/**
* Candlestick Pattern Detection
* detectCandlestickPatterns function
*/
import { HistoricalDataPoint } from '../types'
export interface CandlestickPattern {
type: 'doji' | 'hammer' | 'bullish_engulfing' | 'bearish_engulfing'
index: number
bullish: boolean
}
export interface CandlestickPatternsResult {
patterns: CandlestickPattern[]
}
export function detectCandlestickPatterns(
historicalData: HistoricalDataPoint[],
lookbackPeriod: number = 5
): CandlestickPatternsResult {
if (!historicalData || historicalData.length < lookbackPeriod) {
return {
patterns: []
}
}
const patterns: CandlestickPattern[] = []
const recentCandles = historicalData.slice(-lookbackPeriod)
for (let i = 1; i < recentCandles.length; i++) {
const current = recentCandles[i]
const previous = recentCandles[i - 1]
const bodySize = Math.abs(current.close - current.open)
const upperShadow = current.high - Math.max(current.open, current.close)
const lowerShadow = Math.min(current.open, current.close) - current.low
const totalRange = current.high - current.low
// Doji: Small body, long shadows
if (bodySize < totalRange * 0.1 && (upperShadow > totalRange * 0.3 || lowerShadow > totalRange * 0.3)) {
patterns.push({
type: 'doji',
index: i,
bullish: current.close > current.open
})
}
// Hammer: Small body at top, long lower shadow
if (bodySize < totalRange * 0.3 && lowerShadow > bodySize * 2 && upperShadow < bodySize * 0.5) {
patterns.push({
type: 'hammer',
index: i,
bullish: true
})
}
// Engulfing: Current candle engulfs previous
if (i > 0) {
const prevBodySize = Math.abs(previous.close - previous.open)
const currentBodySize = Math.abs(current.close - current.open)
// Bullish engulfing
if (previous.close < previous.open && current.close > current.open &&
current.open < previous.close && current.close > previous.open &&
currentBodySize > prevBodySize * 1.1) {
patterns.push({
type: 'bullish_engulfing',
index: i,
bullish: true
})
}
// Bearish engulfing
if (previous.close > previous.open && current.close < current.open &&
current.open > previous.close && current.close < previous.open &&
currentBodySize > prevBodySize * 1.1) {
patterns.push({
type: 'bearish_engulfing',
index: i,
bullish: false
})
}
}
}
return {
patterns: patterns
}
}
