use std::{sync::Arc, time::Duration};

use redis::{
    AsyncCommands, cluster::ClusterClient, cluster_async::ClusterConnection,
};
use serde::{Serialize, de::DeserializeOwned};
use tokio::time::timeout;

use crate::{CacheError, CacheResult};

const DEFAULT_COMMAND_TIMEOUT: Duration = Duration::from_secs(3);

#[derive(Clone, Debug)]
pub struct ClusterCacheConfig {
    pub urls: Vec<String>,
    pub key_prefix: Option<String>,
    pub command_timeout: Duration,
}

impl ClusterCacheConfig {
    pub fn new(urls: Vec<String>) -> Self {
        Self {
            urls,
            key_prefix: None,
            command_timeout: DEFAULT_COMMAND_TIMEOUT,
        }
    }
}

#[derive(Clone)]
pub struct ClusterCache {
    connection: ClusterConnection,
    key_prefix: Option<Arc<str>>,
    command_timeout: Duration,
}

impl ClusterCache {
    pub async fn connect(config: ClusterCacheConfig) -> CacheResult<Self> {
        if config.urls.is_empty() {
            return Err(CacheError::Config(
                "redis cluster urls are empty".to_string(),
            ));
        }

        let client =
            ClusterClient::new(config.urls).map_err(CacheError::Redis)?;
        let connection =
            timeout(config.command_timeout, client.get_async_connection())
                .await
                .map_err(|_| CacheError::Timeout("connect redis cluster"))?
                .map_err(CacheError::Redis)?;

        Ok(Self {
            connection,
            key_prefix: config.key_prefix.map(Arc::from),
            command_timeout: config.command_timeout,
        })
    }

    pub async fn get<T>(&self, key: &str) -> CacheResult<Option<T>>
    where
        T: DeserializeOwned,
    {
        let key = self.key(key);
        let mut connection = self.connection.clone();
        let value: Option<Vec<u8>> = self
            .run(redis::cmd("GET").arg(&key).query_async(&mut connection))
            .await?;

        match value {
            Some(value) => serde_json::from_slice(&value)
                .map(Some)
                .map_err(CacheError::Serialize),
            None => Ok(None),
        }
    }

    pub async fn get_json(
        &self,
        key: &str,
    ) -> CacheResult<Option<serde_json::Value>> {
        self.get(key).await
    }

    pub async fn set<T>(
        &self,
        key: &str,
        value: &T,
        ttl: Option<Duration>,
    ) -> CacheResult<()>
    where
        T: Serialize + ?Sized,
    {
        let key = self.key(key);
        let value = serde_json::to_vec(value).map_err(CacheError::Serialize)?;
        let mut connection = self.connection.clone();

        if let Some(ttl) = ttl {
            let seconds = ttl.as_secs().max(1);
            self.run::<(), _>(connection.set_ex(key, value, seconds))
                .await
        } else {
            self.run::<(), _>(connection.set(key, value)).await
        }
    }

    pub async fn remove(&self, key: &str) -> CacheResult<bool> {
        let key = self.key(key);
        let mut connection = self.connection.clone();
        let removed: u64 = self.run(connection.del(key)).await?;
        Ok(removed > 0)
    }

    pub async fn exists(&self, key: &str) -> CacheResult<bool> {
        let key = self.key(key);
        let mut connection = self.connection.clone();
        self.run(connection.exists(key)).await
    }

    pub async fn set_nx_with_ttl<T>(
        &self,
        key: &str,
        value: &T,
        ttl: Duration,
    ) -> CacheResult<bool>
    where
        T: Serialize,
    {
        let key = self.key(key);
        let value = serde_json::to_vec(value).map_err(CacheError::Serialize)?;
        let mut connection = self.connection.clone();
        let result: Option<String> = self
            .run(
                redis::cmd("SET")
                    .arg(&key)
                    .arg(&value)
                    .arg("NX")
                    .arg("EX")
                    .arg(ttl.as_secs().max(1))
                    .query_async(&mut connection),
            )
            .await?;
        Ok(result.is_some())
    }

    pub async fn expire(&self, key: &str, ttl: Duration) -> CacheResult<bool> {
        let key = self.key(key);
        let mut connection = self.connection.clone();
        self.run(connection.expire(key, ttl.as_secs() as i64)).await
    }

    pub async fn delete_pattern(&self, pattern: &str) -> CacheResult<u64> {
        let pattern = self.key(pattern);
        let mut connection = self.connection.clone();
        let keys: Vec<String> = self
            .run(
                redis::cmd("KEYS")
                    .arg(&pattern)
                    .query_async(&mut connection),
            )
            .await?;

        if keys.is_empty() {
            return Ok(0);
        }

        let mut connection = self.connection.clone();
        self.run(connection.del(keys)).await
    }

    pub async fn ping(&self) -> CacheResult<()> {
        let mut connection = self.connection.clone();
        let pong: String = self
            .run(redis::cmd("PING").query_async(&mut connection))
            .await?;
        if pong == "PONG" {
            Ok(())
        } else {
            Err(CacheError::Protocol(format!(
                "unexpected redis PING response: {pong}"
            )))
        }
    }

    pub fn conn(&self) -> ClusterConnection {
        self.connection.clone()
    }

    fn key(&self, key: &str) -> String {
        match &self.key_prefix {
            Some(prefix) => format!("{prefix}:{key}"),
            None => key.to_string(),
        }
    }

    async fn run<T, F>(&self, future: F) -> CacheResult<T>
    where
        F: std::future::Future<Output = redis::RedisResult<T>>,
    {
        timeout(self.command_timeout, future)
            .await
            .map_err(|_| CacheError::Timeout("redis command"))?
            .map_err(CacheError::Redis)
    }
}