skr/ts/skr.types.ts

export type TAccountType =
  | 'asset'
  | 'liability'
  | 'equity'
  | 'revenue'
  | 'expense';

export type TSKRType = 'SKR03' | 'SKR04';

export type TTransactionStatus = 'pending' | 'posted' | 'reversed';

/**
 * DATEV posting keys (Buchungsschlüssel) for German accounting
 * These keys control automatic VAT booking and are checked in tax audits
 */
export type TPostingKey =
  | 3   // Payment with 19% VAT
  | 8   // 7% input VAT
  | 9   // 19% input VAT
  | 19  // 19% input VAT (intra-EU)
  | 40  // Tax-free (disables VAT automatism)
  | 94; // 19% input/output VAT (reverse charge)

export type TReportType =
  | 'trial_balance'
  | 'income_statement'
  | 'balance_sheet'
  | 'general_ledger'
  | 'cash_flow';

/**
 * Posting key validation rule
 */
export interface IPostingKeyRule {
  key: TPostingKey;
  description: string;
  vatRate?: number;              // Expected VAT rate (if applicable)
  requiresVAT: boolean;           // Whether VAT entry is required
  disablesVATAutomatism: boolean; // Whether this key disables automatic VAT
  allowedScenarios?: string[];    // Allowed tax scenarios (e.g., 'reverse_charge')
}

export interface IAccountData {
  accountNumber: string;
  accountName: string;
  accountClass: number;
  accountType: TAccountType;
  skrType: TSKRType;
  description?: string;
  vatRate?: number;
  isActive?: boolean;
  isAutomaticAccount?: boolean; // Automatikkonto (e.g., 1400, 1600) - cannot be posted to directly
}

export interface ITransactionData {
  date: Date;
  debitAccount: string;
  creditAccount: string;
  amount: number;
  description: string;
  reference?: string;
  skrType: TSKRType;
  vatAmount?: number;
  costCenter?: string;
}

export interface IJournalEntry {
  date: Date;
  description: string;
  reference?: string;
  lines: IJournalEntryLine[];
  skrType: TSKRType;
}

export interface IJournalEntryLine {
  accountNumber: string;
  debit?: number;
  credit?: number;
  description?: string;
  costCenter?: string;
  postingKey: TPostingKey; // REQUIRED: DATEV posting key for VAT automation control
}

export interface ITrialBalanceEntry {
  accountNumber: string;
  accountName: string;
  debitBalance: number;
  creditBalance: number;
  netBalance: number;
}

export interface ITrialBalanceReport {
  date: Date;
  skrType: TSKRType;
  entries: ITrialBalanceEntry[];
  totalDebits: number;
  totalCredits: number;
  isBalanced: boolean;
}

export interface IIncomeStatementEntry {
  accountNumber: string;
  accountName: string;
  amount: number;
  percentage?: number;
}

export interface IIncomeStatement {
  date: Date;
  skrType: TSKRType;
  revenue: IIncomeStatementEntry[];
  expenses: IIncomeStatementEntry[];
  totalRevenue: number;
  totalExpenses: number;
  netIncome: number;
}

export interface IBalanceSheetEntry {
  accountNumber: string;
  accountName: string;
  amount: number;
}

export interface IBalanceSheet {
  date: Date;
  skrType: TSKRType;
  assets: {
    current: IBalanceSheetEntry[];
    fixed: IBalanceSheetEntry[];
    totalAssets: number;
  };
  liabilities: {
    current: IBalanceSheetEntry[];
    longTerm: IBalanceSheetEntry[];
    totalLiabilities: number;
  };
  equity: {
    entries: IBalanceSheetEntry[];
    totalEquity: number;
  };
  isBalanced: boolean;
}

export interface IAccountFilter {
  skrType?: TSKRType;
  accountClass?: number;
  accountType?: TAccountType;
  isActive?: boolean;
  searchTerm?: string;
}

export interface ITransactionFilter {
  skrType?: TSKRType;
  dateFrom?: Date;
  dateTo?: Date;
  accountNumber?: string;
  minAmount?: number;
  maxAmount?: number;
  searchTerm?: string;
}

export interface IDatabaseConfig {
  mongoDbUrl: string;
  dbName?: string;
  invoiceExportPath?: string; // Optional path for invoice storage
}

export interface IReportParams {
  dateFrom?: Date;
  dateTo?: Date;
  skrType: TSKRType;
  format?: 'json' | 'csv' | 'datev';
}

export interface IAccountBalance {
  accountNumber: string;
  debitTotal: number;
  creditTotal: number;
  balance: number;
  lastUpdated: Date;
}