use axum::{
    extract::State,
    http::StatusCode,
    routing::{get, post},
    Json, Router,
};
use contracts::auth_middleware::AuthUser;
use serde::{Deserialize, Serialize};
use std::net::SocketAddr;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
use uuid::Uuid;
use sqlx::postgres::PgPool;
use sqlx::FromRow;

pub mod ai_credits;
pub mod packages;
pub mod payu;

#[derive(Clone)]
pub struct AppState {
    beeceptor_url: String,
    client: reqwest::Client,
    pool: PgPool,
    payu: payu::PayuConfig,
}

#[derive(Debug, Serialize, Deserialize)]
struct CreateOrderRequest {
    // Client-supplied amount/currency are accepted for backward
    // compatibility but NOT trusted for pricing -- the real charge is
    // always derived server-side from pricing_packages.price_inr (see
    // create_order). Trusting a client-supplied amount for a real payment
    // gateway would let a client pay any amount it likes for a package.
    #[allow(dead_code)]
    amount: Option<u64>,
    #[allow(dead_code)]
    currency: Option<String>,
    package_id: Option<String>,
}

#[derive(Debug, Serialize)]
struct CreateOrderResponse {
    key: String,
    txnid: String,
    amount: String,
    productinfo: String,
    firstname: String,
    email: String,
    phone: String,
    surl: String,
    furl: String,
    hash: String,
    payu_base_url: String,
    udf1: String,
    udf2: String,
    // Kept for callers still reading the pre-PayU response shape.
    order_id: String,
    currency: String,
    status: String,
}

#[derive(Debug, Serialize, Deserialize)]
struct VerifyPaymentRequest {
    txnid: String,
    mihpayid: String,
    status: String,
    hash: String,
    amount: String,
    productinfo: String,
    firstname: String,
    email: String,
    #[serde(default)]
    phone: Option<String>,
    #[serde(default)]
    udf1: Option<String>,
    #[serde(default)]
    udf2: Option<String>,
}

#[derive(Debug, Serialize)]
struct VerifyPaymentResponse {
    verified: bool,
    payment_id: String,
    status: String,
    message: String,
}

#[derive(Debug, Serialize)]
struct PaymentStatusResponse {
    payment_id: String,
    status: String,
    amount: u64,
    currency: String,
}

#[derive(Debug, FromRow)]
struct PricingPackageRow {
    tracecoins_amount: i32,
    price_inr: i32,
    name: String,
}

#[derive(Debug, FromRow)]
struct UserContactRow {
    email: String,
    full_name: Option<String>,
    phone: Option<String>,
}

#[derive(Debug, FromRow)]
#[allow(dead_code)]
struct PaymentRow {
    id: Uuid,
    user_id: Uuid,
    package_id: Option<Uuid>,
    tracecoins_credited: Option<i32>,
}

async fn create_order(
    auth: AuthUser,
    State(state): State<AppState>,
    Json(payload): Json<CreateOrderRequest>,
) -> Result<Json<CreateOrderResponse>, (StatusCode, String)> {
    let package_id_str = payload.package_id.as_ref().ok_or((StatusCode::BAD_REQUEST, "package_id is required".to_string()))?;
    let package_id = Uuid::parse_str(package_id_str).map_err(|_| (StatusCode::BAD_REQUEST, "Invalid package id".to_string()))?;

    let package = sqlx::query_as::<_, PricingPackageRow>(
        "SELECT tracecoins_amount, price_inr, name FROM pricing_packages WHERE id = $1 AND is_active = true",
    )
    .bind(package_id)
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    let package = package.ok_or((StatusCode::BAD_REQUEST, "Invalid or inactive package".to_string()))?;
    let tracecoins_credited = package.tracecoins_amount;

    tracing::info!("Creating PayU order for package {} (₹{})", package_id, payu::paise_to_rupee_string(package.price_inr));

    let contact = sqlx::query_as::<_, UserContactRow>(
        "SELECT email, full_name, phone FROM users WHERE id = $1",
    )
    .bind(auth.user_id)
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?
    .ok_or((StatusCode::NOT_FOUND, "User not found".to_string()))?;

    let firstname = contact
        .full_name
        .as_deref()
        .and_then(|n| n.split_whitespace().next())
        .unwrap_or("Customer")
        .to_string();
    let phone = contact.phone.unwrap_or_default();

    let txnid = payu::generate_txnid();
    // Price is derived from pricing_packages.price_inr (server-side truth),
    // never from the client-supplied `payload.amount` -- see CreateOrderRequest.
    let amount_str = payu::paise_to_rupee_string(package.price_inr);
    let productinfo = package.name.clone();
    let udf1 = package_id_str.clone();
    let udf2 = String::new();

    let hash = payu::request_hash(
        &state.payu,
        &txnid,
        &amount_str,
        &productinfo,
        &firstname,
        &contact.email,
        &udf1,
        &udf2,
    );

    sqlx::query(
        r#"
        INSERT INTO payments (user_id, package_id, razorpay_order_id, amount_inr, tracecoins_credited, status)
        VALUES ($1, $2, $3, $4, $5, 'PENDING')
        "#,
    )
    .bind(auth.user_id)
    .bind(package_id)
    .bind(&txnid)
    .bind(package.price_inr)
    .bind(tracecoins_credited)
    .execute(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    Ok(Json(CreateOrderResponse {
        key: state.payu.merchant_key.clone(),
        txnid: txnid.clone(),
        amount: amount_str,
        productinfo,
        firstname,
        email: contact.email,
        phone,
        surl: state.payu.surl.clone(),
        furl: state.payu.furl.clone(),
        hash,
        payu_base_url: state.payu.base_url.clone(),
        udf1,
        udf2,
        order_id: txnid,
        currency: "INR".to_string(),
        status: "created".to_string(),
    }))
}

async fn verify_payment(
    auth: AuthUser,
    State(state): State<AppState>,
    Json(payload): Json<VerifyPaymentRequest>,
) -> Result<Json<VerifyPaymentResponse>, (StatusCode, String)> {
    tracing::info!("Verifying PayU payment: txnid={}", payload.txnid);

    if !payu::verify_response_hash(
        &state.payu,
        &payload.status,
        &payload.txnid,
        &payload.amount,
        &payload.productinfo,
        &payload.firstname,
        &payload.email,
        payload.udf1.as_deref().unwrap_or(""),
        payload.udf2.as_deref().unwrap_or(""),
        &payload.hash,
    ) {
        return Err((StatusCode::BAD_REQUEST, "Payment hash verification failed".to_string()));
    }

    if !payload.status.eq_ignore_ascii_case("success") {
        return Err((StatusCode::BAD_REQUEST, "Payment was not successful".to_string()));
    }

    let payment = sqlx::query_as::<_, PaymentRow>(
        r#"
        SELECT id, user_id, package_id, tracecoins_credited
        FROM payments
        WHERE razorpay_order_id = $1 AND status = 'PENDING'
        "#,
    )
    .bind(&payload.txnid)
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    let payment = match payment {
        Some(p) => p,
        None => return Err((StatusCode::NOT_FOUND, "Payment not found or already processed".to_string())),
    };

    if payment.user_id != auth.user_id {
        return Err((StatusCode::FORBIDDEN, "Payment does not belong to user".to_string()));
    }

    let tracecoins = payment.tracecoins_credited.unwrap_or(0);

    sqlx::query(
        r#"
        UPDATE payments SET
            status = 'SUCCESS',
            razorpay_payment_id = $1,
            verified_at = NOW()
        WHERE id = $2
        "#,
    )
    .bind(&payload.mihpayid)
    .bind(payment.id)
    .execute(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    sqlx::query(
        r#"
        INSERT INTO tracecoin_wallets (user_id, balance, reserved)
        VALUES ($1, $2, 0)
        ON CONFLICT (user_id) DO UPDATE SET
            balance = tracecoin_wallets.balance + excluded.balance
        "#,
    )
    .bind(payment.user_id)
    .bind(tracecoins as i64)
    .execute(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    if let Ok(Some(wallet_id)) = sqlx::query_scalar::<_, Uuid>(
        "SELECT id FROM tracecoin_wallets WHERE user_id = $1"
    )
    .bind(payment.user_id)
    .fetch_optional(&state.pool)
    .await
    {
        sqlx::query(
            r#"
            INSERT INTO tracecoin_ledger (wallet_id, transaction_type, amount, balance_after, reference_type, reference_id, description)
            VALUES ($1, 'CREDIT', $2, $2, 'PAYMENT', $3, 'Package purchase')
            "#,
        )
        .bind(wallet_id)
        .bind(tracecoins as i64)
        .bind(payment.id)
        .execute(&state.pool)
        .await
        .ok();
    }

    let _ = sqlx::query(
        r#"
        INSERT INTO notifications (user_id, title, body, notification_type, reference_id)
        VALUES ($1, $2, $3, $4, $5)
        "#,
    )
    .bind(payment.user_id)
    .bind("Tracecoins Purchased Successfully")
    .bind(format!("Your {} Tracecoin package has been credited to your wallet.", tracecoins))
    .bind("PAYMENT")
    .bind(payment.id)
    .execute(&state.pool)
    .await
    .ok();

    Ok(Json(VerifyPaymentResponse {
        verified: true,
        payment_id: payload.mihpayid,
        status: "success".to_string(),
        message: "Payment verified successfully".to_string(),
    }))
}

async fn get_payment_status(
    State(state): State<AppState>,
    axum::extract::Path(payment_id): axum::extract::Path<String>,
) -> Result<Json<PaymentStatusResponse>, (StatusCode, String)> {
    tracing::info!("Getting payment status: payment_id={}", payment_id);

    let status_url = format!("{}/{}", state.beeceptor_url.trim_end_matches('/'), payment_id);
    let resp = state
        .client
        .get(&status_url)
        .send()
        .await
        .map_err(|e| (StatusCode::BAD_GATEWAY, format!("Beeceptor error: {}", e)))?;

    let status = resp.status();
    let body: serde_json::Value = resp
        .json()
        .await
        .map_err(|e| (StatusCode::BAD_GATEWAY, format!("Parse error: {}", e)))?;

    if !status.is_success() {
        return Ok(Json(PaymentStatusResponse {
            payment_id,
            status: "not_found".to_string(),
            amount: 0,
            currency: "INR".to_string(),
        }));
    }

    let amount = body.get("amount").and_then(|v| v.as_u64()).unwrap_or(0);
    let currency = body
        .get("currency")
        .and_then(|v| v.as_str())
        .unwrap_or("INR")
        .to_string();
    let status_str = body
        .get("status")
        .and_then(|v| v.as_str())
        .unwrap_or("unknown")
        .to_string();

    Ok(Json(PaymentStatusResponse {
        payment_id,
        status: status_str,
        amount,
        currency,
    }))
}

#[tokio::main]
async fn main() {
    tracing_subscriber::registry()
        .with(tracing_subscriber::EnvFilter::new(
            std::env::var("RUST_LOG").unwrap_or_else(|_| "info".into()),
        ))
        .with(tracing_subscriber::fmt::layer())
        .init();

    let beeceptor_url = std::env::var("BEECEPTOR_URL")
        .expect("BEECEPTOR_URL must be set");

    let db_url = std::env::var("DATABASE_URL")
        .expect("DATABASE_URL must be set");
    let pool = PgPool::connect(&db_url)
        .await
        .expect("Failed to connect to database");

    let state = AppState {
        beeceptor_url,
        client: reqwest::Client::new(),
        pool,
        payu: payu::PayuConfig::from_env(),
    };

    let app = Router::new()
        .route("/api/payments/create-order", post(create_order))
        .route("/api/payments/verify", post(verify_payment))
        .route("/api/payments/{id}/status", get(get_payment_status))
        .nest("/api/packages", packages::router())
        .nest("/api/ai-credits", ai_credits::router())
        .nest("/api/admin/ai-credits/packages", ai_credits::admin_router())
        .with_state(state);

    let port: u16 = std::env::var("PORT")
        .unwrap_or_else(|_| "9116".to_string())
        .parse()
        .expect("PORT must be a valid u16");
    let addr = SocketAddr::from(([0, 0, 0, 0], port));

    tracing::info!("Payments service listening on {}", addr);

    let listener = tokio::net::TcpListener::bind(&addr).await.unwrap();
    axum::serve(listener, app).await.unwrap();
}