Refactors importer to use core stuff

4 files changed, 364 insertions, 0 deletions

diff --git a/backend/core/src/utils/calculate_budgets_accrual.rs b/backend/core/src/utils/calculate_budgets_accrual.rs
new file mode 100644
index 0000000..bbc197c
--- /dev/null
+++ b/backend/core/src/utils/calculate_budgets_accrual.rs
@@ -0,0 +1,162 @@
+use crate::models::{
+    budget_update::BudgetUpdate,
+    category::Category,
+    date_time_utc::DateTimeUtc
+};
+
+pub fn calculate_budgets_accrual(category: &Category, budget_updates: &[BudgetUpdate]) -> i64 {
+    let mut budget_updates = budget_updates
+        .iter()
+        .filter(|bu| bu.category_id == category.id)
+        .collect::<Vec<&BudgetUpdate>>();
+    budget_updates.sort_by_key(|bu| bu.date);
+    budget_updates.reverse();
+
+    let mut budgets_accrual = 0.0_f64;
+    let mut calculated_back_to_date = DateTimeUtc::now();
+
+    for budget_update in budget_updates {
+        let days_on_this_budget = calculated_back_to_date.day_diff(&budget_update.date);
+        if days_on_this_budget == 0_u32 {
+            continue;
+        }
+        let budget_per_day = budget_update.new_budget as f64 / budget_update.new_period as f64;
+        budgets_accrual += days_on_this_budget as f64 * budget_per_day;
+        calculated_back_to_date = budget_update.date;
+    }
+
+    budgets_accrual.floor() as i64
+}
+
+#[cfg(test)]
+mod test {
+    use chrono::{Days, Timelike, Utc};
+
+    use crate::{
+        models::{budget_update::BudgetUpdate, category::Category, date_time_utc::DateTimeUtc},
+        utils::calculate_budgets_accrual,
+    };
+
+    #[test]
+    fn when_no_budget_updates_then_return_zero() {
+        let category = Category {
+            id: 0,
+            name: String::from("Groceries"),
+        };
+        let budget_updates = [];
+
+        let result = calculate_budgets_accrual(&category, &budget_updates);
+
+        assert_eq!(result, 0_i64);
+    }
+
+    #[test]
+    fn when_one_budget_update_for_another_category_then_return_zero() {
+        let category = Category {
+            id: 0,
+            name: String::from("Groceries"),
+        };
+        let budget_updates = [BudgetUpdate {
+            id: 0,
+            category_id: 1,
+            date: DateTimeUtc::now(),
+            new_budget: 100,
+            new_period: 1,
+        }];
+
+        let result = calculate_budgets_accrual(&category, &budget_updates);
+
+        assert_eq!(result, 0_i64);
+    }
+
+    #[test]
+    fn when_one_budget_update_then_return_quantity_times_days_in_past() {
+        let category = Category {
+            id: 0,
+            name: String::from("Groceries"),
+        };
+        let budget_updates = [BudgetUpdate {
+            id: 0,
+            category_id: 0,
+            date: DateTimeUtc::new(Utc::now().checked_sub_days(Days::new(120)).unwrap()),
+            new_budget: 100,
+            new_period: 1,
+        }];
+
+        let result = calculate_budgets_accrual(&category, &budget_updates);
+
+        assert_eq!(result, 12_000);
+    }
+
+    #[test]
+    fn when_two_budget_updates_then_calculates_as_expected() {
+        let category = Category {
+            id: 0,
+            name: String::from("Groceries"),
+        };
+        let budget_updates = [
+            BudgetUpdate {
+                id: 0,
+                category_id: 0,
+                date: DateTimeUtc::new(Utc::now().checked_sub_days(Days::new(60)).unwrap()),
+                new_budget: 200,
+                new_period: 1,
+            },
+            BudgetUpdate {
+                id: 0,
+                category_id: 0,
+                date: DateTimeUtc::new(Utc::now().checked_sub_days(Days::new(120)).unwrap()),
+                new_budget: 100,
+                new_period: 1,
+            },
+        ];
+
+        let result = calculate_budgets_accrual(&category, &budget_updates);
+
+        assert_eq!(result, 18_000);
+    }
+
+    #[test]
+    fn when_two_budget_updates_on_same_day_then_uses_latest_only() {
+        let category = Category {
+            id: 0,
+            name: String::from("Groceries"),
+        };
+        let budget_updates = [
+            BudgetUpdate {
+                id: 0,
+                category_id: 0,
+                date: DateTimeUtc::new(
+                    Utc::now()
+                        .checked_sub_days(Days::new(120))
+                        .unwrap()
+                        .with_hour(13)
+                        .unwrap(),
+                ),
+                new_budget: 200,
+                new_period: 1,
+            },
+            BudgetUpdate {
+                id: 0,
+                category_id: 0,
+                date: DateTimeUtc::new(
+                    Utc::now()
+                        .checked_sub_days(Days::new(120))
+                        .unwrap()
+                        .with_hour(12)
+                        .unwrap(),
+                ),
+                new_budget: 100,
+                new_period: 1,
+            },
+        ];
+        let mut budget_updates_reversed = budget_updates.clone();
+        budget_updates_reversed.reverse();
+
+        let result_leftways = calculate_budgets_accrual(&category, &budget_updates);
+        let result_rightways = calculate_budgets_accrual(&category, &budget_updates_reversed);
+
+        assert_eq!(result_leftways, 24_000);
+        assert_eq!(result_rightways, 24_000);
+    }
+}
diff --git a/backend/core/src/utils/calculate_category_balance.rs b/backend/core/src/utils/calculate_category_balance.rs
new file mode 100644
index 0000000..5eca05b
--- /dev/null
+++ b/backend/core/src/utils/calculate_category_balance.rs
@@ -0,0 +1,142 @@
+use crate::{
+    models::{budget_update::BudgetUpdate, category::Category},
+    utils::{calculate_budgets_accrual, find_by_id_or},
+};
+
+pub fn calculate_category_balance(
+    category: &Category,
+    transaction_sums: &[(i32, Option<i64>)],
+    category_transfer_from_sums: &[(i32, Option<i64>)],
+    category_transfer_to_sums: &[(i32, Option<i64>)],
+    budget_updates: &[BudgetUpdate],
+) -> 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_updates);
+
+    transaction_sum + budget_accruals_sum + category_transfer_to_sum - category_transfer_from_sum
+}
+
+#[cfg(test)]
+mod test {
+    use chrono::{Days, Utc};
+
+    use crate::{
+        models::{budget_update::BudgetUpdate, category::Category, date_time_utc::DateTimeUtc},
+        utils::calculate_category_balance
+    };
+
+    #[test]
+    fn when_no_data_then_returns_zero() {
+        let category = Category {
+            id: 0,
+            name: String::new(),
+        };
+
+        let result = calculate_category_balance(&category, &[], &[], &[], &[]);
+
+        assert_eq!(result, 0_i64);
+    }
+
+    #[test]
+    fn when_data_only_for_another_category_then_returns_zero() {
+        let category = Category {
+            id: 0,
+            name: String::new(),
+        };
+        let transaction_sums = [(1, Some(100))];
+        let category_transfer_from_sums = [(1, Some(91))];
+        let category_transfer_to_sums = [(2, Some(79))];
+        let budget_updates = [BudgetUpdate {
+            id: 0,
+            category_id: 1,
+            date: DateTimeUtc::new(Utc::now().checked_sub_days(Days::new(120)).unwrap()),
+            new_budget: 77,
+            new_period: 1,
+        }];
+
+        let result = calculate_category_balance(
+            &category,
+            &transaction_sums,
+            &category_transfer_from_sums,
+            &category_transfer_to_sums,
+            &budget_updates,
+        );
+
+        assert_eq!(result, 0_i64);
+    }
+
+    #[test]
+    fn when_transaction_sum_is_none_then_returns_zero() {
+        let category = Category {
+            id: 0,
+            name: String::new(),
+        };
+        let transaction_sums = [(0, None)];
+        let category_transfer_from_sums = [];
+        let category_transfer_to_sums = [];
+        let budget_updates = [];
+
+        let result = calculate_category_balance(
+            &category,
+            &transaction_sums,
+            &category_transfer_from_sums,
+            &category_transfer_to_sums,
+            &budget_updates,
+        );
+
+        assert_eq!(result, 0_i64);
+    }
+
+    #[test]
+    fn when_category_transfers_are_none_then_returns_zero() {
+        let category = Category {
+            id: 0,
+            name: String::new(),
+        };
+        let transaction_sums = [];
+        let category_transfer_from_sums = [(0, None)];
+        let category_transfer_to_sums = [(0, None)];
+        let budget_updates = [];
+
+        let result = calculate_category_balance(
+            &category,
+            &transaction_sums,
+            &category_transfer_from_sums,
+            &category_transfer_to_sums,
+            &budget_updates,
+        );
+
+        assert_eq!(result, 0_i64);
+    }
+
+    #[test]
+    fn when_some_data_then_calculates_as_expected() {
+        let category = Category {
+            id: 0,
+            name: String::new(),
+        };
+        let transaction_sums = [(0, Some(100))];
+        let category_transfer_from_sums = [(0, Some(91))];
+        let category_transfer_to_sums = [(0, Some(79))];
+        let budget_updates = [BudgetUpdate {
+            id: 0,
+            category_id: 0,
+            date: DateTimeUtc::new(Utc::now().checked_sub_days(Days::new(120)).unwrap()),
+            new_budget: 77,
+            new_period: 1,
+        }];
+
+        let result = calculate_category_balance(
+            &category,
+            &transaction_sums,
+            &category_transfer_from_sums,
+            &category_transfer_to_sums,
+            &budget_updates,
+        );
+
+        let expected_result = 100 + (-91) + 79 + 77 * 120;
+        assert_eq!(result, expected_result);
+    }
+}
diff --git a/backend/core/src/utils/find_by_id_or.rs b/backend/core/src/utils/find_by_id_or.rs
new file mode 100644
index 0000000..f5add30
--- /dev/null
+++ b/backend/core/src/utils/find_by_id_or.rs
@@ -0,0 +1,53 @@
+pub fn find_by_id_or<Id: PartialEq, Val: Copy>(
+    arr: &[(Id, Option<Val>)],
+    id: Id,
+    default: Val,
+) -> Val {
+    arr.iter()
+        .find(|(elem_id, _)| *elem_id == id)
+        .map_or(default, |row| match row {
+            (_, Some(quantity)) => *quantity,
+            (_, _) => default,
+        })
+}
+
+#[cfg(test)]
+mod test {
+    use super::find_by_id_or;
+
+    #[test]
+    fn when_no_elements_then_return_default() {
+        let arr = [];
+
+        let result = find_by_id_or(&arr, 1, 42);
+
+        assert_eq!(result, 42);
+    }
+
+    #[test]
+    fn when_id_not_in_elements_then_return_default() {
+        let arr = [(0, Some(100)), (2, Some(200))];
+
+        let result = find_by_id_or(&arr, 1, 42);
+
+        assert_eq!(result, 42);
+    }
+
+    #[test]
+    fn when_value_is_none_then_return_default() {
+        let arr = [(1, None)];
+
+        let result = find_by_id_or(&arr, 1, 42);
+
+        assert_eq!(result, 42);
+    }
+
+    #[test]
+    fn when_value_is_some_then_return_value() {
+        let arr = [(1, Some(67))];
+
+        let result = find_by_id_or(&arr, 1, 42);
+
+        assert_eq!(result, 67);
+    }
+}
diff --git a/backend/core/src/utils/mod.rs b/backend/core/src/utils/mod.rs
new file mode 100644
index 0000000..84a27af
--- /dev/null
+++ b/backend/core/src/utils/mod.rs
@@ -0,0 +1,7 @@
+mod calculate_budgets_accrual;
+mod calculate_category_balance;
+mod find_by_id_or;
+
+pub use calculate_budgets_accrual::calculate_budgets_accrual;
+pub use calculate_category_balance::calculate_category_balance;
+pub use find_by_id_or::find_by_id_or;