use crate::infrastructure::db::DbPool;
use crate::interfaces::http::api::RealtimeEvent;
use reqwest::Client;
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use tokio::sync::broadcast;
use tracing::{error, info, warn};

#[derive(Serialize, Deserialize, Clone, sqlx::FromRow)]
pub struct WebhookRecord {
    pub webhook_id: String,
    pub merchant_id: String,
    pub url: String,
    pub secret: String,
    pub events: serde_json::Value,
}

pub struct WebhookService {
    pool: DbPool,
    client: Client,
}

impl WebhookService {
    pub fn new(pool: DbPool) -> Self {
        Self {
            pool,
            client: Client::builder()
                .timeout(std::time::Duration::from_secs(10))
                .build()
                .unwrap(),
        }
    }

    pub async fn run(&self, mut rx: broadcast::Receiver<RealtimeEvent>) {
        info!("Webhook Service started.");
        loop {
            match rx.recv().await {
                Ok(event) => {
                    let service = self.clone_self();
                    tokio::spawn(async move {
                        if let Err(e) = service.process_event(event).await {
                            error!("Error delivering webhook: {:?}", e);
                        }
                    });
                }
                Err(broadcast::error::RecvError::Lagged(n)) => {
                    warn!("Webhook Service lagged by {} events", n);
                }
                Err(broadcast::error::RecvError::Closed) => break,
            }
        }
    }

    fn clone_self(&self) -> Arc<Self> {
        Arc::new(Self {
            pool: self.pool.clone(),
            client: self.client.clone(),
        })
    }

    async fn process_event(
        &self,
        event: RealtimeEvent,
    ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
        let merchant_id = match &event {
            RealtimeEvent::OrderStatusChanged { merchant_id, .. } => merchant_id,
            RealtimeEvent::NewOrder { merchant_id, .. } => merchant_id,
            RealtimeEvent::RiskAlert { merchant_id, .. } => merchant_id,
            _ => return Ok(()), // Ignore other events for webhooks for now
        };

        let event_type = match &event {
            RealtimeEvent::OrderStatusChanged { new_status, .. } => {
                format!("order.{}", new_status.to_lowercase().replace("_", "."))
            }
            RealtimeEvent::NewOrder { .. } => "order.created".to_string(),
            RealtimeEvent::RiskAlert { .. } => "risk.alert".to_string(),
            _ => "system.event".to_string(),
        };

        // Fetch active webhooks for this merchant
        let webhooks = sqlx::query_as::<_, WebhookRecord>(
            "SELECT webhook_id, merchant_id, url, secret, events FROM merchant_webhooks WHERE merchant_id = $1 AND is_active = TRUE"
        )
        .bind(merchant_id)
        .fetch_all(&self.pool)
        .await?;

        for webhook in webhooks {
            // Check if webhook is subscribed to this event
            let subscribed_events: Vec<String> =
                serde_json::from_value(webhook.events.clone()).unwrap_or_default();
            if !subscribed_events.contains(&event_type)
                && !subscribed_events.contains(&"*".to_string())
            {
                continue;
            }

            self.deliver_webhook(webhook, event.clone(), &event_type)
                .await;
        }

        Ok(())
    }

    async fn deliver_webhook(
        &self,
        webhook: WebhookRecord,
        event: RealtimeEvent,
        event_type: &str,
    ) {
        let payload = serde_json::json!({
            "event": event_type,
            "timestamp": chrono::Utc::now().to_rfc3339(),
            "data": event
        });

        let payload_str = payload.to_string();

        // HMAC-SHA256 signature for security
        use hmac::{Hmac, Mac};
        use sha2::Sha256;
        type HmacSha256 = Hmac<Sha256>;

        let mut mac = HmacSha256::new_from_slice(webhook.secret.as_bytes())
            .expect("HMAC can take key of any size");
        mac.update(payload_str.as_bytes());
        let signature = hex::encode(mac.finalize().into_bytes());

        let max_attempts = 3;
        let mut attempt = 0;
        let mut delay = std::time::Duration::from_secs(1);

        while attempt < max_attempts {
            let attempt_number = attempt + 1;

            let (status_code, success, response_body) = match self
                .client
                .post(&webhook.url)
                .header("Content-Type", "application/json")
                .header("X-Rtix-Signature", &signature)
                .header("X-Rtix-Event", event_type)
                .body(payload_str.clone())
                .send()
                .await
            {
                Ok(resp) => {
                    let status = resp.status();
                    let sc = Some(status.as_u16() as i32);
                    let succ = status.is_success();
                    let body = match resp.text().await {
                        Ok(t) => Some(t),
                        Err(e) => Some(e.to_string()),
                    };

                    if succ {
                        info!(
                            "Webhook {} delivered successfully to {} on attempt {}",
                            webhook.webhook_id, webhook.url, attempt_number
                        );
                    } else {
                        warn!(
                            "Webhook {} delivery failed with status {} on attempt {}/{} to {}",
                            webhook.webhook_id, status, attempt_number, max_attempts, webhook.url
                        );
                    }
                    (sc, succ, body)
                }
                Err(e) => {
                    let body = Some(e.to_string());
                    error!(
                        "Webhook {} delivery error on attempt {}/{} to {}: {}",
                        webhook.webhook_id, attempt_number, max_attempts, webhook.url, e
                    );
                    (None, false, body)
                }
            };

            // Insert a log record
            let log_id = uuid::Uuid::new_v4().to_string();
            let log_query = "INSERT INTO webhook_delivery_logs (log_id, webhook_id, merchant_id, url, event_type, payload, status_code, success, response_body, attempt_number) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)";
            if let Err(err) = sqlx::query(log_query)
                .bind(&log_id)
                .bind(&webhook.webhook_id)
                .bind(&webhook.merchant_id)
                .bind(&webhook.url)
                .bind(event_type)
                .bind(&payload)
                .bind(status_code)
                .bind(success)
                .bind(&response_body)
                .bind(attempt_number)
                .execute(&self.pool)
                .await
            {
                error!("Failed to write webhook delivery log: {}", err);
            }

            if success {
                return;
            }

            attempt += 1;
            if attempt < max_attempts {
                tokio::time::sleep(delay).await;
                delay *= 2;
            }
        }
    }
}