From 74b92e4fd866e33aea409f68a868e246df52a150 Mon Sep 17 00:00:00 2001
From: Luther Wen Xu <lutherchanpublic+git@gmail.com>
Date: Sun, 31 May 2020 22:56:44 +0800
Subject: [PATCH] feat: Add roll command

---
 commands/commands.go |  1 +
 commands/roll.go     | 60 ++++++++++++++++++++++++++++++++++++++++++++
 util/format.go       | 25 ++++++++++--------
 util/rand.go         | 30 ++++++++++++++++++++++
 4 files changed, 106 insertions(+), 10 deletions(-)
 create mode 100644 commands/roll.go
 create mode 100644 util/rand.go

diff --git a/commands/commands.go b/commands/commands.go
index 639bc28..594a5d3 100644
--- a/commands/commands.go
+++ b/commands/commands.go
@@ -22,6 +22,7 @@ var commands = []command{
 	command{"leaderboard", "", handleLeaderboard, 0, true},
 	command{"level", "", handleLevel, 0, false},
 	command{"recalclevel", "", handleRecalculateLevel, 0, false},
+	command{"roll", "[[[number of dice]d]<number of sides>]", handleRoll, 0, false},
 }
 
 func Event(dg *discordgo.Session, m *discordgo.MessageCreate) {
diff --git a/commands/roll.go b/commands/roll.go
new file mode 100644
index 0000000..cbdc533
--- /dev/null
+++ b/commands/roll.go
@@ -0,0 +1,60 @@
+package commands
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/bwmarrin/discordgo"
+
+	"gitea.teamortix.com/chanbakjsd/Milen/util"
+)
+
+func handleRoll(dg *discordgo.Session, m *discordgo.MessageCreate, arguments []string) {
+	if len(arguments) > 1 {
+		util.SendFailEmbed(dg, m.ChannelID, "Error", "Expected zero or one argument.")
+		return
+	}
+	var argument string
+	if len(arguments) == 0 {
+		argument = "6"
+	} else {
+		argument = arguments[0]
+	}
+
+	split := strings.SplitN(argument, "d", 2)
+	if len(split) == 1 {
+		split = []string{"1", split[0]}
+	}
+	if split[0] == "" {
+		split[0] = "1"
+	}
+
+	numberOfDice, err := strconv.Atoi(split[0])
+	if err != nil || numberOfDice < 1 {
+		util.SendFailEmbed(dg, m.ChannelID, "Error", "Unknown dice format. Expected `[num]d[amount of sides]`.")
+		return
+	}
+	if numberOfDice > 5 {
+		util.SendFailEmbed(dg, m.ChannelID, "Error", "I only have five dice.")
+		return
+	}
+	numberOfSides, err := strconv.Atoi(split[1])
+	if err != nil || numberOfSides < 1 {
+		util.SendFailEmbed(dg, m.ChannelID, "Error", "Unknown dice format. Expected `[num]d[amount of sides]`.")
+		return
+	}
+	if numberOfSides > 10000 {
+		util.SendFailEmbed(dg, m.ChannelID, "Error", "The largest dice I have only has 10000 sides.")
+		return
+	}
+
+	result := make([]string, 0, numberOfDice)
+	for i := 0; i < numberOfDice; i++ {
+		result = append(result, strconv.Itoa(util.Rand.Intn(numberOfSides)+1))
+	}
+	util.SendEmbed(dg, m.ChannelID, &discordgo.MessageEmbed{
+		Title:       "Roll Results",
+		Description: "Your roll results are: " + util.FormatCommaSeparatedList(result),
+		Color:       0x00D000,
+	})
+}
diff --git a/util/format.go b/util/format.go
index 023da9a..01f7788 100644
--- a/util/format.go
+++ b/util/format.go
@@ -23,21 +23,26 @@ func FormatTime(seconds int64) string {
 		seconds %= 60
 	}
 	listedTime = append(listedTime, FormatPlural(seconds, "second", "seconds"))
-	switch len(listedTime) {
+	return FormatCommaSeparatedList(listedTime)
+}
+
+func FormatCommaSeparatedList(list []string) string {
+	switch len(list) {
+	case 0:
+		return ""
 	case 1:
-		return listedTime[0]
+		return list[0]
 	case 2:
-		return listedTime[0] + " and " + listedTime[1]
+		return list[0] + " and " + list[1]
 	}
-	time := ""
-	for i := 0; i < len(listedTime)-2; i++ {
-		time += listedTime[i] + ", "
+	result := ""
+	for i := 0; i < len(list)-2; i++ {
+		result += list[i] + ", "
 	}
-	time += listedTime[len(listedTime)-2] + ", and "
-	time += listedTime[len(listedTime)-1]
-	return time
+	result += list[len(list)-2] + ", and "
+	result += list[len(list)-1]
+	return result
 }
-
 func FormatPlural(count int64, singular string, plural string) string {
 	if count == 0 || count == 1 {
 		return strconv.FormatInt(count, 10) + " " + singular
diff --git a/util/rand.go b/util/rand.go
new file mode 100644
index 0000000..4df0b59
--- /dev/null
+++ b/util/rand.go
@@ -0,0 +1,30 @@
+package util
+
+import (
+	crand "crypto/rand"
+	mrand "math/rand"
+)
+
+type src struct{}
+
+func (s src) Int63() int64 {
+	result := make([]byte, 8)
+	_, err := crand.Read(result)
+	if err != nil {
+		panic(err)
+	}
+	return int64(result[0]&0x7F)<<56 |
+		int64(result[1])<<48 |
+		int64(result[2])<<40 |
+		int64(result[3])<<32 |
+		int64(result[4])<<24 |
+		int64(result[5])<<16 |
+		int64(result[6])<<8 |
+		int64(result[7])<<0
+}
+
+func (s src) Seed(seed int64) {
+	// We don't do seeds here.
+}
+
+var Rand = mrand.New(src{})