use super::models::DatabaseError;
use deadpool_redis::{Config, Runtime};
use itertools::Itertools;
use redis::{cmd, Cmd};
use std::fmt::Display;

const DEFAULT_EXPIRY: i64 = 1800; // 30 minutes

#[derive(Clone)]
pub struct RedisPool {
    pub pool: deadpool_redis::Pool,
    meta_namespace: String,
}

pub struct RedisConnection {
    pub connection: deadpool_redis::Connection,
    meta_namespace: String,
}

impl RedisPool {
    // initiate a new redis pool
    // testing pool uses a hashmap to mimic redis behaviour for very small data sizes (ie: tests)
    // PANICS: production pool will panic if redis url is not set
    pub fn new(meta_namespace: Option<String>) -> Self {
        let redis_pool = Config::from_url(dotenvy::var("REDIS_URL").expect("Redis URL not set"))
            .builder()
            .expect("Error building Redis pool")
            .max_size(
                dotenvy::var("DATABASE_MAX_CONNECTIONS")
                    .ok()
                    .and_then(|x| x.parse().ok())
                    .unwrap_or(10000),
            )
            .runtime(Runtime::Tokio1)
            .build()
            .expect("Redis connection failed");

        RedisPool {
            pool: redis_pool,
            meta_namespace: meta_namespace.unwrap_or("".to_string()),
        }
    }

    pub async fn connect(&self) -> Result<RedisConnection, DatabaseError> {
        Ok(RedisConnection {
            connection: self.pool.get().await?,
            meta_namespace: self.meta_namespace.clone(),
        })
    }
}

impl RedisConnection {
    pub async fn set(
        &mut self,
        namespace: &str,
        id: &str,
        data: &str,
        expiry: Option<i64>,
    ) -> Result<(), DatabaseError> {
        let mut cmd = cmd("SET");
        redis_args(
            &mut cmd,
            vec![
                format!("{}_{}:{}", self.meta_namespace, namespace, id),
                data.to_string(),
                "EX".to_string(),
                expiry.unwrap_or(DEFAULT_EXPIRY).to_string(),
            ]
            .as_slice(),
        );
        redis_execute(&mut cmd, &mut self.connection).await?;
        Ok(())
    }

    pub async fn set_serialized_to_json<Id, D>(
        &mut self,
        namespace: &str,
        id: Id,
        data: D,
        expiry: Option<i64>,
    ) -> Result<(), DatabaseError>
    where
        Id: Display,
        D: serde::Serialize,
    {
        self.set(
            namespace,
            &id.to_string(),
            &serde_json::to_string(&data)?,
            expiry,
        )
        .await
    }

    pub async fn get(
        &mut self,
        namespace: &str,
        id: &str,
    ) -> Result<Option<String>, DatabaseError> {
        let mut cmd = cmd("GET");
        redis_args(
            &mut cmd,
            vec![format!("{}_{}:{}", self.meta_namespace, namespace, id)].as_slice(),
        );
        let res = redis_execute(&mut cmd, &mut self.connection).await?;
        Ok(res)
    }

    pub async fn get_deserialized_from_json<R>(
        &mut self,
        namespace: &str,
        id: &str,
    ) -> Result<Option<R>, DatabaseError>
    where
        R: for<'a> serde::Deserialize<'a>,
    {
        Ok(self
            .get(namespace, id)
            .await?
            .and_then(|x| serde_json::from_str(&x).ok()))
    }

    pub async fn multi_get<R>(
        &mut self,
        namespace: &str,
        ids: impl IntoIterator<Item = impl Display>,
    ) -> Result<Vec<Option<R>>, DatabaseError>
    where
        R: for<'a> serde::Deserialize<'a>,
    {
        let mut cmd = cmd("MGET");

        redis_args(
            &mut cmd,
            &ids.into_iter()
                .map(|x| format!("{}_{}:{}", self.meta_namespace, namespace, x))
                .collect_vec(),
        );
        let res: Vec<Option<String>> = redis_execute(&mut cmd, &mut self.connection).await?;
        Ok(res
            .into_iter()
            .map(|x| x.and_then(|x| serde_json::from_str(&x).ok()))
            .collect())
    }

    pub async fn delete<T1>(&mut self, namespace: &str, id: T1) -> Result<(), DatabaseError>
    where
        T1: Display,
    {
        let mut cmd = cmd("DEL");
        redis_args(
            &mut cmd,
            vec![format!("{}_{}:{}", self.meta_namespace, namespace, id)].as_slice(),
        );
        redis_execute(&mut cmd, &mut self.connection).await?;
        Ok(())
    }

    pub async fn delete_many(
        &mut self,
        iter: impl IntoIterator<Item = (&str, Option<String>)>,
    ) -> Result<(), DatabaseError> {
        let mut cmd = cmd("DEL");
        let mut any = false;
        for (namespace, id) in iter {
            if let Some(id) = id {
                redis_args(
                    &mut cmd,
                    [format!("{}_{}:{}", self.meta_namespace, namespace, id)].as_slice(),
                );
                any = true;
            }
        }

        if any {
            redis_execute(&mut cmd, &mut self.connection).await?;
        }

        Ok(())
    }
}

pub fn redis_args(cmd: &mut Cmd, args: &[String]) {
    for arg in args {
        cmd.arg(arg);
    }
}

pub async fn redis_execute<T>(
    cmd: &mut Cmd,
    redis: &mut deadpool_redis::Connection,
) -> Result<T, deadpool_redis::PoolError>
where
    T: redis::FromRedisValue,
{
    let res = cmd.query_async::<_, T>(redis).await?;
    Ok(res)
}