/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! Implementation of cookie storage as specified in
//! <http://tools.ietf.org/html/rfc6265>

use std::cmp::Ordering;
use std::collections::hash_map::Entry;
use std::collections::HashMap;
use std::time::SystemTime;

use log::{debug, info};
use net_traits::pub_domains::reg_suffix;
use net_traits::CookieSource;
use serde::{Deserialize, Serialize};
use servo_url::ServoUrl;

use crate::cookie::ServoCookie;

#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct CookieStorage {
    version: u32,
    cookies_map: HashMap<String, Vec<ServoCookie>>,
    max_per_host: usize,
}

#[derive(Debug)]
pub enum RemoveCookieError {
    Overlapping,
    NonHTTP,
}

impl CookieStorage {
    pub fn new(max_cookies: usize) -> CookieStorage {
        CookieStorage {
            version: 1,
            cookies_map: HashMap::new(),
            max_per_host: max_cookies,
        }
    }

    // http://tools.ietf.org/html/rfc6265#section-5.3
    pub fn remove(
        &mut self,
        cookie: &ServoCookie,
        url: &ServoUrl,
        source: CookieSource,
    ) -> Result<Option<ServoCookie>, RemoveCookieError> {
        let domain = reg_host(cookie.cookie.domain().as_ref().unwrap_or(&""));
        let cookies = self.cookies_map.entry(domain).or_default();

        // https://www.ietf.org/id/draft-ietf-httpbis-cookie-alone-01.txt Step 2
        if !cookie.cookie.secure().unwrap_or(false) && !url.is_secure_scheme() {
            let new_domain = cookie.cookie.domain().as_ref().unwrap().to_owned();
            let new_path = cookie.cookie.path().as_ref().unwrap().to_owned();

            let any_overlapping = cookies.iter().any(|c| {
                let existing_domain = c.cookie.domain().as_ref().unwrap().to_owned();
                let existing_path = c.cookie.path().as_ref().unwrap().to_owned();

                c.cookie.name() == cookie.cookie.name() &&
                    c.cookie.secure().unwrap_or(false) &&
                    (ServoCookie::domain_match(new_domain, existing_domain) ||
                        ServoCookie::domain_match(existing_domain, new_domain)) &&
                    ServoCookie::path_match(new_path, existing_path)
            });

            if any_overlapping {
                return Err(RemoveCookieError::Overlapping);
            }
        }

        // Step 11.1
        let position = cookies.iter().position(|c| {
            c.cookie.domain() == cookie.cookie.domain() &&
                c.cookie.path() == cookie.cookie.path() &&
                c.cookie.name() == cookie.cookie.name()
        });

        if let Some(ind) = position {
            // Step 11.4
            let c = cookies.remove(ind);

            // http://tools.ietf.org/html/rfc6265#section-5.3 step 11.2
            if c.cookie.http_only().unwrap_or(false) && source == CookieSource::NonHTTP {
                // Undo the removal.
                cookies.push(c);
                Err(RemoveCookieError::NonHTTP)
            } else {
                Ok(Some(c))
            }
        } else {
            Ok(None)
        }
    }
    pub fn clear_storage(&mut self, url: &ServoUrl) {
        let domain = reg_host(url.host_str().unwrap_or(""));
        let cookies = self.cookies_map.entry(domain).or_default();
        for cookie in cookies.iter_mut() {
            cookie.set_expiry_time_in_past();
        }
    }

    // http://tools.ietf.org/html/rfc6265#section-5.3
    pub fn push(&mut self, mut cookie: ServoCookie, url: &ServoUrl, source: CookieSource) {
        // https://www.ietf.org/id/draft-ietf-httpbis-cookie-alone-01.txt Step 1
        if cookie.cookie.secure().unwrap_or(false) && !url.is_secure_scheme() {
            return;
        }

        let old_cookie = self.remove(&cookie, url, source);
        if old_cookie.is_err() {
            // This new cookie is not allowed to overwrite an existing one.
            return;
        }

        // Step 11
        if let Some(old_cookie) = old_cookie.unwrap() {
            // Step 11.3
            cookie.creation_time = old_cookie.creation_time;
        }

        // Step 12
        let domain = reg_host(cookie.cookie.domain().as_ref().unwrap_or(&""));
        let cookies = self.cookies_map.entry(domain).or_default();

        if cookies.len() == self.max_per_host {
            let old_len = cookies.len();
            cookies.retain(|c| !is_cookie_expired(c));
            let new_len = cookies.len();

            // https://www.ietf.org/id/draft-ietf-httpbis-cookie-alone-01.txt
            if new_len == old_len &&
                !evict_one_cookie(cookie.cookie.secure().unwrap_or(false), cookies)
            {
                return;
            }
        }
        cookies.push(cookie);
    }

    pub fn cookie_comparator(a: &ServoCookie, b: &ServoCookie) -> Ordering {
        let a_path_len = a.cookie.path().as_ref().map_or(0, |p| p.len());
        let b_path_len = b.cookie.path().as_ref().map_or(0, |p| p.len());
        match a_path_len.cmp(&b_path_len) {
            Ordering::Equal => a.creation_time.cmp(&b.creation_time),
            // Ensure that longer paths are sorted earlier than shorter paths
            Ordering::Greater => Ordering::Less,
            Ordering::Less => Ordering::Greater,
        }
    }

    pub fn remove_expired_cookies_for_url(&mut self, url: &ServoUrl) {
        let domain = reg_host(url.host_str().unwrap_or(""));
        if let Entry::Occupied(mut entry) = self.cookies_map.entry(domain) {
            let cookies = entry.get_mut();
            cookies.retain(|c| !is_cookie_expired(c));
            if cookies.is_empty() {
                entry.remove_entry();
            }
        }
    }

    // http://tools.ietf.org/html/rfc6265#section-5.4
    pub fn cookies_for_url(&mut self, url: &ServoUrl, source: CookieSource) -> Option<String> {
        let filterer = |c: &&mut ServoCookie| -> bool {
            debug!(
                " === SENT COOKIE : {} {} {:?} {:?}",
                c.cookie.name(),
                c.cookie.value(),
                c.cookie.domain(),
                c.cookie.path()
            );
            debug!(
                " === SENT COOKIE RESULT {}",
                c.appropriate_for_url(url, source)
            );
            // Step 1
            c.appropriate_for_url(url, source)
        };
        // Step 2
        let domain = reg_host(url.host_str().unwrap_or(""));
        let cookies = self.cookies_map.entry(domain).or_default();

        let mut url_cookies: Vec<&mut ServoCookie> = cookies.iter_mut().filter(filterer).collect();
        url_cookies.sort_by(|a, b| CookieStorage::cookie_comparator(a, b));

        let reducer = |acc: String, c: &mut &mut ServoCookie| -> String {
            // Step 3
            c.touch();

            // Step 4
            (match acc.len() {
                0 => acc,
                _ => acc + "; ",
            }) + c.cookie.name() +
                "=" +
                c.cookie.value()
        };
        let result = url_cookies.iter_mut().fold("".to_owned(), reducer);

        info!(" === COOKIES SENT: {}", result);
        match result.len() {
            0 => None,
            _ => Some(result),
        }
    }

    pub fn cookies_data_for_url<'a>(
        &'a mut self,
        url: &'a ServoUrl,
        source: CookieSource,
    ) -> impl Iterator<Item = cookie::Cookie<'static>> + 'a {
        let domain = reg_host(url.host_str().unwrap_or(""));
        let cookies = self.cookies_map.entry(domain).or_default();

        cookies
            .iter_mut()
            .filter(move |c| c.appropriate_for_url(url, source))
            .map(|c| {
                c.touch();
                c.cookie.clone()
            })
    }
}

fn reg_host(url: &str) -> String {
    reg_suffix(url).to_lowercase()
}

fn is_cookie_expired(cookie: &ServoCookie) -> bool {
    matches!(cookie.expiry_time, Some(date_time) if date_time <= SystemTime::now())
}

fn evict_one_cookie(is_secure_cookie: bool, cookies: &mut Vec<ServoCookie>) -> bool {
    // Remove non-secure cookie with oldest access time
    let oldest_accessed = get_oldest_accessed(false, cookies);

    if let Some((index, _)) = oldest_accessed {
        cookies.remove(index);
    } else {
        // All secure cookies were found
        if !is_secure_cookie {
            return false;
        }
        let oldest_accessed = get_oldest_accessed(true, cookies);
        if let Some((index, _)) = oldest_accessed {
            cookies.remove(index);
        }
    }
    true
}

fn get_oldest_accessed(
    is_secure_cookie: bool,
    cookies: &mut [ServoCookie],
) -> Option<(usize, SystemTime)> {
    let mut oldest_accessed = None;
    for (i, c) in cookies.iter().enumerate() {
        if (c.cookie.secure().unwrap_or(false) == is_secure_cookie) &&
            oldest_accessed
                .as_ref()
                .map_or(true, |(_, current_oldest_time)| {
                    c.last_access < *current_oldest_time
                })
        {
            oldest_accessed = Some((i, c.last_access));
        }
    }
    oldest_accessed
}