calculation/ts/calculation.classes.currency.ts

import * as plugins from './calculation.plugins.js';
import { Calculator } from './calculation.classes.calculator.js';

export interface ICurrencyOptions {
  code: string;
  symbol?: string;
  decimals?: number;
  thousandsSeparator?: string;
  decimalSeparator?: string;
  symbolPosition?: 'before' | 'after';
  spaceBetweenSymbolAndValue?: boolean;
}

export interface IExchangeRate {
  from: string;
  to: string;
  rate: plugins.Decimal.Value;
  timestamp?: Date;
}

export interface IMoneyValue {
  amount: plugins.Decimal;
  currency: string;
}

/**
 * Currency calculations and formatting class
 */
export class Currency extends Calculator {
  private currencies: Map<string, ICurrencyOptions> = new Map();
  private exchangeRates: Map<string, plugins.Decimal> = new Map();

  constructor() {
    super({ precision: 10 });
    this.initializeCommonCurrencies();
  }

  /**
   * Initialize common currencies with their default options
   */
  private initializeCommonCurrencies(): void {
    const commonCurrencies: ICurrencyOptions[] = [
      { code: 'USD', symbol: '$', decimals: 2, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'EUR', symbol: '€', decimals: 2, thousandsSeparator: '.', decimalSeparator: ',', symbolPosition: 'before' },
      { code: 'GBP', symbol: '£', decimals: 2, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'JPY', symbol: '¥', decimals: 0, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'CHF', symbol: 'Fr.', decimals: 2, thousandsSeparator: "'", decimalSeparator: '.', symbolPosition: 'after', spaceBetweenSymbolAndValue: true },
      { code: 'CAD', symbol: 'C$', decimals: 2, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'AUD', symbol: 'A$', decimals: 2, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'CNY', symbol: '¥', decimals: 2, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'INR', symbol: '₹', decimals: 2, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' },
      { code: 'BTC', symbol: '₿', decimals: 8, thousandsSeparator: ',', decimalSeparator: '.', symbolPosition: 'before' }
    ];

    commonCurrencies.forEach(currency => {
      this.currencies.set(currency.code, currency);
    });
  }

  /**
   * Register a new currency or update existing one
   */
  public registerCurrency(options: ICurrencyOptions): void {
    this.currencies.set(options.code, {
      ...options,
      decimals: options.decimals ?? 2,
      thousandsSeparator: options.thousandsSeparator ?? ',',
      decimalSeparator: options.decimalSeparator ?? '.',
      symbolPosition: options.symbolPosition ?? 'before',
      spaceBetweenSymbolAndValue: options.spaceBetweenSymbolAndValue ?? false
    });
  }

  /**
   * Set exchange rate between two currencies
   * @param from Source currency code
   * @param to Target currency code
   * @param rate Exchange rate (how many 'to' units per 'from' unit)
   */
  public setExchangeRate(from: string, to: string, rate: plugins.Decimal.Value): void {
    const key = `${from}_${to}`;
    this.exchangeRates.set(key, this.decimal(rate));
    
    // Also set the inverse rate
    const inverseKey = `${to}_${from}`;
    const inverseRate = this.divide(1, rate);
    this.exchangeRates.set(inverseKey, inverseRate);
  }

  /**
   * Set multiple exchange rates at once
   */
  public setExchangeRates(rates: IExchangeRate[]): void {
    rates.forEach(rate => {
      this.setExchangeRate(rate.from, rate.to, rate.rate);
    });
  }

  /**
   * Convert amount from one currency to another
   * @param amount The amount to convert
   * @param from Source currency code
   * @param to Target currency code
   */
  public convert(
    amount: plugins.Decimal.Value,
    from: string,
    to: string
  ): plugins.Decimal {
    if (from === to) {
      return this.decimal(amount);
    }

    const key = `${from}_${to}`;
    const rate = this.exchangeRates.get(key);

    if (!rate) {
      throw new Error(`Exchange rate not found for ${from} to ${to}`);
    }

    return this.multiply(amount, rate);
  }

  /**
   * Create a money value object
   */
  public money(amount: plugins.Decimal.Value, currency: string): IMoneyValue {
    return {
      amount: this.decimal(amount),
      currency
    };
  }

  /**
   * Add two money values (must be same currency)
   */
  public addMoney(money1: IMoneyValue, money2: IMoneyValue): IMoneyValue {
    if (money1.currency !== money2.currency) {
      throw new Error('Cannot add money values with different currencies');
    }

    return {
      amount: this.add(money1.amount, money2.amount),
      currency: money1.currency
    };
  }

  /**
   * Subtract two money values (must be same currency)
   */
  public subtractMoney(money1: IMoneyValue, money2: IMoneyValue): IMoneyValue {
    if (money1.currency !== money2.currency) {
      throw new Error('Cannot subtract money values with different currencies');
    }

    return {
      amount: this.subtract(money1.amount, money2.amount),
      currency: money1.currency
    };
  }

  /**
   * Format currency value for display
   * @param amount The amount to format
   * @param currencyCode The currency code
   * @param options Override formatting options
   */
  public format(
    amount: plugins.Decimal.Value,
    currencyCode: string,
    options?: Partial<ICurrencyOptions>
  ): string {
    const currency = this.currencies.get(currencyCode);
    
    if (!currency) {
      throw new Error(`Currency ${currencyCode} not registered`);
    }

    const formatOptions = { ...currency, ...options };
    const value = this.decimal(amount);
    
    // Round to the correct number of decimal places
    const rounded = this.round(value, formatOptions.decimals || 0);
    
    // Convert to string with fixed decimals
    let numberStr = this.toFixed(rounded, formatOptions.decimals || 0);
    
    // Split into integer and decimal parts
    const parts = numberStr.split('.');
    
    // Apply thousands separator to integer part
    if (formatOptions.thousandsSeparator) {
      parts[0] = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, formatOptions.thousandsSeparator);
    }
    
    // Join parts with appropriate decimal separator
    if (parts.length === 2) {
      numberStr = parts.join(formatOptions.decimalSeparator || '.');
    } else {
      numberStr = parts[0];
    }
    
    // Add currency symbol
    if (formatOptions.symbol) {
      const space = formatOptions.spaceBetweenSymbolAndValue ? ' ' : '';
      
      if (formatOptions.symbolPosition === 'after') {
        return `${numberStr}${space}${formatOptions.symbol}`;
      } else {
        return `${formatOptions.symbol}${space}${numberStr}`;
      }
    }
    
    return numberStr;
  }

  /**
   * Parse a formatted currency string back to a decimal value
   * @param formattedValue The formatted string
   * @param currencyCode The currency code
   */
  public parse(formattedValue: string, currencyCode: string): plugins.Decimal {
    const currency = this.currencies.get(currencyCode);
    
    if (!currency) {
      throw new Error(`Currency ${currencyCode} not registered`);
    }
    
    // Remove currency symbol
    let cleanValue = formattedValue;
    if (currency.symbol) {
      cleanValue = cleanValue.replace(currency.symbol, '');
    }
    
    // Remove thousands separator
    if (currency.thousandsSeparator) {
      cleanValue = cleanValue.replace(new RegExp(`\\${currency.thousandsSeparator}`, 'g'), '');
    }
    
    // Replace decimal separator with standard dot
    if (currency.decimalSeparator && currency.decimalSeparator !== '.') {
      cleanValue = cleanValue.replace(currency.decimalSeparator, '.');
    }
    
    // Remove any remaining spaces and parse
    cleanValue = cleanValue.trim();
    
    return this.decimal(cleanValue);
  }

  /**
   * Round amount to currency's standard decimal places
   */
  public roundToCurrency(amount: plugins.Decimal.Value, currencyCode: string): plugins.Decimal {
    const currency = this.currencies.get(currencyCode);
    
    if (!currency) {
      throw new Error(`Currency ${currencyCode} not registered`);
    }
    
    return this.round(amount, currency.decimals || 0);
  }

  /**
   * Calculate percentage of amount
   * @param amount The base amount
   * @param percentage The percentage (e.g., 15 for 15%)
   */
  public percentage(amount: plugins.Decimal.Value, percentage: plugins.Decimal.Value): plugins.Decimal {
    const percent = this.divide(percentage, 100);
    return this.multiply(amount, percent);
  }

  /**
   * Calculate markup amount
   * @param cost The base cost
   * @param markupPercentage The markup percentage
   */
  public markup(cost: plugins.Decimal.Value, markupPercentage: plugins.Decimal.Value): plugins.Decimal {
    const markupAmount = this.percentage(cost, markupPercentage);
    return this.add(cost, markupAmount);
  }

  /**
   * Calculate discount amount
   * @param price The original price
   * @param discountPercentage The discount percentage
   */
  public discount(price: plugins.Decimal.Value, discountPercentage: plugins.Decimal.Value): plugins.Decimal {
    const discountAmount = this.percentage(price, discountPercentage);
    return this.subtract(price, discountAmount);
  }

  /**
   * Calculate tax amount
   * @param amount The base amount
   * @param taxRate The tax rate (e.g., 0.08 for 8%)
   */
  public tax(amount: plugins.Decimal.Value, taxRate: plugins.Decimal.Value): plugins.Decimal {
    return this.multiply(amount, taxRate);
  }

  /**
   * Calculate total with tax
   * @param amount The base amount
   * @param taxRate The tax rate
   */
  public withTax(amount: plugins.Decimal.Value, taxRate: plugins.Decimal.Value): plugins.Decimal {
    const taxAmount = this.tax(amount, taxRate);
    return this.add(amount, taxAmount);
  }

  /**
   * Extract base amount from a tax-inclusive price
   * @param totalAmount The total amount including tax
   * @param taxRate The tax rate
   */
  public extractTax(totalAmount: plugins.Decimal.Value, taxRate: plugins.Decimal.Value): {
    baseAmount: plugins.Decimal;
    taxAmount: plugins.Decimal;
  } {
    const divisor = this.add(1, taxRate);
    const baseAmount = this.divide(totalAmount, divisor);
    const taxAmount = this.subtract(totalAmount, baseAmount);
    
    return { baseAmount, taxAmount };
  }
}