use entity::{expenditure, transaction};
use sea_orm::sea_query::OnConflict;
use sea_orm::QueryFilter;
use sea_orm::{ColumnTrait, DatabaseConnection, DbErr, EntityTrait, Iterable, TransactionTrait};

pub struct Insertion {
    pub transaction: transaction::ActiveModel,
    pub contained_expenditures: Vec<expenditure::ActiveModel>,
}

// Note while this is more efficient in db calls, it does bind together the entire group.
// We employ a batching process for now to try balance speed and failure rate but it is worth trying
// to move failures earlier and improve reporting.
pub async fn insert(db: &DatabaseConnection, insertions: Vec<Insertion>) -> Result<(), DbErr> {
    for insertions in insertions.chunks(400) {
        let tx = db.begin().await?;

        transaction::Entity::insert_many(insertions.iter().map(|i| &i.transaction).cloned())
            .on_conflict(
                OnConflict::column(transaction::Column::Id)
                    .update_columns(transaction::Column::iter())
                    .to_owned(),
            )
            .exec(&tx)
            .await?;

        // Expenditures can change as we recagegorise them, so we delete all the old ones and insert
        // an entirely new set to ensure we don't end up leaving old ones around.
        expenditure::Entity::delete_many()
            .filter(
                expenditure::Column::TransactionId
                    .is_in(insertions.iter().map(|i| i.transaction.id.as_ref())),
            )
            .exec(&tx)
            .await?;

        expenditure::Entity::insert_many(
            insertions
                .iter()
                .flat_map(|i| &i.contained_expenditures)
                .cloned(),
        )
        .on_conflict(
            OnConflict::columns(vec![
                expenditure::Column::TransactionId,
                expenditure::Column::Category,
            ])
            .update_columns(expenditure::Column::iter())
            .to_owned(),
        )
        .exec(&tx)
        .await?;

        tx.commit().await?;
    }

    Ok(())
}