//! Database Driver for Postgres
//!
//! Use of this driver requires enabling the `postgres` feature. The `postgres`
//! feature is enabled by default.
//!
//! Uses the [Postgres](https://crates.io/crates/postgres) crate for
//! interfacing with the database
use super::*;

use pg::{Client, Error, NoTls, Row};
use std::any::Any;
use std::cell::RefCell;

/// The struct implementing the `DatabaseDriver` trait
pub struct PostgresDriver {
    connection: RefCell<Option<Client>>,
}

impl PostgresDriver {
    /// Create a PostgresDriver driver
    pub fn new(dsn: &str) -> Self {
        let mut driver = PostgresDriver {
            connection: RefCell::new(None),
        };

        driver.connect(dsn);

        driver
    }

    fn connect(&mut self, dsn: &str) {
        let connection = Client::connect(dsn, NoTls).unwrap();

        self.connection = RefCell::new(Some(connection));
    }
}

impl DatabaseDriver for PostgresDriver {
    fn explain(&self, sql: &str) -> String {
        format!("EXPLAIN VERBOSE {}", sql)
    }

    fn random(&self) -> String {
        String::from(" RANDOM()")
    }

    fn query(&self, sql: &str) -> Result<Box<dyn Any>, Box<dyn Any>> {
        if self.connection.borrow().is_none() {
            panic!("No database connection.");
        }

        let result = self
            .connection
            .borrow_mut()
            .as_mut()
            .unwrap()
            .query(sql, &[]);

        match result {
            Ok(res) => Ok(Box::new(res)),
            Err(e) => Err(Box::new(e)),
        }
    }
}