/**
* Moving Average Envelope Indicator
* Creates bands around a moving average for overbought/oversold signals
*/
/**
* Calculate Moving Average Envelope
* @param prices Array of prices
* @param period MA period (default 20)
* @param percentage Envelope percentage (default 2.5%)
* @param maType Type of moving average ('sma' | 'ema', default 'sma')
* @returns MAEnvelopeData object
*/
export function calculateMAEnvelope(prices, period = 20, percentage = 2.5, maType = 'sma') {
if (prices.length < period) {
return null;
}
// Calculate moving average
let ma;
if (maType === 'ema') {
// Exponential Moving Average
const multiplier = 2 / (period + 1);
ma = prices[0];
for (let i = 1; i < prices.length; i++) {
ma = (prices[i] - ma) * multiplier + ma;
}
}
else {
// Simple Moving Average
const sum = prices.slice(-period).reduce((acc, price) => acc + price, 0);
ma = sum / period;
}
// Calculate envelope bands
const bandOffset = ma * (percentage / 100);
const upperBand = ma + bandOffset;
const lowerBand = ma - bandOffset;
// Get current price
const currentPrice = prices[prices.length - 1];
// Determine position
let position;
if (currentPrice > upperBand) {
position = 'above_upper';
}
else if (currentPrice > ma) {
position = 'above_ma';
}
else if (currentPrice < ma) {
position = 'below_ma';
}
else {
position = 'below_lower';
}
// Generate signal
let signal = 'neutral';
if (position === 'above_upper') {
signal = 'overbought';
}
else if (position === 'below_lower') {
signal = 'oversold';
}
// Calculate distances
const distanceFromUpper = ((currentPrice - upperBand) / upperBand) * 100;
const distanceFromLower = ((lowerBand - currentPrice) / lowerBand) * 100;
// Calculate band width
const bandWidth = ((upperBand - lowerBand) / ma) * 100;
return {
ma,
upperBand,
lowerBand,
percentage,
position,
signal,
distanceFromUpper,
distanceFromLower,
bandWidth
};
}
/**
* Calculate Multiple MA Envelopes
* @param prices Array of prices
* @param periods Array of periods for different envelopes
* @param percentage Envelope percentage
* @returns Array of MAEnvelopeData objects
*/
export function calculateMultipleMAEnvelopes(prices, periods = [10, 20, 50], percentage = 2.5) {
return periods
.map(period => calculateMAEnvelope(prices, period, percentage))
.filter((envelope) => envelope !== null);
}
/**
* Get MA Envelope Signal Strength
* @param envelope MAEnvelopeData object
* @returns Signal strength (0-100)
*/
export function getMAEnvelopeSignalStrength(envelope) {
const { position, distanceFromUpper, distanceFromLower, percentage } = envelope;
if (position === 'above_upper') {
// Overbought signal strength based on distance from upper band
const maxDistance = percentage * 2; // Consider 2x the band percentage as max
return Math.min(100, (distanceFromUpper / maxDistance) * 100);
}
else if (position === 'below_lower') {
// Oversold signal strength based on distance from lower band
const maxDistance = percentage * 2;
return Math.min(100, (distanceFromLower / maxDistance) * 100);
}
return 0; // Neutral
}
