From f1112c2fbf723e7eae1ed0b261b90d5dcca84607 Mon Sep 17 00:00:00 2001
From: Luther Wen Xu <lutherchanpublic+git@gmail.com>
Date: Mon, 18 Nov 2019 12:25:34 +0800
Subject: [PATCH] xp: Implement level querying

---
 messageCreate.go | 18 ++++++++++++++++--
 xp.go            | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/messageCreate.go b/messageCreate.go
index 68840f2..e01c1dc 100644
--- a/messageCreate.go
+++ b/messageCreate.go
@@ -1,6 +1,10 @@
 package main
 
-import "github.com/bwmarrin/discordgo"
+import (
+	"fmt"
+
+	"github.com/bwmarrin/discordgo"
+)
 
 func messageCreate(s *discordgo.Session, m *discordgo.MessageCreate) {
 	if m.Author.Bot {
@@ -8,5 +12,15 @@ func messageCreate(s *discordgo.Session, m *discordgo.MessageCreate) {
 	}
 	go incrementXP(s, m.Author.ID)
 
-	//TODO Handle commands
+	if m.Content == "p!level" {
+		handleXPRequest(s, m)
+	}
+}
+
+func handleXPRequest(s *discordgo.Session, m *discordgo.MessageCreate) {
+	level, xp := getLevelAndXP(s, m.Author.ID)
+	s.ChannelMessageSend(
+		m.ChannelID,
+		fmt.Sprintf("<@%s> is now level %d. (%d XP/%d XP)", m.Author.ID, level, xp, levelUpRequirementCache[level-1]),
+	)
 }
diff --git a/xp.go b/xp.go
index 98862bc..3998790 100644
--- a/xp.go
+++ b/xp.go
@@ -13,6 +13,7 @@ import (
 var db *sql.DB
 var lastMessage = make(map[string]time.Time)
 var incrementMutex = sync.Mutex{}
+var levelUpRequirementCache [30]int
 
 func init() {
 	var err error
@@ -22,6 +23,13 @@ func init() {
 	}
 	db.SetMaxOpenConns(1)
 	db.Exec("CREATE TABLE xp(id STRING NOT NULL UNIQUE, xp INTEGER NOT NULL)")
+
+	for i := 1; i <= 30; i++ {
+		//Constructed on Desmos:
+		//y=2^{\frac{x}{3}}+.1x^{2}+1.2x-1
+		fi := float64(i)
+		levelUpRequirementCache[i-1] = int(10000 * (math.Pow(2, fi/3) + 0.1*fi*fi + 1.2*fi - 1))
+	}
 }
 
 func incrementXP(dg *discordgo.Session, discordID string) {
@@ -45,6 +53,21 @@ func incrementXP(dg *discordgo.Session, discordID string) {
 	}
 }
 
+func getLevelAndXP(dg *discordgo.Session, discordID string) (int, int) {
+	rows, err := db.Query("SELECT xp FROM xp WHERE id=?", discordID)
+	if err != nil {
+		logError(dg, "getLevelAndXP", "select", discordID, err)
+		return 1, 0
+	}
+	defer rows.Close()
+	if rows.Next() {
+		var xp int
+		rows.Scan(&xp)
+		return convertXPIntoLevel(xp)
+	}
+	return 1, 0
+}
+
 func calculateIncrement(discordID string) int {
 	incrementMutex.Lock()
 	defer incrementMutex.Unlock()
@@ -61,3 +84,15 @@ func calculateIncrement(discordID string) int {
 	//y=\frac{100}{\left(1+e^{-\left(\frac{x-15}{3}\right)}\right)}
 	return int(100 / (1 + math.Pow(math.E, -((delta.Seconds()-15)/3))))
 }
+
+func convertXPIntoLevel(xp int) (int, int) {
+	if xp < levelUpRequirementCache[0] {
+		return 1, xp
+	}
+	for i := 0; i < 30; i++ {
+		if levelUpRequirementCache[i] > xp {
+			return i + 1, xp - levelUpRequirementCache[i-1]
+		}
+	}
+	return 30, xp - levelUpRequirementCache[29]
+}