use mongodb::bson::doc;

use crate::{
    cdb_col, get_mongo,
    transaction::{BatchTransaction, Price, Transaction},
};

/// Represents a specific instance of an item with potential variations.
///
/// This struct is used to describe a particular variation or instance of an item
/// in the real world. It may include attributes or properties that deviate from
/// the standard definition of the item. For example, different colors, sizes, or
/// configurations.
pub struct Variant {
    pub item: String,
    pub variant: String,
}

impl Variant {
    pub async fn demand(&self, uuid: &str, price: Price, destination: String) -> Option<String> {
        let db = get_mongo!();

        // check if supply transaction exists
        let supply_t = cdb_col!(db, "supply");
        if supply_t
            .find_one(doc! { "_id": uuid }, None)
            .await
            .unwrap()
            .is_none()
        {
            return None;
        }

        // todo : demand batch

        // mark as used
        let demand_t = cdb_col!(db, "demand");
        demand_t
            .insert_one(
                doc! {
                    "_id": uuid,
                    "destination": destination,
                    "price": price.as_bson()
                },
                None,
            )
            .await
            .unwrap();

        Some(uuid.to_string())
    }

    /// Records a supply transaction in the database.
    ///
    /// # Arguments
    ///
    /// * `amount` - The quantity of items supplied.
    /// * `price` - The price of the supplied items.
    /// * `origin` - The origin or source of the supplied items.
    ///
    /// # Returns
    ///
    /// Returns a UUID string representing the transaction.
    pub async fn supply(&self, amount: usize, price: Price, origin: &str) -> String {
        let db = get_mongo!();

        let mut ses = db.start_session(None).await.unwrap();
        ses.start_transaction(None).await.unwrap();

        let col: mongodb::Collection<mongodb::bson::Document> =
            ses.client().database("cdb").collection("supply");

        let mut transactions = vec![];
        for _ in 0..amount {
            transactions.push(Transaction::new(
                &self.item,
                &self.variant,
                price.clone(),
                origin,
            ));
        }

        for transaction in &transactions {
            let r = col
                .insert_one_with_session(transaction.as_doc(), None, &mut ses)
                .await
                .unwrap();
        }

        // batch transaction
        let ret_uuid = if amount == 1 {
            transactions.first().unwrap().uuid.clone()
        } else {
            let batch =
                BatchTransaction::new(transactions.iter().map(|x| x.uuid.clone()).collect());
            let col: mongodb::Collection<mongodb::bson::Document> = ses
                .client()
                .database("cdb")
                .collection("transactions_batch");
            col.insert_one_with_session(batch.as_doc(), None, &mut ses)
                .await
                .unwrap();
            batch.uuid
        };

        // todo : transaction overlap cache -> scale

        ses.commit_transaction().await.unwrap();

        ret_uuid
    }
}