use crate::auth::session::issue_session;
use crate::auth::validate::get_user_record_from_bearer_token;
use crate::auth::{get_user_from_headers, AuthenticationError};
use crate::database::models::flow_item::Flow;
use crate::file_hosting::FileHost;
use crate::models::ids::base62_impl::{parse_base62, to_base62};
use crate::models::ids::random_base62_rng;
use crate::models::pats::Scopes;
use crate::models::users::{Badges, Role};
use crate::parse_strings_from_var;
use crate::queue::session::AuthQueue;
use crate::routes::ApiError;
use crate::util::captcha::check_turnstile_captcha;
use crate::util::ext::{get_image_content_type, get_image_ext};
use crate::util::validate::{validation_errors_to_string, RE_URL_SAFE};
use actix_web::web::{scope, Data, Query, ServiceConfig};
use actix_web::{delete, get, post, web, HttpRequest, HttpResponse};
use argon2::password_hash::SaltString;
use argon2::{Argon2, PasswordHash, PasswordHasher, PasswordVerifier};
use chrono::{Duration, Utc};
use rand_chacha::rand_core::SeedableRng;
use rand_chacha::ChaCha20Rng;
use reqwest::header::AUTHORIZATION;
use rust_decimal::Decimal;
use serde::{Deserialize, Serialize};
use sqlx::postgres::PgPool;
use std::collections::HashMap;
use std::sync::Arc;
use validator::Validate;

pub fn config(cfg: &mut ServiceConfig) {
    cfg.service(scope("auth").service(auth_callback).service(init))
        .service(create_account_with_password)
        .service(login_password)
        .service(login_2fa)
        .service(begin_2fa_flow)
        .service(finish_2fa_flow)
        .service(remove_2fa);
}

#[derive(Serialize, Deserialize, Default, Eq, PartialEq, Clone, Copy)]
#[serde(rename_all = "lowercase")]
pub enum AuthProvider {
    #[default]
    GitHub,
    Discord,
    Microsoft,
    GitLab,
    Google,
    Steam,
}

#[derive(Debug)]
pub struct TempUser {
    pub id: String,
    pub username: String,
    pub email: Option<String>,

    pub avatar_url: Option<String>,
    pub bio: Option<String>,
    pub name: Option<String>,
}

impl AuthProvider {
    pub fn get_redirect_url(&self, state: String) -> Result<String, AuthenticationError> {
        let self_addr = dotenvy::var("SELF_ADDR")?;
        let raw_redirect_uri = format!("{}/v2/auth/callback", self_addr);
        let redirect_uri = urlencoding::encode(&raw_redirect_uri);

        Ok(match self {
            AuthProvider::GitHub => {
                let client_id = dotenvy::var("GITHUB_CLIENT_ID")?;

                format!(
                    "https://github.com/login/oauth/authorize?client_id={}&state={}&scope=read%3Auser%20user%3Aemail&redirect_uri={}",
                    client_id,
                    state,
                    redirect_uri,
                )
            }
            AuthProvider::Discord => {
                let client_id = dotenvy::var("DISCORD_CLIENT_ID")?;

                format!("https://discord.com/api/oauth2/authorize?client_id={}&state={}&response_type=code&scope=identify%20email&redirect_uri={}", client_id, state, redirect_uri)
            }
            AuthProvider::Microsoft => {
                let client_id = dotenvy::var("MICROSOFT_CLIENT_ID")?;

                format!("https://login.live.com/oauth20_authorize.srf?client_id={}&response_type=code&scope=user.read&state={}&prompt=select_account&redirect_uri={}", client_id, state, redirect_uri)
            }
            AuthProvider::GitLab => {
                let client_id = dotenvy::var("GITLAB_CLIENT_ID")?;

                format!(
                    "https://gitlab.com/oauth/authorize?client_id={}&state={}&scope=read_user+profile+email&response_type=code&redirect_uri={}",
                    client_id,
                    state,
                    redirect_uri,
                )
            }
            AuthProvider::Google => {
                let client_id = dotenvy::var("GOOGLE_CLIENT_ID")?;

                format!(
                    "https://accounts.google.com/o/oauth2/v2/auth?client_id={}&state={}&scope={}&response_type=code&redirect_uri={}",
                    client_id,
                    state,
                    urlencoding::encode("https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/userinfo.profile"),
                    redirect_uri,
                )
            }
            AuthProvider::Steam => {
                format!(
                    "https://steamcommunity.com/openid/login?openid.ns={}&openid.mode={}&openid.return_to={}{}{}&openid.realm={}&openid.identity={}&openid.claimed_id={}",
                    urlencoding::encode("http://specs.openid.net/auth/2.0"),
                    "checkid_setup",
                    redirect_uri, urlencoding::encode("?state="), state,
                    self_addr,
                    "http://specs.openid.net/auth/2.0/identifier_select",
                    "http://specs.openid.net/auth/2.0/identifier_select",
                )
            }
        })
    }

    pub async fn get_token(
        &self,
        query: HashMap<String, String>,
    ) -> Result<String, AuthenticationError> {
        let redirect_uri = format!("{}/v2/auth/callback", dotenvy::var("SELF_ADDR")?);

        #[derive(Deserialize)]
        struct AccessToken {
            pub access_token: String,
        }

        let res = match self {
            AuthProvider::GitHub => {
                let code = query
                    .get("code")
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;
                let client_id = dotenvy::var("GITHUB_CLIENT_ID")?;
                let client_secret = dotenvy::var("GITHUB_CLIENT_SECRET")?;

                let url = format!(
                    "https://github.com/login/oauth/access_token?client_id={}&client_secret={}&code={}&redirect_uri={}",
                    client_id, client_secret, code, redirect_uri
                );

                let token: AccessToken = reqwest::Client::new()
                    .post(&url)
                    .header(reqwest::header::ACCEPT, "application/json")
                    .send()
                    .await?
                    .json()
                    .await?;

                token.access_token
            }
            AuthProvider::Discord => {
                let code = query
                    .get("code")
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;
                let client_id = dotenvy::var("DISCORD_CLIENT_ID")?;
                let client_secret = dotenvy::var("DISCORD_CLIENT_SECRET")?;

                let mut map = HashMap::new();
                map.insert("client_id", &*client_id);
                map.insert("client_secret", &*client_secret);
                map.insert("code", code);
                map.insert("grant_type", "authorization_code");
                map.insert("redirect_uri", &redirect_uri);

                let token: AccessToken = reqwest::Client::new()
                    .post("https://discord.com/api/v10/oauth2/token")
                    .header(reqwest::header::ACCEPT, "application/json")
                    .form(&map)
                    .send()
                    .await?
                    .json()
                    .await?;

                token.access_token
            }
            AuthProvider::Microsoft => {
                let code = query
                    .get("code")
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;
                let client_id = dotenvy::var("MICROSOFT_CLIENT_ID")?;
                let client_secret = dotenvy::var("MICROSOFT_CLIENT_SECRET")?;

                let mut map = HashMap::new();
                map.insert("client_id", &*client_id);
                map.insert("client_secret", &*client_secret);
                map.insert("code", code);
                map.insert("grant_type", "authorization_code");
                map.insert("redirect_uri", &redirect_uri);

                let token: AccessToken = reqwest::Client::new()
                    .post("https://login.live.com/oauth20_token.srf")
                    .header(reqwest::header::ACCEPT, "application/json")
                    .form(&map)
                    .send()
                    .await?
                    .json()
                    .await?;

                token.access_token
            }
            AuthProvider::GitLab => {
                let code = query
                    .get("code")
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;
                let client_id = dotenvy::var("GITLAB_CLIENT_ID")?;
                let client_secret = dotenvy::var("GITLAB_CLIENT_SECRET")?;

                let mut map = HashMap::new();
                map.insert("client_id", &*client_id);
                map.insert("client_secret", &*client_secret);
                map.insert("code", code);
                map.insert("grant_type", "authorization_code");
                map.insert("redirect_uri", &redirect_uri);

                let token: AccessToken = reqwest::Client::new()
                    .post("https://gitlab.com/oauth/token")
                    .header(reqwest::header::ACCEPT, "application/json")
                    .form(&map)
                    .send()
                    .await?
                    .json()
                    .await?;

                token.access_token
            }
            AuthProvider::Google => {
                let code = query
                    .get("code")
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;
                let client_id = dotenvy::var("GOOGLE_CLIENT_ID")?;
                let client_secret = dotenvy::var("GOOGLE_CLIENT_SECRET")?;

                let mut map = HashMap::new();
                map.insert("client_id", &*client_id);
                map.insert("client_secret", &*client_secret);
                map.insert("code", code);
                map.insert("grant_type", "authorization_code");
                map.insert("redirect_uri", &redirect_uri);

                let token: AccessToken = reqwest::Client::new()
                    .post("https://oauth2.googleapis.com/token")
                    .header(reqwest::header::ACCEPT, "application/json")
                    .form(&map)
                    .send()
                    .await?
                    .json()
                    .await?;

                token.access_token
            }
            AuthProvider::Steam => {
                let mut form = HashMap::new();

                let signed = query
                    .get("openid.signed")
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;
                form.insert(
                    "openid.assoc_handle".to_string(),
                    &**query
                        .get("openid.assoc_handle")
                        .ok_or_else(|| AuthenticationError::InvalidCredentials)?,
                );
                form.insert("openid.signed".to_string(), &**signed);
                form.insert(
                    "openid.sig".to_string(),
                    &**query
                        .get("openid.sig")
                        .ok_or_else(|| AuthenticationError::InvalidCredentials)?,
                );
                form.insert("openid.ns".to_string(), "http://specs.openid.net/auth/2.0");
                form.insert("openid.mode".to_string(), "check_authentication");

                for val in signed.split(',') {
                    if let Some(arr_val) = query.get(&format!("openid.{}", val)) {
                        form.insert(format!("openid.{}", val), &**arr_val);
                    }
                }

                let res = reqwest::Client::new()
                    .post("https://steamcommunity.com/openid/login")
                    .header("Accept-language", "en")
                    .form(&form)
                    .send()
                    .await?
                    .text()
                    .await?;

                if res.contains("is_valid:true") {
                    let identity = query
                        .get("openid.identity")
                        .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

                    identity
                        .rsplit('/')
                        .next()
                        .ok_or_else(|| AuthenticationError::InvalidCredentials)?
                        .to_string()
                } else {
                    return Err(AuthenticationError::InvalidCredentials);
                }
            }
        };

        Ok(res)
    }

    pub async fn get_user(&self, token: &str) -> Result<TempUser, AuthenticationError> {
        let res = match self {
            AuthProvider::GitHub => {
                let response = reqwest::Client::new()
                    .get("https://api.github.com/user")
                    .header(reqwest::header::USER_AGENT, "Modrinth")
                    .header(AUTHORIZATION, format!("token {token}"))
                    .send()
                    .await?;

                if token.starts_with("gho_") {
                    let client_id = response
                        .headers()
                        .get("x-oauth-client-id")
                        .and_then(|x| x.to_str().ok());

                    if client_id != Some(&*dotenvy::var("GITHUB_CLIENT_ID").unwrap()) {
                        return Err(AuthenticationError::InvalidClientId);
                    }
                }

                #[derive(Serialize, Deserialize, Debug)]
                pub struct GitHubUser {
                    pub login: String,
                    pub id: u64,
                    pub avatar_url: String,
                    pub name: Option<String>,
                    pub email: Option<String>,
                    pub bio: Option<String>,
                }

                let github_user: GitHubUser = response.json().await?;

                TempUser {
                    id: github_user.id.to_string(),
                    username: github_user.login,
                    email: github_user.email,
                    avatar_url: Some(github_user.avatar_url),
                    bio: github_user.bio,
                    name: github_user.name,
                }
            }
            AuthProvider::Discord => {
                #[derive(Serialize, Deserialize, Debug)]
                pub struct DiscordUser {
                    pub username: String,
                    pub id: String,
                    pub avatar: Option<String>,
                    pub global_name: Option<String>,
                    pub email: Option<String>,
                }

                let discord_user: DiscordUser = reqwest::Client::new()
                    .get("https://discord.com/api/v10/users/@me")
                    .header(reqwest::header::USER_AGENT, "Modrinth")
                    .header(AUTHORIZATION, format!("Bearer {token}"))
                    .send()
                    .await?
                    .json()
                    .await?;

                let id = discord_user.id.clone();
                TempUser {
                    id: discord_user.id,
                    username: discord_user.username,
                    email: discord_user.email,
                    avatar_url: discord_user
                        .avatar
                        .map(|x| format!("https://cdn.discordapp.com/avatars/{}/{}.webp", id, x)),
                    bio: None,
                    name: discord_user.global_name,
                }
            }
            AuthProvider::Microsoft => {
                #[derive(Deserialize, Debug)]
                #[serde(rename_all = "camelCase")]
                pub struct MicrosoftUser {
                    pub id: String,
                    pub display_name: Option<String>,
                    pub mail: Option<String>,
                    pub user_principal_name: String,
                }

                let microsoft_user: MicrosoftUser = reqwest::Client::new()
                    .get("https://graph.microsoft.com/v1.0/me?$select=id,displayName,mail,userPrincipalName")
                    .header(reqwest::header::USER_AGENT, "Modrinth")
                    .header(AUTHORIZATION, format!("Bearer {token}"))
                    .send()
                    .await?.json().await?;

                TempUser {
                    id: microsoft_user.id,
                    username: microsoft_user
                        .user_principal_name
                        .split('@')
                        .next()
                        .unwrap_or_default()
                        .to_string(),
                    email: microsoft_user.mail,
                    avatar_url: None,
                    bio: None,
                    name: microsoft_user.display_name,
                }
            }
            AuthProvider::GitLab => {
                #[derive(Serialize, Deserialize, Debug)]
                pub struct GitLabUser {
                    pub id: i32,
                    pub username: String,
                    pub email: Option<String>,
                    pub avatar_url: Option<String>,
                    pub name: Option<String>,
                    pub bio: Option<String>,
                }

                let gitlab_user: GitLabUser = reqwest::Client::new()
                    .get("https://gitlab.com/api/v4/user")
                    .header(reqwest::header::USER_AGENT, "Modrinth")
                    .header(AUTHORIZATION, format!("Bearer {token}"))
                    .send()
                    .await?
                    .json()
                    .await?;

                TempUser {
                    id: gitlab_user.id.to_string(),
                    username: gitlab_user.username,
                    email: gitlab_user.email,
                    avatar_url: gitlab_user.avatar_url,
                    bio: gitlab_user.bio,
                    name: gitlab_user.name,
                }
            }
            AuthProvider::Google => {
                #[derive(Deserialize, Debug)]
                pub struct GoogleUser {
                    pub id: String,
                    pub email: String,
                    pub name: Option<String>,
                    pub bio: Option<String>,
                    pub picture: Option<String>,
                }

                let google_user: GoogleUser = reqwest::Client::new()
                    .get("https://www.googleapis.com/userinfo/v2/me")
                    .header(reqwest::header::USER_AGENT, "Modrinth")
                    .header(AUTHORIZATION, format!("Bearer {token}"))
                    .send()
                    .await?
                    .json()
                    .await?;

                TempUser {
                    id: google_user.id,
                    username: google_user
                        .email
                        .split('@')
                        .next()
                        .unwrap_or_default()
                        .to_string(),
                    email: Some(google_user.email),
                    avatar_url: google_user.picture,
                    bio: None,
                    name: google_user.name,
                }
            }
            AuthProvider::Steam => {
                let api_key = dotenvy::var("STEAM_API_KEY")?;

                #[derive(Deserialize)]
                struct SteamResponse {
                    response: Players,
                }

                #[derive(Deserialize)]
                struct Players {
                    players: Vec<Player>,
                }

                #[derive(Deserialize)]
                struct Player {
                    steamid: String,
                    personaname: String,
                    profileurl: String,
                    avatar: Option<String>,
                }

                let response: String = reqwest::get(
                    &format!(
                        "https://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key={}&steamids={}",
                        api_key,
                        token
                    )
                )
                    .await?
                    .text()
                    .await?;

                let mut response: SteamResponse = serde_json::from_str(&response)?;

                if let Some(player) = response.response.players.pop() {
                    let username = player
                        .profileurl
                        .trim_matches('/')
                        .rsplit('/')
                        .next()
                        .unwrap_or(&player.steamid)
                        .to_string();
                    TempUser {
                        id: player.steamid,
                        username,
                        email: None,
                        avatar_url: player.avatar,
                        bio: None,
                        name: Some(player.personaname),
                    }
                } else {
                    return Err(AuthenticationError::InvalidCredentials);
                }
            }
        };

        Ok(res)
    }

    pub async fn get_user_id<'a, 'b, E>(
        &self,
        id: &str,
        executor: E,
    ) -> Result<Option<crate::database::models::UserId>, AuthenticationError>
    where
        E: sqlx::Executor<'a, Database = sqlx::Postgres>,
    {
        Ok(match self {
            AuthProvider::GitHub => {
                let value = sqlx::query!(
                    "SELECT id FROM users WHERE github_id = $1",
                    id.parse::<i64>()
                        .map_err(|_| AuthenticationError::InvalidCredentials)?
                )
                .fetch_optional(executor)
                .await?;

                value.map(|x| crate::database::models::UserId(x.id))
            }
            AuthProvider::Discord => {
                let value = sqlx::query!(
                    "SELECT id FROM users WHERE discord_id = $1",
                    id.parse::<i64>()
                        .map_err(|_| AuthenticationError::InvalidCredentials)?
                )
                .fetch_optional(executor)
                .await?;

                value.map(|x| crate::database::models::UserId(x.id))
            }
            AuthProvider::Microsoft => {
                let value = sqlx::query!("SELECT id FROM users WHERE microsoft_id = $1", id)
                    .fetch_optional(executor)
                    .await?;

                value.map(|x| crate::database::models::UserId(x.id))
            }
            AuthProvider::GitLab => {
                let value = sqlx::query!(
                    "SELECT id FROM users WHERE gitlab_id = $1",
                    id.parse::<i64>()
                        .map_err(|_| AuthenticationError::InvalidCredentials)?
                )
                .fetch_optional(executor)
                .await?;

                value.map(|x| crate::database::models::UserId(x.id))
            }
            AuthProvider::Google => {
                let value = sqlx::query!("SELECT id FROM users WHERE google_id = $1", id)
                    .fetch_optional(executor)
                    .await?;

                value.map(|x| crate::database::models::UserId(x.id))
            }
            AuthProvider::Steam => {
                let value = sqlx::query!(
                    "SELECT id FROM users WHERE steam_id = $1",
                    id.parse::<i64>()
                        .map_err(|_| AuthenticationError::InvalidCredentials)?
                )
                .fetch_optional(executor)
                .await?;

                value.map(|x| crate::database::models::UserId(x.id))
            }
        })
    }
}

#[derive(Serialize, Deserialize)]
pub struct AuthorizationInit {
    pub url: String,
    #[serde(default)]
    pub provider: AuthProvider,
    pub token: Option<String>,
}
#[derive(Serialize, Deserialize)]
pub struct Authorization {
    pub code: String,
    pub state: String,
}

// Init link takes us to GitHub API and calls back to callback endpoint with a code and state
// http://localhost:8000/auth/init?url=https://modrinth.com
#[get("init")]
pub async fn init(
    req: HttpRequest,
    Query(info): Query<AuthorizationInit>, // callback url
    client: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    session_queue: Data<AuthQueue>,
) -> Result<HttpResponse, AuthenticationError> {
    let url = url::Url::parse(&info.url).map_err(|_| AuthenticationError::Url)?;

    let allowed_callback_urls = parse_strings_from_var("ALLOWED_CALLBACK_URLS").unwrap_or_default();
    let domain = url.host_str().ok_or(AuthenticationError::Url)?;
    if !allowed_callback_urls.iter().any(|x| domain.ends_with(x)) && domain != "modrinth.com" {
        return Err(AuthenticationError::Url);
    }

    let user_id = if let Some(token) = info.token {
        let (_, user) = get_user_record_from_bearer_token(
            &req,
            Some(&token),
            &**client,
            &redis,
            &session_queue,
        )
        .await?
        .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

        Some(user.id)
    } else {
        None
    };

    let state = Flow::OAuth {
        user_id,
        url: info.url,
        provider: info.provider,
    }
    .insert(Utc::now() + Duration::minutes(30), &redis)
    .await?;

    let url = info.provider.get_redirect_url(state)?;
    Ok(HttpResponse::TemporaryRedirect()
        .append_header(("Location", &*url))
        .json(serde_json::json!({ "url": url })))
}

#[get("callback")]
pub async fn auth_callback(
    req: HttpRequest,
    Query(query): Query<HashMap<String, String>>,
    client: Data<PgPool>,
    file_host: Data<Arc<dyn FileHost + Send + Sync>>,
    redis: Data<deadpool_redis::Pool>,
) -> Result<HttpResponse, AuthenticationError> {
    let state = query
        .get("state")
        .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

    let flow = Flow::get(state, &redis).await?;

    // Extract cookie header from request
    if let Some(Flow::OAuth {
        user_id,
        provider,
        url,
    }) = flow
    {
        Flow::remove(state, &redis).await?;

        let token = provider.get_token(query).await?;
        let oauth_user = provider.get_user(&token).await?;

        let user_id_opt = provider.get_user_id(&oauth_user.id, &**client).await?;

        let mut transaction = client.begin().await?;
        if let Some(id) = user_id {
            if user_id_opt.is_some() {
                return Err(AuthenticationError::DuplicateUser);
            }

            match provider {
                AuthProvider::GitHub => {
                    sqlx::query!(
                        "
                        UPDATE users
                        SET github_id = $2
                        WHERE (id = $1)
                        ",
                        id as crate::database::models::UserId,
                        oauth_user.id.parse::<i64>().ok(),
                    )
                    .execute(&mut *transaction)
                    .await?;
                }
                AuthProvider::Discord => {
                    sqlx::query!(
                        "
                        UPDATE users
                        SET discord_id = $2
                        WHERE (id = $1)
                        ",
                        id as crate::database::models::UserId,
                        oauth_user.id.parse::<i64>().ok(),
                    )
                    .execute(&mut *transaction)
                    .await?;
                }
                AuthProvider::Microsoft => {
                    sqlx::query!(
                        "
                        UPDATE users
                        SET microsoft_id = $2
                        WHERE (id = $1)
                        ",
                        id as crate::database::models::UserId,
                        oauth_user.id,
                    )
                    .execute(&mut *transaction)
                    .await?;
                }
                AuthProvider::GitLab => {
                    sqlx::query!(
                        "
                        UPDATE users
                        SET gitlab_id = $2
                        WHERE (id = $1)
                        ",
                        id as crate::database::models::UserId,
                        oauth_user.id.parse::<i64>().ok(),
                    )
                    .execute(&mut *transaction)
                    .await?;
                }
                AuthProvider::Google => {
                    sqlx::query!(
                        "
                        UPDATE users
                        SET google_id = $2
                        WHERE (id = $1)
                        ",
                        id as crate::database::models::UserId,
                        oauth_user.id,
                    )
                    .execute(&mut *transaction)
                    .await?;
                }
                AuthProvider::Steam => {
                    sqlx::query!(
                        "
                        UPDATE users
                        SET steam_id = $2
                        WHERE (id = $1)
                        ",
                        id as crate::database::models::UserId,
                        oauth_user.id.parse::<i64>().ok(),
                    )
                    .execute(&mut *transaction)
                    .await?;
                }
            }

            crate::database::models::User::clear_caches(&[(id, None)], &redis).await?;
            transaction.commit().await?;

            Ok(HttpResponse::TemporaryRedirect()
                .append_header(("Location", &*url))
                .json(serde_json::json!({ "url": url })))
        } else {
            let user_id = if let Some(user_id) = user_id_opt {
                let user = crate::database::models::User::get_id(user_id, &**client, &redis)
                    .await?
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

                if user.totp_secret.is_some() {
                    let flow = Flow::Login2FA { user_id: user.id }
                        .insert(Utc::now() + Duration::minutes(30), &redis)
                        .await?;

                    let redirect_url = format!(
                        "{}{}error=2fa_required&flow={}",
                        url,
                        if url.contains('?') { "&" } else { "?" },
                        flow
                    );

                    return Ok(HttpResponse::TemporaryRedirect()
                        .append_header(("Location", &*redirect_url))
                        .json(serde_json::json!({ "url": redirect_url })));
                }

                user_id
            } else {
                if let Some(email) = &oauth_user.email {
                    if crate::database::models::User::get_email(email, &**client)
                        .await?
                        .is_some()
                    {
                        return Err(AuthenticationError::DuplicateUser);
                    }
                }

                let user_id = crate::database::models::generate_user_id(&mut transaction).await?;

                let mut username_increment: i32 = 0;
                let mut username = None;

                while username.is_none() {
                    let test_username = format!(
                        "{}{}",
                        oauth_user.username,
                        if username_increment > 0 {
                            username_increment.to_string()
                        } else {
                            "".to_string()
                        }
                    );

                    let new_id =
                        crate::database::models::User::get(&test_username, &**client, &redis)
                            .await?;

                    if new_id.is_none() {
                        username = Some(test_username);
                    } else {
                        username_increment += 1;
                    }
                }

                let avatar_url = if let Some(avatar_url) = oauth_user.avatar_url {
                    let cdn_url = dotenvy::var("CDN_URL")?;

                    let res = reqwest::get(&avatar_url).await?;
                    let headers = res.headers().clone();

                    let img_data = if let Some(content_type) = headers
                        .get(reqwest::header::CONTENT_TYPE)
                        .and_then(|ct| ct.to_str().ok())
                    {
                        get_image_ext(content_type).map(|ext| (ext, content_type))
                    } else if let Some(ext) = avatar_url.rsplit('.').next() {
                        get_image_content_type(ext).map(|content_type| (ext, content_type))
                    } else {
                        None
                    };

                    if let Some((ext, content_type)) = img_data {
                        let bytes = res.bytes().await?;
                        let hash = sha1::Sha1::from(&bytes).hexdigest();

                        let upload_data = file_host
                            .upload_file(
                                content_type,
                                &format!(
                                    "user/{}/{}.{}",
                                    crate::models::users::UserId::from(user_id),
                                    hash,
                                    ext
                                ),
                                bytes,
                            )
                            .await?;

                        Some(format!("{}/{}", cdn_url, upload_data.file_name))
                    } else {
                        None
                    }
                } else {
                    None
                };

                if let Some(username) = username {
                    crate::database::models::User {
                        id: user_id,
                        github_id: if provider == AuthProvider::GitHub {
                            Some(
                                oauth_user
                                    .id
                                    .clone()
                                    .parse()
                                    .map_err(|_| AuthenticationError::InvalidCredentials)?,
                            )
                        } else {
                            None
                        },
                        discord_id: if provider == AuthProvider::Discord {
                            Some(
                                oauth_user
                                    .id
                                    .parse()
                                    .map_err(|_| AuthenticationError::InvalidCredentials)?,
                            )
                        } else {
                            None
                        },
                        gitlab_id: if provider == AuthProvider::GitLab {
                            Some(
                                oauth_user
                                    .id
                                    .parse()
                                    .map_err(|_| AuthenticationError::InvalidCredentials)?,
                            )
                        } else {
                            None
                        },
                        google_id: if provider == AuthProvider::Google {
                            Some(oauth_user.id.clone())
                        } else {
                            None
                        },
                        steam_id: if provider == AuthProvider::Steam {
                            Some(
                                oauth_user
                                    .id
                                    .parse()
                                    .map_err(|_| AuthenticationError::InvalidCredentials)?,
                            )
                        } else {
                            None
                        },
                        microsoft_id: if provider == AuthProvider::Microsoft {
                            Some(oauth_user.id)
                        } else {
                            None
                        },
                        password: None,
                        totp_secret: None,
                        username,
                        name: oauth_user.name,
                        email: oauth_user.email,
                        email_verified: true,
                        avatar_url,
                        bio: oauth_user.bio,
                        created: Utc::now(),
                        role: Role::Developer.to_string(),
                        badges: Badges::default(),
                        balance: Decimal::ZERO,
                        payout_wallet: None,
                        payout_wallet_type: None,
                        payout_address: None,
                    }
                    .insert(&mut transaction)
                    .await?;

                    user_id
                } else {
                    return Err(AuthenticationError::InvalidCredentials);
                }
            };

            let session = issue_session(req, user_id, &mut transaction, &redis).await?;
            transaction.commit().await?;

            let redirect_url = if url.contains('?') {
                format!("{}&code={}", url, session.session)
            } else {
                format!("{}?code={}", url, session.session)
            };

            Ok(HttpResponse::TemporaryRedirect()
                .append_header(("Location", &*redirect_url))
                .json(serde_json::json!({ "url": redirect_url })))
        }
    } else {
        Err(AuthenticationError::InvalidCredentials)
    }
}

#[derive(Deserialize, Validate)]
pub struct NewAccount {
    #[validate(length(min = 1, max = 39), regex = "RE_URL_SAFE")]
    pub username: String,
    #[validate(length(min = 8, max = 256))]
    pub password: String,
    #[validate(email)]
    pub email: String,
    pub challenge: String,
}

#[post("create")]
pub async fn create_account_with_password(
    req: HttpRequest,
    pool: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    new_account: web::Json<NewAccount>,
) -> Result<HttpResponse, ApiError> {
    new_account
        .0
        .validate()
        .map_err(|err| ApiError::InvalidInput(validation_errors_to_string(err, None)))?;

    if check_turnstile_captcha(&req, &new_account.challenge).await? {
        return Err(ApiError::Turnstile);
    }

    if crate::database::models::User::get(&new_account.username, &**pool, &redis)
        .await?
        .is_some()
    {
        return Err(ApiError::InvalidInput("Username is taken!".to_string()));
    }

    let mut transaction = pool.begin().await?;
    let user_id = crate::database::models::generate_user_id(&mut transaction).await?;

    let new_account = new_account.0;

    let score = zxcvbn::zxcvbn(
        &new_account.password,
        &[&new_account.username, &new_account.email],
    )?;

    if score.score() < 3 {
        return Err(ApiError::InvalidInput(
            if let Some(feedback) = score.feedback().clone().and_then(|x| x.warning()) {
                format!("Password too weak: {}", feedback)
            } else {
                "Specified password is too weak! Please improve its strength.".to_string()
            },
        ));
    }

    let hasher = Argon2::default();
    let salt = SaltString::generate(&mut ChaCha20Rng::from_entropy());
    let password_hash = hasher
        .hash_password(new_account.password.as_bytes(), &salt)?
        .to_string();

    if crate::database::models::User::get_email(&new_account.email, &**pool)
        .await?
        .is_some()
    {
        return Err(ApiError::InvalidInput(
            "Email is already registered on Modrinth!".to_string(),
        ));
    }

    crate::database::models::User {
        id: user_id,
        github_id: None,
        discord_id: None,
        gitlab_id: None,
        google_id: None,
        steam_id: None,
        microsoft_id: None,
        password: Some(password_hash),
        totp_secret: None,
        username: new_account.username.clone(),
        name: Some(new_account.username),
        email: Some(new_account.email),
        email_verified: false,
        avatar_url: None,
        bio: None,
        created: Utc::now(),
        role: Role::Developer.to_string(),
        badges: Badges::default(),
        balance: Decimal::ZERO,
        payout_wallet: None,
        payout_wallet_type: None,
        payout_address: None,
    }
    .insert(&mut transaction)
    .await?;

    let session = issue_session(req, user_id, &mut transaction, &redis).await?;
    let res = crate::models::sessions::Session::from(session, true);
    transaction.commit().await?;

    Ok(HttpResponse::Ok().json(res))
}

#[derive(Deserialize, Validate)]
pub struct Login {
    pub username: String,
    pub password: String,
    pub challenge: String,
}

#[post("login")]
pub async fn login_password(
    req: HttpRequest,
    pool: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    login: web::Json<Login>,
) -> Result<HttpResponse, ApiError> {
    if check_turnstile_captcha(&req, &login.challenge).await? {
        return Err(ApiError::Turnstile);
    }

    let user = if let Some(user) =
        crate::database::models::User::get(&login.username, &**pool, &redis).await?
    {
        user
    } else {
        let user = crate::database::models::User::get_email(&login.username, &**pool)
            .await?
            .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

        crate::database::models::User::get_id(user, &**pool, &redis)
            .await?
            .ok_or_else(|| AuthenticationError::InvalidCredentials)?
    };

    let hasher = Argon2::default();
    hasher
        .verify_password(
            login.password.as_bytes(),
            &PasswordHash::new(
                &user
                    .password
                    .ok_or_else(|| AuthenticationError::InvalidCredentials)?,
            )?,
        )
        .map_err(|_| AuthenticationError::InvalidCredentials)?;

    if user.totp_secret.is_some() {
        let flow = Flow::Login2FA { user_id: user.id }
            .insert(Utc::now() + Duration::minutes(30), &redis)
            .await?;

        Ok(HttpResponse::Ok().json(serde_json::json!({
            "error": "2fa_required",
            "description": "2FA is required to complete this operation.",
            "flow": flow,
        })))
    } else {
        let mut transaction = pool.begin().await?;
        let session = issue_session(req, user.id, &mut transaction, &redis).await?;
        let res = crate::models::sessions::Session::from(session, true);
        transaction.commit().await?;

        Ok(HttpResponse::Ok().json(res))
    }
}

#[derive(Deserialize, Validate)]
pub struct Login2FA {
    pub code: String,
    pub flow: String,
}

fn get_2fa_code(secret: String) -> Result<String, AuthenticationError> {
    let totp = totp_rs::TOTP::new(
        totp_rs::Algorithm::SHA1,
        6,
        1,
        30,
        totp_rs::Secret::Encoded(secret)
            .to_bytes()
            .map_err(|_| AuthenticationError::InvalidCredentials)?,
    )
    .map_err(|_| AuthenticationError::InvalidCredentials)?;
    let token = totp
        .generate_current()
        .map_err(|_| AuthenticationError::InvalidCredentials)?;

    Ok(token)
}

#[post("login/2fa")]
pub async fn login_2fa(
    req: HttpRequest,
    pool: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    login: web::Json<Login2FA>,
) -> Result<HttpResponse, ApiError> {
    let flow = Flow::get(&login.flow, &redis)
        .await?
        .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

    if let Flow::Login2FA { user_id } = flow {
        let user = crate::database::models::User::get_id(user_id, &**pool, &redis)
            .await?
            .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

        let token = get_2fa_code(
            user.totp_secret
                .ok_or_else(|| AuthenticationError::InvalidCredentials)?,
        )?;

        let mut transaction = pool.begin().await?;
        if token != login.code {
            let backup_codes =
                crate::database::models::User::get_backup_codes(user_id, &**pool).await?;

            if !backup_codes.contains(&login.code) {
                return Err(ApiError::Authentication(
                    AuthenticationError::InvalidCredentials,
                ));
            } else {
                let code = parse_base62(&login.code).unwrap_or_default();

                sqlx::query!(
                    "
                    DELETE FROM user_backup_codes
                    WHERE user_id = $1 AND code = $2
                    ",
                    user_id as crate::database::models::ids::UserId,
                    code as i64,
                )
                .execute(&mut *transaction)
                .await?;

                crate::database::models::User::clear_caches(&[(user_id, None)], &redis).await?;
            }
        }
        Flow::remove(&login.flow, &redis).await?;

        let session = issue_session(req, user_id, &mut transaction, &redis).await?;
        let res = crate::models::sessions::Session::from(session, true);
        transaction.commit().await?;

        Ok(HttpResponse::Ok().json(res))
    } else {
        Err(ApiError::Authentication(
            AuthenticationError::InvalidCredentials,
        ))
    }
}

#[get("2fa")]
pub async fn begin_2fa_flow(
    req: HttpRequest,
    pool: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    session_queue: Data<AuthQueue>,
) -> Result<HttpResponse, ApiError> {
    let user = get_user_from_headers(
        &req,
        &**pool,
        &redis,
        &session_queue,
        Some(&[Scopes::USER_AUTH_WRITE]),
    )
    .await?
    .1;

    if !user.has_totp.unwrap_or(false) {
        let string = totp_rs::Secret::generate_secret();
        let encoded = string.to_encoded();

        let flow = Flow::Initialize2FA {
            user_id: user.id.into(),
            secret: encoded.to_string(),
        }
        .insert(Utc::now() + Duration::minutes(30), &redis)
        .await?;

        Ok(HttpResponse::Ok().json(serde_json::json!({
            "secret": encoded.to_string(),
            "flow": flow,
        })))
    } else {
        Err(ApiError::InvalidInput(
            "User already has 2FA enabled on their account!".to_string(),
        ))
    }
}

#[post("2fa")]
pub async fn finish_2fa_flow(
    req: HttpRequest,
    pool: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    login: web::Json<Login2FA>,
    session_queue: Data<AuthQueue>,
) -> Result<HttpResponse, ApiError> {
    let flow = Flow::get(&login.flow, &redis)
        .await?
        .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

    if let Flow::Initialize2FA { user_id, secret } = flow {
        let user = get_user_from_headers(
            &req,
            &**pool,
            &redis,
            &session_queue,
            Some(&[Scopes::USER_AUTH_WRITE]),
        )
        .await?
        .1;

        if user.id != user_id.into() {
            return Err(ApiError::Authentication(
                AuthenticationError::InvalidCredentials,
            ));
        }

        let token = get_2fa_code(secret.clone())?;

        if token != login.code {
            return Err(ApiError::Authentication(
                AuthenticationError::InvalidCredentials,
            ));
        }
        Flow::remove(&login.flow, &redis).await?;

        let mut transaction = pool.begin().await?;

        sqlx::query!(
            "
            UPDATE users
            SET totp_secret = $1
            WHERE (id = $2)
            ",
            secret,
            user_id as crate::database::models::ids::UserId,
        )
        .execute(&mut *transaction)
        .await?;

        sqlx::query!(
            "
            DELETE FROM user_backup_codes
            WHERE user_id = $1
            ",
            user_id as crate::database::models::ids::UserId,
        )
        .execute(&mut *transaction)
        .await?;

        let mut codes = Vec::new();

        for _ in 0..6 {
            let mut rng = ChaCha20Rng::from_entropy();
            let val = random_base62_rng(&mut rng, 11);

            sqlx::query!(
                "
                INSERT INTO user_backup_codes (
                    user_id, code
                )
                VALUES (
                    $1, $2
                )
                ",
                user_id as crate::database::models::ids::UserId,
                val as i64,
            )
            .execute(&mut *transaction)
            .await?;

            codes.push(to_base62(val));
        }

        crate::database::models::User::clear_caches(&[(user.id.into(), None)], &redis).await?;
        transaction.commit().await?;

        Ok(HttpResponse::Ok().json(serde_json::json!({
            "backup_codes": codes,
        })))
    } else {
        Err(ApiError::Authentication(
            AuthenticationError::InvalidCredentials,
        ))
    }
}

#[derive(Deserialize)]
pub struct Remove2FA {
    pub code: String,
}

#[delete("2fa")]
pub async fn remove_2fa(
    req: HttpRequest,
    pool: Data<PgPool>,
    redis: Data<deadpool_redis::Pool>,
    login: web::Json<Login2FA>,
    session_queue: Data<AuthQueue>,
) -> Result<HttpResponse, ApiError> {
    let (scopes, user) =
        get_user_record_from_bearer_token(&req, None, &**pool, &redis, &session_queue)
            .await?
            .ok_or_else(|| AuthenticationError::InvalidCredentials)?;

    if !scopes.contains(Scopes::USER_AUTH_WRITE) {
        return Err(ApiError::Authentication(
            AuthenticationError::InvalidCredentials,
        ));
    }

    let token = get_2fa_code(user.totp_secret.ok_or_else(|| {
        ApiError::InvalidInput("User does not have 2FA enabled on the account!".to_string())
    })?)?;

    if token != login.code {
        return Err(ApiError::Authentication(
            AuthenticationError::InvalidCredentials,
        ));
    }

    let mut transaction = pool.begin().await?;

    sqlx::query!(
        "
        UPDATE users
        SET totp_secret = NULL
        WHERE (id = $1)
        ",
        user.id as crate::database::models::ids::UserId,
    )
    .execute(&mut *transaction)
    .await?;

    sqlx::query!(
        "
        DELETE FROM user_backup_codes
        WHERE user_id = $1
        ",
        user.id as crate::database::models::ids::UserId,
    )
    .execute(&mut *transaction)
    .await?;

    crate::database::models::User::clear_caches(&[(user.id, None)], &redis).await?;

    transaction.commit().await?;

    Ok(HttpResponse::NoContent().finish())
}