ledgerr/docs/01-data-model.md

# 01 — Data Model

Models are scoped to their feature under `dev.achmad.ledgerr.domain.<feature>.model`. No shared/common package — features import from each other's model package where needed.

---

## Feature: expense

```kotlin
// DateRange.kt
data class DateRange(
    val start: LocalDate,
    val end: LocalDate
) {
    companion object {
        fun thisMonth(): DateRange {
            val now = LocalDate.now()
            return DateRange(now.withDayOfMonth(1), now.withDayOfMonth(now.lengthOfMonth()))
        }
        fun thisWeek(): DateRange {
            val now = LocalDate.now()
            return DateRange(now.with(DayOfWeek.MONDAY), now.with(DayOfWeek.SUNDAY))
        }
    }
}

// Expense.kt
data class Expense(
    val id: Long = 0,
    val amount: Double,               // always positive; represents outflow
    val categoryId: Long,
    val date: LocalDate,
    val note: String? = null,
    val recurringExpenseId: Long? = null, // set if auto-generated from a RecurringExpense
    val createdAt: Long = System.currentTimeMillis()
)

// ExpenseWithCategory.kt
data class ExpenseWithCategory(
    val expense: Expense,
    val category: Category            // imported from domain.category.model
)

// ExpenseSummary.kt
data class ExpenseSummary(
    val totalAmount: Double,
    val byCategory: List<Pair<Category, Double>>, // sorted by amount DESC
    val period: DateRange
)
```

---

## Feature: category

```kotlin
// Category.kt
data class Category(
    val id: Long = 0,
    val name: String,
    val color: Int,               // ARGB
    val iconName: String? = null, // Material icon name
    val isDefault: Boolean = false // non-deletable; "Other" is always true
)
```

Default categories seeded on first install:

| Name | color (ARGB hex) | isDefault |
|------|------------------|-----------|
| Food & Drink | `0xFFFF9800` (orange) | false |
| Transport | `0xFF2196F3` (blue) | false |
| Housing | `0xFF795548` (brown) | false |
| Health | `0xFFF44336` (red) | false |
| Entertainment | `0xFF9C27B0` (purple) | false |
| Shopping | `0xFFE91E63` (pink) | false |
| Education | `0xFF4CAF50` (green) | false |
| Other | `0xFF9E9E9E` (grey) | **true** |

`Other` is the permanent fallback when a user-defined category is deleted.

---

## Feature: recurring

```kotlin
// RecurringInterval.kt
enum class RecurringInterval {
    DAILY, WEEKLY, MONTHLY, YEARLY;

    fun advance(from: LocalDate): LocalDate = when (this) {
        DAILY   -> from.plusDays(1)
        WEEKLY  -> from.plusWeeks(1)
        MONTHLY -> from.plusMonths(1)
        YEARLY  -> from.plusYears(1)
    }
}

// RecurringExpense.kt
data class RecurringExpense(
    val id: Long = 0,
    val amount: Double,
    val categoryId: Long,
    val note: String? = null,
    val interval: RecurringInterval,
    val startDate: LocalDate,
    val nextDueDate: LocalDate, // initialized = startDate; advances after each processing
    val isActive: Boolean = true
)

// RecurringExpenseWithCategory.kt
data class RecurringExpenseWithCategory(
    val recurring: RecurringExpense,
    val category: Category
)
```

---

## Feature: bankstatement

Each bank has its own raw model representing a single parsed row from the bank's PDF format. These exist so bank-specific parsing logic produces typed data before converting to the common `PendingImportExpense`.

```kotlin
// PendingImportExpense.kt — common output for the review screen
data class PendingImportExpense(
    val amount: Double,
    val date: LocalDate,
    val description: String,          // raw text from PDF
    val suggestedCategoryId: Long? = null,
    val isSelected: Boolean = true    // user can deselect before committing
)

// BRIStatementEntry.kt
data class BRIStatementEntry(
    val date: String,       // raw string as it appears in PDF
    val description: String,
    val debit: String?,     // raw amount string, null if not a debit
    val credit: String?,
    val balance: String?
)

// JagoStatementEntry.kt
data class JagoStatementEntry(
    val date: String,
    val description: String,
    val amount: String,
    val type: String        // e.g. "DEBIT" / "KREDIT"
)

// BNIStatementEntry.kt
data class BNIStatementEntry(
    val date: String,
    val description: String,
    val debit: String?,
    val credit: String?,
    val balance: String?
)
```

---

## Feature: export

No domain models — uses `Expense`, `ExpenseWithCategory`, and `DateRange` from the expense feature.

---

## Room Entities (data layer only)

Live in `data/local/entity/`. Mirror domain models with Room annotations; dates stored as `Long` (epoch day via `LocalDateConverter`).

- `CategoryEntity`
- `ExpenseEntity`
- `RecurringExpenseEntity`