1 files changed, 101 insertions, 0 deletions
diff --git a/bingo/tiles.go b/bingo/tiles.go
new file mode 100644
index 0000000..81e945f
--- /dev/null
+++ b/bingo/tiles.go
@@ -0,0 +1,101 @@
+package bingo
+
+import (
+	"iter"
+	"math/rand"
+	"slices"
+)
+
+type TilePool map[string][]string
+
+func (pool TilePool) All() iter.Seq[string] {
+	return func(yield func(string) bool) {
+		for _, list := range pool {
+			for _, tile := range list {
+				if !yield(tile) {
+					return
+				}
+			}
+		}
+	}
+}
+
+type TilePicker interface {
+	All() iter.Seq[string]              // provides an iterator over an entire TilePool
+	Iter(int) iter.Seq2[string, string] // provides an iterator over n elements of a TilePool
+	Reset()                             // reset the internal state of a TilePicker
+}
+
+type RandomTilePicker struct {
+	ChosenTags []string
+	tilePool   TilePool
+	rand       rand.Rand
+}
+
+func NewRandomTilePicker(tiles TilePool, r rand.Rand) *RandomTilePicker {
+	tp := new(RandomTilePicker)
+	tp.tilePool = tiles
+	tp.rand = r
+
+	return tp
+}
+
+// Iterate over all elements of a TilePool in a random order
+func (tp RandomTilePicker) All() iter.Seq[string] {
+	return func(yield func(string) bool) {
+		tiles := slices.Collect(tp.tilePool.All())
+		if len(tiles) == 0 {
+			return
+		}
+
+		tp.rand.Shuffle(len(tiles), func(i int, j int) {
+			tiles[i], tiles[j] = tiles[j], tiles[i]
+		})
+
+		for _, tile := range tiles {
+			if !yield(tile) {
+				return
+			}
+		}
+	}
+}
+
+// Iterator over a TilePool by choosing one tile per tag until pool is exhausted or size tiles have been yielded
+func (tp RandomTilePicker) Iter(size int) iter.Seq2[string, string] {
+	return func(yield func(string, string) bool) {
+		if len(tp.tilePool) == 0 {
+			return
+		}
+
+		tags := make([]string, len(tp.tilePool))
+		for tag := range tp.tilePool {
+			tags = append(tags, tag)
+		}
+		tp.rand.Shuffle(len(tags), func(i int, j int) {
+			tags[i], tags[j] = tags[j], tags[i]
+		})
+
+		yielded := 0
+		for _, tag := range tags {
+			if yielded == size {
+				return
+			}
+
+			list := tp.tilePool[tag]
+			if len(list) == 0 {
+				continue
+			}
+
+			tile := list[tp.rand.Intn(len(list))]
+			if !yield(tag, tile) {
+				return
+			}
+			yielded++
+		}
+
+	}
+}
+
+func (tp RandomTilePicker) Reset() {
+	tp.ChosenTags = make([]string, len(tp.ChosenTags))
+}