@accounter/server
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Accounter GraphQL server
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text/typescript
import type { EntityBalance, LedgerRecord, ValidationContext } from './types.js';
/**
* Parse a numeric amount from a string, handling null/undefined values
*
* PostgreSQL returns numeric values as strings when queried via pg driver.
* This utility safely converts them to numbers for arithmetic operations.
*
* @param value - The string value to parse (may be null or undefined)
* @returns The parsed number, or 0 if value is null/undefined/invalid
*
* @example
* parseAmount('100.50') // 100.50
* parseAmount(null) // 0
* parseAmount('invalid') // 0
*/
export function parseAmount(value: string | null | undefined): number {
if (value == null) {
return 0;
}
const parsed = parseFloat(value);
if (Number.isNaN(parsed)) {
return 0;
}
return parsed;
}
/**
* Check if two numeric values are balanced within a tolerance
*
* Uses tolerance-based comparison to handle floating-point arithmetic
* imprecision. Two values are considered balanced if their absolute
* difference is less than or equal to the tolerance.
*
* @param a - First value to compare
* @param b - Second value to compare
* @param tolerance - Maximum acceptable difference (default: 0.005)
* @returns True if values are balanced within tolerance, false otherwise
*
* @example
* isBalanced(100, 100) // true
* isBalanced(100, 100.004, 0.005) // true
* isBalanced(100, 102, 0.005) // false
*/
export function isBalanced(a: number, b: number, tolerance = 0.005): boolean {
return Math.abs(a - b) <= tolerance;
}
/**
* Validate per-record internal balance (FR1)
*
* Ensures each ledger record is internally balanced according to double-entry
* bookkeeping principles: total debits must equal total credits within tolerance.
* Also detects empty records where all amounts are zero.
*
* This is a fundamental validation that must pass for every record individually
* before aggregate-level validations can be meaningful.
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID and tolerance
* @returns Array of error messages (empty if all records are valid)
*
* Functional Requirement: FR1 - Per-Record Internal Balance
* - Rule: (debit_local_amount1 + debit_local_amount2) == (credit_local_amount1 + credit_local_amount2)
* - Tolerance: Specified in context (typically ±0.005 for accounting rounding)
* - Also implements FR10: Empty Ledger Detection
*
* @example
* const errors = validateRecordInternalBalance(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or error messages like:
* // ["monthly-expense - Record 0 (uuid-123): internal imbalance (debit=100.00, credit=99.98)"]
*/
export function validateRecordInternalBalance(
records: LedgerRecord[],
context: ValidationContext,
): string[] {
const errors: string[] = [];
records.map((record, index) => {
const totalDebit =
parseAmount(record.debit_local_amount1) + parseAmount(record.debit_local_amount2);
const totalCredit =
parseAmount(record.credit_local_amount1) + parseAmount(record.credit_local_amount2);
// FR10: Empty record detection
if (totalDebit === 0 && totalCredit === 0) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): empty record (all amounts zero)`,
);
return; // Skip balance check for empty records
}
// FR1: Internal balance check
if (!isBalanced(totalDebit, totalCredit, context.tolerance)) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): internal imbalance ` +
`(debit=${totalDebit.toFixed(2)}, credit=${totalCredit.toFixed(2)})`,
);
}
});
return errors;
}
/**
* Validate aggregate balance across all records (FR2)
*
* Validates that the sum of all debits equals the sum of all credits across
* all ledger records for a use-case. This is the second level of validation
* (after per-record balance) and ensures the entire ledger set balances.
*
* This refactors and enhances the existing aggregate balance validation logic
* that was previously only applied to a single use-case. The new implementation
* applies to all use-cases with expectations.
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID and tolerance
* @returns Array of error messages (empty if aggregate is balanced)
*
* Functional Requirement: FR2 - Aggregate Balance Validation
* - Rule: Σ(all debits) == Σ(all credits)
* - Tolerance: Specified in context (typically ±0.005)
* - Enhancement: Now applies to ALL use-cases, not just first one
*
* @example
* const errors = validateAggregateBalance(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or error like:
* // ["monthly-expense: aggregate ledger not balanced (debit 1000.00, credit 999.50)"]
*/
export function validateAggregateBalance(
records: LedgerRecord[],
context: ValidationContext,
): string[] {
const errors: string[] = [];
const totalDebit = records.reduce((sum, rec) => {
return sum + parseAmount(rec.debit_local_amount1) + parseAmount(rec.debit_local_amount2);
}, 0);
const totalCredit = records.reduce((sum, rec) => {
return sum + parseAmount(rec.credit_local_amount1) + parseAmount(rec.credit_local_amount2);
}, 0);
if (!isBalanced(totalDebit, totalCredit, context.tolerance)) {
errors.push(
`${context.useCaseId}: aggregate ledger not balanced ` +
`(debit ${totalDebit.toFixed(2)}, credit ${totalCredit.toFixed(2)})`,
);
}
return errors;
}
/**
* Validate entity-level balance (FR3)
*
* Validates that each financial entity's net position across all ledger records
* balances to zero (or within tolerance). This is the third level of validation
* in the hierarchy:
* 1. Per-record balance (FR1) - each record internally balanced
* 2. Aggregate balance (FR2) - all records collectively balanced
* 3. Entity balance (FR3) - each entity's position balanced across records
*
* In double-entry bookkeeping, every entity that appears in the ledger should
* have a net zero position when considering all transactions. If an entity has
* debits totaling $500 across various records, it should also have credits
* totaling $500 across those same or other records.
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID and tolerance
* @returns Array of error messages (empty if all entities are balanced)
*
* Functional Requirement: FR3 - Entity-Level Balance Validation
* - Rule: For each entity, Σ(debits) - Σ(credits) ≈ 0
* - Tolerance: Specified in context (typically ±0.005)
* - Tracks: debit/credit amounts across all 4 entity fields per record
*
* Implementation:
* - Accumulates debits and credits per entity across all records
* - Calculates net balance (totalDebit - totalCredit) for each entity
* - Validates net balance is within tolerance of zero
*
* @example
* const errors = validateEntityBalance(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or errors like:
* // ["monthly-expense: Entity entity-123 unbalanced (net=50.00, debit=150.00, credit=100.00, records=3)"]
*/
export function validateEntityBalance(
records: LedgerRecord[],
context: ValidationContext,
): string[] {
const errors: string[] = [];
const entityBalances = new Map<string, EntityBalance>();
/**
* Helper function to accumulate entity balance
* Adds debit/credit amounts to an entity's running totals
*/
const addToEntity = (entityId: string | null, debit: number, credit: number) => {
if (!entityId) return;
const current = entityBalances.get(entityId) || {
entityId,
totalDebit: 0,
totalCredit: 0,
netBalance: 0,
recordCount: 0,
};
current.totalDebit += debit;
current.totalCredit += credit;
current.netBalance = current.totalDebit - current.totalCredit;
current.recordCount += 1;
entityBalances.set(entityId, current);
};
// Accumulate balances for all entities across all records
records.map(record => {
addToEntity(record.debit_entity1, parseAmount(record.debit_local_amount1), 0);
addToEntity(record.debit_entity2, parseAmount(record.debit_local_amount2), 0);
addToEntity(record.credit_entity1, 0, parseAmount(record.credit_local_amount1));
addToEntity(record.credit_entity2, 0, parseAmount(record.credit_local_amount2));
});
// Validate each entity balances to zero (within tolerance)
Array.from(entityBalances.values()).map(balance => {
if (!isBalanced(balance.netBalance, 0, context.tolerance)) {
errors.push(
`${context.useCaseId}: Entity ${balance.entityId} unbalanced ` +
`(net=${balance.netBalance.toFixed(2)}, debit=${balance.totalDebit.toFixed(2)}, ` +
`credit=${balance.totalCredit.toFixed(2)}, records=${balance.recordCount})`,
);
}
});
return errors;
}
/**
* Validate ledger record count (FR8)
*
* Validates that the actual number of ledger records matches the expected count
* specified in the use-case expectations. This ensures data completeness and
* detects cases where records may be missing or extra records were created.
*
* This enhances the existing record count validation by applying it to all
* use-cases systematically rather than ad-hoc checks.
*
* @param records - Array of ledger records to validate
* @param expectedCount - Expected number of ledger records for this use-case
* @param context - Validation context containing use-case ID
* @returns Array of error messages (empty if count matches)
*
* Functional Requirement: FR8 - Record Count Validation
* - Rule: Actual record count must match expected count exactly
* - Enhancement: Future support for minimum count validation for cases
* where ledger generation may create additional balancing entries
*
* @example
* const errors = validateRecordCount(records, 24, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if count matches, or error like:
* // ["monthly-expense: ledger record count mismatch (expected 24, got 23)"]
*/
export function validateRecordCount(
records: LedgerRecord[],
expectedCount: number,
context: ValidationContext,
): string[] {
const errors: string[] = [];
if (records.length !== expectedCount) {
errors.push(
`${context.useCaseId}: ledger record count mismatch ` +
`(expected ${expectedCount}, got ${records.length})`,
);
}
return errors;
}
/**
* Validate all amounts are positive (FR5)
*
* Ensures data integrity by validating that all amount fields contain
* non-negative values. Negative amounts are not allowed in the ledger
* system as they violate accounting principles where debits and credits
* must always be positive or zero.
*
* This validation checks all 8 amount fields per record:
* - Local amounts: debit_local_amount1/2, credit_local_amount1/2
* - Foreign amounts: debit_foreign_amount1/2, credit_foreign_amount1/2
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID
* @returns Array of error messages (empty if all amounts are non-negative)
*
* Functional Requirement: FR5 - Positive Amount Validation
* - Checks all amount fields for negative values
* - Reports specific field and value for any negative amounts found
*
* @example
* const errors = validatePositiveAmounts(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or errors like:
* // ["monthly-expense - Record 0 (uuid-123): negative amount in debit_local_amount1 (-100.00)"]
*/
export function validatePositiveAmounts(
records: LedgerRecord[],
context: ValidationContext,
): string[] {
const errors: string[] = [];
const amountFields = [
'debit_local_amount1',
'debit_local_amount2',
'credit_local_amount1',
'credit_local_amount2',
'debit_foreign_amount1',
'debit_foreign_amount2',
'credit_foreign_amount1',
'credit_foreign_amount2',
] as const;
records.map((record, index) => {
amountFields.map(field => {
const value = parseAmount(record[field]);
if (value < 0) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`negative amount in ${field} (${value.toFixed(2)})`,
);
}
});
});
return errors;
}
/**
* Validate dates (FR7)
*
* Ensures all ledger records have valid invoice_date and value_date fields
* within acceptable ranges. Proper date validation is critical for:
* - Financial reporting accuracy
* - Tax compliance and audit trails
* - Chronological transaction ordering
* - Preventing data entry errors
*
* Validation rules:
* - Both invoice_date and value_date must be present (not null)
* - Both dates must be valid Date objects (not NaN)
* - Both dates must fall within the range 2020-01-01 to 2030-12-31
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID
* @returns Array of error messages (empty if all dates are valid)
*
* Functional Requirement: FR7 - Date Validation
* - Checks for missing dates (null values)
* - Checks for invalid dates (parse errors)
* - Checks for dates outside reasonable business range
*
* @example
* const errors = validateDates(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or errors like:
* // ["monthly-expense - Record 0 (uuid-123): missing invoice_date"]
* // ["monthly-expense - Record 1 (uuid-456): invoice_date out of range (1999-01-01T00:00:00.000Z)"]
*/
export function validateDates(records: LedgerRecord[], context: ValidationContext): string[] {
const errors: string[] = [];
const minDate = new Date('2020-01-01');
const maxDate = new Date('2030-12-31');
records.map((record, index) => {
// Check invoice_date
if (record.invoice_date) {
const invoiceDate = new Date(record.invoice_date);
if (Number.isNaN(invoiceDate.getTime())) {
errors.push(`${context.useCaseId} - Record ${index} (${record.id}): invalid invoice_date`);
} else if (invoiceDate < minDate || invoiceDate > maxDate) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`invoice_date out of range (${invoiceDate.toISOString()})`,
);
}
} else {
errors.push(`${context.useCaseId} - Record ${index} (${record.id}): missing invoice_date`);
}
// Check value_date
if (record.value_date) {
const valueDate = new Date(record.value_date);
if (Number.isNaN(valueDate.getTime())) {
errors.push(`${context.useCaseId} - Record ${index} (${record.id}): invalid value_date`);
} else if (valueDate < minDate || valueDate > maxDate) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`value_date out of range (${valueDate.toISOString()})`,
);
}
} else {
errors.push(`${context.useCaseId} - Record ${index} (${record.id}): missing value_date`);
}
});
return errors;
}
/**
* Validate foreign currency handling (FR6)
*
* Ensures proper handling of foreign currency transactions by validating:
* 1. Currency field consistency with foreign amount fields
* 2. Presence of foreign amounts when currency is not the default (ILS)
* 3. Absence of foreign amounts when currency is the default (ILS)
* 4. Reasonableness of implied exchange rates between local and foreign amounts
*
* Foreign currency validation is critical for:
* - Accurate financial reporting in multi-currency environments
* - Compliance with international accounting standards
* - Detection of data entry errors in currency conversion
* - Prevention of fraudulent or suspicious exchange rate manipulation
*
* Exchange rate validation:
* - Implied rate = local_amount / foreign_amount
* - Rate must be between 0.1 and 10.0 to be considered reasonable
* - Rates outside this range likely indicate data entry errors
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID and default currency
* @returns Array of error messages (empty if all currency handling is valid)
*
* Functional Requirement: FR6 - Foreign Currency Validation
* - Validates currency field matches foreign amount presence/absence
* - Checks exchange rate consistency within reasonable bounds
* - Applies to all 4 amount pairs (debit1, debit2, credit1, credit2)
*
* @example
* const errors = validateForeignCurrency(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or errors like:
* // ["monthly-expense - Record 0 (uuid-123): foreign currency (USD) but no foreign amounts"]
* // ["monthly-expense - Record 1 (uuid-456): local currency (ILS) but has foreign amounts"]
* // ["monthly-expense - Record 2 (uuid-789): suspicious exchange rate in debit1 (rate=15.2000)"]
*/
export function validateForeignCurrency(
records: LedgerRecord[],
context: ValidationContext,
): string[] {
const errors: string[] = [];
records.map((record, index) => {
const isForeignCurrency = record.currency !== context.defaultCurrency;
const hasForeignAmounts =
record.debit_foreign_amount1 !== null ||
record.debit_foreign_amount2 !== null ||
record.credit_foreign_amount1 !== null ||
record.credit_foreign_amount2 !== null;
// Validate currency field consistency with foreign amounts
if (isForeignCurrency && !hasForeignAmounts) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`foreign currency (${record.currency}) but no foreign amounts`,
);
}
if (!isForeignCurrency && hasForeignAmounts) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`local currency (${record.currency}) but has foreign amounts`,
);
}
// Validate exchange rate consistency for foreign currency records
if (isForeignCurrency) {
/**
* Helper function to check exchange rate reasonableness
* @param localAmount - Local currency amount (e.g., ILS)
* @param foreignAmount - Foreign currency amount (e.g., USD)
* @param field - Field identifier for error reporting
*/
const checkExchangeRate = (
localAmount: string | null,
foreignAmount: string | null,
field: string,
) => {
// Skip if either amount is null or zero
if (!localAmount || !foreignAmount) return;
const local = parseAmount(localAmount);
const foreign = parseAmount(foreignAmount);
if (foreign === 0) return; // Avoid division by zero
const impliedRate = local / foreign;
// Check if rate is reasonable (between 0.1 and 10.0)
// This catches obvious data entry errors like:
// - Swapped local/foreign amounts (rate would be inverted)
// - Missing decimal points (e.g., 350 instead of 3.50)
// - Completely incorrect amounts
if (impliedRate < 0.1 || impliedRate > 10.0) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`suspicious exchange rate in ${field} (rate=${impliedRate.toFixed(4)})`,
);
}
};
// Check exchange rates for all 4 amount pairs
checkExchangeRate(record.debit_local_amount1, record.debit_foreign_amount1, 'debit1');
checkExchangeRate(record.debit_local_amount2, record.debit_foreign_amount2, 'debit2');
checkExchangeRate(record.credit_local_amount1, record.credit_foreign_amount1, 'credit1');
checkExchangeRate(record.credit_local_amount2, record.credit_foreign_amount2, 'credit2');
}
});
return errors;
}
/**
* Validate no orphaned amounts (FR4)
*
* Ensures data integrity by validating that every non-zero amount field has
* a corresponding entity reference. This prevents "orphaned" amounts that
* cannot be attributed to any financial entity.
*
* An "orphaned amount" is a ledger entry where an amount value exists but
* its corresponding entity field is null. This violates double-entry
* bookkeeping principles where every amount must be associated with an entity.
*
* Rules enforced:
* - Primary fields (entity1): If amount > 0, entity must be present
* - Secondary fields (entity2): If entity is null, amount must also be null
*
* @param records - Array of ledger records to validate
* @param context - Validation context containing use-case ID
* @returns Array of error messages (empty if no orphaned amounts found)
*
* Functional Requirement: FR4 - Orphaned Amount Detection
* - Checks all 4 amount/entity pairs per record
* - Detects amounts without entities
* - Detects secondary fields that should be null
*
* @example
* const errors = validateNoOrphanedAmounts(records, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* // Returns: [] if valid, or errors like:
* // ["monthly-expense - Record 0 (uuid-123): orphaned amount in debit_local_amount1/debit_entity1 (100.00 without entity)"]
*/
export function validateNoOrphanedAmounts(
records: LedgerRecord[],
context: ValidationContext,
): string[] {
const errors: string[] = [];
records.map((record, index) => {
const checks = [
// Debit entity 1 (primary - always required to have entity if amount > 0)
{
amount: parseAmount(record.debit_local_amount1),
entity: record.debit_entity1,
field: 'debit_local_amount1/debit_entity1',
},
// Debit entity 2 (secondary - both should be null or both populated)
{
amount: parseAmount(record.debit_local_amount2),
entity: record.debit_entity2,
field: 'debit_local_amount2/debit_entity2',
},
// Credit entity 1 (primary)
{
amount: parseAmount(record.credit_local_amount1),
entity: record.credit_entity1,
field: 'credit_local_amount1/credit_entity1',
},
// Credit entity 2 (secondary)
{
amount: parseAmount(record.credit_local_amount2),
entity: record.credit_entity2,
field: 'credit_local_amount2/credit_entity2',
},
];
checks.map(({ amount, entity, field }) => {
if (amount > 0 && !entity) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`orphaned amount in ${field} (${amount.toFixed(2)} without entity)`,
);
}
// Secondary fields: if entity is null, amount should also be null
if (
field.includes('2') &&
!entity &&
record[field.split('/')[0] as keyof LedgerRecord] !== null
) {
errors.push(
`${context.useCaseId} - Record ${index} (${record.id}): ` +
`${field} should be null when entity is null`,
);
}
});
});
return errors;
}
/**
* Master validation function - runs all validators (FR1-FR10)
*
* Orchestrates comprehensive ledger validation by executing all individual
* validation functions in a logical sequence. This is the main entry point
* for validating a complete set of ledger records for a use-case.
*
* Validation hierarchy:
* 1. Per-record validation (FR1, FR10) - Each record is internally balanced
* 2. Aggregate validation (FR2) - Total debits equal total credits
* 3. Entity validation (FR3) - Each entity's position balances
* 4. Data integrity (FR4, FR5) - No orphaned amounts, all amounts positive
* 5. Business rules (FR6, FR7) - Foreign currency and date validation
* 6. Structural validation (FR8) - Record count matches expectations
*
* This function implements NFR2 (Error Reporting): Collects ALL errors before
* failing (no fail-fast), allowing comprehensive error discovery in a single run.
*
* @param records - Array of ledger records to validate
* @param expectedRecordCount - Expected number of ledger records for this use-case
* @param context - Validation context containing use-case ID, currency, and tolerance
* @returns Array of all error messages from all validators (empty if fully valid)
*
* Functional Requirements Implemented:
* - FR1: Per-Record Internal Balance
* - FR2: Aggregate Balance Validation
* - FR3: Entity-Level Balance Validation
* - FR4: Orphaned Amount Detection
* - FR5: Positive Amount Validation
* - FR6: Foreign Currency Validation
* - FR7: Date Validation
* - FR8: Record Count Validation
* - FR10: Empty Ledger Detection (within FR1)
*
* @example
* const errors = validateLedgerRecords(records, 24, {
* useCaseId: 'monthly-expense',
* defaultCurrency: 'ILS',
* tolerance: 0.005
* });
* if (errors.length > 0) {
* console.error('Validation failed:', errors);
* } else {
* console.log('All validations passed');
* }
*/
export function validateLedgerRecords(
records: LedgerRecord[],
expectedRecordCount: number,
context: ValidationContext,
): string[] {
const allErrors: string[] = [];
// Run all validators in logical order
// Each validator adds its errors to the aggregate array
allErrors.push(...validateRecordInternalBalance(records, context));
allErrors.push(...validateAggregateBalance(records, context));
allErrors.push(...validateEntityBalance(records, context));
allErrors.push(...validateNoOrphanedAmounts(records, context));
allErrors.push(...validatePositiveAmounts(records, context));
allErrors.push(...validateForeignCurrency(records, context));
allErrors.push(...validateDates(records, context));
allErrors.push(...validateRecordCount(records, expectedRecordCount, context));
return allErrors;
}