国际象棋 (#720)

* init commit for chess

* fix lint & error

* remove issue link

* fix lint

* remove embed

* regex fix

* use strings.Builder

* 改不动了，先 push 了备份下

* 基本上改好了

* limit

* 使用等宽字体渲染棋盘

* use syncx

* 不会更新依赖库😭

* 先 push 备份下

* 更新依赖版本，确保能读取到字体文件

* fix log

plugin/chess/elo.go

@@ -0,0 +1,37 @@
+package chess
+
+import (
+	"math"
+)
+
+// calculateNewRate calculate new rate of the player
+func calculateNewRate(whiteRate, blackRate int, whiteScore, blackScore float64) (int, int) {
+	k := getKFactor(whiteRate, blackRate)
+	exceptionWhite := calculateException(whiteRate, blackRate)
+	exceptionBlack := calculateException(blackRate, whiteRate)
+	whiteRate = calculateRate(whiteRate, whiteScore, exceptionWhite, k)
+	blackRate = calculateRate(blackRate, blackScore, exceptionBlack, k)
+	return whiteRate, blackRate
+}
+
+func calculateException(rate int, opponentRate int) float64 {
+	return 1.0 / (1.0 + math.Pow(10.0, float64(opponentRate-rate)/400.0))
+}
+
+func calculateRate(rate int, score float64, exception float64, k int) int {
+	newRate := int(math.Round(float64(rate) + float64(k)*(score-exception)))
+	if newRate < 1 {
+		newRate = 1
+	}
+	return newRate
+}
+
+func getKFactor(rateA, rateB int) int {
+	if rateA > 2400 && rateB > 2400 {
+		return 16
+	}
+	if rateA > 2100 && rateB > 2100 {
+		return 24
+	}
+	return 32
+}