WIP components (as built)

market_data.go

@@ -7,38 +7,46 @@ import (
 	"time"
 )
 
-// Candle is one period of trading: open, high, low, close and volume.
+// Candle holds OHLC prices, time, and volume.
 type Candle struct {
 	Time                   time.Time
 	Open, High, Low, Close float64
 	Volume                 float64
 }
 
-// marketCheckCandles panics on candles out of time order or with impossible prices.
+// marketCheckCandles validates chronological candles and finite OHLC values.
 func marketCheckCandles(candles []Candle) {
 	for i, c := range candles {
 		if c.Time.IsZero() || i > 0 && !c.Time.After(candles[i-1].Time) {
 			panic(fmt.Sprintf("mujica: candle %d time is zero or not after the one before", i))
 		}
+		for _, v := range []float64{c.Open, c.High, c.Low, c.Close, c.Volume} {
+			if math.IsNaN(v) || math.IsInf(v, 0) {
+				panic("mujica: candle values must be finite")
+			}
+		}
 		if !(c.Low <= min(c.Open, c.Close)) || !(c.High >= max(c.Open, c.Close)) || c.Volume < 0 || math.IsNaN(c.Volume) {
 			panic(fmt.Sprintf("mujica: candle %d has impossible prices or volume", i))
 		}
 	}
 }
 
-// MarketView is the caller-held window of a market chart: zoom and pan.
+// MarketView holds the visible candle window.
 type MarketView struct {
 	// Count is how many candles show; zero shows 120.
 	Count int
-	// End is one past the last shown candle; zero follows the newest.
+	// End is exclusive; zero follows the newest candle.
 	End int
 }
 
-// marketWindow resolves the view to [from, to) over n candles, at most room wide.
+// marketWindow resolves the visible range, bounded by room.
 func marketWindow(v MarketView, n, room int) (from, to int) {
 	if v.Count < 0 || v.End < 0 {
 		panic("mujica: MarketView Count and End must not be negative")
 	}
+	if n == 0 {
+		return 0, 0
+	}
 	count := v.Count
 	if count == 0 {
 		count = 120
@@ -51,7 +59,7 @@ func marketWindow(v MarketView, n, room int) (from, to int) {
 	return to - count, to
 }
 
-// marketPan moves the view by delta candles; reaching the newest follows it again.
+// marketPan moves the window; the newest edge enables following.
 func marketPan(v *MarketView, n, room, delta int) {
 	from, to := marketWindow(*v, n, room)
 	v.Count = to - from
@@ -63,7 +71,7 @@ func marketPan(v *MarketView, n, room, delta int) {
 	}
 }
 
-// marketZoom scales the shown count by f, keeping the newest shown candle, within 10 and room.
+// marketZoom changes visible count while preserving the right edge.
 func marketZoom(v *MarketView, n, room int, f float64) {
 	from, to := marketWindow(*v, n, room)
 	count := int(math.Round(float64(to-from) * f))
@@ -76,18 +84,18 @@ func marketZoom(v *MarketView, n, room int, f float64) {
 	}
 }
 
-// marketIndexAt finds the candle at or before t, or -1 before the first.
+// marketIndexAt finds the candle at or before t.
 func marketIndexAt(candles []Candle, t time.Time) int {
 	return sort.Search(len(candles), func(i int) bool { return candles[i].Time.After(t) }) - 1
 }
 
-// Interval names a candle period: 1m 3m 5m 15m 30m 1h 2h 4h 6h 12h 1D 3D 1W 1M.
+// Interval names a supported candle period.
 type Interval string
 
 // Intervals lists every Interval, shortest first.
 var Intervals = []Interval{"1m", "3m", "5m", "15m", "30m", "1h", "2h", "4h", "6h", "12h", "1D", "3D", "1W", "1M"}
 
-// Close returns when the candle holding t closes: periods align to the clock in loc, weeks start Monday.
+// Close aligns periods locally; weeks start Monday.
 func (iv Interval) Close(t time.Time, loc *time.Location) time.Time {
 	t = t.In(loc)
 	day := time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, loc)