//! Federation API endpoints.

use axum::{
    extract::{Path, State},
    http::StatusCode,
    routing::{get, post},
    Json, Router,
};
use serde::Deserialize;
use serde_json::{json, Value};
use sqlx::PgPool;
use uuid::Uuid;

use crate::auth::AuthUser;
use crate::plugins::builtin::federation::{
    CommunityFederation, FederatedInstance, FederationService,
};

// ============================================================================
// Request Types
// ============================================================================

#[derive(Debug, Deserialize)]
pub struct RegisterInstanceRequest {
    pub url: String,
    pub name: String,
    pub description: Option<String>,
    pub public_key: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct CreateFederationRequest {
    pub remote_instance_id: Uuid,
    pub remote_community_id: Uuid,
    pub remote_community_name: String,
    pub sync_direction: String,
}

#[derive(Debug, Deserialize)]
pub struct SetTrustLevelRequest {
    pub trust_level: i32,
}

#[derive(Debug, Deserialize)]
pub struct IncomingFederationRequest {
    pub from_instance_url: String,
    pub from_community_name: String,
    pub message: Option<String>,
}

// ============================================================================
// Handlers
// ============================================================================

/// Get all federated instances
async fn get_instances(
    _auth: AuthUser,
    State(pool): State<PgPool>,
) -> Result<Json<Vec<FederatedInstance>>, (StatusCode, String)> {
    let instances = FederationService::get_instances(&pool)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(instances))
}

/// Register a new federated instance
async fn register_instance(
    _auth: AuthUser,
    State(pool): State<PgPool>,
    Json(req): Json<RegisterInstanceRequest>,
) -> Result<Json<Value>, (StatusCode, String)> {
    let instance_id = FederationService::register_instance(
        &pool,
        &req.url,
        &req.name,
        req.description.as_deref(),
        req.public_key.as_deref(),
    )
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(json!({"id": instance_id})))
}

/// Get federation statistics
async fn get_stats(
    _auth: AuthUser,
    Path(community_id): Path<Uuid>,
    State(pool): State<PgPool>,
) -> Result<Json<Value>, (StatusCode, String)> {
    let stats = FederationService::get_stats(&pool, community_id)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(stats))
}

/// Get community federations
async fn get_community_federations(
    _auth: AuthUser,
    Path(community_id): Path<Uuid>,
    State(pool): State<PgPool>,
) -> Result<Json<Vec<CommunityFederation>>, (StatusCode, String)> {
    let federations = FederationService::get_community_federations(&pool, community_id)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(federations))
}

/// Request federation with another community
async fn request_federation(
    _auth: AuthUser,
    Path(community_id): Path<Uuid>,
    State(pool): State<PgPool>,
    Json(req): Json<CreateFederationRequest>,
) -> Result<Json<Value>, (StatusCode, String)> {
    let federation_id = FederationService::create_federation(
        &pool,
        community_id,
        req.remote_instance_id,
        req.remote_community_id,
        &req.remote_community_name,
        &req.sync_direction,
    )
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(json!({"id": federation_id})))
}

/// Approve a federation request
async fn approve_federation(
    auth: AuthUser,
    Path(federation_id): Path<Uuid>,
    State(pool): State<PgPool>,
) -> Result<Json<Value>, (StatusCode, String)> {
    FederationService::approve_federation(&pool, federation_id, auth.user_id)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(json!({"success": true})))
}

/// Set trust level for an instance
async fn set_trust_level(
    _auth: AuthUser,
    Path(instance_id): Path<Uuid>,
    State(pool): State<PgPool>,
    Json(req): Json<SetTrustLevelRequest>,
) -> Result<Json<Value>, (StatusCode, String)> {
    FederationService::set_trust_level(&pool, instance_id, req.trust_level)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(json!({"success": true})))
}

/// Handle incoming federation request from another instance
/// Note: This endpoint is intentionally unauthenticated for server-to-server federation.
/// The request creates a PENDING entry that must be approved by a community admin.
/// TODO: Add rate limiting and instance signature verification for production.
async fn receive_federation_request(
    Path(community_id): Path<Uuid>,
    State(pool): State<PgPool>,
    Json(req): Json<IncomingFederationRequest>,
) -> Result<Json<Value>, (StatusCode, String)> {
    // Validate the community exists and accepts federation requests
    let community_exists = sqlx::query_scalar!(
        "SELECT EXISTS(SELECT 1 FROM communities WHERE id = $1 AND is_active = true) as \"exists!\"",
        community_id
    )
    .fetch_one(&pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    if !community_exists {
        return Err((
            StatusCode::NOT_FOUND,
            "Community not found or inactive".to_string(),
        ));
    }

    let request_id = FederationService::request_federation(
        &pool,
        &req.from_instance_url,
        &req.from_community_name,
        community_id,
        req.message.as_deref(),
    )
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(json!({"id": request_id})))
}

// ============================================================================
// Router
// ============================================================================

pub fn router(pool: PgPool) -> Router {
    Router::new()
        // Instances
        .route(
            "/api/federation/instances",
            get(get_instances).post(register_instance),
        )
        .route(
            "/api/federation/instances/{instance_id}/trust",
            post(set_trust_level),
        )
        // Community federations
        .route(
            "/api/communities/{community_id}/federation",
            get(get_community_federations).post(request_federation),
        )
        .route(
            "/api/communities/{community_id}/federation/stats",
            get(get_stats),
        )
        .route(
            "/api/communities/{community_id}/federation/request",
            post(receive_federation_request),
        )
        .route(
            "/api/federation/{federation_id}/approve",
            post(approve_federation),
        )
        .with_state(pool)
}