use argon2::password_hash::Salt;
use diesel::Connection;
use serde::{Serialize, Deserialize};
use uuid::Uuid;
use diesel::{PgConnection, ExpressionMethods, QueryDsl, RunQueryDsl, Insertable, Queryable};
use diesel_derive_enum::DbEnum;
use argon2::password_hash::SaltString;
use argon2::PasswordHash;
use argon2::PasswordVerifier;
use argon2::Argon2;
use argon2::password_hash::PasswordHasher;
use validator::ValidationError;
use crate::util::GetConnection;
use super::schema::{pwd, users};
pub use super::error::DatabaseError;
use ::rand_core::{OsRng,TryRngCore};
use crate::request::requests::RegisterContext;

#[derive(Serialize, Deserialize, Debug, Insertable, Queryable)]
#[diesel(table_name = pwd)]
struct Pwd {
    user_id: Uuid,
    password: String,
}

#[derive(Serialize, Deserialize, Debug, Insertable, Queryable)]
#[diesel(table_name = users)]
pub struct User {
    pub id: Uuid,
    pub username: String,
    pub email: String,
    pub role: Role,
}

#[derive(DbEnum, Debug, Serialize, Deserialize, Clone, Copy, PartialEq)]
#[ExistingTypePath = "crate::schema::schema::sql_types::Role"]
pub enum Role {
    Admin,
    User
}

pub struct LoginUser {
    pub username: String,
    pub password: String
}

#[derive(Serialize, Deserialize)]
pub struct LoginResult {
    pub result: bool,
    pub user: Option<User>,
}

#[derive(Serialize, Deserialize)]
pub struct RegisterResult {
    pub result: bool,
}

#[derive(Serialize, Deserialize)]
pub struct Register {
    pub username: String,
    pub email: String,
    pub password: String
}

pub fn login(conn: &mut PgConnection, user: LoginUser) -> Result<Option<User>, DatabaseError> {
    let id: Uuid = users::table
        .filter(users::username.eq(&user.username))
        .or_filter(users::email.eq(&user.username))
        .select(users::id)
        .first(conn)?;

    let pwd: String = pwd::table
        .filter(pwd::user_id.eq(id))
        .select(pwd::password)
        .first(conn)?;

    let parsed_hash = PasswordHash::new(&pwd)?;

    if Argon2::default()
        .verify_password(user.password.as_bytes(), &parsed_hash)
        .is_ok()
    {
        Ok(Some(users::table.find(id).first(conn)?))
    } else {
        Ok(None)
    } 
}

pub fn get_user(conn: &mut PgConnection, id: Uuid) -> Result<User, DatabaseError> {
    Ok(users::table.find(id).first(conn)?)
}

pub fn unique_username(username: &String, context: &RegisterContext) -> Result<(), ValidationError> {
    let mut conn = context.pool.get().expect("Couldn't get db connection from pool");

    match users::table
        .count()
        .filter(users::username.eq(username))
        .get_result(&mut conn)
    {
        Ok(0) => Ok(()),
        Ok(_) => Err(ValidationError::new("User already exists")),
        Err(_) => Err(ValidationError::new("Database error while validating user")),
    }
}

pub fn unique_email(email: &String, context: &RegisterContext) -> Result<(), ValidationError> {
    let mut conn = context.pool.get_conn();

    match users::table
        .count()
        .filter(users::email.eq(email))
        .get_result(&mut conn)
    {
        Ok(0) => Ok(()),
        Ok(_) => Err(ValidationError::new("email already exists")),
        Err(_) => Err(ValidationError::new(
            "Database error while validating email",
        )),
    }
}

pub fn register(conn: &mut PgConnection, register: Register) -> Result<(), DatabaseError> {
    let mut bytes = [0u8; Salt::RECOMMENDED_LENGTH];
    OsRng.try_fill_bytes(&mut bytes).unwrap();
    let salt = SaltString::encode_b64(&bytes).unwrap();
    let argon2 = Argon2::default();

    let password_hash = argon2
        .hash_password(register.password.as_bytes(), &salt)?
        .to_string();

    conn.transaction(|c| {
        let id = Uuid::new_v4();

        diesel::insert_into(users::table)
            .values(User {
                id,
                username: register.username,
                email: register.email,
                role: Role::User,
            })
            .execute(c)?;

        diesel::insert_into(pwd::table)
            .values(Pwd {
                user_id: id,
                password: password_hash,
            })
            .execute(c)?;

        Ok(())
    })
}