use axum::{
    extract::State,
    http::StatusCode,
    response::Json,
    routing::post,
    Router,
};
use bcrypt::hash;
use chrono::Utc;
use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use std::env;
use std::sync::Arc;
use tracing::{info, warn};
use validator::Validate;

#[derive(Clone)]
struct AppState {
    db: PgPool,
}

#[derive(Deserialize, Validate)]
struct RegisterRequest {
    #[validate(length(min = 3, max = 50))]
    username: String,
    #[validate(length(min = 6))]
    password: String,
    #[validate(email)]
    email: String,
}

#[derive(Serialize)]
struct RegisterResponse {
    success: bool,
    user_id: Option<i32>,
    message: String,
}

#[derive(Serialize)]
struct ErrorResponse {
    error: String,
}

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt::init();
    
    info!("Starting user-register service...");
    
    let database_url = env::var("DATABASE_URL").expect("DATABASE_URL must be set");
    let pool = sqlx::postgres::PgPool::connect(&database_url)
        .await
        .expect("Failed to connect to database");
    
    info!("Database connected");
    
    let state = Arc::new(AppState { db: pool });
    
    let app = Router::new()
        .route("/register", post(register_handler))
        .route("/health", axum::routing::get(health_handler))
        .with_state(state);
    
    let port = env::var("SERVICE_PORT").unwrap_or_else(|_| "8080".to_string());
    let listener = tokio::net::TcpListener::bind(format!("0.0.0.0:{}", port))
        .await
        .unwrap();
    
    info!("User-register service listening on port {}", port);
    
    axum::serve(listener, app).await.unwrap();
}

async fn register_handler(
    State(state): State<Arc<AppState>>,
    Json(payload): Json<RegisterRequest>,
) -> (StatusCode, Json<RegisterResponse>) {
    info!("Registration attempt for user: {}", payload.username);
    
    // 参数校验
    if let Err(e) = payload.validate() {
        return (
            StatusCode::BAD_REQUEST,
            Json(RegisterResponse {
                success: false,
                user_id: None,
                message: format!("Validation error: {}", e),
            }),
        );
    }
    
    // 检查用户名是否存在
    let existing: Option<(i32,)> = sqlx::query_as("SELECT id FROM users WHERE username = $1")
        .bind(&payload.username)
        .fetch_optional(&state.db)
        .await
        .unwrap_or(None);
    
    if existing.is_some() {
        return (
            StatusCode::CONFLICT,
            Json(RegisterResponse {
                success: false,
                user_id: None,
                message: "Username already exists".to_string(),
            }),
        );
    }
    
    // 检查邮箱是否存在
    let existing_email: Option<(i32,)> = sqlx::query_as("SELECT id FROM users WHERE email = $1")
        .bind(&payload.email)
        .fetch_optional(&state.db)
        .await
        .unwrap_or(None);
    
    if existing_email.is_some() {
        return (
            StatusCode::CONFLICT,
            Json(RegisterResponse {
                success: false,
                user_id: None,
                message: "Email already exists".to_string(),
            }),
        );
    }
    
    // 密码哈希
    let password_hash = match hash(&payload.password, bcrypt::DEFAULT_COST) {
        Ok(h) => h,
        Err(e) => {
            warn!("Password hashing failed: {}", e);
            return (
                StatusCode::INTERNAL_SERVER_ERROR,
                Json(RegisterResponse {
                    success: false,
                    user_id: None,
                    message: "Internal error".to_string(),
                }),
            );
        }
    };
    
    // 插入用户
    let result = sqlx::query_as::<_, (i32,)>(
        "INSERT INTO users (username, password_hash, email, created_at, updated_at) 
         VALUES ($1, $2, $3, $4, $4) 
         RETURNING id"
    )
    .bind(&payload.username)
    .bind(&password_hash)
    .bind(&payload.email)
    .bind(Utc::now())
    .fetch_one(&state.db)
    .await;
    
    match result {
        Ok((user_id,)) => {
            info!("User {} registered with id {}", payload.username, user_id);
            (
                StatusCode::CREATED,
                Json(RegisterResponse {
                    success: true,
                    user_id: Some(user_id),
                    message: "User registered successfully".to_string(),
                }),
            )
        }
        Err(e) => {
            warn!("Registration failed: {}", e);
            (
                StatusCode::INTERNAL_SERVER_ERROR,
                Json(RegisterResponse {
                    success: false,
                    user_id: None,
                    message: "Registration failed".to_string(),
                }),
            )
        }
    }
}

async fn health_handler() -> &'static str {
    "OK"
}