transform budget drips

4 files changed, 285 insertions, 13 deletions

diff --git a/rust/schist_actualbudget_importer/Cargo.toml b/rust/schist_actualbudget_importer/Cargo.toml
index 3fa308a..a4bfbd1 100644
--- a/rust/schist_actualbudget_importer/Cargo.toml
+++ b/rust/schist_actualbudget_importer/Cargo.toml
@@ -4,10 +4,13 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+actualbudget_fakes = { path = "../actualbudget_fakes" }
 actualbudget_models = { path = "../actualbudget_models" }
 actualbudget_queries = { path = "../actualbudget_queries" }
 anyhow = { workspace = true }
 diesel = { workspace = true, features = ["sqlite"] }
+itertools = { workspace = true }
 libsqlite3-sys = { workspace = true, features = ["bundled"] }
 schist_models = { path = "../schist_models" }
 schist_queries = { path = "../schist_queries" }
+schist_traits = { path = "../schist_traits" }
diff --git a/rust/schist_actualbudget_importer/src/transform_state/transform_accounts.rs b/rust/schist_actualbudget_importer/src/transform_state/transform_accounts.rs
index c100377..917c62d 100644
--- a/rust/schist_actualbudget_importer/src/transform_state/transform_accounts.rs
+++ b/rust/schist_actualbudget_importer/src/transform_state/transform_accounts.rs
@@ -25,11 +25,3 @@ fn transform_account(
         opening_date: opening_date.clone(),
     }
 }
-
-#[cfg(test)]
-mod test {
-    #[test]
-    fn todo() {
-        todo!()
-    }
-}
diff --git a/rust/schist_actualbudget_importer/src/transform_state/transform_budget_drips.rs b/rust/schist_actualbudget_importer/src/transform_state/transform_budget_drips.rs
index 418c759..2e9125b 100644
--- a/rust/schist_actualbudget_importer/src/transform_state/transform_budget_drips.rs
+++ b/rust/schist_actualbudget_importer/src/transform_state/transform_budget_drips.rs
@@ -1,6 +1,283 @@
-use anyhow::Result;
-use schist_models::budget_drip::BudgetDrip;
+use actualbudget_models::ActualbudgetZeroBudget;
+use anyhow::{Context, Result};
+use itertools::Itertools;
+use schist_models::{budget_drip::BudgetDrip, date_utc::DateUtc};
+use schist_traits::dateable::Dateable;
 
-pub fn transform_budget_drips() -> Result<Vec<BudgetDrip>> {
-    todo!();
+use super::{transform_date::transform_date, transform_id::transform_id};
+
+pub fn transform_budget_drips(actualbudget_zero_budgets: &[ActualbudgetZeroBudget]) -> Result<Vec<BudgetDrip>> {
+    let budget_drips = group_actualbudget_zero_budgets_by_category_id(actualbudget_zero_budgets)
+        .iter()
+        .map(sort_actualbudget_zero_budgets_by_month)
+        .flat_map(|sorted_actualbudget_zero_budgets| sorted_actualbudget_zero_budgets
+            .iter()
+            .map(map_actualbudget_zero_budget_to_budget_drips)
+            .collect::<Result<Vec<Vec<BudgetDrip>>>>()
+        ).flatten()
+        .flatten()
+        .collect();
+    Ok(budget_drips)
+}
+
+fn map_actualbudget_zero_budget_to_budget_drips(
+    actualbudget_zero_budget: &ActualbudgetZeroBudget,
+) -> Result<Vec<BudgetDrip>> {
+    let context = || "failed to map actualbudget zero budgets to budget drips";
+
+    let first_day_of_month: DateUtc = Into::<DateUtc>::into(transform_date(&actualbudget_zero_budget.month).with_context(context)?);
+    let month = first_day_of_month.month();
+    let days_in_month: Vec<DateUtc> = (0..31)
+        .map(|i| first_day_of_month.add_days(i))
+        .take_while(|d| match d {
+            Err(_) => true,
+            Ok(d) => d.month() == month,
+        })
+        .filter(Result::is_ok)
+        .map(Result::unwrap)
+        .collect();
+
+    // unwrap() can panic, but days_in_month is guaranteed to have between 0 and
+    // 31 elements, so we should be grand
+    let num_days_in_month: i32 = days_in_month.len().try_into().unwrap();
+
+    let quantity = actualbudget_zero_budget.amount / num_days_in_month;
+    let remainder_quantity = actualbudget_zero_budget.amount - (quantity * num_days_in_month);
+
+    let budget_drips: Vec<BudgetDrip> = days_in_month.iter().map(|&date|
+        BudgetDrip {
+            id: transform_id(&actualbudget_zero_budget.id),
+            category_id: transform_id(&actualbudget_zero_budget.category_id),
+            date,
+            quantity: if date == first_day_of_month {
+                quantity + remainder_quantity
+            } else {
+                quantity
+            }
+        }
+    ).collect();
+
+    Ok(budget_drips)
+}
+
+fn sort_actualbudget_zero_budgets_by_month(
+    actualbudget_zero_budgets_by_category_id: &Vec<ActualbudgetZeroBudget>,
+) -> Vec<ActualbudgetZeroBudget> {
+    let mut actualbudget_zero_budgets = actualbudget_zero_budgets_by_category_id.clone();
+    actualbudget_zero_budgets.sort_by_key(|zb| zb.month.clone());
+    actualbudget_zero_budgets
+}
+
+fn group_actualbudget_zero_budgets_by_category_id(
+    actualbudget_zero_budgets: &[ActualbudgetZeroBudget],
+) -> Vec<Vec<ActualbudgetZeroBudget>> {
+    let category_ids = actualbudget_zero_budgets
+        .iter()
+        .map(|zb| zb.category_id.clone())
+        .unique();
+
+    category_ids
+        .map(|category_id| actualbudget_zero_budgets
+            .iter()
+            .filter(|zb| zb.category_id == category_id)
+            .map(ActualbudgetZeroBudget::clone)
+            .collect()
+        ).collect()
+}
+
+#[cfg(test)]
+mod test {
+    use actualbudget_fakes::actualbudget_zero_budget::make_fake_actualbudget_zero_budget_builder;
+    use actualbudget_models::ActualbudgetDate;
+    use schist_models::budget_drip::BudgetDrip;
+    use schist_traits::dateable::Dateable;
+
+    use crate::transform_state::transform_id::transform_id;
+
+    use super::transform_budget_drips;
+
+    mod map_actualbudget_zero_budget_to_budget_drips {
+        use actualbudget_fakes::actualbudget_zero_budget::make_fake_actualbudget_zero_budget_builder;
+        use actualbudget_models::ActualbudgetDate;
+        use schist_models::budget_drip::BudgetDrip;
+        use schist_traits::dateable::Dateable;
+
+        use crate::transform_state::transform_budget_drips::map_actualbudget_zero_budget_to_budget_drips;
+
+        #[test]
+        fn when_zero_budget_with_integer_budget_per_day_then_evenly_divided_budget_drips() {
+            let actualbudget_zero_budget = make_fake_actualbudget_zero_budget_builder("0")
+                .amount(31 * 100)
+                .category_id(String::from("0"))
+                .month(ActualbudgetDate::from_i32(202401))
+                .build()
+                .unwrap();
+
+            let result = map_actualbudget_zero_budget_to_budget_drips(&actualbudget_zero_budget);
+
+            assert!(result.is_ok());
+            let mut budget_drips = result.unwrap();
+            assert_eq!(31, budget_drips.len());
+            assert!(budget_drips.iter().all(|bd| bd.quantity == 100));
+            budget_drips.sort_by_key(|bd| bd.date);
+            for i in 1..31 {
+                assert_eq!(Ok(i), budget_drips.get(i - 1).unwrap().date.day().try_into());
+            }
+        }
+
+        #[test]
+        fn when_zero_budget_with_non_integer_budget_per_day_then_remainder_on_one_day() {
+            let actualbudget_zero_budget = make_fake_actualbudget_zero_budget_builder("0")
+                .amount(31 * 100 + 30)
+                .category_id(String::from("0"))
+                .month(ActualbudgetDate::from_i32(202401))
+                .build()
+                .unwrap();
+
+            let result = map_actualbudget_zero_budget_to_budget_drips(&actualbudget_zero_budget);
+
+            assert!(result.is_ok());
+            let budget_drips = result.unwrap();
+            assert_eq!(31, budget_drips.len());
+
+            let budget_drips_quantity_not_floored: Vec<&BudgetDrip> = budget_drips
+                .iter()
+                .filter(|bd| bd.quantity != 100)
+                .collect();
+            assert_eq!(1, budget_drips_quantity_not_floored.len());
+
+            let budget_drips_floored: Vec<&BudgetDrip> = budget_drips
+                .iter()
+                .filter(|bd| bd.quantity == 100)
+                .collect();
+            assert_eq!(30, budget_drips_floored.len());
+        }
+    }
+
+    #[test]
+    fn when_no_zero_budgets_then_no_budget_drips() {
+        let actualbudget_zero_budgets = [];
+        let result = transform_budget_drips(&actualbudget_zero_budgets);
+        assert!(result.is_ok());
+        assert_eq!(result.unwrap().len(), 0);
+    }
+
+    #[test]
+    fn when_one_zero_budget_with_integer_budget_per_day_then_evenly_divided_budget_drips() {
+        let actualbudget_zero_budgets = [
+            make_fake_actualbudget_zero_budget_builder("0")
+                .amount(31 * 100)
+                .category_id(String::from("0"))
+                .month(ActualbudgetDate::from_i32(202401))
+                .build()
+                .unwrap()
+        ];
+
+        let result = transform_budget_drips(&actualbudget_zero_budgets);
+
+        assert!(result.is_ok());
+        let mut budget_drips = result.unwrap();
+        assert_eq!(31, budget_drips.len());
+        assert!(budget_drips.iter().all(|bd| bd.quantity == 100));
+        budget_drips.sort_by_key(|bd| bd.date);
+        for i in 1..31 {
+            assert_eq!(Ok(i), budget_drips.get(i - 1).unwrap().date.day().try_into());
+        }
+    }
+
+    #[test]
+    fn when_one_zero_budgets_with_non_integer_budget_per_day_then_remainder_on_one_day() {
+        let actualbudget_zero_budgets = [
+            make_fake_actualbudget_zero_budget_builder("0")
+                .amount(31 * 100 + 30)
+                .category_id(String::from("0"))
+                .month(ActualbudgetDate::from_i32(202401))
+                .build()
+                .unwrap()
+        ];
+
+        let result = transform_budget_drips(&actualbudget_zero_budgets);
+
+        assert!(result.is_ok());
+        let budget_drips = result.unwrap();
+        assert_eq!(31, budget_drips.len());
+
+        let budget_drips_quantity_not_floored: Vec<&BudgetDrip> = budget_drips
+            .iter()
+            .filter(|bd| bd.quantity != 100)
+            .collect();
+        assert_eq!(1, budget_drips_quantity_not_floored.len());
+
+        let budget_drips_floored: Vec<&BudgetDrip> = budget_drips
+            .iter()
+            .filter(|bd| bd.quantity == 100)
+            .collect();
+        assert_eq!(30, budget_drips_floored.len());
+    }
+
+    #[test]
+    fn when_multiple_zero_budgets_with_integer_budget_per_day_across_multiple_categories_then_evenly_divided_budget_drips() {
+        let actualbudget_zero_budgets = [
+            make_fake_actualbudget_zero_budget_builder("0")
+                .amount(31 * 100)
+                .category_id(String::from("0"))
+                .month(ActualbudgetDate::from_i32(202401))
+                .build()
+                .unwrap(),
+            make_fake_actualbudget_zero_budget_builder("1")
+                .amount(31 * 200)
+                .category_id(String::from("1"))
+                .month(ActualbudgetDate::from_i32(202401))
+                .build()
+                .unwrap(),
+            make_fake_actualbudget_zero_budget_builder("2")
+                .amount(29 * 110)
+                .category_id(String::from("0"))
+                .month(ActualbudgetDate::from_i32(202402))
+                .build()
+                .unwrap(),
+            make_fake_actualbudget_zero_budget_builder("3")
+                .amount(29 * 210)
+                .category_id(String::from("1"))
+                .month(ActualbudgetDate::from_i32(202402))
+                .build()
+                .unwrap(),
+        ];
+
+        let result = transform_budget_drips(&actualbudget_zero_budgets);
+        let category_0_id = transform_id("0");
+        let category_1_id = transform_id("1");
+
+        assert!(result.is_ok());
+        let budget_drips = result.unwrap();
+        assert_eq!(31 + 31 + 29 + 29, budget_drips.len());
+
+        let budget_drips_jan_category_0: Vec<&BudgetDrip> = budget_drips
+            .iter()
+            .filter(|bd| bd.category_id == category_0_id && bd.date.month() == 1)
+            .collect();
+        assert_eq!(31, budget_drips_jan_category_0.len());
+        assert!(budget_drips_jan_category_0.iter().all(|bd| bd.quantity == 100));
+
+        let budget_drips_jan_category_1: Vec<&BudgetDrip> = budget_drips
+            .iter()
+            .filter(|bd| bd.category_id == category_1_id && bd.date.month() == 1)
+            .collect();
+        assert_eq!(31, budget_drips_jan_category_1.len());
+        assert!(budget_drips_jan_category_1.iter().all(|bd| bd.quantity == 200));
+
+        let budget_drips_feb_category_0: Vec<&BudgetDrip> = budget_drips
+            .iter()
+            .filter(|bd| bd.category_id == category_0_id && bd.date.month() == 2)
+            .collect();
+        assert_eq!(29, budget_drips_feb_category_0.len());
+        assert!(budget_drips_feb_category_0.iter().all(|bd| bd.quantity == 110));
+
+        let budget_drips_feb_category_1: Vec<&BudgetDrip> = budget_drips
+            .iter()
+            .filter(|bd| bd.category_id == category_1_id && bd.date.month() == 2)
+            .collect();
+        assert_eq!(29, budget_drips_feb_category_1.len());
+        assert!(budget_drips_feb_category_1.iter().all(|bd| bd.quantity == 210));
+    }
 }
diff --git a/rust/schist_actualbudget_importer/src/transform_state/transform_state.rs b/rust/schist_actualbudget_importer/src/transform_state/transform_state.rs
index d8918bc..2285276 100644
--- a/rust/schist_actualbudget_importer/src/transform_state/transform_state.rs
+++ b/rust/schist_actualbudget_importer/src/transform_state/transform_state.rs
@@ -10,7 +10,7 @@ pub fn transform_state(actualbudget_state: ActualbudgetState) -> Result<SchistSt
         transform_date(&actualbudget_state.actualbudget_first_transaction_date)?;
     let accounts: Vec<Account> =
         transform_accounts(&actualbudget_state.actualbudget_accounts, &first_transaction_date);
-    let budget_drips = transform_budget_drips()?;
+    let budget_drips = transform_budget_drips(&actualbudget_state.actualbudget_zero_budgets)?;
     let categories: Vec<Category> =
         transform_categories(&actualbudget_state.actualbudget_categories);
     let (transactions, transaction_categorisations): (Vec<Transaction>, Vec<TransactionCategorisation>) =