export function calculateSMA(prices: number[], period: number = 20): number {
  if (prices.length < period) return 0;
  const sum = prices.slice(0, period).reduce((a, b) => a + b, 0);
  return sum / period;
}

export function calculateEMA(prices: number[], period: number = 20): number {
  if (prices.length < period) return 0;
  const multiplier = 2 / (period + 1);
  let ema = prices[period - 1];
  for (let i = period; i < prices.length; i++) {
    ema = prices[i] * multiplier + ema * (1 - multiplier);
  }
  return ema;
}

export function calculateRSI(prices: number[], period: number = 14): number {
  if (prices.length < period + 1) return 0;
  let gains = 0;
  let losses = 0;
  for (let i = 1; i <= period; i++) {
    const diff = prices[i] - prices[i - 1];
    if (diff > 0) gains += diff;
    else losses -= diff;
  }
  const avgGain = gains / period;
  const avgLoss = losses / period;
  if (avgLoss === 0) return 100;
  const rs = avgGain / avgLoss;
  return 100 - (100 / (1 + rs));
}

export function calculateMACD(
  prices: number[],
  fastPeriod: number = 12,
  slowPeriod: number = 26,
  signalPeriod: number = 9
): number {
  if (prices.length < slowPeriod) return 0;
  const emaFast = calculateEMA(prices, fastPeriod);
  const emaSlow = calculateEMA(prices, slowPeriod);
  const macdLine = emaFast - emaSlow;
  const signal = calculateEMA([macdLine], signalPeriod);
  return macdLine - signal;
}