use crate::USER_AGENT;
use asklyphe_common::ldb::{linkrelstore, linkstore, metastore, sitestore, titlestore, wordstore, DBConn};
use async_nats::jetstream;
use async_nats::jetstream::kv;
use futures::AsyncReadExt;
use image::EncodableLayout;
use isahc::config::RedirectPolicy;
use isahc::prelude::Configurable;
use isahc::HttpClient;
use log::{debug, error, warn};
use std::collections::{BTreeMap, BTreeSet};
use std::hash::{DefaultHasher, Hasher};
use std::sync::atomic::AtomicBool;
use std::sync::{mpsc, Arc};
use std::time::Duration;
use stopwords::{Language, Spark, Stopwords};
use texting_robots::{get_robots_url, Robot};
use thirtyfour::{By, WebDriver};
use asklyphe_common::nats::vorebot::CrawlRequest;
use asklyphe_common::nats::vorebot::VOREBOT_SERVICE;

pub fn allowed_to_crawl(robotstxt: &[u8], url: &str) -> Result<bool, ()> {
    let robot1 = Robot::new("Vorebot", robotstxt);
    if let Err(e) = robot1 {
        warn!(
            "potentially malformed robots.txt ({}), not crawling {}",
            e, url
        );
        return Err(());
    }
    let robot1 = robot1.unwrap();
    Ok(robot1.allowed(url))
}

// returns Err if we cannot access a page, but the error associated with it seems temporary (i.e. it's worth trying again later)
// otherwise, returns Ok
pub async fn web_parse(
    nats: jetstream::Context,
    db: DBConn,
    driver: &WebDriver,
    url: &str,
    damping: f64,
) -> Result<(), ()> {

    driver.delete_all_cookies().await.map_err(|_| ())?;
    let robots_bucket = nats.get_key_value("robots").await;
    let robots_bucket = if robots_bucket.is_err() {
        let robots_bucket = nats
            .create_key_value(kv::Config {
                bucket: "robots".to_string(),
                description: "storage of robots.txt data for given hosts".to_string(),
                ..Default::default()
            })
            .await;
        if let Err(e) = robots_bucket {
            error!("could not create robots.txt bucket: {}", e);
            None
        } else {
            Some(robots_bucket.unwrap())
        }
    } else {
        robots_bucket.ok()
    };
    let hosts_bucket = nats.get_key_value("hosts").await;
    let hosts_bucket = if hosts_bucket.is_err() {
        let hosts_bucket = nats
            .create_key_value(kv::Config {
                bucket: "hosts".to_string(),
                description: "prevent the same host from being scraped too quickly".to_string(),
                max_age: Duration::from_secs(60 * 10),
                ..Default::default()
            })
            .await;
        if let Err(e) = hosts_bucket {
            error!("could not create hosts bucket: {}", e);
            return Err(());
        } else {
            hosts_bucket.unwrap()
        }
    } else {
        hosts_bucket.unwrap()
    };

    let robots_url = get_robots_url(url);
    if robots_url.is_err() {
        error!("could not get a robots.txt url from {}, not crawling", url);
        return Ok(());
    }
    let robots_url = robots_url.unwrap();
    let mut hash = DefaultHasher::new();
    hash.write(robots_url.as_bytes());
    let hash = hash.finish();

    if let Ok(Some(host)) = hosts_bucket.get(hash.to_string()).await {
        let count = *host.first().unwrap_or(&0);
        if count > 10 {
            warn!("scraping {} too quickly, avoiding for one minute", robots_url);
            return Err(());
        }
        hosts_bucket.put(hash.to_string(), vec![count + 1].into()).await.expect("COULDN'T INSERT INTO HOSTS BUCKET!");
    } else {
        hosts_bucket.put(hash.to_string(), vec![1].into()).await.expect("COULDN'T INSERT INTO HOSTS BUCKET!");
    }

    let mut skip_robots_check = false;
    if let Some(robots_bucket) = &robots_bucket {
        if let Ok(Some(entry)) = robots_bucket.get(hash.to_string()).await {
            if let Ok(res) = allowed_to_crawl(entry.as_bytes(), url) {
                if !res {
                    debug!("robots.txt does not allow us to crawl {}", url);
                    return Ok(());
                } else {
                    skip_robots_check = true;
                }
            }
        }
    }

    if !skip_robots_check {
        // check manually
        debug!("checking new robots.txt \"{}\"", robots_url);
        let client = HttpClient::builder()
            .redirect_policy(RedirectPolicy::Limit(10))
            .timeout(Duration::from_secs(60))
            .build();
        if let Err(e) = client {
            error!("could not create new robots.txt httpclient: {}", e);
            return Err(());
        }
        let client = client.unwrap();
        let request = isahc::Request::get(&robots_url)
            .header("user-agent", USER_AGENT.as_str())
            .body(());
        if let Err(e) = request {
            error!("could not create robots.txt get request: {}", e);
            return Ok(());
        }
        let request = request.unwrap();
        let response = client.send_async(request).await;
        if let Err(e) = response {
            warn!("could not get robots.txt page: {}", e);
            return Err(());
        }
        let mut response = response.unwrap();
        if response.status() == 429 {
            // too many requests
            warn!("too many requests for {}", robots_url);
            return Err(());
        }
        if response.status().is_server_error() {
            // don't crawl at the moment
            debug!("not crawling {} due to server error", robots_url);
            return Err(());
        }

        let mut body = "".to_string();
        if let Err(e) = response.body_mut().read_to_string(&mut body).await {
            warn!("could not read from robots.txt response: {}", e);
            return Err(());
        }

        if let Ok(res) = allowed_to_crawl(body.as_bytes(), url) {
            if let Some(robots_bucket) = &robots_bucket {
                if let Err(e) = robots_bucket
                    .put(hash.to_string(), body.as_bytes().to_vec().into())
                    .await
                {
                    warn!("could not put robots.txt data: {}", e);
                }
            }

            if !res {
                debug!("robots.txt does not allow us to crawl {}", url);
                return Ok(());
            } else {
                // we're allowed to crawl!
            }
        }
    }

    let start = std::time::Instant::now();
    debug!("handling request for {}", url);

    // check for bad status codes
    // fixme: i hate this solution, can we get something that actually checks the browser's request?
    let client = HttpClient::builder()
        .redirect_policy(RedirectPolicy::Limit(10))
        .timeout(Duration::from_secs(60))
        .build();
    if let Err(e) = client {
        error!("could not create new badstatuscode httpclient: {}", e);
        return Err(());
    }
    let client = client.unwrap();
    let request = isahc::Request::get(url)
        .header("user-agent", USER_AGENT.as_str())
        .body(());
    if let Err(e) = request {
        error!("could not create badstatuscode get request: {}", e);
        return Ok(());
    }
    let request = request.unwrap();
    let response = client.send_async(request).await;
    if let Err(e) = response {
        warn!("could not get badstatuscode page: {}", e);
        return Err(());
    }
    let mut response = response.unwrap();
    if response.status() == 429 {
        // too many requests
        warn!("too many requests for {}", url);
        return Err(());
    }
    if response.status().is_server_error() || response.status().is_client_error() {
        // don't crawl at the moment
        debug!("not crawling {} due to bad status code {}", url, response.status());
        return Err(());
    }

    // i guess we're good
    driver.goto(url).await.map_err(|_| ())?;

    let html_element = driver.find(By::Tag("html")).await.map_err(|_| ())?;

    if let Some(lang) = html_element.attr("lang").await.ok().flatten() {
        if !lang.starts_with("en") && !lang.starts_with("unknown") {
            // i.e. non-english language
            // fixme: remove this once we start expanding to non-english-speaking markets?
            warn!("skipping {} due to {} language (currently prioritizing english", url, lang);
            return Err(());
        }
    }

    let meta_elements = driver.find_all(By::Tag("meta")).await.map_err(|_| ())?;

    let title = driver.title().await.map_err(|_| ())?;
    let mut description = None;
    let mut keywords = vec![];
    for elem in meta_elements {
        if let Ok(Some(name)) = elem.attr("name").await {
            match name.as_str() {
                "description" => {
                    if let Ok(Some(content)) = elem.attr("content").await {
                        description = Some(content);
                    }
                }
                "keywords" => {
                    if let Ok(Some(content)) = elem.attr("content").await {
                        keywords = content
                            .split(',')
                            .map(|v| v.to_lowercase())
                            .filter(|v| !v.is_empty())
                            .collect();
                    }
                }
                _ => {}
            }
        }
    }

    let body = driver.find(By::Tag("body")).await.map_err(|_| ())?;
    let raw_page_content = body.text().await.map_err(|_| ())?;

    async fn gather_elements_with_multiplier(
        driver: &WebDriver,
        wordmap: &mut BTreeMap<String, f64>,
        stops: &BTreeSet<&&str>,
        elements: &[&str],
        multiplier: f64,
    ) {
        let mut elms = vec![];
        for tag in elements {
            elms.push(driver.find_all(By::Tag(*tag)).await);
        }
        let elms = elms.iter().flatten().flatten().collect::<Vec<_>>();
        let mut sentences = vec![];
        let mut sentence_set = BTreeSet::new();

        debug!("processing elements...");
        for node in elms {
            let _ = node.scroll_into_view().await;
            let boxmodel = node.rect().await;
            if boxmodel.is_err() {
                // not visible
                continue;
            }
            let boxmodel = boxmodel.unwrap();
            let current_text = node.text().await;
            if current_text.is_err() {
                // no text on this node
                continue;
            }
            let current_text = current_text.unwrap().trim().to_string();
            if current_text.is_empty() {
                continue;
            }
            let sqs = (boxmodel.width * boxmodel.height).max(1.0); // no 0 divides pls (:
            let ccount = current_text.chars().count() as f64;
            let cssq = if ccount > 0.0 { sqs / ccount } else { 0.0 };
            if sentence_set.contains(&current_text) {
                continue;
            }
            sentence_set.insert(current_text.clone());
            sentences.push((current_text, cssq));
        }

        for (sentence, cssq) in sentences {
            let mut cssq = (cssq / 500.0).powi(2) * multiplier;
            for word in sentence.split_whitespace() {
                let word = word
                    .to_lowercase()
                    .trim_end_matches(|v: char| v.is_ascii_punctuation())
                    .to_string();
                if stops.contains(&word.as_str()) {
                    // less valuable
                    cssq /= 100.0;
                }
                if let Some(wentry) = wordmap.get_mut(&word) {
                    *wentry += cssq;
                } else {
                    if word.is_empty() {
                        continue;
                    }
                    wordmap.insert(word.to_string(), cssq);
                }
            }
        }
    }

    let mut wordmap: BTreeMap<String, f64> = BTreeMap::new();
    let stops: BTreeSet<_> = Spark::stopwords(Language::English)
        .unwrap()
        .iter()
        .collect();

    debug!("headers...");
    gather_elements_with_multiplier(driver, &mut wordmap, &stops, &["h1","h2","h3","h4","h5","h6"], 3.0)
        .await;

    debug!("paragraphs...");
    gather_elements_with_multiplier(driver, &mut wordmap, &stops, &["p","div"], 1.0).await;

    let mut wordmap = wordmap.into_iter().collect::<Vec<_>>();
    wordmap.sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap());

    let mut db_error_so_requeue_anyways = false;

    let words = wordmap
        .iter()
        .map(|(word, _)| word.as_str())
        .collect::<Vec<_>>();
    #[allow(clippy::collapsible_if)]
    if !words.is_empty() {
        if wordstore::add_url_to_keywords(&db, &words, url)
            .await
            .is_err()
        {
            warn!("couldn't add {} to keywords!", url);
            db_error_so_requeue_anyways = true;
        }
    }

    let mut metawords = keywords.iter().map(|v| v.as_str()).collect::<Vec<_>>();
    let desc2 = description.clone();
    let desc2 = desc2.map(|v| {
        v.to_lowercase()
            .split_whitespace()
            .map(String::from)
            .collect::<Vec<_>>()
    });
    if let Some(description) = &desc2 {
        for word in description {
            let word = word.trim_end_matches(|v: char| v.is_ascii_punctuation());
            if word.is_empty() {
                continue;
            }
            metawords.push(word);
        }
    }
    #[allow(clippy::collapsible_if)]
    if !metawords.is_empty() {
        if metastore::add_url_to_metawords(&db, &metawords, url)
            .await
            .is_err()
        {
            warn!("couldn't add {} to metawords!", url);
            db_error_so_requeue_anyways = true;
        }
    }

    let mut titlewords = vec![];
    let title2 = title.clone();
    let title2 = title2.to_lowercase();
    for word in title2.split_whitespace() {
        let word = word.trim_end_matches(|v: char| v.is_ascii_punctuation());
        if word.is_empty() {
            continue;
        }
        titlewords.push(word);
    }
    #[allow(clippy::collapsible_if)]
    if !titlewords.is_empty() {
        if titlestore::add_url_to_titlewords(&db, &titlewords, url)
            .await
            .is_err()
        {
            warn!("couldn't add {} to titlewords!", url);
            db_error_so_requeue_anyways = true;
        }
    }

    if sitestore::add_website(
        &db,
        url,
        Some(title),
        description,
        if keywords.is_empty() {
            None
        } else {
            Some(keywords)
        },
        &wordmap,
        raw_page_content,
        damping
    )
    .await
    .is_err()
    {
        warn!("couldn't add {} to sitestore!", url);
        db_error_so_requeue_anyways = true;
    }
    
    debug!("finished with main site stuff for {}", url);

    let linkelms = driver.find_all(By::Tag("a")).await.map_err(|_| ())?;

    for linkelm in linkelms {
        if linkelm.scroll_into_view().await.is_err() {
            debug!("couldn't scroll into view!");
        }
        let href = linkelm.prop("href").await.map_err(|_| ())?;
        if href.is_none() {
            debug!("no href!");
            continue;
        }
        let href = href.unwrap();
        if href.contains('#') {
            continue;
        }
        let linktext = linkelm.text().await.map_err(|_| ())?.to_lowercase();
        let linkimgs = linkelm.find_all(By::Tag("img")).await.map_err(|_| ())?;
        let mut alts = "".to_string();
        for img in linkimgs {
            if let Ok(Some(alt)) = img.attr("alt").await {
                alts.push_str(&alt);
                alts.push(' ');
            }
        }
        let alts = alts.trim().to_lowercase();
        let mut linkwords = vec![];
        for word in linktext.split_whitespace() {
            let word = word.trim_end_matches(|v: char| v.is_ascii_punctuation());
            linkwords.push(word);
        }
        for word in alts.split_whitespace() {
            let word = word.trim_end_matches(|v: char| v.is_ascii_punctuation());
            linkwords.push(word);
        }
        
        #[allow(clippy::collapsible_if)]
        if !linkwords.is_empty() {
            if linkstore::add_url_to_linkwords(&db, &linkwords, &href).await.is_err() {
                warn!("couldn't add {} to linkwords!", url);
            }
        }
        
        if linkrelstore::a_linksto_b(&db, url, &href).await.is_err() {
            warn!("couldn't perform a_linksto_b (a {url} b {href})");
        }

        nats.publish(VOREBOT_SERVICE.to_string(), rmp_serde::to_vec(&CrawlRequest {
            url: href,
            damping: 0.85,
        }).unwrap().into()).await.unwrap();
    }
    
    let elapsed = start.elapsed().as_secs_f64();
    
    debug!("crawled {} in {} seconds", url, elapsed);
    
    Ok(())
}