//module declarations
const Snoowrap = require('snoowrap');
const fs  = require("fs");
const util = require('util')

//authentication variables, change as required
const USER_AGENT =
const CLIENT_ID =
const CLIENT_SECRET =
const REDDIT_USER =
const REDDIT_PASS =

// this function reads names.txt and returns an array of the names, and removes duplicates
function readFile() {
    //replaces '\r' char with empty string. happens when you use windows to edit your text file...
    var str = fs.readFileSync('names.txt').toString().replace(/(\r)/gm,"");
    var arr = str.toString().split("\n");

    //remove duplicates
    var hashSet = new Set();
    for(var i=0;i<arr.length;i++) {
        hashSet.add(arr[i]);
    }

    //add back to array and return
    arr = [];
    const it = hashSet.entries();
    for(let entry of it) {
        arr.push(entry[0]);
    }
    return arr;
}

// this function creates the an object array of {name: reddit name, text: custom flair, cssClass: surveyresponder2018}
function convertArray(names) {
    var arr = [];
    for(var i=0;i<names.length;i++) {
        arr.push({name: names[i], text: ':SR2018_1::SR2018_2::SR2018_3::SR2018_4::SR2018_5::SR2018_6:', cssClass: 'surveyresponder2018'});
    }
    return arr;
}

// this function changes the flairs of specified users in the subreddit
async function changeFlairs(nameArray) {
    var isSuccessful = true;
    var error = {};
    //authenticate with reddit API
    const r = new Snoowrap({
        userAgent: USER_AGENT,
        clientId: CLIENT_ID,
        clientSecret: CLIENT_SECRET,
        username: REDDIT_USER,
        password: REDDIT_PASS
    });

    //access subreddit
    var sub = r.getSubreddit('SGExams');

    //change flairs according text file inputted and catch error
    try {
        await sub.setMultipleUserFlairs(nameArray);
    } catch(e) {
        error = e;
        isSuccessful = false;
    }
    return {isSuccessful: isSuccessful, error: error};
}

// this function handles the response given to the user,
// including names of reddit accounts which were not changed successfully.
function handleResponse(response, nameArray) {
    if(response.isSuccessful) {
        console.log("Flairs for all names were changed successfully :)\n");
    } else {
        var error = response.error;

        //save the error object into errorMessage.txt
        fs.appendFile('errorMessage.txt', util.inspect(error, {showHidden: false, depth: null}), 'ascii', function(err, data) {
            if(err) {
                console.log(err);
            }
        });

        //output and save the usernames which have failed
        var failedNames = [];
        for(var i=0;i<error.length;i++) {
            let str = error[i].errors.user.name;
            let firstPos = 24;
            let lastPos = str.indexOf("', ignoring");
            failedNames.push(str.slice(firstPos, lastPos));
        }
        console.log(nameArray.length - error.length + "/" + nameArray.length + " flairs changed successfully.\n");
        console.log("Names of reddit users that were not changed successfully:");
        for(var i=0;i<failedNames.length;i++) {
            let failedName = failedNames[i] + '\r\n';
            fs.appendFile('failedNames.txt', failedName, 'ascii', function(err, data) {
                if (err) {
                    console.log(err);
                }
            });
            console.log(failedNames[i]);
        }
    }
    console.log("Names of those which have failed are saved in failedNames.txt " +
        "and the corresponding error message can be viewed in errorMessage.txt.\n" +
        "Both files can be found in the same directory as the script.");
}

async function main() {
    var names = readFile();
    var nameArray = convertArray(names);
    var response = await changeFlairs(nameArray);
    handleResponse(response, nameArray);
}

main();