Multi-transfer

command/transfer_coin.go

@@ -1,8 +1,12 @@
 package command
 
 import (
+	"errors"
 	"fmt"
+	"math/rand"
 	"strconv"
+	"strings"
+	"time"
 
 	"github.com/hex337/alex-koin-go/config"
 	"github.com/hex337/alex-koin-go/model"
@@ -14,64 +18,140 @@ import (
 type TransferCoinCommand struct{}
 
 func (c *TransferCoinCommand) Run(msg string, event *CoinEvent) (string, error) {
-	re := regexp.MustCompile(`^(?i)transfer (?P<amount>[0-9]+) (?:to )?\<@(?P<to_slack_id>[0-9A-Z]+)\> (?:for)??(?P<reason>.+)`)
-	matches := re.FindStringSubmatch(event.Message)
-
-	if len(matches) < 4 {
-		return "Invalid transfer format. Expected something like `@Alex Koin transfer 3 to @alexk for being amazing`. See the channel details for command syntax.", nil
+	parsedResult, err := parseMessage(event.Message)
+	if err != nil {
+		return err.Error(), nil
 	}
 
-	amount, err := strconv.Atoi(matches[1])
-	if err != nil {
-		log.Printf("INF amount not parsed as int: %s", matches[1])
-		return "Invalid transfer amount.", nil
+	// parsing error should be covered in func validateMessage
+	totalAmount, _ := strconv.Atoi(parsedResult["amount"])
+	toUserIds := strings.Split(parsedResult["to_slack_ids"], ",")
+	reason := parsedResult["reason"]
+	splitAmounts := splitCoins(totalAmount, len(toUserIds))
+
+	for i, toUserId := range toUserIds {
+		amount := splitAmounts[i]
+		log.Printf("INF transfer coin amt: %d, toUserIds: %s, reason: %s", totalAmount, toUserIds, reason)
+
+		toUser, err := model.GetOrCreateUserBySlackID(toUserId)
+
+		if err != nil {
+			log.Printf("Could not find user with slack id %s: %s", toUserId, err.Error())
+			return "", err
+		}
+
+		canTransfer, msg := canTransferCoin(event.User, toUser, amount)
+
+		if !canTransfer {
+			return msg, nil
+		}
+
+		var coinIds []int
+		err = config.DB.Table("coins").Select("id").Where("user_id = ?", event.User.ID).Limit(amount).Find(&coinIds).Error
+		if err != nil {
+			log.Printf("ERR error fetching coin ids: %s", err)
+			return "So uh... something went wrong. D'oh.", err
+		}
+
+		err = config.DB.Table("coins").Where("user_id = ? AND id IN ?", event.User.ID, coinIds).UpdateColumn("user_id", toUser.ID).Error
+		if err != nil {
+			log.Printf("ERR error updating coins: %s", err)
+			return "So uh... something went wrong. D'oh.", err
+		}
+
+		transfer := &model.Transaction{
+			Amount:     amount,
+			Memo:       reason,
+			FromUserID: event.User.ID,
+			ToUserID:   toUser.ID,
+		}
+
+		err = model.CreateTransaction(transfer)
+
+		if err != nil {
+			log.Printf("Could not transfer coin(s) : %s", err.Error())
+			return "", err
+		}
+
+		log.Printf("Transfered %d koin from %d to %s.", amount, event.User.ID, toUserId)
 	}
-	toUserId := matches[2]
-	reason := matches[3]
 
-	log.Printf("INF transfer coin amt: %d, toUserId: %s, reason: %s", amount, toUserId, reason)
+	return fmt.Sprintf("Transfered %d koin.", totalAmount), nil
+}
 
-	toUser, err := model.GetOrCreateUserBySlackID(toUserId)
+func parseMessage(message string) (map[string]string, error) {
+	re := regexp.MustCompile(`^(?i)transfer (?P<amount>[0-9]+) (?:to )?(?P<to_slack_ids>\<[@0-9A-Z<> ]+\>) (?:for)?(?P<reason>.+)`)
+	matches := re.FindStringSubmatch(message)
 
-	if err != nil {
-		log.Printf("Could not find user with slack id %s: %s", toUserId, err.Error())
-		return "", err
+	result := make(map[string]string)
+	for i, name := range re.SubexpNames() {
+		if i != 0 && name != "" {
+			result[name] = matches[i]
+		}
 	}
 
-	canTransfer, msg := canTransferCoin(event.User, toUser, amount)
+	slackIdsRe := regexp.MustCompile(`(<@(?P<to_slack_id>[0-9A-Z]+)>)+`)
+	slackIdMatches := slackIdsRe.FindAllStringSubmatch(result["to_slack_ids"], -1)
+	slackIds := make([]string, len(slackIdMatches))
 
-	if !canTransfer {
-		return msg, nil
-	}
+	for i, name := range slackIdsRe.SubexpNames() {
+		if name != "to_slack_id" {
+			continue
+		}
 
-	var coinIds []int
-	err = config.DB.Table("coins").Select("id").Where("user_id = ?", event.User.ID).Limit(amount).Find(&coinIds).Error
-	if err != nil {
-		log.Printf("ERR error fetching coin ids: %s", err)
-		return "So uh... something went wrong. D'oh.", err
+		for j, v := range slackIdMatches {
+			slackIds[j] = v[i]
+		}
 	}
+	result["to_slack_ids"] = strings.Join(slackIds, ",")
 
-	err = config.DB.Table("coins").Where("user_id = ? AND id IN ?", event.User.ID, coinIds).UpdateColumn("user_id", toUser.ID).Error
+	err := validateMessage(result)
 	if err != nil {
-		log.Printf("ERR error updating coins: %s", err)
-		return "So uh... something went wrong. D'oh.", err
+		return nil, err
 	}
+	return result, nil
+}
 
-	transfer := &model.Transaction{
-		Amount:     amount,
-		Memo:       reason,
-		FromUserID: event.User.ID,
-		ToUserID:   toUser.ID,
+func validateMessage(parsedResult map[string]string) error {
+	requiredKeys := []string {
+		"amount",
+		"to_slack_ids",
+		"reason",
 	}
 
-	err = model.CreateTransaction(transfer)
+	for _, key := range requiredKeys {
+		value, ok := parsedResult[key]
+		if !ok || len(value) == 0 {
+			return errors.New("Invalid transfer format. Expected something like `@Alex Koin transfer 3 to @alexk for being amazing`. See the channel details for command syntax.")
+		}
+	}
 
+	amount, err := strconv.Atoi(parsedResult["amount"])
 	if err != nil {
-		log.Printf("Could not transfer coin(s) : %s", err.Error())
-		return "", err
+		log.Printf("INF amount not parsed as int: %s", parsedResult["amount"])
+		return errors.New("Invalid transfer amount.")
+	}
+
+	numOfReceivers := len(strings.Split(parsedResult["to_slack_ids"], ","))
+	if amount < numOfReceivers {
+		log.Printf("amount is not enough for split: amount: %d, receivers: %d", amount, numOfReceivers)
+		return errors.New(fmt.Sprintf("alex koin does not support fraction"))
 	}
 
-	return fmt.Sprintf("Transfered %d koin.", amount), nil
+	return nil
+}
+
+func splitCoins(amount int, count int) []int {
+	rand.Seed(time.Now().UnixNano())
+	coins := make([]int, count)
+	leftCount := count - 1
+	for i, _ := range coins {
+		coins[i] = rand.Intn(amount - leftCount - 1) + 1
+		leftCount -= 1
+		amount -= coins[i]
+	}
+	coins[rand.Intn(len(coins))] += amount
+	return coins
 }
 
 func canTransferCoin(sender *model.User, receiver *model.User, amount int) (bool, string) {

command/transfer_coin_test.go

@@ -0,0 +1,58 @@
+package command
+
+import (
+	"fmt"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestParseMessageWithSingleReceiver(t *testing.T) {
+	numOfCoins := "10"
+	receiverId := "U000AAA"
+	reason := "being awesome"
+
+	parsedResult, err := parseMessage(fmt.Sprintf("transfer %s to <@%s> %s", numOfCoins, receiverId, reason))
+	assert.Nil(t, err, "parse without errors")
+
+	assert.Equal(t, numOfCoins, parsedResult["amount"], "matches coin")
+	assert.Equal(t, receiverId, parsedResult["to_slack_ids"], "matches receiverId")
+	assert.Equal(t, reason, parsedResult["reason"], "matches reason")
+}
+
+func TestParseMessageWithMultipleReceivers(t *testing.T) {
+	numOfCoins := "10"
+	receiverId := "U000AAA"
+	secondReceiverId := "U000BBB"
+	reason := "being awesome"
+
+	parsedResult, err := parseMessage(fmt.Sprintf("transfer %s to <@%s> <@%s> %s", numOfCoins, receiverId, secondReceiverId, reason))
+	assert.Nil(t, err, "parse without errors")
+
+	assert.Equal(t, numOfCoins, parsedResult["amount"], "matches coin")
+	assert.Equal(t, fmt.Sprintf("%s,%s", receiverId, secondReceiverId), parsedResult["to_slack_ids"], "matches receiverId")
+	assert.Equal(t, reason, parsedResult["reason"], "matches reason")
+}
+
+func TestSplitCoinsWithSingleReceiver(t *testing.T) {
+	coins := splitCoins(5, 3)
+
+	sum := 0
+	for _, coin := range coins {
+		assert.LessOrEqual(t, coin, 5, "each coin amount is <= max")
+		sum += coin
+	}
+
+	assert.Equal(t, 5, sum, "amount is the same")
+}
+
+func TestSplitCoinsWithMultipleReceivers(t *testing.T) {
+	coins := splitCoins(5, 1)
+
+	sum := 0
+	for _, coin := range coins {
+		assert.LessOrEqual(t, 5, coin, "each coin amount is <= max")
+		sum += coin
+	}
+
+	assert.Equal(t, 5, sum, "amount is the same")
+}

go.mod

@@ -9,8 +9,8 @@ require (
 	github.com/google/uuid v1.0.0
 	github.com/joho/godotenv v1.3.0
 	github.com/nleeper/goment v1.4.2
-	github.com/pkg/errors v0.8.1
 	github.com/slack-go/slack v0.9.1
+	github.com/stretchr/testify v1.7.0
 	gorm.io/driver/postgres v1.1.0
 	gorm.io/gorm v1.21.11
 )

go.sum

@@ -324,9 +324,10 @@ github.com/stretchr/objx v0.2.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoH
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-github.com/stretchr/testify v1.5.1 h1:nOGnQDM7FYENwehXlg/kFVnos3rEvtKTjRvOWSzb6H4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/tkuchiki/go-timezone v0.2.0 h1:yyZVHtQRVZ+wvlte5HXvSpBkR0dPYnPEIgq9qqAqltk=
 github.com/tkuchiki/go-timezone v0.2.0/go.mod h1:b1Ean9v2UXtxSq4TZF0i/TU9NuoWa9hOzOKoGCV2zqY=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20170815181823-89b8d40f7ca8/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
@@ -475,8 +476,8 @@ gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWD
 gopkg.in/warnings.v0 v0.1.2/go.mod h1:jksf8JmL6Qr/oQM2OXTHunEvvTAsrWBLb6OOjuVWRNI=
 gopkg.in/yaml.v2 v2.0.0-20170812160011-eb3733d160e7/go.mod h1:JAlM8MvJe8wmxCU4Bli9HhUf9+ttbYbLASfIpnQbh74=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gorm.io/driver/postgres v1.1.0 h1:afBljg7PtJ5lA6YUWluV2+xovIPhS+YiInuL3kUjrbk=
 gorm.io/driver/postgres v1.1.0/go.mod h1:hXQIwafeRjJvUm+OMxcFWyswJ/vevcpPLlGocwAwuqw=