Merge pull request #5 from AllanCapistrano/feat/limit-messages

feat: create GetLastHourMessagesByIndex function

example.go

@@ -51,4 +51,11 @@ func main() {
 	}
 	fmt.Println(message.Index)
 	fmt.Println(message.Data)
+
+	// Reading max of three messages by an index.
+	limitedMessages, err := messages.GetLastHourMessagesByIndex(nodeURL, "92015a2d-4bae-428d-a428-6338f465e72c", 1)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(limitedMessages)
 }

messages/getLastHourMessagesByIndex.go

@@ -0,0 +1,87 @@
+package messages
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"log"
+	"time"
+
+	iotago "github.com/iotaledger/iota.go/v2"
+)
+
+// Get a limited amount of messages created in the last hour, available on the 
+// node by a given index.
+func GetLastHourMessagesByIndex(nodeUrl string, index string, maxMessages int) ([]Message, error) {
+	node := iotago.NewNodeHTTPAPIClient(nodeUrl)
+
+	msgIdsResponse, err := node.MessageIDsByIndex(
+		context.Background(),
+		[]byte(index),
+	)
+
+	if err != nil {
+		return nil, errors.New("unable to get message IDs")
+	}
+
+	var i uint32
+	var messages []Message
+
+	if msgIdsResponse.Count > 0 {
+		for i = 0; i < msgIdsResponse.Count; i++ {
+			var message Message
+
+			messageReturned, err := getMessageByMessageID(nodeUrl, msgIdsResponse.MessageIDs[i])
+
+			if err != nil {
+				log.Println(err)
+
+				message = Message{
+					Index: "Error",
+					Data:  err.Error(),
+				}
+			} else {
+				indexationPayload := messageReturned.Payload.(*iotago.Indexation)
+
+				message = Message{
+					Index: string(indexationPayload.Index),
+					Data:  string(indexationPayload.Data),
+				}
+			}
+
+			var data map[string]interface{}
+			var createdAtInt64 int64
+
+			err = json.Unmarshal([]byte(message.Data), &data)
+
+			if err != nil {
+				return nil, errors.New("error trying to decode JSON")
+			}
+
+			if createdAt, ok := data["createdAt"].(float64); ok {
+				// One-hour time limit
+				timeLimit := time.Now().UnixMilli() - 1*60*60*1000
+
+				createdAtInt64 = int64(createdAt)
+
+				if createdAtInt64 >= timeLimit {
+					messages = append(messages, message)
+				}
+
+				if len(messages) == maxMessages {
+					break
+				}
+			} else {
+				return nil, errors.New("error, this JSON doesn't have 'createdAt' parameter")
+			}
+		}
+
+		if (len(messages) == 0) {
+			log.Println("No messages have been created in the last hour.")
+		}
+	} else {
+		log.Println("No messages with this index were found.")
+	}
+
+	return messages, nil
+}