/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2024 metamuffin <metamuffin.org>
*/
pub mod session;
pub mod settings;

use super::{error::MyError, layout::LayoutPage};
use crate::{
    database::DataAcid,
    routes::ui::{
        account::session::Session, error::MyResult, home::rocket_uri_macro_r_home,
        layout::DynLayoutPage,
    },
    uri,
};
use anyhow::anyhow;
use argon2::{password_hash::Salt, Argon2, PasswordHasher};
use chrono::Duration;
use jellybase::{
    database::{Ser, TableExt, T_INVITE, T_USER},
    CONF,
};
use jellycommon::user::{PermissionSet, Theme, User, UserPermission};
use rocket::{
    form::{Contextual, Form},
    get,
    http::{Cookie, CookieJar},
    post,
    response::Redirect,
    FromForm, State,
};
use serde::{Deserialize, Serialize};
use std::collections::HashSet;

#[derive(FromForm)]
pub struct RegisterForm {
    #[field(validate = len(8..128))]
    pub invitation: String,
    #[field(validate = len(4..32))]
    pub username: String,
    #[field(validate = len(4..64))]
    pub password: String,
}

#[get("/account/register")]
pub async fn r_account_register() -> DynLayoutPage<'static> {
    LayoutPage {
        title: "Register".to_string(),
        content: markup::new! {
            form.account[method="POST", action=""] {
                h1 { "Register"  }

                label[for="inp-invitation"] { "Invite Code" }
                input[type="text", id="inp-invitation", name="invitation"]; br;

                label[for="inp-username"] { "Username" }
                input[type="text", id="inp-username", name="username"]; br;
                label[for="inp-password"] { "Password" }
                input[type="password", id="inp-password", name="password"]; br;

                input[type="submit", value="Register now!"];

                p { "Already have an account? " a[href=uri!(r_account_login())] { "Login here" } }
            }
        },
        ..Default::default()
    }
}

#[derive(FromForm, Serialize, Deserialize)]
pub struct LoginForm {
    #[field(validate = len(4..32))]
    pub username: String,
    #[field(validate = len(..64))]
    pub password: String,
    #[field(default = 604800)] // one week
    pub expire: u64,
}

#[get("/account/login")]
pub fn r_account_login(sess: Option<Session>) -> DynLayoutPage<'static> {
    let logged_in = sess.is_some();
    let title = if logged_in { "Switch Account" } else { "Login" };
    LayoutPage {
        title: title.to_string(),
        content: markup::new! {
            form.account[method="POST", action=""] {
                h1 { @title }

                label[for="inp-username"] { "Username" }
                input[type="text", id="inp-username", name="username"]; br;
                label[for="inp-password"] { "Password" }
                input[type="password", id="inp-password", name="password"]; br;

                input[type="submit", value=title];

                @if logged_in {
                    p { "Need another account? " a[href=uri!(r_account_register())] { "Register here" } }
                } else {
                    p { "While logged in, a cookie will be used to identify you." }
                    p { "Don't have an account yet? " a[href=uri!(r_account_register())] { "Register here" } }
                }
            }
        },
        ..Default::default()
    }
}

#[get("/account/logout")]
pub fn r_account_logout() -> DynLayoutPage<'static> {
    LayoutPage {
        title: "Log out".to_string(),
        content: markup::new! {
            form.account[method="POST", action=""] {
                h1 { "Log out" }
                input[type="submit", value="Log out."];
            }
        },
        ..Default::default()
    }
}

#[post("/account/register", data = "<form>")]
pub fn r_account_register_post<'a>(
    database: &'a State<DataAcid>,
    _sess: Option<Session>,
    form: Form<Contextual<'a, RegisterForm>>,
) -> MyResult<DynLayoutPage<'a>> {
    let logged_in = _sess.is_some();
    let form = match &form.value {
        Some(v) => v,
        None => return Err(format_form_error(form)),
    };

    let txn = database.begin_write()?;
    let mut invites = txn.open_table(T_INVITE)?;
    let mut users = txn.open_table(T_USER)?;

    if invites.remove(&*form.invitation)?.is_none() {
        Err(anyhow!("invitation invalid"))?;
    }
    let prev_user = users
        .insert(
            &*form.username,
            Ser(User {
                display_name: form.username.clone(),
                name: form.username.clone(),
                password: hash_password(&form.username, &form.password),
                admin: false,
                theme: Theme::Dark,
                permissions: PermissionSet::default(),
            }),
        )?
        .map(|x| x.value().0);
    if prev_user.is_some() {
        Err(anyhow!("username taken"))?;
    }

    drop(users);
    drop(invites);
    txn.commit()?;

    Ok(LayoutPage {
        title: "Registration successful".to_string(),
        content: markup::new! {
            h1 { @if logged_in {
                "Registration successful, you may switch account now."
            } else {
                "Registration successful, you may log in now."
            }}
        },
        ..Default::default()
    })
}

#[post("/account/login", data = "<form>")]
pub fn r_account_login_post(
    database: &State<DataAcid>,
    jar: &CookieJar,
    form: Form<Contextual<LoginForm>>,
) -> MyResult<Redirect> {
    let form = match &form.value {
        Some(v) => v,
        None => return Err(format_form_error(form)),
    };
    jar.add(
        Cookie::build((
            "session",
            login_logic(database, &form.username, &form.password, None, None)?,
        ))
        .permanent()
        .build(),
    );

    Ok(Redirect::found(rocket::uri!(r_home())))
}

#[post("/account/logout")]
pub fn r_account_logout_post(jar: &CookieJar) -> MyResult<Redirect> {
    jar.remove_private(Cookie::build("session"));
    Ok(Redirect::found(rocket::uri!(r_home())))
}

pub fn login_logic(
    database: &DataAcid,
    username: &str,
    password: &str,
    expire: Option<i64>,
    drop_permissions: Option<HashSet<UserPermission>>,
) -> MyResult<String> {
    // hashing the password regardless if the accounts exists to prevent timing attacks
    let password = hash_password(username, password);

    let mut user = T_USER
        .get(database, username)?
        .ok_or(anyhow!("invalid password"))?;

    if user.password != password {
        Err(anyhow!("invalid password"))?
    }

    if let Some(ep) = drop_permissions {
        // remove all grant perms that are in `ep`
        user.permissions
            .0
            .retain(|p, val| if *val { !ep.contains(p) } else { true })
    }

    Ok(session::token::create(
        user.name,
        user.permissions,
        Duration::days(CONF.login_expire.min(expire.unwrap_or(i64::MAX))),
    ))
}

pub fn format_form_error<T>(form: Form<Contextual<T>>) -> MyError {
    let mut k = String::from("form validation failed:");
    for e in form.context.errors() {
        k += &format!(
            "\n\t{}: {e}",
            e.name
                .as_ref()
                .map(|e| e.to_string())
                .unwrap_or("<unknown>".to_string())
        )
    }
    MyError(anyhow!(k))
}

pub fn hash_password(username: &str, password: &str) -> Vec<u8> {
    Argon2::default()
        .hash_password(
            format!("{username}\0{password}").as_bytes(),
            <&str as TryInto<Salt>>::try_into("IYMa13osbNeLJKnQ1T8LlA").unwrap(),
        )
        .unwrap()
        .hash
        .unwrap()
        .as_bytes()
        .to_vec()
}