/**
* Moving Average Envelope Indicator
* Creates bands around a moving average for overbought/oversold signals
*/
export interface MAEnvelopeData {
// Moving average value
ma: number
// Envelope bands
upperBand: number
lowerBand: number
// Band percentage
percentage: number
// Current price position
position: 'above_upper' | 'above_ma' | 'below_ma' | 'below_lower'
// Signal based on envelope
signal: 'overbought' | 'oversold' | 'neutral'
// Distance from bands
distanceFromUpper: number // % distance from upper band
distanceFromLower: number // % distance from lower band
// Band width
bandWidth: number // Width of the envelope band
}
/**
* 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: number[],
period: number = 20,
percentage: number = 2.5,
maType: 'sma' | 'ema' = 'sma'
): MAEnvelopeData | null {
if (prices.length < period) {
return null
}
// Calculate moving average
let ma: number
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: 'above_upper' | 'above_ma' | 'below_ma' | 'below_lower'
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: 'overbought' | 'oversold' | 'neutral' = '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: number[],
periods: number[] = [10, 20, 50],
percentage: number = 2.5
): MAEnvelopeData[] {
return periods
.map(period => calculateMAEnvelope(prices, period, percentage))
.filter((envelope): envelope is MAEnvelopeData => envelope !== null)
}
/**
* Get MA Envelope Signal Strength
* @param envelope MAEnvelopeData object
* @returns Signal strength (0-100)
*/
export function getMAEnvelopeSignalStrength(envelope: MAEnvelopeData): number {
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
}
