add emote combos

Author: slugalisk

combos.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"errors"
+	"strings"
+	"sync"
+)
+
+var ErrComboDuplicate = errors.New("user has already participated in combo")
+
+var combos = Combos{}
+
+type comboVariant struct {
+	modifiers []string
+	count     int
+}
+
+type Combos struct {
+	lock         sync.Mutex
+	emote        string
+	count        int
+	variants     map[string]*comboVariant
+	participants map[string]struct{}
+}
+
+func (c *Combos) Transform(msg *EventDataOut) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	if !isEmoteMessage(msg) {
+		c.reset()
+		return nil
+	}
+
+	emote := msg.Entities.Emotes[0]
+
+	// if the combo was broken by another emote message reset
+	if c.emote != emote.Name {
+		c.reset()
+	}
+
+	if _, ok := c.participants[msg.Nick]; ok {
+		return ErrComboDuplicate
+	}
+
+	c.emote = emote.Name
+	c.count++
+	c.participants[msg.Nick] = struct{}{}
+
+	variant := strings.Join(emote.Modifiers, ":")
+	if _, ok := c.variants[variant]; !ok {
+		c.variants[variant] = &comboVariant{
+			modifiers: emote.Modifiers,
+			count:     0,
+		}
+	}
+	c.variants[variant].count++
+
+	// if this was the first emote in the combo don't mark a combo yet
+	if c.count == 1 {
+		return nil
+	}
+
+	emote.Combo = c.count
+
+	topVariantCount := -1
+	for _, v := range c.variants {
+		if v.count > topVariantCount {
+			topVariantCount = c.count
+			emote.Modifiers = v.modifiers
+		}
+	}
+
+	return nil
+}
+
+func (c *Combos) reset() {
+	c.emote = ""
+	c.count = 0
+	c.variants = map[string]*comboVariant{}
+	c.participants = map[string]struct{}{}
+}
+
+func isEmoteMessage(msg *EventDataOut) bool {
+	if len(msg.Entities.Emotes) != 1 {
+		return false
+	}
+	b := msg.Entities.Emotes[0].Bounds
+	return b[0] == 0 && b[1] == len(msg.Data)
+}

connection.go

@@ -457,6 +457,12 @@ func (c *Connection) OnMsg(data []byte) {
 	out := c.getEventDataOut()
 	out.Data = msg
 	out.Entities = entities.Extract(msg)
+
+	if err := combos.Transform(out); err == ErrComboDuplicate {
+		c.SendError("duplicate")
+		return
+	}
+
 	c.Broadcast("MSG", out)
 }
 

entities.go

@@ -162,6 +162,7 @@ type Emote struct {
 	Name      string   `json:"name,omitempty"`
 	Modifiers []string `json:"modifiers,omitempty"`
 	Bounds    [2]int   `json:"bounds,omitempty"`
+	Combo     int      `json:"combo,omitempty"`
 }
 
 type Nick struct {