use diesel::prelude::*;
use diesel::r2d2::{ConnectionManager, Pool};
use diesel::SqliteConnection;
use diesel_migrations::{embed_migrations, EmbeddedMigrations, MigrationHarness};

pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!();

/// Establishes a connection to the database using the given URL.
///
/// # Arguments
/// * `url` - The database URL to connect to.
///
/// # Panics
/// Panics if the database URL is not set or if the connection cannot be
/// established.
pub fn establish_connection(url: &str) -> SqliteConnection {
    SqliteConnection::establish(url).unwrap_or_else(|_| panic!("Error connecting to {}", url))
}

/// Builds a connection pool for the given URL.
///
/// # Arguments
/// * `url` - The database URL to connect to.
///
/// # Panics
/// Panics if the connection pool cannot be created.
pub fn build_connection_pool(url: &str) -> Pool<ConnectionManager<SqliteConnection>> {
    let manager = ConnectionManager::<SqliteConnection>::new(url);
    Pool::builder().build(manager).expect("Failed to create connection pool.")
}

/// Runs any pending migrations.
///
/// This function should be called before the application starts.
///
/// # Arguments
/// * `conn` - The database connection to run the migrations on.
///
/// # Panics
/// Panics if there is an error running the migrations.
pub fn migrate(conn: &mut SqliteConnection) {
    conn.run_pending_migrations(MIGRATIONS).unwrap();
}