use ldap3::{LdapConn, Mod, Scope, SearchEntry};
use std::collections::HashSet;

use base64::{engine::general_purpose, Engine as _};
use crypto::{digest::Digest, sha2::Sha512};

// for teh webserver
use dotenv::dotenv;
use skynet_ldap_server::db_init;
use sqlx::{Pool, Sqlite};
use std::env;
use tide::prelude::{json, Deserialize};
use tide::Request;

#[derive(Clone)]
struct State {
    db: Pool<Sqlite>,
    config: Config,
}

#[async_std::main]
async fn main() -> tide::Result<()> {
    let config = get_config();
    let db = db_init(&config.database).await?;

    let host_port = config.host_port.clone();

    tide::log::start();

    let state = State {
        db,
        config,
    };

    let mut app = tide::with_state(state);

    app.at("/ldap/update").post(post_update_ldap);

    app.listen(host_port).await?;
    Ok(())
}

#[derive(Debug, Clone)]
struct Config {
    ldap_host: String,
    database: String,
    host_port: String,
}
fn get_config() -> Config {
    dotenv().ok();

    // reasonable defaults
    let mut config = Config {
        ldap_host: "".to_string(),
        database: "database.db".to_string(),
        host_port: "127.0.0.1:8087".to_string(),
    };

    if let Ok(x) = env::var("LDAP_HOST") {
        config.ldap_host = x.trim().to_string();
    }
    if let Ok(x) = env::var("DATABASE") {
        config.database = x.trim().to_string();
    }
    if let Ok(x) = env::var("HOST_PORT") {
        config.host_port = x.trim().to_string();
    }

    config
}

//https://stackoverflow.com/a/44532957
pub fn hex_to_base64(hex: &str) -> String {
    // Make vector of bytes from octets
    let mut bytes = Vec::new();
    for i in 0..(hex.len() / 2) {
        let res = u8::from_str_radix(&hex[2 * i..2 * i + 2], 16);
        match res {
            Ok(v) => bytes.push(v),
            Err(e) => println!("Problem with hex: {}", e),
        };
    }

    general_purpose::STANDARD.encode(&bytes) // now convert from Vec<u8> to b64-encoded String
}

#[derive(Debug, Deserialize)]
struct LdapUpdate {
    user: String,
    pass: String,
    field: String,
    value: String,
}
async fn post_update_ldap(mut req: Request<State>) -> tide::Result {
    let LdapUpdate {
        user,
        pass,
        field,
        value,
    } = req.body_json().await?;

    let config = &req.state().config;

    // easier to give each request its own connection
    let mut ldap = LdapConn::new(&config.ldap_host)?;

    let dn = format!("uid={},ou=users,dc=skynet,dc=ie", user);
    ldap.simple_bind(&dn, &pass)?.success()?;

    // always assume insecure
    let mut pw_keep_same = false;

    // get the users current password hash
    let (rs, _res) = ldap.search(&dn, Scope::Base, "(objectClass=*)", vec!["userPassword"])?.success()?;
    if !rs.is_empty() {
        let tmp = SearchEntry::construct(rs[0].clone());
        if !tmp.attrs["userPassword"].is_empty() && tmp.attrs["userPassword"][0].starts_with("{SHA512}") {
            pw_keep_same = true;
        }
    }

    let mut mods = vec![];

    // check if the password field itself is being updated
    let pass_new = if &field != "userPassword" {
        mods.push(Mod::Replace(field, HashSet::from([value])));
        // retain the older password
        pass
    } else {
        pw_keep_same = false;
        value
    };

    if !pw_keep_same {
        let mut hasher = Sha512::new();

        hasher.input_str(&pass_new);

        // get it as hex string
        let hex = hasher.result_str();

        // convert it to b64
        let pass_tmp = format!("{{SHA512}}{}", hex_to_base64(&hex));

        mods.push(Mod::Replace(String::from("userPassword"), HashSet::from([pass_tmp])));
    };

    ldap.modify(&dn, mods)?.success()?;

    ldap.unbind()?;

    Ok(json!({"result": "success"}).into())
}