use std::time::Duration;

use axum::extract::State;
use axum::http::{HeaderMap, StatusCode};
use axum::Json;
use chrono::Utc;
use rand::Rng;
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::auth::jwt;
use crate::auth::middleware::AuthUser;
use crate::error::AppError;
use crate::models::event::Event;
use crate::models::session::Session;
use crate::models::user::{User, UserRole};
use crate::services::rate_limiter::client_ip;
use crate::state::AppState;

#[derive(Deserialize)]
pub struct JoinRequest {
    pub display_name: String,
}

#[derive(Serialize)]
pub struct JoinResponse {
    pub jwt: String,
    pub pin: String,
    pub user_id: Uuid,
    pub is_new: bool,
}

pub async fn join(
    State(state): State<AppState>,
    headers: HeaderMap,
    Json(body): Json<JoinRequest>,
) -> Result<(StatusCode, Json<JoinResponse>), AppError> {
    let ip = client_ip(&headers, "unknown");
    if !state.rate_limiter.check(format!("join:{ip}"), 5, Duration::from_secs(60)) {
        return Err(AppError::TooManyRequests(
            "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
        ));
    }

    let display_name = body.display_name.trim();
    if display_name.is_empty() || display_name.len() > 50 {
        return Err(AppError::BadRequest(
            "Name muss zwischen 1 und 50 Zeichen lang sein.".into(),
        ));
    }

    let event = Event::find_or_create(
        &state.pool,
        &state.config.event_slug,
        &state.config.event_name,
    )
    .await?;

    // Generate a 4-digit PIN
    let pin: String = format!("{:04}", rand::rng().random_range(0..10000u32));
    let pin_hash =
        bcrypt::hash(&pin, 12).map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?;

    let user = User::create(&state.pool, event.id, display_name, &pin_hash).await?;

    let token = jwt::create_token(
        user.id,
        event.id,
        user.role.clone(),
        &state.config.jwt_secret,
        state.config.session_expiry_days,
    )
    .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?;

    let token_hash = jwt::hash_token(&token);
    let expires_at = Utc::now() + chrono::Duration::days(state.config.session_expiry_days);
    Session::create(&state.pool, user.id, &token_hash, expires_at).await?;

    Ok((
        StatusCode::CREATED,
        Json(JoinResponse {
            jwt: token,
            pin,
            user_id: user.id,
            is_new: true,
        }),
    ))
}

#[derive(Deserialize)]
pub struct RecoverRequest {
    pub display_name: String,
    pub pin: String,
}

#[derive(Serialize)]
pub struct RecoverResponse {
    pub jwt: String,
    pub user_id: Uuid,
}

pub async fn recover(
    State(state): State<AppState>,
    Json(body): Json<RecoverRequest>,
) -> Result<Json<RecoverResponse>, AppError> {
    let display_name = body.display_name.trim();

    let event = Event::find_by_slug(&state.pool, &state.config.event_slug)
        .await?
        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;

    let users =
        User::find_by_event_and_name(&state.pool, event.id, display_name).await?;

    if users.is_empty() {
        return Err(AppError::NotFound(
            "Kein Benutzer mit diesem Namen gefunden.".into(),
        ));
    }

    for user in &users {
        // Check PIN lockout
        if let Some(locked_until) = user.pin_locked_until {
            if Utc::now() < locked_until {
                return Err(AppError::TooManyRequests(
                    "Zu viele Versuche. Bitte warte 15 Minuten.".into(),
                ));
            }
        }

        let pin_matches = bcrypt::verify(&body.pin, &user.recovery_pin_hash)
            .unwrap_or(false);

        if pin_matches {
            // Reset failed attempts on success
            User::reset_pin_attempts(&state.pool, user.id).await?;

            let token = jwt::create_token(
                user.id,
                event.id,
                user.role.clone(),
                &state.config.jwt_secret,
                state.config.session_expiry_days,
            )
            .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?;

            let token_hash = jwt::hash_token(&token);
            let expires_at = Utc::now() + chrono::Duration::days(state.config.session_expiry_days);
            Session::create(&state.pool, user.id, &token_hash, expires_at).await?;

            return Ok(Json(RecoverResponse {
                jwt: token,
                user_id: user.id,
            }));
        }

        // Wrong PIN — increment failure count
        let attempts = User::increment_failed_pin(&state.pool, user.id).await?;
        if attempts >= 3 {
            let lockout = Utc::now() + chrono::Duration::minutes(15);
            User::lock_pin(&state.pool, user.id, lockout).await?;
        }
    }

    Err(AppError::Unauthorized("PIN ist falsch.".into()))
}

#[derive(Deserialize)]
pub struct AdminLoginRequest {
    pub password: String,
}

#[derive(Serialize)]
pub struct AdminLoginResponse {
    pub jwt: String,
}

pub async fn admin_login(
    State(state): State<AppState>,
    Json(body): Json<AdminLoginRequest>,
) -> Result<Json<AdminLoginResponse>, AppError> {
    if state.config.admin_password_hash.is_empty() {
        return Err(AppError::Forbidden(
            "Admin-Login ist nicht konfiguriert.".into(),
        ));
    }

    let valid = bcrypt::verify(&body.password, &state.config.admin_password_hash)
        .unwrap_or(false);

    if !valid {
        return Err(AppError::Unauthorized("Falsches Passwort.".into()));
    }

    let event = Event::find_or_create(
        &state.pool,
        &state.config.event_slug,
        &state.config.event_name,
    )
    .await?;

    // Find or create the admin user for this event
    let admin_name = "Admin";
    let users = User::find_by_event_and_name(&state.pool, event.id, admin_name).await?;
    let admin_user = if let Some(u) = users.into_iter().find(|u| u.role == UserRole::Admin) {
        u
    } else {
        // Create admin user with a dummy PIN (admin authenticates via password)
        let dummy_hash = bcrypt::hash("0000", 4)
            .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?;
        let user = User::create(&state.pool, event.id, admin_name, &dummy_hash).await?;
        sqlx::query("UPDATE \"user\" SET role = 'admin' WHERE id = $1")
            .bind(user.id)
            .execute(&state.pool)
            .await?;
        User::find_by_id(&state.pool, user.id)
            .await?
            .ok_or_else(|| AppError::Internal(anyhow::anyhow!("admin user creation failed")))?
    };

    let token = jwt::create_token(
        admin_user.id,
        event.id,
        UserRole::Admin,
        &state.config.jwt_secret,
        1, // Admin sessions expire after 1 day
    )
    .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?;

    let token_hash = jwt::hash_token(&token);
    let expires_at = Utc::now() + chrono::Duration::days(1);
    Session::create(&state.pool, admin_user.id, &token_hash, expires_at).await?;

    Ok(Json(AdminLoginResponse { jwt: token }))
}

pub async fn logout(
    State(state): State<AppState>,
    auth: AuthUser,
) -> Result<StatusCode, AppError> {
    Session::delete_by_token_hash(&state.pool, &auth.token_hash).await?;
    Ok(StatusCode::NO_CONTENT)
}