go: Implement voting

There are currently no ways to start vote so the code cannot be tested currently.

GoBot/db.go

@@ -23,4 +23,12 @@ func init() {
 	if err != nil {
 		panic(err)
 	}
+	_, err = db.Exec("CREATE TABLE IF NOT EXISTS vote (id INTEGER PRIMARY KEY, messageId TEXT, name TEXT, finished BOOLEAN, UNIQUE(id))")
+	if err != nil {
+		panic(err)
+	}
+	_, err = db.Exec("CREATE TABLE IF NOT EXISTS choices (voteId INTEGER, userId INTEGER, date TIMEDATE, value INTEGER, UNIQUE(voteId, userId))")
+	if err != nil {
+		panic(err)
+	}
 }

GoBot/db_vote.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"errors"
+	"time"
+)
+
+const (
+	forceRejectionVote = -1
+	nuclearOptionVote  = 10
+)
+
+var errForceRejectionVoteReuse = errors.New("db: the user has used force rejection vote in the last month")
+var errVoteIsOver = errors.New("db: the vote cannot be changed once it's over")
+
+func getVoteName(id int) (string, error) {
+	rows, err := db.Query("SELECT name FROM vote WHERE id=?", id)
+	if err != nil {
+		return "", err
+	}
+	if rows.Next() {
+		var name string
+		err := rows.Scan(&name)
+		if err != nil {
+			return "", err
+		}
+		return name, nil
+	}
+	return "", errNotFound
+}
+
+func getVoteFromMessageID(msgID string) (int, error) {
+	rows, err := db.Query("SELECT id FROM vote WHERE messageId=?", msgID)
+	if err != nil {
+		return 0, err
+	}
+	if rows.Next() {
+		var id int
+		err := rows.Scan(&id)
+		if err != nil {
+			return 0, err
+		}
+		return id, nil
+	}
+	return 0, errNotFound
+}
+
+func updateVote(voteID int, userID string, voteValue int) error {
+	if voteValue == forceRejectionVote {
+		//Check if they used it within a month.
+		rows, err := db.Query("SELECT voteId FROM choices WHERE date >= ? AND value=?", time.Now().AddDate(0, -1, 0))
+		if err != nil {
+			return err
+		}
+		if rows.Next() {
+			return errForceRejectionVoteReuse
+		}
+	}
+
+	//Check if the vote is finished and don't allow change of vote that way.
+	rows, err := db.Query("SELECT finished FROM vote WHERE id=? AND finished=?", voteID, true)
+	if rows.Next() {
+		return errVoteIsOver
+	}
+
+	_, err = db.Exec("REPLACE INTO choices (voteId, userId, date, value) VALUES (?, ?, ?, ?)", voteID, userID, time.Now(), voteValue)
+	return err
+}

GoBot/main.go

@@ -18,6 +18,7 @@ func main() {
 		panic(err)
 	}
 	dg.AddHandler(messageCreate)
+	dg.AddHandler(checkForVote)
 	if err := dg.Open(); err != nil {
 		panic(err)
 	}

GoBot/messageUtil.go

@@ -5,6 +5,8 @@ import "github.com/bwmarrin/discordgo"
 const guildID = "626424729234046987"
 const memberRoleID = "626434632614805526"
 
+const auditChannel = "631789849929711627"
+
 func enforceDM(s *discordgo.Session, m *discordgo.MessageCreate) bool {
 	if m.GuildID != "" {
 		//This command can only be used in DM to protect the invite creator.
@@ -38,3 +40,16 @@ func membersOnly(s *discordgo.Session, m *discordgo.MessageCreate) bool {
 	)
 	return false
 }
+
+func sendPrivateMessage(s *discordgo.Session, recipient, message string) error {
+	channel, err := s.UserChannelCreate(recipient)
+	if err != nil {
+		return err
+	}
+	_, err = s.ChannelMessageSend(channel.ID, message)
+	return err
+}
+
+func auditLog(s *discordgo.Session, message string) {
+	s.ChannelMessageSend(auditChannel, message)
+}

GoBot/vote.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/bwmarrin/discordgo"
+)
+
+func checkForVote(s *discordgo.Session, r *discordgo.MessageReactionAdd) {
+	voteID, err := getVoteFromMessageID(r.MessageID)
+	if err != nil {
+		return
+	}
+
+	s.MessageReactionRemove(r.ChannelID, r.MessageID, r.Emoji.ID, r.UserID)
+
+	var value int
+	switch r.Emoji.Name {
+	case "x":
+		value = forceRejectionVote
+	case "one":
+		value = 1
+	case "two":
+		value = 2
+	case "three":
+		value = 3
+	case "four":
+		value = 4
+	case "five":
+		value = 5
+	case "white_check_mark":
+		value = nuclearOptionVote
+	default:
+		return
+	}
+
+	err = updateVote(voteID, r.UserID, value)
+
+	if err == errForceRejectionVoteReuse {
+		sendPrivateMessage(s, r.UserID, "您在这个月内已使用过:x:。请选择其他选项。\nYou have used :x: this month. Please choose another option.")
+		return
+	}
+	if err == errVoteIsOver {
+		sendPrivateMessage(s, r.UserID, "这个投票已结束。你投的票没有被记录。\nThe vote is over so your vote is not recorded.")
+		return
+	}
+
+	var voteName string
+	if err == nil {
+		voteName, err = getVoteName(voteID)
+	}
+
+	if err != nil {
+		sendPrivateMessage(s, r.UserID, "一个错误已发生，请重新尝试。\nAn error has occurred while voting. Please try again.")
+		auditLog(s,
+			fmt.Sprintf("Error occurred while processing vote for <@%s>.\n%v\nError: %s", r.UserID, r, err.Error()),
+		)
+		return
+	}
+
+	sendPrivateMessage(s, r.UserID, "您投票已成功。\nYou have voted successfully.\n名字Vote Name: "+voteName+"\n目前投的票： :"+r.Emoji.Name+":")
+}