castle/docs/PHASE3_COMPLETE.md
2025-11-04 01:19:30 +01:00

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# Phase 3: Core Logic Refactoring - COMPLETE ✅
## Summary
Phase 3 of the Beancount-inspired refactor focused on **separating business logic from database operations** and creating a clean, testable core module. This phase improves code quality, maintainability, and follows best practices from Beancount's architecture.
## Completed Features
### 1. Core Module Structure ✅
**Purpose**: Separate pure accounting logic from database and API concerns
**Implementation** (`core/__init__.py`):
- Created `core/` module package
- Exports main classes and functions
- Clean separation of concerns
**Benefits**:
- Testable without database
- Reusable across different storage backends
- Easier to audit and verify
- Clear architecture
### 2. CastleInventory for Position Tracking ✅
**Purpose**: Track balances across multiple currencies with cost basis information (following Beancount's Inventory pattern)
**Implementation** (`core/inventory.py`):
**CastlePosition** (Lines 11-84):
- Immutable dataclass representing a single position
- Tracks currency, amount, cost basis, and metadata
- Supports addition and negation operations
- Automatic Decimal conversion in `__post_init__`
```python
@dataclass(frozen=True)
class CastlePosition:
currency: str # "SATS", "EUR", "USD"
amount: Decimal
cost_currency: Optional[str] = None
cost_amount: Optional[Decimal] = None
date: Optional[datetime] = None
metadata: Dict[str, Any] = field(default_factory=dict)
```
**CastleInventory** (Lines 87-201):
- Container for multiple positions
- Positions keyed by `(currency, cost_currency)` tuple
- Methods for querying balances:
- `get_balance_sats()` - Total satoshis
- `get_balance_fiat(currency)` - Fiat balance for specific currency
- `get_all_fiat_balances()` - All fiat balances
- Utility methods:
- `is_empty()` - Check if no positions
- `is_zero()` - Check if all positions sum to zero
- `to_dict()` - Export to dictionary
### 3. BalanceCalculator ✅
**Purpose**: Pure logic for calculating balances from journal entries
**Implementation** (`core/balance.py`):
**AccountType Enum** (Lines 13-19):
```python
class AccountType(str, Enum):
ASSET = "asset"
LIABILITY = "liability"
EQUITY = "equity"
REVENUE = "revenue"
EXPENSE = "expense"
```
**BalanceCalculator Class** (Lines 22-217):
**Static Methods**:
1. **`calculate_account_balance()`** (Lines 29-54):
- Calculate balance based on account type
- Normal balances:
- Assets/Expenses: Debit balance (debit - credit)
- Liabilities/Equity/Revenue: Credit balance (credit - debit)
2. **`build_inventory_from_entry_lines()`** (Lines 56-117):
- Build CastleInventory from journal entry lines
- Handles both sats and fiat currency tracking
- Accounts for account type when determining sign
3. **`calculate_user_balance()`** (Lines 119-168):
- Calculate user's total balance across all accounts
- Returns both sats balance and fiat balances by currency
- Properly handles asset (receivable) vs liability (payable) accounts
4. **`check_balance_matches()`** (Lines 170-187):
- Verify balance assertion for sats
5. **`check_fiat_balance_matches()`** (Lines 189-202):
- Verify balance assertion for fiat currency
### 4. Comprehensive Validation ✅
**Purpose**: Validation rules for accounting operations
**Implementation** (`core/validation.py`):
**ValidationError Exception** (Lines 10-18):
- Custom exception for validation failures
- Includes detailed error information
**Validation Functions**:
1. **`validate_journal_entry()`** (Lines 21-124):
- Checks:
- At least 2 lines (double-entry requirement)
- Entry is balanced (debits = credits)
- Valid amounts (non-negative)
- No line has both debit and credit
- All lines have account_id
2. **`validate_balance()`** (Lines 127-177):
- Validates balance assertions
- Checks both sats and fiat within tolerance
3. **`validate_receivable_entry()`** (Lines 180-199):
- Validates receivable (user owes castle) entries
- Ensures positive amount
- Ensures revenue account type
4. **`validate_expense_entry()`** (Lines 202-227):
- Validates expense entries
- Ensures positive amount
- Checks account type (expense or equity)
5. **`validate_payment_entry()`** (Lines 230-245):
- Validates payment entries
- Ensures positive amount
6. **`validate_metadata()`** (Lines 248-284):
- Validates entry line metadata
- Checks for required keys
- Validates fiat currency/amount consistency
- Validates Decimal conversion
### 5. Refactored CRUD Operations ✅
**Purpose**: Use core logic in database operations
**Modified Files**: `crud.py`
**Changes**:
1. **Imports** (Lines 26-36):
- Import core accounting logic
- Import validation functions
2. **`get_account_balance()`** (Lines 347-377):
- Refactored to use `BalanceCalculator.calculate_account_balance()`
- Removed duplicate logic
3. **`get_user_balance()`** (Lines 380-435):
- Completely refactored to use:
- `BalanceCalculator.build_inventory_from_entry_lines()`
- `BalanceCalculator.calculate_user_balance()`
- Cleaner separation of database queries vs business logic
4. **`get_all_user_balances()`** (Lines 438-459):
- Simplified to call `get_user_balance()` for each user
- Eliminates code duplication
## Architecture
### Before Phase 3
```
views_api.py → crud.py (mixed DB + logic)
database
```
All accounting logic was embedded in crud.py alongside database operations.
### After Phase 3
```
views_api.py → crud.py → core/
↓ ↓
database Pure Logic
(testable)
```
**Separation of Concerns**:
- `core/` - Pure accounting logic (no DB dependencies)
- `crud.py` - Database operations + orchestration
- `views_api.py` - HTTP API layer
## Benefits
### Code Quality
-**Testability**: Core logic can be tested without database
-**Maintainability**: Clear separation makes code easier to understand
-**Reusability**: Core logic can be used in different contexts
-**Consistency**: Centralized accounting rules
### Developer Experience
-**Type Safety**: Immutable dataclasses with proper types
-**Documentation**: Well-documented core functions
-**Debugging**: Easier to trace accounting logic
-**Refactoring**: Safer to make changes
### Reliability
-**Validation**: Comprehensive validation rules
-**Correctness**: Pure functions easier to verify
-**Auditability**: Clear accounting rules
## File Structure
```
lnbits/extensions/castle/
├── core/
│ ├── __init__.py # Module exports
│ ├── inventory.py # CastleInventory, CastlePosition
│ ├── balance.py # BalanceCalculator
│ └── validation.py # Validation functions
├── crud.py # DB operations (refactored to use core/)
├── models.py # Pydantic models
├── views_api.py # API endpoints
└── PHASE3_COMPLETE.md # This file
```
## Usage Examples
### Using CastleInventory
```python
from decimal import Decimal
from castle.core.inventory import CastleInventory, CastlePosition
# Create inventory
inv = CastleInventory()
# Add positions
inv.add_position(CastlePosition(
currency="SATS",
amount=Decimal("100000")
))
inv.add_position(CastlePosition(
currency="SATS",
amount=Decimal("50000"),
cost_currency="EUR",
cost_amount=Decimal("25.00")
))
# Query balances
total_sats = inv.get_balance_sats() # Decimal("150000")
eur_balance = inv.get_balance_fiat("EUR") # Decimal("25.00")
# Export
data = inv.to_dict()
# {"sats": 150000, "fiat": {"EUR": 25.00}}
```
### Using BalanceCalculator
```python
from castle.core.balance import BalanceCalculator, AccountType
# Calculate account balance
balance = BalanceCalculator.calculate_account_balance(
total_debit=100000,
total_credit=50000,
account_type=AccountType.ASSET
)
# Returns: 50000 (debit balance for asset)
# Build inventory from entry lines
entry_lines = [
{"debit": 100000, "credit": 0, "metadata": '{"fiat_currency": "EUR", "fiat_amount": "50.00"}'},
{"debit": 0, "credit": 50000, "metadata": "{}"}
]
inventory = BalanceCalculator.build_inventory_from_entry_lines(
entry_lines,
AccountType.ASSET
)
# Check balance matches
is_valid = BalanceCalculator.check_balance_matches(
actual_balance_sats=100000,
expected_balance_sats=99900,
tolerance_sats=100
)
# Returns: True (within tolerance)
```
### Using Validation
```python
from castle.core.validation import validate_journal_entry, ValidationError
entry = {
"id": "abc123",
"description": "Test entry",
"entry_date": datetime.now()
}
entry_lines = [
{"account_id": "acc1", "debit": 100000, "credit": 0},
{"account_id": "acc2", "debit": 0, "credit": 100000}
]
try:
validate_journal_entry(entry, entry_lines)
print("Valid!")
except ValidationError as e:
print(f"Invalid: {e.message}")
print(f"Details: {e.details}")
```
## Testing Checklist
- [x] CastleInventory created and tested
- [x] CastlePosition addition works
- [x] Inventory balance calculations work
- [x] BalanceCalculator account balance calculation works
- [x] BalanceCalculator inventory building works
- [x] BalanceCalculator user balance calculation works
- [x] Validation functions work
- [x] crud.py refactored to use core logic
- [x] Existing balance calculations still work
- [ ] Unit tests for core module (future work)
## Next Steps
**Phase 4: Validation Plugins** (Medium Priority)
- Create plugin system architecture
- Implement `check_balanced` plugin
- Implement `check_receivables` plugin
- Add plugin configuration UI
**Future Enhancements**:
- Add unit tests for core/ module
- Add integration tests
- Add lot tracking to inventory
- Support multi-currency in single entry
- Add more validation plugins
## Conclusion
Phase 3 successfully refactors Castle's accounting logic into a clean, testable core module. By following Beancount's architecture patterns, we've created:
- **Pure accounting logic** separated from database concerns
- **CastleInventory** for position tracking across currencies
- **BalanceCalculator** for consistent balance calculations
- **Comprehensive validation** for data integrity
The refactoring improves code quality, maintainability, and sets the foundation for Phase 4's plugin system.
**Phase 3 Status**: ✅ COMPLETE
---
*Generated: 2025-10-23*
*Next: Phase 4 - Validation Plugins*