split queue package into multiple files. other minor fixes

2026-02-24 08:34:28 -05:00
parent d55cfb2411
commit 352fa9da61
8 changed files with 1337 additions and 1217 deletions
@@ -0,0 +1,132 @@
+package queue
+
+import "math/rand/v2"
+
+// nextIndex returns the next track index respecting shuffle and repeat modes.
+// Returns -1 if there is no next track (queue exhausted).
+func (q *Queue) nextIndex() int {
+	if len(q.tracks) == 0 {
+		return -1
+	}
+
+	if q.shuffleMode && len(q.shuffleOrder) > 0 {
+		return q.nextShuffledIndex()
+	}
+
+	next := q.currentIndex + 1
+	if next >= len(q.tracks) {
+		if q.repeatMode == RepeatAll {
+			return 0
+		}
+
+		return -1
+	}
+
+	return next
+}
+
+// previousIndex returns the previous track index respecting shuffle and repeat.
+// Returns -1 if there is no previous track.
+func (q *Queue) previousIndex() int {
+	if len(q.tracks) == 0 {
+		return -1
+	}
+
+	if q.shuffleMode && len(q.shuffleOrder) > 0 {
+		return q.previousShuffledIndex()
+	}
+
+	prev := q.currentIndex - 1
+	if prev < 0 {
+		if q.repeatMode == RepeatAll {
+			return len(q.tracks) - 1
+		}
+
+		return -1
+	}
+
+	return prev
+}
+
+// nextShuffledIndex finds the next index in the shuffle order.
+func (q *Queue) nextShuffledIndex() int {
+	shufflePos := q.currentShufflePosition()
+	if shufflePos == -1 {
+		// Current track not found in shuffle order — shouldn't happen.
+		return -1
+	}
+
+	nextShufflePos := shufflePos + 1
+	if nextShufflePos >= len(q.shuffleOrder) {
+		if q.repeatMode == RepeatAll {
+			return q.shuffleOrder[0]
+		}
+
+		return -1
+	}
+
+	return q.shuffleOrder[nextShufflePos]
+}
+
+// previousShuffledIndex finds the previous index in the shuffle order.
+func (q *Queue) previousShuffledIndex() int {
+	shufflePos := q.currentShufflePosition()
+	if shufflePos == -1 {
+		return -1
+	}
+
+	prevShufflePos := shufflePos - 1
+	if prevShufflePos < 0 {
+		if q.repeatMode == RepeatAll {
+			return q.shuffleOrder[len(q.shuffleOrder)-1]
+		}
+
+		return -1
+	}
+
+	return q.shuffleOrder[prevShufflePos]
+}
+
+// currentShufflePosition finds where the current track index is in the shuffle order.
+func (q *Queue) currentShufflePosition() int {
+	for i, idx := range q.shuffleOrder {
+		if idx == q.currentIndex {
+			return i
+		}
+	}
+
+	return -1
+}
+
+// generateShuffleOrder creates a Fisher-Yates shuffled index order,
+// placing the current track at position 0 so it doesn't replay immediately.
+func (q *Queue) generateShuffleOrder() {
+	n := len(q.tracks)
+	if n == 0 {
+		q.shuffleOrder = nil
+
+		return
+	}
+
+	order := make([]int, n)
+	for i := range order {
+		order[i] = i
+	}
+
+	// Fisher-Yates shuffle.
+	for i := n - 1; i > 0; i-- {
+		j := rand.IntN(i + 1)
+		order[i], order[j] = order[j], order[i]
+	}
+
+	// Move the current track to position 0 so it doesn't replay immediately.
+	for i, idx := range order {
+		if idx == q.currentIndex {
+			order[0], order[i] = order[i], order[0]
+
+			break
+		}
+	}
+
+	q.shuffleOrder = order
+}