]);
                embd.setTitle("Removed query!");
                embd.setDescription("Removed the following query:");
            }
            interaction.reply({embeds : [embd]});
        });
    }
});

/**
 * Processes to run when the bot is added to a new Discord server.
 * @listens "guildCreate"
 */
client.on("guildCreate", guild => {
    clearInterval(handle);
    var channels = [];
    guild.channels.cache.forEach((channel) => {
        if(channel.type == "GUILD_TEXT" 
        && channel.permissionsFor(client.user).has("VIEW_CHANNEL")
        && channel.permissionsFor(client.user).has("SEND_MESSAGES")) {
            channels.push(channel.id);
        }
    })

    new ServerPost({ //TODO: figure out a way to not need to upload dummy entry to database
        _id: guild.id,
        channels: channels,
        queries: [{
            query: "asgagagasgasag",
            subreddit: "asgagagasgasag"
        }]
    }).save();

    registerCommands();
});

/**
 * Processes to run when the bot is removed from a Discord server.
 * @listens "guildDelete"
 */
client.on("guildDelete", guild => {
    clearInterval(handle);
    ServerPost.findOneAndRemove({_id: guild.id}).then(data => {});
    registerCommands();
});

client.login(process.env.DISCORDBOTTOKEN); // Formally turn on bot