server.js

const express = require('express');
const axios = require('axios');
const path = require('path');
const fs = require('fs').promises;

const app = express();
const port = 3000;

app.use(express.static(path.join(__dirname, 'public')));

app.get('/api/languages', async (req, res) => {
    try {
        const data = await fs.readFile('wikipedias.json', 'utf-8');
        res.json(JSON.parse(data));
    } catch (error) {
        console.error(error);
        res.status(500).json({ error: 'Failed to fetch languages' });
    }
});

app.get('/api/pageviews', async (req, res) => {
    try {
        const { year, month, lang, limit = 50 } = req.query;

        if (!year || !month || !lang) {
            return res.status(400).json({ error: 'Year, month, and language are required.' });
        }

        const projectUrlPart = `${lang}.wikipedia.org`;

        const topPagesUrl = `https://wikimedia.org/api/rest_v1/metrics/pageviews/top/${projectUrlPart}/all-access/${year}/${month}/all-days`;

        const topPagesResponse = await axios.get(topPagesUrl, { headers: { 'accept': 'application/json' } });

        if (!topPagesResponse.data.items || topPagesResponse.data.items.length === 0) {
            return res.json([]);
        }

        const topArticles = topPagesResponse.data.items[0].articles.slice(0, parseInt(limit, 10));

        const startOfMonth = `${year}${month.padStart(2, '0')}0100`;
        const lastDayOfMonth = new Date(year, month, 0).getDate();
        const endOfMonth = `${year}${month.padStart(2, '0')}${lastDayOfMonth}00`;

        const detailedDataPromises = topArticles.map(async (article) => {
            const articleTitle = encodeURIComponent(article.article.replace(/ /g, '_'));
            const baseUrl = `https://wikimedia.org/api/rest_v1/metrics/pageviews/per-article/${projectUrlPart}`;

            const urls = {
                desktop: `${baseUrl}/desktop/all-agents/${articleTitle}/monthly/${startOfMonth}/${endOfMonth}`,
                mobileApp: `${baseUrl}/mobile-app/all-agents/${articleTitle}/monthly/${startOfMonth}/${endOfMonth}`,
                mobileWeb: `${baseUrl}/mobile-web/all-agents/${articleTitle}/monthly/${startOfMonth}/${endOfMonth}`,
                user: `${baseUrl}/all-access/user/${articleTitle}/monthly/${startOfMonth}/${endOfMonth}`,
                spider: `${baseUrl}/all-access/spider/${articleTitle}/monthly/${startOfMonth}/${endOfMonth}`,
                automated: `${baseUrl}/all-access/automated/${articleTitle}/monthly/${startOfMonth}/${endOfMonth}`
            };

            const requests = Object.values(urls).map(url =>
                axios.get(url, { headers: { 'accept': 'application/json' } }).catch(e => ({ data: { items: [] } }))
            );

            const responses = await Promise.all(requests);

            const extractViews = (response) => {
                return response?.data?.items?.[0]?.views || 0;
            };

            const desktopViews = extractViews(responses[0]);
            const mobileAppViews = extractViews(responses[1]);
            const mobileWebViews = extractViews(responses[2]);
            const allViews = desktopViews + mobileAppViews + mobileWebViews;

            const userViews = extractViews(responses[3]);
            const spiderViews = extractViews(responses[4]);
            const automatedViews = extractViews(responses[5]);

            return {
                url: `https://${projectUrlPart}/wiki/${article.article.replace(/ /g, '_')}`,
                visits: allViews,
                returnVisits: 0,
                avgDuration: 10,
                regions: getRegions(),
                devices: getDeviceDistribution(desktopViews, mobileAppViews, mobileWebViews),
                agentBreakdown: `user:${userViews};spider:${spiderViews};automated:${automatedViews}`
            };
        });

        const formattedData = await Promise.all(detailedDataPromises);
        formattedData.sort((a, b) => b.visits - a.visits);

        res.json(formattedData);
    } catch (error) {
        console.error(error);
        res.status(500).json({ error: 'Failed to fetch page views' });
    }
});

function getRegions() {
    return 'global';
}

function getDeviceDistribution(desktopViews, mobileAppViews, mobileWebViews) {
    const total = desktopViews + mobileAppViews + mobileWebViews;
    if (total === 0) {
        return 'desktop:0;mobile-app:0;mobile-web:0';
    }
    const desktopPercent = Math.round((desktopViews / total) * 100);
    const mobileAppPercent = Math.round((mobileAppViews / total) * 100);
    
    // To avoid rounding errors making the sum != 100, the last one can be calculated by subtraction.
    const mobileWebPercent = Math.max(0, 100 - desktopPercent - mobileAppPercent);
    
    return `desktop:${desktopPercent};mobile-app:${mobileAppPercent};mobile-web:${mobileWebPercent}`;
}

app.listen(port, () => {
    console.log(`Server running at http://localhost:${port}`);
});