import puppeteer from 'puppeteer';

/**
 * Threads Search Scraper
 * Navigates to the search page, enters a keyword, and extracts post URLs.
 * * @param {string} keyword - The search term.
 * @param {number} limit - Maximum number of URLs to return.
 * @param {Array} cookies - Optional: Array of Puppeteer-formatted cookies to handle login.
 */
export async function searchThreads(keyword, limit = 20, cookies = [], searchMode='KEYWORD') {
    if (!keyword) {
        throw new Error("Please provide a keyword for the search.");
    }

    const searchUrl = `https://www.threads.net/search?`
        +`q=${encodeURIComponent(keyword)}`
        +`&search_type=TOP`
        +`&limit=${limit}`
        +`&search_mode=${searchMode}`
        +`&media_type=TEXT`;
    console.log(`[Search Start] Keyword: "${keyword}" | URL: ${searchUrl}`);

    const browser = await puppeteer.launch({
        headless: "new",
        args: [
            '--disable-blink-features=AutomationControlled',
            '--no-sandbox',
            '--disable-setuid-sandbox'
        ]
    });

    try {
        const page = await browser.newPage();
        
        // Anti-detection headers
        await page.setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36');
        await page.setExtraHTTPHeaders({
            'Accept-Language': 'en-US,en;q=0.9',
        });

        // Inject cookies if provided to bypass login wall
        if (cookies && cookies.length > 0) {
            console.log("[Auth] Injecting session cookies...");
            await page.setCookie(...cookies);
        }
        
        await page.setViewport({ width: 1280, height: 900 });

        // Navigate to search results
        const response = await page.goto(searchUrl, { waitUntil: 'networkidle2', timeout: 60000 });

        // Check if we were redirected to the login page
        const currentUrl = page.url();
        if (currentUrl.includes('/login')) {
            console.error("[Auth Error] Threads redirected to login. You must provide valid session cookies.");
            throw new Error("Authentication required: Threads search is restricted to logged-in users.");
        }

        // Wait for the results to start appearing
        try {
            // Threads search result container or post links
            await page.waitForSelector('a[href*="/post/"]', { timeout: 20000 });
        } catch (e) {
            console.warn("[Warning] Results did not load. This might be a login wall or no results found.");
            // Take a screenshot for debugging if needed (local environment only)
            // await page.screenshot({ path: 'search_debug.png' });
        }

        // Scroll logic to gather more results
        await page.evaluate(async (maxItems) => {
            await new Promise((resolve) => {
                let totalHeight = 0;
                let distance = 500;
                let timer = setInterval(() => {
                    let scrollHeight = document.body.scrollHeight;
                    window.scrollBy(0, distance);
                    totalHeight += distance;

                    const currentLinks = document.querySelectorAll('a[href*="/post/"]').length;
                    // Stop if we hit the limit, bottom of page, or a safety cap
                    if (totalHeight >= scrollHeight || currentLinks >= maxItems || totalHeight > 15000) {
                        clearInterval(timer);
                        resolve();
                    }
                }, 300);
            });
        }, limit);

        // Extracting the URLs
        const postUrls = await page.evaluate(() => {
            const links = Array.from(document.querySelectorAll('a[href*="/post/"]'));
            return links
                .map(a => a.href)
                // Filter for actual post links and ignore UI elements like repost/share buttons
                .filter(href => {
                    const isPost = href.includes('/post/');
                    const isNotAction = !href.includes('/reposts') && !href.includes('/replies');
                    return isPost && isNotAction;
                });
        });

        // Deduplicate using a Set
        const uniqueUrls = [...new Set(postUrls)].slice(0, limit);

        console.log(`[Search Success] Found ${uniqueUrls.length} unique post URLs.`);
        
        return {
            keyword,
            count: uniqueUrls.length,
            urls: uniqueUrls
        };

    } catch (error) {
        console.error(`[Search Error] ${error.message}`);
        throw error;
    } finally {
        await browser.close();
    }
}