use anyhow::Result;
use schist_models::{Bucket, Drip};

use super::{find_by_id_or, sum_drips_for_bucket};

pub fn calculate_bucket_balance(
    bucket: &Bucket,
    transaction_sums: &[(i32, i64)],
    bucket_transfer_from_sums: &[(i32, i64)],
    bucket_transfer_to_sums: &[(i32, i64)],
    budget_drips: &[Drip],
) -> Result<i64> {
    let transaction_sum = find_by_id_or(transaction_sums, bucket.id, 0);
    let bucket_transfer_from_sum = find_by_id_or(bucket_transfer_from_sums, bucket.id, 0);
    let bucket_transfer_to_sum = find_by_id_or(bucket_transfer_to_sums, bucket.id, 0);
    let budget_accruals_sum = sum_drips_for_bucket(bucket, budget_drips)?;

    Ok(transaction_sum + budget_accruals_sum + bucket_transfer_to_sum - bucket_transfer_from_sum)
}

#[cfg(test)]
mod test {
    use schist_fakes::{bucket::make_fake_bucket, drip::make_fake_drip_builder};

    use super::calculate_bucket_balance;

    #[test]
    fn when_no_data_then_returns_zero() {
        let bucket = make_fake_bucket(0);

        let result = calculate_bucket_balance(&bucket, &[], &[], &[], &[]);

        assert!(result.is_ok());
        assert_eq!(result.unwrap(), 0_i64);
    }

    #[test]
    fn when_data_only_for_another_bucket_then_returns_zero() {
        let bucket = make_fake_bucket(0);
        let transaction_sums = [(1, 100)];
        let bucket_transfer_from_sums = [(1, 91)];
        let bucket_transfer_to_sums = [(2, 79)];
        let budget_drips = [make_fake_drip_builder(0)
            .amount(100)
            .bucket_id(1)
            .build()
            .unwrap()];

        let result = calculate_bucket_balance(
            &bucket,
            &transaction_sums,
            &bucket_transfer_from_sums,
            &bucket_transfer_to_sums,
            &budget_drips,
        );

        assert!(result.is_ok());
        assert_eq!(result.unwrap(), 0_i64);
    }

    #[test]
    fn when_transaction_sum_is_zero_then_returns_zero() {
        let bucket = make_fake_bucket(0);
        let transaction_sums = [(0, 0)];
        let bucket_transfer_from_sums = [];
        let bucket_transfer_to_sums = [];
        let budget_drips = [];

        let result = calculate_bucket_balance(
            &bucket,
            &transaction_sums,
            &bucket_transfer_from_sums,
            &bucket_transfer_to_sums,
            &budget_drips,
        );

        assert!(result.is_ok());
        assert_eq!(result.unwrap(), 0_i64);
    }

    #[test]
    fn when_bucket_transfers_are_zero_then_returns_zero() {
        let bucket = make_fake_bucket(0);
        let transaction_sums = [];
        let bucket_transfer_from_sums = [(0, 0)];
        let bucket_transfer_to_sums = [(0, 0)];
        let budget_drips = [];

        let result = calculate_bucket_balance(
            &bucket,
            &transaction_sums,
            &bucket_transfer_from_sums,
            &bucket_transfer_to_sums,
            &budget_drips,
        );

        assert!(result.is_ok());
        assert_eq!(result.unwrap(), 0_i64);
    }

    #[test]
    fn when_some_data_then_calculates_as_expected() {
        let bucket = make_fake_bucket(0);
        let transaction_sums = [(0, 100)];
        let bucket_transfer_from_sums = [(0, 91)];
        let bucket_transfer_to_sums = [(0, 79)];
        let budget_drips = [
            make_fake_drip_builder(0)
                .amount(77)
                .bucket_id(0)
                .build()
                .unwrap(),
            make_fake_drip_builder(0)
                .amount(77)
                .bucket_id(0)
                .build()
                .unwrap(),
            make_fake_drip_builder(0)
                .amount(77)
                .bucket_id(0)
                .build()
                .unwrap(),
            make_fake_drip_builder(0)
                .amount(77)
                .bucket_id(0)
                .build()
                .unwrap(),
            make_fake_drip_builder(0)
                .amount(77)
                .bucket_id(0)
                .build()
                .unwrap(),
        ];

        let result = calculate_bucket_balance(
            &bucket,
            &transaction_sums,
            &bucket_transfer_from_sums,
            &bucket_transfer_to_sums,
            &budget_drips,
        );

        let expected_result = 100 + (-91) + 79 + 77 * 5;
        assert!(result.is_ok());
        assert_eq!(result.unwrap(), expected_result);
    }
}