use axum::extract::FromRequestParts;
use axum::http::request::Parts;
use uuid::Uuid;

use crate::auth::jwt;
use crate::error::AppError;
use crate::models::session::Session;
use crate::models::user::UserRole;
use crate::state::AppState;

#[derive(Debug, Clone)]
pub struct AuthUser {
    pub user_id: Uuid,
    pub event_id: Uuid,
    pub role: UserRole,
    pub token_hash: String,
}

impl FromRequestParts<AppState> for AuthUser {
    type Rejection = AppError;

    async fn from_request_parts(
        parts: &mut Parts,
        state: &AppState,
    ) -> Result<Self, Self::Rejection> {
        let header = parts
            .headers
            .get("authorization")
            .and_then(|v| v.to_str().ok())
            .ok_or_else(|| AppError::Unauthorized("Token fehlt.".into()))?;

        let token = header
            .strip_prefix("Bearer ")
            .ok_or_else(|| AppError::Unauthorized("Ungültiges Token-Format.".into()))?;

        let claims = jwt::verify_token(token, &state.config.jwt_secret)
            .map_err(|_| AppError::Unauthorized("Token ungültig oder abgelaufen.".into()))?;

        let token_hash = jwt::hash_token(token);

        // Reconcile the session against the live `user` row. We do NOT trust the
        // JWT claims for role/ban/event — a token can outlive a ban or demotion
        // (default lifetime 30 days). The single JOIN query is the same number
        // of round-trips as the old existence check.
        let ctx = Session::find_auth_context(&state.pool, &token_hash)
            .await
            .map_err(|e| AppError::Internal(e.into()))?
            .ok_or_else(|| AppError::Unauthorized("Sitzung nicht gefunden oder abgelaufen.".into()))?;

        // Ban takes effect immediately on the next request, regardless of the
        // token's remaining lifetime.
        if ctx.is_banned {
            return Err(AppError::Forbidden("Du bist gesperrt.".into()));
        }

        // Defend against a JWT that was issued for a different user/event than
        // the session's DB row points at (e.g. a swapped or replayed token).
        if claims.sub != ctx.user_id || claims.event_id != ctx.event_id {
            return Err(AppError::Unauthorized("Token passt nicht zur Sitzung.".into()));
        }

        // Update last_seen_at in the background (fire-and-forget). Failures are
        // non-fatal but worth surfacing — silent swallowing hides DB connection
        // pressure that would otherwise be the first symptom of a real problem.
        let pool = state.pool.clone();
        let session_id = ctx.session_id;
        tokio::spawn(async move {
            if let Err(e) = Session::touch(&pool, session_id).await {
                tracing::warn!(error = ?e, session_id = %session_id, "session touch failed");
            }
        });

        Ok(Self {
            user_id: ctx.user_id,
            event_id: ctx.event_id,
            // Live role from the DB, not the claim — demotion/promotion takes
            // effect on the next request.
            role: ctx.role,
            token_hash,
        })
    }
}

/// Extractor that requires at least Host role.
pub struct RequireHost(pub AuthUser);

impl FromRequestParts<AppState> for RequireHost {
    type Rejection = AppError;

    async fn from_request_parts(
        parts: &mut Parts,
        state: &AppState,
    ) -> Result<Self, Self::Rejection> {
        let auth = AuthUser::from_request_parts(parts, state).await?;
        match auth.role {
            UserRole::Host | UserRole::Admin => Ok(Self(auth)),
            _ => Err(AppError::Forbidden("Nur für Hosts und Admins.".into())),
        }
    }
}

/// Extractor that requires Admin role.
pub struct RequireAdmin(pub AuthUser);

impl FromRequestParts<AppState> for RequireAdmin {
    type Rejection = AppError;

    async fn from_request_parts(
        parts: &mut Parts,
        state: &AppState,
    ) -> Result<Self, Self::Rejection> {
        let auth = AuthUser::from_request_parts(parts, state).await?;
        match auth.role {
            UserRole::Admin => Ok(Self(auth)),
            _ => Err(AppError::Forbidden("Nur für Admins.".into())),
        }
    }
}