use bb8::PooledConnection;
use diesel::PgConnection;
use error_stack::ResultExt;
use hyperswitch_domain_models::errors::StorageError;

use crate::{errors::RedisErrorExt, metrics, DatabaseStore};

pub async fn pg_connection_read<T: DatabaseStore>(
    store: &T,
) -> error_stack::Result<
    PooledConnection<'_, async_bb8_diesel::ConnectionManager<PgConnection>>,
    StorageError,
> {
    // If only OLAP is enabled get replica pool.
    #[cfg(all(feature = "olap", not(feature = "oltp")))]
    let pool = store.get_replica_pool();

    // If either one of these are true we need to get master pool.
    //  1. Only OLTP is enabled.
    //  2. Both OLAP and OLTP is enabled.
    //  3. Both OLAP and OLTP is disabled.
    #[cfg(any(
        all(not(feature = "olap"), feature = "oltp"),
        all(feature = "olap", feature = "oltp"),
        all(not(feature = "olap"), not(feature = "oltp"))
    ))]
    let pool = store.get_master_pool();

    pool.get()
        .await
        .change_context(StorageError::DatabaseConnectionError)
}

pub async fn pg_connection_write<T: DatabaseStore>(
    store: &T,
) -> error_stack::Result<
    PooledConnection<'_, async_bb8_diesel::ConnectionManager<PgConnection>>,
    StorageError,
> {
    // Since all writes should happen to master DB only choose master DB.
    let pool = store.get_master_pool();

    pool.get()
        .await
        .change_context(StorageError::DatabaseConnectionError)
}

pub async fn try_redis_get_else_try_database_get<F, RFut, DFut, T>(
    redis_fut: RFut,
    database_call_closure: F,
) -> error_stack::Result<T, StorageError>
where
    F: FnOnce() -> DFut,
    RFut: futures::Future<Output = error_stack::Result<T, redis_interface::errors::RedisError>>,
    DFut: futures::Future<Output = error_stack::Result<T, StorageError>>,
{
    let redis_output = redis_fut.await;
    match redis_output {
        Ok(output) => Ok(output),
        Err(redis_error) => match redis_error.current_context() {
            redis_interface::errors::RedisError::NotFound => {
                metrics::KV_MISS.add(1, &[]);
                database_call_closure().await
            }
            // Keeping the key empty here since the error would never go here.
            _ => Err(redis_error.to_redis_failed_response("")),
        },
    }
}