use actix_web::client::Client;
use actix_web::{http, web, HttpRequest, HttpResponse};
use base64::URL_SAFE_NO_PAD;
use percent_encoding::percent_decode_str;
use rand::rngs::OsRng;
use rand::Rng;
use rand::RngCore;
use regex::Regex;
use std::collections::HashMap;
use std::time::Duration;

use crate::config::{ADJ_LIST, NAME_LIST, PROXY_TIMEOUT, USER_AGENT};
use crate::debug;
use crate::errors::{crash, TrainCrash};
use crate::templates::get_lang;
use crate::CONFIG;

#[derive(Serialize)]
struct NCLoginForm<'a> {
    pub user: &'a str,
    pub password: &'a str,
    pub timezone: &'a str,
    pub timezone_offset: &'a str,
    pub requesttoken: &'a str,
}

// check if the user is connected to Nextcloud
// returns Some(cookie_raw_value) if connected
// returns None if disconnected
pub fn is_logged_in(req: &HttpRequest) -> Option<&str> {
    let c = req.headers().get("Cookie")?.to_str().ok()?;
    if c.contains("nc_username") {
        Some(c)
    } else {
        None
    }
}

// attempts to create the account from Nextcloud's API
// returns the newly created username.
// if it fails (bad return code), returns None.
pub async fn create_account(
    client: &web::Data<Client>,
    user: &str,
    password: &str,
    lang: String,
) -> Result<String, TrainCrash> {
    let mut register_query = client
        .post(format!(
            "{}/{}",
            CONFIG.nextcloud_url, "ocs/v1.php/cloud/users"
        ))
        .timeout(Duration::new(PROXY_TIMEOUT, 0))
        .basic_auth(&CONFIG.admin_username, Some(&CONFIG.admin_password))
        .header(
            http::header::CONTENT_TYPE,
            "application/x-www-form-urlencoded",
        )
        .header("OCS-APIRequest", "true")
        .send_form(&NCCreateAccountForm {
            userid: user,
            password,
            quota: "0B",
            language: &lang,
        })
        .await
        .map_err(|e| {
            eprintln!("error_createaccount_post: {}", e);
            crash(lang.clone(), "error_createaccount_post")
        })?;

    // only 200 http status code is allowed
    if register_query.status() != 200 {
        eprintln!("error_createaccount_status: {}", register_query.status());
        // + extract response body for debugging purposes
        let response_body = register_query.body().await.map_err(|e| {
            eprintln!("error_createaccount_post_body: {}", e);
            crash(lang.clone(), "error_createaccount_post_body")
        })?;
        debug(&format!("Body: {:#?}", response_body));
        return Err(crash(lang.clone(), "error_createaccount_status"));
    }

    // extract response body
    let response_body = register_query.body().await.map_err(|e| {
        eprintln!("error_createaccount_post_body: {}", e);
        crash(lang.clone(), "error_createaccount_post_body")
    })?;
    let response_body = String::from_utf8_lossy(&response_body);
    // grasp NC status code
    let status_start = response_body.find("<statuscode>").ok_or_else(|| {
        eprintln!("error_createaccount_ncstatus_parse: start missing");
        crash(lang.clone(), "error_createaccount_ncstatus_parse")
    })? + 12;
    let status_end = response_body.find("</statuscode>").ok_or_else(|| {
        eprintln!("error_createaccount_ncstatus_parse: end missing");
        crash(lang.clone(), "error_createaccount_ncstatus_parse")
    })?;
    let code = &response_body[status_start..status_end];
    match code.parse::<u16>() {
        Ok(100) => Ok(String::from(user)), // success
        Ok(r) => {
            eprintln!("error_createaccount_ncstatus: {}", r);
            Err(crash(lang.clone(), "error_createaccount_ncstatus"))
        }
        Err(e) => {
            eprintln!("error_createaccount_ncstatus_parse: {}", e);
            Err(crash(lang.clone(), "error_createaccount_ncstatus_parse"))
        }
    }
}

#[derive(Serialize)]
struct NCCreateAccountForm<'a> {
    pub userid: &'a str,
    pub password: &'a str,
    pub quota: &'a str,
    pub language: &'a str,
}

pub async fn login(
    client: &web::Data<Client>,
    req: &HttpRequest,
    user: &str,
    password: &str,
) -> Result<HttpResponse, TrainCrash> {
    debug(&format!("Sending forged login for user {}", user));

    // 1. GET /csrftoken
    let mut login_get = client
        .get(format!("{}/{}", CONFIG.nextcloud_url, "csrftoken"))
        .timeout(Duration::new(PROXY_TIMEOUT, 0))
        .header("User-Agent", USER_AGENT)
        .send()
        .await
        .map_err(|e| {
            eprintln!("error_login_get: {}", e);
            crash(get_lang(&req), "error_login_get")
        })?;

    // rewrite cookie headers from GET to POST
    let mut str_cookiepair = String::new();

    // remove duplicate oc<id> cookie (nextcloud bug)
    // leading to sncf being unable to forge logins
    let cookie_set = login_get.headers().get_all("set-cookie");
    let mut cookie_map: HashMap<String, String> = HashMap::new();
    for c in cookie_set {
        // get str version of cookie header
        let c_str = c.to_str().map_err(|e| {
            eprintln!("error_login_cookiepair (1): {}", e);
            crash(get_lang(&req), "error_login_cookiepair")
        })?;

        // percent decode
        let c_str = percent_decode_str(c_str).decode_utf8_lossy();

        //then remove values after ';'
        let c_str_arr = c_str.split(';').collect::<Vec<&str>>();

        let c_str = c_str_arr
            .first()
            .expect("error: cookiepair split does not have a first value. shouldn't happen.");

        // split cookie key and cookie value
        // split_once would work best but it's nightly-only for now
        let c_str_arr = c_str.split('=').collect::<Vec<&str>>();

        let c_key = c_str_arr
            .first()
            .expect("error: cookie key split does not have a first value, shouldn't happen.");

        let c_value = c_str.replace(&format!("{}=", c_key), "");

        if c_key != c_str {
            // if the key already exists in hashmap, replace its value
            // else, insert it
            if let Some(c_sel) = cookie_map.get_mut(*c_key) {
                *c_sel = c_value;
            } else {
                cookie_map.insert(c_key.to_string(), c_value);
            }
        } else {
            eprintln!("error_login_cookiepair (2)");
            return Err(crash(get_lang(&req), "error_login_cookiepair"));
        }
    }

    for (cookie_k, cookie_v) in cookie_map {
        str_cookiepair.push_str(&format!("{}={}; ", cookie_k, cookie_v));
    }

    // load requesttoken regex
    lazy_static! {
        static ref RE: Regex = Regex::new(r#"\{"token":"(?P<token>[^"]*)"\}"#)
            .expect("Error while parsing the requesttoken regex");
    }

    let post_body = login_get.body().await.map_err(|e| {
        eprintln!("error_login_get_body: {}", e);
        crash(get_lang(&req), "error_login_get_body")
    })?;
    let post_body_str = String::from_utf8_lossy(&post_body);

    // save requesttoken (CSRF) for POST
    let requesttoken = RE
        .captures(&post_body_str)
        .ok_or_else(|| {
            eprintln!("error_login_regex (no capture)");
            crash(get_lang(&req), "error_login_regex")
        })?
        .name("token")
        .ok_or_else(|| {
            eprintln!("error_login_regex (no capture named token)");
            crash(get_lang(&req), "error_login_regex")
        })?
        .as_str();

    // 2. POST /login
    let mut login_post = client
        .post(format!("{}/{}", CONFIG.nextcloud_url, "login"))
        .timeout(Duration::new(PROXY_TIMEOUT, 0))
        .header("User-Agent", USER_AGENT);

    // include all NC cookies in one cookie (cookie pair)
    login_post = login_post.header("Cookie", str_cookiepair);

    // send the same POST data as you'd log in from a web browser
    let response_post = login_post
        .send_form(&NCLoginForm {
            user,
            password,
            timezone: "UTC",
            timezone_offset: "2",
            requesttoken,
        })
        .await
        .map_err(|e| {
            eprintln!("error_login_post: {}", e);
            crash(get_lang(&req), "error_login_post")
        })?;

    // 3. set the same cookies in the user's browser
    let mut user_response = HttpResponse::SeeOther();

    for item in response_post.headers().clone().get_all("set-cookie") {
        user_response.header(
            "Set-Cookie",
            item.to_str().map_err(|e| {
                eprintln!("error_login_setcookie: {}", e);
                crash(get_lang(&req), "error_login_setcookie")
            })?,
        );
    }

    // redirect to forms!
    Ok(user_response
        .header(http::header::LOCATION, "/apps/forms")
        .finish()
        .await
        .map_err(|e| {
            eprintln!("error_login_redir: {}", e);
            crash(get_lang(&req), "error_login_redir")
        })?)
}

// checks if the token seems valid before asking the db.
// The token must be 45 bytes long and base64-encoded.
// returns true if the token is valid
pub fn check_token(token: &str) -> bool {
    let token_dec = base64::decode_config(token, URL_SAFE_NO_PAD);
    if let Ok(token_bytes) = token_dec {
        token_bytes.len() == 45
    } else {
        false
    }
}

// generates a new token
pub fn gen_token(size: usize) -> String {
    // Using /dev/random to generate random bytes
    let mut r = OsRng;

    let mut my_secure_bytes = vec![0u8; size];
    r.fill_bytes(&mut my_secure_bytes);
    base64::encode_config(my_secure_bytes, URL_SAFE_NO_PAD)
}

// generates a random username composed of
// an adjective, a name and a 4-byte base64-encoded token.
// with the default list, that represents:
// 141 * 880 = 124 080
// 255^4 / 2 = 2 114 125 312 (we lose approx. the half because of uppercase)
// 2 114 125 312 * 124 080 = 2.623206687*10^14 possible combinations??
pub fn gen_name() -> String {
    // uppercasing gen_token because NC would probably refuse two
    // users with the same name but a different case
    // and that'd be a pain to debug
    format!(
        "{}{}-{}",
        list_rand(&ADJ_LIST),
        list_rand(&NAME_LIST),
        gen_token(4).to_uppercase()
    )
}

pub fn list_rand(list: &[String]) -> &String {
    let mut rng = rand::thread_rng();
    let roll = rng.gen_range(0..list.len() - 1);
    &list[roll]
}