Code cleaning

README.md

@@ -2,3 +2,11 @@
 
 Command to build the executable for manual upload to Lambda:
 GOOS=linux CGO_ENABLED=0 go build -o main .
+
+Required variables:
+
+- FETCH_SIZE: how many news to fetch
+- BATCH_SIZE: batch size for DB write
+- REGION: AWS region
+- SENDER: sender email address
+- RECIPIENT: recipient email address

db/db.go

@@ -70,8 +70,10 @@ func CreateTable(basics Table) (*types.TableDescription, error) {
 		if err != nil {
 			log.Printf("Wait for table exists failed. Here's why: %v\n", err)
 		}
+
 		tableDesc = table.TableDescription
 	}
+
 	return tableDesc, err
 }
 
@@ -87,19 +89,24 @@ func AddNewsBatch(basics Table, news []News, batchSize int) (int, error) {
 	written := 0
 	start := 0
 	end := start + batchSize
+
 	for start < len(news) {
 		var writeReqs []types.WriteRequest
+
 		if end > len(news) {
 			end = len(news)
 		}
+
 		for _, entry := range news[start:end] {
 			item, err = attributevalue.MarshalMap(entry)
+
 			if err != nil {
 				log.Printf("Couldn't marshal news %v for batch writing: %v\n", entry.Title, err)
 			} else {
 				writeReqs = append(writeReqs, types.WriteRequest{PutRequest: &types.PutRequest{Item: item}})
 			}
 		}
+
 		_, err = basics.DynamoDbClient.BatchWriteItem(context.TODO(), &dynamodb.BatchWriteItemInput{
 			RequestItems: map[string][]types.WriteRequest{basics.TableName: writeReqs}})
 		if err != nil {
@@ -107,6 +114,7 @@ func AddNewsBatch(basics Table, news []News, batchSize int) (int, error) {
 		} else {
 			written += len(writeReqs)
 		}
+
 		start = end
 		end += batchSize
 	}
@@ -120,7 +128,7 @@ func ReadTodayNews(basics Table, timeStart int, timeEnd int) ([]News, error) {
 	var news []News
 	params, err := attributevalue.MarshalList([]interface{}{timeStart, timeEnd})
 	if err != nil {
-		panic(err)
+		log.Fatalln(err)
 	}
 
 	response, err := basics.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{

hackernews/hackernews.go

@@ -23,8 +23,8 @@ func GetTopNewsIds(url string) (response []string) {
 		log.Fatalln(err)
 	}
 
-	body_string := string(body)
-	response = strings.Split(body_string[1:len(body_string)-1], ",")
+	bodyString := string(body)
+	response = strings.Split(bodyString[1:len(bodyString)-1], ",")
 
 	fmt.Println("Done.")
 

handler/handler.go

@@ -8,6 +8,9 @@ import (
 	"hackernewsletter/hackernews"
 	"hackernewsletter/mail"
 	"html/template"
+	"log"
+	"os"
+	"strconv"
 	"time"
 
 	"github.com/aws/aws-sdk-go-v2/config"
@@ -15,11 +18,15 @@ import (
 )
 
 func Handler(ctx context.Context) (string, error) {
+	batchSize, _ := strconv.Atoi(os.Getenv("BATCH_SIZE"))
+	fetchSize, _ := strconv.Atoi(os.Getenv("FETCH_SIZE"))
+
+	var newsBatch []db.News
 	table := "news_table"
 
 	cfg, err := config.LoadDefaultConfig(context.TODO())
 	if err != nil {
-		panic("Unable to load SDK config, " + err.Error())
+		log.Fatalln("Unable to load SDK config, " + err.Error())
 	}
 
 	client := dynamodb.NewFromConfig(cfg)
@@ -35,7 +42,7 @@ func Handler(ctx context.Context) (string, error) {
 		println(("Table not found. Creating it..."))
 		_, new_err := db.CreateTable(newsTable)
 		if new_err != nil {
-			panic("Failed creating table " + table)
+			log.Fatalln("Failed creating table.")
 		}
 
 		resp, err = db.GetTableInfo(context.TODO(), client, input)
@@ -45,14 +52,12 @@ func Handler(ctx context.Context) (string, error) {
 
 	newsIds := hackernews.GetTopNewsIds("https://hacker-news.firebaseio.com/v0/topstories.json")
 
-	var newsBatch []db.News
-
-	for i := 0; i < 10; i++ {
+	for i := 0; i < fetchSize; i++ {
 		myNews := hackernews.GetNewsById(newsIds[i], "https://hacker-news.firebaseio.com/v0/item/{ID}.json")
 		newsBatch = append(newsBatch, myNews)
 	}
 
-	db.AddNewsBatch(newsTable, newsBatch, 25)
+	db.AddNewsBatch(newsTable, newsBatch, batchSize)
 
 	timeEnd := time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day(), 0, 0, 0, 0, time.UTC)
 	timeStart := timeEnd.Add(-time.Hour * 24)
@@ -60,28 +65,24 @@ func Handler(ctx context.Context) (string, error) {
 	todayNews, _ := db.ReadTodayNews(newsTable, int(timeStart.Unix()), int(timeEnd.Unix()))
 
 	t, err := template.ParseFiles("mail/index.gohtml")
-
 	if err != nil {
-		panic(err)
+		log.Fatalln(err)
 	}
 
-	data := struct {
+	emailNews := struct {
 		News []db.News
 	}{
 		News: todayNews,
 	}
 
-	var doc bytes.Buffer
-
-	err = t.Execute(&doc, data)
+	var emailNewsBuffer bytes.Buffer
 
+	err = t.Execute(&emailNewsBuffer, emailNews)
 	if err != nil {
-		panic(err)
+		log.Fatalln(err)
 	}
 
-	body := doc.String()
-
-	mail.SendNewsletter(body)
+	mail.SendNewsletter(emailNewsBuffer.String())
 
 	return "Completed.", err
 }