//@version=6
indicator("Moving Average Convergence Divergence", "MACD", timeframe = "", timeframe_gaps = true)

// Inputs
float  sourceInput  = input.source(close, "Source")
int    fastLenInput = input.int(12, "Fast length",   1)
int    slowLenInput = input.int(26, "Slow length",   1)
int    sigLenInput  = input.int(9,  "Signal length", 1)
string oscTypeInput = input.string("EMA", "Oscillator MA type", ["EMA", "SMA"], display = display.none)
string sigTypeInput = input.string("EMA", "Signal MA type",     ["EMA", "SMA"], display = display.none)

// @function    Calculates an EMA or SMA of a `source` series.
ma(float source, int length, simple string maType) =>
    switch maType
        "EMA" => ta.ema(source, length)
        "SMA" => ta.sma(source, length)

// Calculate and plot the MACD, signal, and histogram values.
float maFast = ma(sourceInput, fastLenInput, oscTypeInput)
float maSlow = ma(sourceInput, slowLenInput, oscTypeInput)
float macd   = maFast - maSlow
float signal = ma(macd, sigLenInput, sigTypeInput)
float hist   = macd - signal
color hColor = hist >= 0 ? hist > hist[1] ? #26a69a : #b2dfdb : hist > hist[1] ? #ffcdd2 : #ff5252

hline(0, "Zero", #787b8680)
plot(hist, "Histogram", hColor, style = plot.style_columns)
plot(macd, "MACD")
plot(signal, "Signal line", #ff6d00)

// Create alert conditions.
alertcondition(hist[1] >= 0 and hist < 0, "Rising to falling", "MACD histogram switched from a rising to falling state")
alertcondition(hist[1] <= 0 and hist > 0, "Falling to rising", "MACD histogram switched from a falling to rising state")