use axum::extract::{Path, State};
use axum::http::StatusCode;
use axum::Json;
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::auth::middleware::RequireHost;
use crate::error::AppError;
use crate::models::comment::Comment;
use crate::models::event::Event;
use crate::models::upload::Upload;
use crate::models::user::UserRole;
use crate::state::{AppState, SseEvent};

// ── DTOs ─────────────────────────────────────────────────────────────────────

#[derive(Serialize, sqlx::FromRow)]
pub struct UserSummary {
    pub id: Uuid,
    pub display_name: String,
    pub role: String,
    pub is_banned: bool,
    pub uploads_hidden: bool,
    pub upload_count: i64,
    pub total_upload_bytes: i64,
    pub created_at: DateTime<Utc>,
}

#[derive(Serialize)]
pub struct EventStatus {
    pub name: String,
    pub is_active: bool,
    pub uploads_locked: bool,
    pub export_released: bool,
}

#[derive(Deserialize)]
pub struct BanRequest {
    pub hide_uploads: bool,
}

#[derive(Deserialize)]
pub struct SetRoleRequest {
    pub role: String,
}

// ── Handlers ─────────────────────────────────────────────────────────────────

pub async fn get_event_status(
    State(state): State<AppState>,
    RequireHost(_auth): RequireHost,
) -> Result<Json<EventStatus>, AppError> {
    let event = Event::find_by_slug(&state.pool, &state.config.event_slug)
        .await?
        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;

    Ok(Json(EventStatus {
        name: event.name,
        is_active: event.is_active,
        uploads_locked: event.uploads_locked_at.is_some(),
        export_released: event.export_released_at.is_some(),
    }))
}

pub async fn list_users(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
) -> Result<Json<Vec<UserSummary>>, AppError> {
    let rows = sqlx::query_as::<_, UserSummary>(
        "SELECT u.id,
                u.display_name,
                u.role::text AS role,
                u.is_banned,
                u.uploads_hidden,
                COALESCE(COUNT(up.id), 0) AS upload_count,
                u.total_upload_bytes,
                u.created_at
         FROM \"user\" u
         LEFT JOIN upload up ON up.user_id = u.id AND up.deleted_at IS NULL
         WHERE u.event_id = $1
         GROUP BY u.id
         ORDER BY u.created_at ASC",
    )
    .bind(auth.event_id)
    .fetch_all(&state.pool)
    .await?;

    Ok(Json(rows))
}

pub async fn ban_user(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
    Path(user_id): Path<Uuid>,
    Json(body): Json<BanRequest>,
) -> Result<StatusCode, AppError> {
    // Cannot ban yourself or another host/admin
    if user_id == auth.user_id {
        return Err(AppError::BadRequest("Du kannst dich nicht selbst sperren.".into()));
    }
    let target = sqlx::query_as::<_, (String,)>(
        "SELECT role::text FROM \"user\" WHERE id = $1 AND event_id = $2",
    )
    .bind(user_id)
    .bind(auth.event_id)
    .fetch_optional(&state.pool)
    .await?
    .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;

    if target.0 == "admin" || (target.0 == "host" && auth.role != crate::models::user::UserRole::Admin) {
        return Err(AppError::Forbidden("Du kannst diesen Benutzer nicht sperren.".into()));
    }

    sqlx::query(
        "UPDATE \"user\" SET is_banned = TRUE, uploads_hidden = $2 WHERE id = $1 AND event_id = $3",
    )
    .bind(user_id)
    .bind(body.hide_uploads)
    .bind(auth.event_id)
    .execute(&state.pool)
    .await?;

    tracing::info!(
        actor_user_id = %auth.user_id,
        target_user_id = %user_id,
        event_id = %auth.event_id,
        hide_uploads = body.hide_uploads,
        "host: ban_user"
    );

    Ok(StatusCode::NO_CONTENT)
}

pub async fn unban_user(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
    Path(user_id): Path<Uuid>,
) -> Result<StatusCode, AppError> {
    let result = sqlx::query(
        "UPDATE \"user\" SET is_banned = FALSE WHERE id = $1 AND event_id = $2",
    )
    .bind(user_id)
    .bind(auth.event_id)
    .execute(&state.pool)
    .await?;
    if result.rows_affected() == 0 {
        return Err(AppError::NotFound("Benutzer nicht gefunden.".into()));
    }
    tracing::info!(
        actor_user_id = %auth.user_id,
        target_user_id = %user_id,
        event_id = %auth.event_id,
        "host: unban_user"
    );
    Ok(StatusCode::NO_CONTENT)
}

pub async fn set_role(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
    Path(user_id): Path<Uuid>,
    Json(body): Json<SetRoleRequest>,
) -> Result<StatusCode, AppError> {
    if user_id == auth.user_id {
        return Err(AppError::BadRequest(
            "Du kannst deine eigene Rolle nicht ändern.".into(),
        ));
    }
    let new_role = match body.role.as_str() {
        "guest" => "guest",
        "host" => "host",
        _ => {
            return Err(AppError::BadRequest(
                "Ungültige Rolle. Erlaubt: guest, host.".into(),
            ))
        }
    };

    // Look up the current role so we can apply the host-vs-admin guard. Hosts may
    // promote guests and demote *other* hosts (the user explicitly requested this
    // expansion). Hosts may not touch admins. Admins may do anything (except change
    // themselves, blocked above).
    let target = sqlx::query_as::<_, (String,)>(
        "SELECT role::text FROM \"user\" WHERE id = $1 AND event_id = $2",
    )
    .bind(user_id)
    .bind(auth.event_id)
    .fetch_optional(&state.pool)
    .await?
    .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;

    if target.0 == "admin" {
        return Err(AppError::Forbidden(
            "Admins können nicht geändert werden.".into(),
        ));
    }

    sqlx::query("UPDATE \"user\" SET role = $2::user_role WHERE id = $1 AND event_id = $3")
        .bind(user_id)
        .bind(new_role)
        .bind(auth.event_id)
        .execute(&state.pool)
        .await?;
    tracing::info!(
        actor_user_id = %auth.user_id,
        target_user_id = %user_id,
        event_id = %auth.event_id,
        old_role = %target.0,
        new_role,
        "host: set_role"
    );
    Ok(StatusCode::NO_CONTENT)
}

#[derive(Serialize)]
pub struct PinResetResponse {
    /// Plaintext PIN — shown to the operator **once**. Never persisted client-side.
    pub pin: String,
}

/// Generate a fresh PIN for another user, returning the plaintext exactly once.
///
/// Authorisation:
/// - Host caller → may reset **guest** PINs only.
/// - Admin caller → may reset **guest** and **host** PINs (never another admin).
/// - Target ≠ caller.
pub async fn reset_user_pin(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
    Path(user_id): Path<Uuid>,
) -> Result<Json<PinResetResponse>, AppError> {
    use rand::Rng;

    if user_id == auth.user_id {
        return Err(AppError::BadRequest(
            "Du kannst deine eigene PIN nicht über diese Funktion zurücksetzen.".into(),
        ));
    }

    let target = sqlx::query_as::<_, (String,)>(
        "SELECT role::text FROM \"user\" WHERE id = $1 AND event_id = $2",
    )
    .bind(user_id)
    .bind(auth.event_id)
    .fetch_optional(&state.pool)
    .await?
    .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;

    match (auth.role.clone(), target.0.as_str()) {
        (UserRole::Admin, "guest" | "host") => {}
        (UserRole::Host, "guest") => {}
        _ => {
            return Err(AppError::Forbidden(
                "Du darfst die PIN dieses Benutzers nicht zurücksetzen.".into(),
            ))
        }
    }

    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)))?;

    sqlx::query(
        "UPDATE \"user\"
         SET recovery_pin_hash = $1,
             failed_pin_attempts = 0,
             pin_locked_until = NULL
         WHERE id = $2",
    )
    .bind(&pin_hash)
    .bind(user_id)
    .execute(&state.pool)
    .await?;

    // Notify the *recipient* device(s) if they happen to be online so they can clear
    // their cached local PIN. They'll save the new one on the next /recover.
    let _ = state.sse_tx.send(SseEvent::new(
        "pin-reset",
        serde_json::json!({ "user_id": user_id }).to_string(),
    ));

    tracing::info!(
        actor_user_id = %auth.user_id,
        target_user_id = %user_id,
        event_id = %auth.event_id,
        "host: reset_user_pin"
    );

    Ok(Json(PinResetResponse { pin }))
}

pub async fn host_delete_upload(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
    Path(upload_id): Path<Uuid>,
) -> Result<StatusCode, AppError> {
    let upload = Upload::find_by_id_and_event(&state.pool, upload_id, auth.event_id)
        .await?
        .ok_or_else(|| AppError::NotFound("Upload nicht gefunden.".into()))?;

    let deleted = Upload::soft_delete_in_event(&state.pool, upload_id, auth.event_id).await?;
    if !deleted {
        return Err(AppError::NotFound("Upload nicht gefunden.".into()));
    }

    let _ = state.sse_tx.send(SseEvent::new(
        "upload-deleted",
        serde_json::json!({ "upload_id": upload.id }).to_string(),
    ));

    tracing::info!(
        actor_user_id = %auth.user_id,
        event_id = %auth.event_id,
        upload_id = %upload.id,
        "host: host_delete_upload"
    );

    Ok(StatusCode::NO_CONTENT)
}

pub async fn host_delete_comment(
    State(state): State<AppState>,
    RequireHost(auth): RequireHost,
    Path(comment_id): Path<Uuid>,
) -> Result<StatusCode, AppError> {
    let deleted =
        Comment::soft_delete_in_event(&state.pool, comment_id, auth.event_id).await?;
    if !deleted {
        return Err(AppError::NotFound("Kommentar nicht gefunden.".into()));
    }
    tracing::info!(
        actor_user_id = %auth.user_id,
        event_id = %auth.event_id,
        comment_id = %comment_id,
        "host: host_delete_comment"
    );
    Ok(StatusCode::NO_CONTENT)
}

pub async fn close_event(
    State(state): State<AppState>,
    RequireHost(_auth): RequireHost,
) -> Result<StatusCode, AppError> {
    let result = sqlx::query(
        "UPDATE event SET uploads_locked_at = NOW() WHERE slug = $1 AND uploads_locked_at IS NULL",
    )
    .bind(&state.config.event_slug)
    .execute(&state.pool)
    .await?;

    // Only broadcast when this call actually flipped the lock — closing an
    // already-closed event is a no-op and shouldn't spam listeners.
    if result.rows_affected() > 0 {
        let _ = state.sse_tx.send(SseEvent::new("event-closed", "{}"));
    }

    Ok(StatusCode::NO_CONTENT)
}

pub async fn open_event(
    State(state): State<AppState>,
    RequireHost(_auth): RequireHost,
) -> Result<StatusCode, AppError> {
    let result = sqlx::query(
        "UPDATE event SET uploads_locked_at = NULL WHERE slug = $1 AND uploads_locked_at IS NOT NULL",
    )
    .bind(&state.config.event_slug)
    .execute(&state.pool)
    .await?;

    if result.rows_affected() > 0 {
        let _ = state.sse_tx.send(SseEvent::new("event-opened", "{}"));
    }

    Ok(StatusCode::NO_CONTENT)
}

pub async fn release_gallery(
    State(state): State<AppState>,
    RequireHost(_auth): RequireHost,
) -> Result<StatusCode, AppError> {
    let event = Event::find_by_slug(&state.pool, &state.config.event_slug)
        .await?
        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;

    if event.export_released_at.is_some() {
        return Err(AppError::BadRequest("Galerie wurde bereits freigegeben.".into()));
    }

    sqlx::query("UPDATE event SET export_released_at = NOW() WHERE slug = $1")
        .bind(&state.config.event_slug)
        .execute(&state.pool)
        .await?;

    // Enqueue export jobs
    for export_type in ["zip", "html"] {
        sqlx::query(
            "INSERT INTO export_job (event_id, type) VALUES ($1, $2::export_type)
             ON CONFLICT (event_id, type) DO NOTHING",
        )
        .bind(event.id)
        .bind(export_type)
        .execute(&state.pool)
        .await?;
    }

    // Spawn export workers
    crate::services::export::spawn_export_jobs(
        event.id,
        event.name,
        state.pool.clone(),
        state.config.media_path.clone(),
        state.sse_tx.clone(),
    );

    Ok(StatusCode::NO_CONTENT)
}