use threadpool::ThreadPool;

use colored::*;
use linkify::{LinkFinder, LinkKind};

use std::fs::File;
use std::io::prelude::*;


use reqwest::header;
use std::time::Duration;

use std::sync::Arc;
use std::sync::Mutex;

use std::sync::atomic::Ordering;

use rustc_hash::{FxHashMap, FxHashSet};

enum UrlStatus {
    Unknown,
    UrlOk,
    UrlError(String),
}

struct HashVal {
    paths: FxHashSet<String>,
    status: UrlStatus,
}

type UrlHash = FxHashMap<String, HashVal>;

pub struct LinkCheck {
    pool: Mutex<ThreadPool>,
    urlhash: Arc<Mutex<UrlHash>>,
    print_all: bool,
}

impl LinkCheck {
    pub fn new(num_threads: usize, print_all: bool) -> LinkCheck {
        openssl_probe::init_ssl_cert_env_vars();
        let pool = Mutex::new(ThreadPool::new(num_threads));
        LinkCheck {
            pool,
            urlhash: Arc::new(Mutex::new(FxHashMap::default())),
            print_all,
        }
    }

    pub fn check_urls(&self, fname: &str) {
        let print_all = self.print_all;
        if let Some(links) = get_links(fname) {
            for l in links {
                let urlhash = self.urlhash.clone();
                let fname_s = String::from(fname);
                self.pool.lock().unwrap().execute(move || {
                    check_link(&l, &fname_s, &urlhash, print_all);
                });
            }
        }
    }
}

impl Drop for LinkCheck {
    fn drop(&mut self) {
        //println!("Now dropping ...");
        let pool = self.pool.lock().unwrap();
        pool.join();
    }
}

fn check_link(url: &str, fname: &str, urlhash: &Arc<Mutex<UrlHash>>, print_all: bool) {
    let url = String::from(url);

    let mut run_check_link = false;

    // It is very important to keep the lock for the urlhash
    // only for a short period of time
    //
    // If we don't find the url in the urlhash then
    // we set `run_check_link` to `true` so that we will
    // check the url
    {
        let f = String::from(fname);

        let mut urlhash = urlhash.lock().unwrap();
        if !urlhash.contains_key(&url) {
            let mut hs = FxHashSet::default();
            hs.insert(f);
            let url1 = url.clone();

            urlhash.insert(
                url1,
                HashVal {
                    status: UrlStatus::Unknown,
                    paths: hs,
                },
            );
            run_check_link = true;
        } else if let Some(hs) = urlhash.get_mut(&url) {
            match &hs.status {
                UrlStatus::Unknown => {
                    hs.paths.insert(f);
                }
                UrlStatus::UrlOk => {
                    if print_all {
                        print_ok(no_colors!(), &url, &f);
                    };
                }
                UrlStatus::UrlError(e) => {
                    e0022!(f, e);
                }
            }
        }
    }

    //
    if run_check_link {
        match check_link_inner(&url, true) {
            UrlStatus::UrlOk => {
                let mut urlhash = urlhash.lock().unwrap();
                if let Some(mut hs) = urlhash.get_mut(&url) {
                    if print_all {
                        for p in hs.paths.iter() {
                            print_ok(no_colors!(), &url, p);
                        }
                    }
                    hs.status = UrlStatus::UrlOk;
                }
            }
            UrlStatus::UrlError(e) => {
                let mut urlhash = urlhash.lock().unwrap();
                if let Some(mut hs) = urlhash.get_mut(&url) {
                    for p in hs.paths.iter() {
                        e0022!(p, e);
                    }
                    hs.status = UrlStatus::UrlError(e);
                }
            }
            _ => (),
        }
    }
}

fn get_links(fname: &str) -> Option<Vec<String>> {
    let fhdl = File::open(fname);
    match fhdl {
        Ok(mut f) => {
            let mut buf = Vec::new();

            match f.read_to_end(&mut buf) {
                Ok(_bytes_read) => {
                    return get_links_inner(&String::from_utf8_lossy(&buf));
                }
                Err(e) => println!("Error reading file {}: {:?}", fname, e),
            }
        }
        Err(e) => println!("Error opening file {}: {}", fname, e),
    }

    None
}

fn resolve_entities(url: &str) -> String {
    if !url.contains('&') {
        return String::from(url);
    }

    let v = vec![
        ("&ouml;", "ö"),
        ("&uuml;", "ü"),
    ];
    let mut url_new = String::from(url);
    for (e,r) in v {
        url_new = url_new.replace(e, r);
    }
    url_new
}

// retrieves links in a string and then checks those links
fn get_links_inner(s: &str) -> Option<Vec<String>> {
    let mut finder = LinkFinder::new();
    finder.kinds(&[LinkKind::Url]);

    // finder.links() does the actual search for URLs
    let links: Vec<_> = finder.links(s).collect();
    let result: Vec<&str> = links.iter().map(|e| e.as_str()).collect();

    let mut links = vec![];
    for r in result {
        if !r.starts_with("http://") && !r.starts_with("https://") && !r.starts_with("ftp://") {
            continue;
        }

        // This is a workaround to prevent URLs ending with certain characters
        let url = resolve_entities(r.trim_end_matches(|c| c == '。' || c == '`'));

        links.push(url);
    }
    if !links.is_empty() {
        Some(links)
    } else {
        None
    }
}

fn check_link_inner(l: &str, head: bool) -> UrlStatus {
    let mut headers = header::HeaderMap::new();
    headers.insert(
        header::USER_AGENT,
        header::HeaderValue::from_static(
            "Mozilla/5.0 (X11; Linux i686; rv:64.0) Gecko/20100101 Firefox/64.0",
        ),
    );

    let default_policy = reqwest::redirect::Policy::default();
    let policy = reqwest::redirect::Policy::custom(move |attempt| {
        if attempt.url().host_str() == Some("127.0.0.1") {
            attempt.stop()
        } else {
            default_policy.redirect(attempt)
        }
    });

    let cb = reqwest::blocking::Client::builder()
        .gzip(true)
        .redirect(policy)
        .default_headers(headers)
        .timeout(Duration::from_secs(7))
        .build()
        .unwrap();
    // let url: Url =
    // match l.parse() {
    //    Ok(url) => url,
    //    Err(e) => {  println!("Error: {:?}", e); panic!("Scheiss"); }
    // };
    let resp = if head {
        cb.head(l).send()
    } else {
        cb.get(l).send()
    };
    match resp {
        Ok(s) => {
            if s.status().is_informational()
                || s.status().is_success()
                || s.status().is_redirection()
            {
                return UrlStatus::UrlOk;
            }

            if head {
                check_link_inner(l, false)
            } else {
                let e = format!("{}: {}", l, s.status());
                UrlStatus::UrlError(e)
            }
        }
        Err(e) => {
            let e = format!("{}", e);
            UrlStatus::UrlError(e)
        }
    }
}

fn print_ok(no_colors: bool, url: &str, f: &str) {
    if no_colors {
        println!("✔    {} in {}", &url, f);
    } else {
        //        println!("✔    {} in {}", &url, f);
        println!("{}    {} in {}", "✔".bright_green().bold(), url, f);
    }
}