pub use tosin_macros::gather_migrations as gather;

use diesel::{Connection, result::Error as DieselError};

use crate::db::backend::Connectable;

mod change;

pub use change::*;

pub struct Migration {
    pub id: usize,
    pub name: &'static str,
    pub prereqs: &'static [(&'static str, usize)],
    pub changes: &'static [DatabaseChange],
}

impl Migration {
    pub fn apply<C: Connectable>(&self, app_name: &str, connection: &C::Connection) {
        // TODO prevent double-applying
        connection.transaction::<_, DieselError, _>(|| {
            for change in self.changes {
                change.apply::<C>(app_name, connection);
            }

            Ok(())
        }).unwrap();
    }
}