use dotenv;
use utils;
use diesel::{Connection, PgConnection};
use r2d2::{CustomizeConnection, Pool};
use r2d2_diesel::{ConnectionManager, Error};

fn test_database_url() -> String {
    dotenv::var("TEST_DATABASE_URL")
        .or_else(|_| dotenv::var("DATABASE_URL"))
        .expect("DATABASE_URL must be set in order to run tests")
}

#[derive(Debug)]
struct TestConnectionCustomizer{}

impl CustomizeConnection<PgConnection, Error> for TestConnectionCustomizer {
    /// Customize connections returned by the pool, so that
    /// our tests don't modify the real database.
    fn on_acquire(&self, conn: &mut PgConnection) -> Result<(), Error> {
        conn
            .begin_test_transaction()
            .map_err(|e| Error::QueryError(e))
    }

    fn on_release(&self, _conn: PgConnection) {}
}

pub fn init_test_db_pool() -> utils::Pool {
    let manager = ConnectionManager::<PgConnection>::new(test_database_url());
    Pool::builder()
        .connection_customizer(Box::new(TestConnectionCustomizer {}))
        .build(manager)
        .expect("db pool")
}