noctbot/bot/src/plugins/rcg.ts

import { Message } from "discord.js";
import got from "got";
import { logger } from "src/logging";
import { Command, ICommandData, Plugin } from "src/model/plugin";
import { tryDo } from "@shared/common/async_utils";
import Jimp from "jimp";

const rcgRe = /<div class="rcg-panels">\s*<img src="([^"]*)" .*\/>\s*<img src="([^"]*)" .*\/>\s*<img src="([^"]*)" .*\/>\s*<\/div>/i;

interface XkcdResponse {
    img: string;
}

@Plugin
export class Rcg {
    async sendErrorMessage(msg: Message): Promise<void> {
        const xkcdResult = await tryDo(got.get<XkcdResponse>("https://xkcd.com/info.0.json", { responseType: "json" }));
        if(!xkcdResult.ok || !xkcdResult.result) {
            await msg.reply({ content: "sorry, I couldn't get any comics :(.", failIfNotExists: false });
            return;
        }
        await msg.reply({
            content: "sorry, I couldn't get a random comic! Here is today's XKCD instead:",
            files: [ xkcdResult.result.body.img ]
        });
    }

    @Command({
        type: "mention",
        pattern: "random comic",
        auth: false,
        documentation: {description: "Generates a comic just for you!", example: "random comic"}
    })
    async randomComic({ message }: ICommandData): Promise<void> {
        const result = await tryDo(got.get("http://explosm.net/rcg/view/?promo=false"));
    
        if (!result.ok) {
            logger.error("Failed to get RCG. Got error: %s", result.error);
            await this.sendErrorMessage(message);
            return;
        }

        const regexResult = rcgRe.exec(result.result.body);

        if(!regexResult || regexResult.length == 0) {
            logger.error("Could not find RCG from body. Got response body: %s", result.result.body);
            await this.sendErrorMessage(message);
            return;
        }

        const panelUrls = [regexResult[1], regexResult[2], regexResult[3]];

        const panels = [];
        let totalWidth = 0;
        let maxHeight = 0;
        for (const panelUrl of panelUrls) {
            const panelImgResult = await tryDo(Jimp.read(panelUrl));

            if (!panelImgResult.ok) {
                logger.error("Failed to download panel %s",  panelUrl);
                await this.sendErrorMessage(message);
                return;
            }

            const img = panelImgResult.result;
            const [w, h] = [ img.getWidth(), img.getHeight() ];
            panels.push(img);
            totalWidth += w;
            
            if (h > maxHeight) {
                maxHeight = h;
            }
        }

        const PADDING = 5;
        let newImg = await Jimp.create(PADDING * 4 + totalWidth, PADDING * 2 + maxHeight, "white");
        let curX = PADDING;
        for (const panel of panels) {
            newImg = await newImg.blit(panel, curX, PADDING);
            curX += panel.getWidth() + PADDING;
        }
        
        newImg.quality(80);
        const buffer = await newImg.getBufferAsync(Jimp.MIME_JPEG);

        const messagePostResult = await tryDo(message.reply({
            content: "I find this very funny:",
            files: [ buffer ]
        }));

        if (!messagePostResult.ok) {
            logger.error("Failed to get RCG. Got error: %s", messagePostResult.error);
            await this.sendErrorMessage(message);
        }
    }
}