use anyhow::Result;
use schist_models::{budget_drip::BudgetDrip, category::Category};

use super::{calculate_budgets_accrual, find_by_id_or};

pub fn calculate_category_balance(
    category: &Category,
    transaction_sums: &[(i32, i64)],
    category_transfer_from_sums: &[(i32, i64)],
    category_transfer_to_sums: &[(i32, i64)],
    budget_drips: &[BudgetDrip],
) -> Result<i64> {
    let transaction_sum = find_by_id_or(transaction_sums, category.id, 0);
    let category_transfer_from_sum = find_by_id_or(category_transfer_from_sums, category.id, 0);
    let category_transfer_to_sum = find_by_id_or(category_transfer_to_sums, category.id, 0);
    let budget_accruals_sum = calculate_budgets_accrual(category, budget_drips)?;

    Ok(
        transaction_sum
            + budget_accruals_sum
            + category_transfer_to_sum
            - category_transfer_from_sum
    )
}

#[cfg(test)]
mod test {
    use schist_fakes::{budget_drip::make_fake_budget_drip_builder, category::make_fake_category};

    use super::calculate_category_balance;

    #[test]
    fn when_no_data_then_returns_zero() {
        let category = make_fake_category(0);

        let result = calculate_category_balance(&category, &[], &[], &[], &[]);

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

    #[test]
    fn when_data_only_for_another_category_then_returns_zero() {
        let category = make_fake_category(0);
        let transaction_sums = [(1, 100)];
        let category_transfer_from_sums = [(1, 91)];
        let category_transfer_to_sums = [(2, 79)];
        let budget_drips = [
            make_fake_budget_drip_builder(0).quantity(100).category_id(1).build().unwrap(),
        ];

        let result = calculate_category_balance(
            &category,
            &transaction_sums,
            &category_transfer_from_sums,
            &category_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 category = make_fake_category(0);
        let transaction_sums = [(0, 0)];
        let category_transfer_from_sums = [];
        let category_transfer_to_sums = [];
        let budget_drips = [];

        let result = calculate_category_balance(
            &category,
            &transaction_sums,
            &category_transfer_from_sums,
            &category_transfer_to_sums,
            &budget_drips,
        );

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

    #[test]
    fn when_category_transfers_are_zero_then_returns_zero() {
        let category = make_fake_category(0);
        let transaction_sums = [];
        let category_transfer_from_sums = [(0, 0)];
        let category_transfer_to_sums = [(0, 0)];
        let budget_drips = [];

        let result = calculate_category_balance(
            &category,
            &transaction_sums,
            &category_transfer_from_sums,
            &category_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 category = make_fake_category(0);
        let transaction_sums = [(0, 100)];
        let category_transfer_from_sums = [(0, 91)];
        let category_transfer_to_sums = [(0, 79)];
        let budget_drips = [
            make_fake_budget_drip_builder(0).quantity(77).category_id(0).build().unwrap(),
            make_fake_budget_drip_builder(0).quantity(77).category_id(0).build().unwrap(),
            make_fake_budget_drip_builder(0).quantity(77).category_id(0).build().unwrap(),
            make_fake_budget_drip_builder(0).quantity(77).category_id(0).build().unwrap(),
            make_fake_budget_drip_builder(0).quantity(77).category_id(0).build().unwrap(),
        ];

        let result = calculate_category_balance(
            &category,
            &transaction_sums,
            &category_transfer_from_sums,
            &category_transfer_to_sums,
            &budget_drips,
        );

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