use rocket::{Request, http::Status, outcome::Outcome, request::FromRequest};
use serde::{Deserialize, Serialize};
use serde_json::json;
use sqlx::FromRow;

use super::{Session, gen_token};
use crate::{get_pg, request::api::ToAPI};

/// User
///
/// # Example:
///
/// ```ignore
///
/// // Needs login
/// #[get("/myaccount")]
/// pub async fn account_page(ctx: RequestContext, user: User) -> StringResponse {
///     ...
/// }
/// ```
#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
pub struct User {
    /// The username chosen by the user
    pub username: String,
    /// The hashed password for the user
    pub password: String,
    /// The role of the user
    pub user_role: UserRole,
}

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::Type)]
#[sqlx(type_name = "user_role", rename_all = "lowercase")]
pub enum UserRole {
    /// A regular user with limited permissions
    Regular,
    /// An admin user with full system privileges
    Admin,
}

impl User {
    // Get a user from session ID
    pub async fn from_session(session: &str) -> Option<Self> {
        sqlx::query_as("SELECT * FROM users WHERE username = (SELECT \"user\" FROM user_session WHERE token = $1)").bind(session).fetch_optional(get_pg!()).await.unwrap()
    }

    /// Find a user by their username
    pub async fn find(username: &str) -> Option<Self> {
        sqlx::query_as("SELECT * FROM users WHERE username = $1")
            .bind(username)
            .fetch_optional(get_pg!())
            .await
            .unwrap()
    }

    /// Create a new user with the given details
    ///
    /// Returns an Option containing the created user, or None if a user already exists with the same username
    pub async fn create(username: &str, password: &str, role: UserRole) -> Option<Self> {
        // Check if a user already exists with the same username
        if Self::find(username).await.is_some() {
            return None;
        }

        let u = Self {
            username: username.to_string(),
            password: bcrypt::hash(password, bcrypt::DEFAULT_COST).unwrap(),
            user_role: role,
        };

        sqlx::query("INSERT INTO users (username, \"password\", user_role) VALUES ($1, $2, $3)")
            .bind(&u.username)
            .bind(&u.password)
            .bind(&u.user_role)
            .execute(get_pg!())
            .await
            .unwrap();

        Some(u)
    }

    /// Login a user with the given username and password
    pub async fn login(username: &str, password: &str) -> Option<(Session, UserRole)> {
        let u = Self::find(username).await?;

        if !u.verify_pw(password) {
            return None;
        }

        Some((u.session().await, u.user_role))
    }

    /// Change the password of a User
    ///
    /// Returns a Result indicating whether the password change was successful or not
    pub async fn passwd(self, old: &str, new: &str) -> Result<(), ()> {
        if self.verify_pw(old) {
            sqlx::query("UPDATE users SET \"password\" = $1 WHERE username = $2;")
                .bind(bcrypt::hash(new, bcrypt::DEFAULT_COST).unwrap())
                .bind(&self.username)
                .fetch_one(get_pg!())
                .await
                .unwrap();

            return Ok(());
        }

        Err(())
    }

    /// Find all users in the system
    pub async fn find_all() -> Vec<Self> {
        sqlx::query_as("SELECT * FROM users")
            .fetch_all(get_pg!())
            .await
            .unwrap()
    }

    /// Generate a new session token for the user
    ///
    /// Returns a Session instance containing the generated token and associated user
    pub async fn session(&self) -> Session {
        sqlx::query_as(
            "INSERT INTO user_session (token, \"user\") VALUES ($1, $2) RETURNING id, token, \"user\"",
        )
        .bind(gen_token(64))
        .bind(&self.username)
        .fetch_one(get_pg!())
        .await
        .unwrap()
    }

    /// Check if the user is an admin
    pub const fn is_admin(&self) -> bool {
        matches!(self.user_role, UserRole::Admin)
    }

    /// Verify that a provided password matches the hashed password for the user
    ///
    /// Returns a boolean indicating whether the passwords match or not
    pub fn verify_pw(&self, password: &str) -> bool {
        bcrypt::verify(password, &self.password).unwrap()
    }
}

impl ToAPI for User {
    async fn api(&self) -> serde_json::Value {
        json!({
            "username": self.username,
            "role": self.user_role
        })
    }
}

async fn extract_user<'r>(request: &'r Request<'_>) -> Option<User> {
    if let Some(session_id) = request.cookies().get("session_id") {
        if let Some(user) = User::from_session(session_id.value()).await {
            return Some(user);
        } else {
            return None;
        }
    }

    match request.headers().get_one("token") {
        Some(key) => {
            if let Some(user) = User::from_session(key).await {
                return Some(user);
            } else {
                return None;
            }
        }
        None => None,
    }
}

#[rocket::async_trait]
impl<'r> FromRequest<'r> for User {
    type Error = ();

    async fn from_request(request: &'r Request<'_>) -> rocket::request::Outcome<Self, Self::Error> {
        if let Some(user) = extract_user(request).await {
            return Outcome::Success(user);
        } else {
            return Outcome::Error((Status::Unauthorized, ()));
        }
    }
}

/// Maybe User?
///
/// This struct extracts a user if possible, but also allows anybody.
///
/// # Example:
///
/// ```ignore
///
/// // Publicly accessable
/// #[get("/")]
/// pub async fn index(ctx: RequestContext, user: MaybeUser) -> StringResponse {
///     match user {
///         MaybeUser::User(user) => println!("You are {}", user.username),
///         MaybeUser::Anonymous => println!("Who are you?")
///     }
/// }
/// ```
pub enum MaybeUser {
    User(User),
    Anonymous,
}

#[rocket::async_trait]
impl<'r> FromRequest<'r> for MaybeUser {
    type Error = ();

    async fn from_request(request: &'r Request<'_>) -> rocket::request::Outcome<Self, Self::Error> {
        if let Some(user) = extract_user(request).await {
            return Outcome::Success(MaybeUser::User(user));
        } else {
            return Outcome::Success(MaybeUser::Anonymous);
        }
    }
}

/// Admin User
///
/// This struct expects an Admin User and returns `Forbidden` otherwise.
///
/// # Example:
///
/// ```ignore
///
/// // Only admin users can access this route
/// #[get("/admin")]
/// pub async fn admin_panel(ctx: RequestContext, user: AdminUser) -> StringResponse {
///     ...
/// }
/// ```
pub struct AdminUser(User);

#[rocket::async_trait]
impl<'r> FromRequest<'r> for AdminUser {
    type Error = ();

    async fn from_request(request: &'r Request<'_>) -> rocket::request::Outcome<Self, Self::Error> {
        if let Some(user) = extract_user(request).await {
            if user.is_admin() {
                return Outcome::Success(AdminUser(user));
            }
        } else {
        }
        Outcome::Error((Status::Unauthorized, ()))
    }
}