const path = require('path');
const fs = require('fs');
const fetch = require('node-fetch');
const { Util: DiscordUtil } = require('discord.js');

const has = (o, k) => Object.prototype.hasOwnProperty.call(o, k);

class Util {

    constructor() {
        throw new Error("Class may not be instantiated.");
    }

    static paginate(items, page = 1, pageLength = 10) {
        const maxPage = Math.ceil(items.length / pageLength);
        if(page < 1) page = 1;
        if(page > maxPage) page = maxPage;
        const startIndex = (page - 1) * pageLength;
        return {
            items: items.length > pageLength ? items.slice(startIndex, startIndex + pageLength) : items,
            page,
            maxPage,
            pageLength
        };
    }

    static downloadAsBuffer(source) {
        return new Promise((resolve, reject) => {
            fetch(source).then((res) => {
                if(res.ok) resolve(res.buffer());
                else reject(res.statusText);
            });
        });
    }

    static readdirRecursive(directory) {

        const result = [];

        (function read(directory) {
            const files = fs.readdirSync(directory);
            for(const file of files) {
                const filePath = path.join(directory, file);

                if(fs.statSync(filePath).isDirectory()) {
                    read(filePath);
                } else {
                    result.push(filePath);
                }
            }
        }(directory));

        return result;

    }

    static wait(ms) {
        return this.delayFor(ms);
    }

    static delayFor(ms) {
        return new Promise((resolve) => {
            setTimeout(resolve, ms);
        });
    }
    
    static mergeDefault(def, given) {
        if (!given) return def;
        for (const key in def) {
            if (!has(given, key) || given[key] === undefined) {
                given[key] = def[key];
            } else if (given[key] === Object(given[key])) {
                given[key] = Util.mergeDefault(def[key], given[key]);
            }
        }
        return given;
    }

    //Shard Managing

    static fetchRecommendedShards(token, guildsPerShard = 1000) {
        if(!token) throw new Error("[util] Token missing.");
        return fetch("https://discord.com/api/v7/gateway/bot", {
            method: 'GET',
            headers: { Authorization: `Bot ${token.replace(/^Bot\s*/iu, '')}` }
        }).then((res) => {
            if (res.ok) return res.json();
            throw res;
        })
            .then((data) => data.shards * (1000 / guildsPerShard));
    }

    static makePlainError(err) {
        return {
            name: err.name,
            message: err.message,
            stack: err.stack
        };
    }

    static escapeMarkdown(text, options) {
        if (!text) return;
        return DiscordUtil.escapeMarkdown(text, options);
    }

    static get formattingPatterns() {
        return [
            ['\\*{1,3}([^*]*)\\*{1,3}', '$1'],
            ['_{1,3}([^_]*)_{1,3}', '$1'],
            ['`{1,3}([^`]*)`{1,3}', '$1'],
            ['~~([^~])~~', '$1']
        ];
    }

    static removeMarkdown(content) {
        if (!content) throw new Error('Missing content');
        this.formattingPatterns.forEach(([pattern, replacer]) => {
            content = content.replace(new RegExp(pattern, 'gu'), replacer);
        });
        return content;
    }

    /**
     * Sanitise user given regex; escapes unauthorised characters
     *
     * @static
     * @param {string} input
     * @param {string[]} [allowed=['?', '\\', '(', ')', '|']]
     * @return {string} The sanitised expression
     * @memberof Util
     */
    static sanitiseRegex(input, allowed = ['?', '\\', '(', ')', '|']) {
        if (!input) throw new Error('Missing input');
        const reg = new RegExp(`[${this.regChars.filter((char) => !allowed.includes(char)).join('')}]`, 'gu');
        return input.replace(reg, '\\$&');
    }

    static get regChars() {
        return ['.', '+', '*', '?', '\\[', '\\]', '^', '$', '(', ')', '{', '}', '=', '<', '>', '|', ':', '\\\\', '-'];
    }

    static duration(seconds) {
        const { plural } = this;
        let s = 0, 
            m = 0, 
            h = 0, 
            d = 0, 
            w = 0;
        s = Math.floor(seconds);
        m = Math.floor(s/60);
        s %= 60;
        h = Math.floor(m/60);
        m %= 60;
        d = Math.floor(h/24);
        h %= 24;
        w = Math.floor(d/7);
        d %= 7;
        return `${w ? `${w} ${plural(w, 'week')} ` : ''}${d ? `${d} ${plural(d, 'day')} ` : ''}${h ? `${h} ${plural(h, 'hour')} ` : ''}${m ? `${m} ${plural(m, 'minute')} ` : ''}${s ? `${s} ${plural(s, 'second')} ` : ''}`.trim();
    }

    static plural(amt, word) {
        if(amt === 1) return word;
        return `${word}s`;
    }


}

module.exports = Util;