const fs = require('fs');
const yaml = require('js-yaml');
const axios = require('axios');
const path = require('path');
const https = require('https');
const http = require('http');

const linksPath = path.join(__dirname, '../themes/Ying/data/links.yaml');
const outputPath = path.join(__dirname, '../static/link_status.json');

// Ensure static dir exists
if (!fs.existsSync(path.dirname(outputPath))) {
    fs.mkdirSync(path.dirname(outputPath), { recursive: true });
}

// Config
const CONCURRENCY = 10;
const TIMEOUT = 10000;

// Optimized Axios Instance with Keep-Alive
const axiosInstance = axios.create({
    timeout: TIMEOUT,
    maxRedirects: 5,
    httpAgent: new http.Agent({ keepAlive: true }),
    httpsAgent: new https.Agent({ keepAlive: true }),
    headers: {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36'
    },
    validateStatus: (status) => status >= 200 && status < 400
});

async function checkUrl(url) {
    try {
        await axiosInstance.head(url);
        return true;
    } catch (error) {
        try {
            await axiosInstance.get(url);
            return true;
        } catch (err2) {
            return false;
        }
    }
}

async function checkLinks() {
    console.log('Starting link check...');
    const start = Date.now();
    
    try {
        const fileContents = fs.readFileSync(linksPath, 'utf8');
        const data = yaml.load(fileContents);
        
        if (!data || !data.blogs) {
            console.log('No blogs found in links.yaml');
            return;
        }

        const blogs = data.blogs.filter(b => b.url);
        const results = {};
        const failedLinks = [];
        let completed = 0;
        const total = blogs.length;

        // Concurrency Pool
        async function worker() {
            while (blogs.length > 0) {
                const blog = blogs.shift();
                const status = await checkUrl(blog.url);
                results[blog.url] = status;
                
                completed++;
                const icon = status ? '🟢' : '🔴';
                console.log(`[${completed}/${total}] ${icon} ${blog.name}`);
                
                if (!status) {
                    failedLinks.push(`- ${blog.name}: ${blog.url}`);
                }
            }
        }

        // Start workers
        const workers = Array(Math.min(blogs.length, CONCURRENCY))
            .fill(null)
            .map(() => worker());

        await Promise.all(workers);

        fs.writeFileSync(outputPath, JSON.stringify(results, null, 2));
        const duration = ((Date.now() - start) / 1000).toFixed(2);
        console.log(`✨ Check finished in ${duration}s. Status saved to ${outputPath}`);
        
        // Write failed links to summary file for email notification
        const summaryPath = path.join(__dirname, '../failed_links_summary.txt');
        if (failedLinks.length > 0) {
            const summaryContent = `\n🚫 监测到 ${failedLinks.length} 个异常友链:\n${failedLinks.join('\n')}\n`;
            fs.writeFileSync(summaryPath, summaryContent);
            console.log(`Failed links summary saved to ${summaryPath}`);
        } else {
            fs.writeFileSync(summaryPath, '\n✅ 所有友链状态正常\n');
        }

    } catch (e) {
        console.error(e);
        process.exit(1);
    }
}

checkLinks();