Initial commit

main.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/aws/aws-lambda-go/events"
+	"github.com/aws/aws-lambda-go/lambda"
+
+	"github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/feature/dynamodb/attributevalue"
+	"github.com/aws/aws-sdk-go-v2/service/dynamodb"
+)
+
+// Reading represents a single IoT measurement item returned to clients
+type Reading struct {
+	DeviceID    string  `json:"deviceId" dynamodbav:"deviceId"`
+	Timestamp   string  `json:"timestamp" dynamodbav:"timestamp"`
+	Temperature float64 `json:"temperature" dynamodbav:"temperature"`
+	Humidity    float64 `json:"humidity" dynamodbav:"humidity"`
+}
+
+type ResponseBody struct {
+	Data []Reading `json:"data"`
+}
+
+func handler(ctx context.Context, req events.APIGatewayV2HTTPRequest) (events.APIGatewayV2HTTPResponse, error) {
+	tableName := os.Getenv("TABLE_NAME")
+	if tableName == "" {
+		log.Print("TABLE_NAME environment variable not set")
+		return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
+	}
+
+	cfg, err := config.LoadDefaultConfig(ctx)
+	if err != nil {
+		log.Printf("failed to load AWS config: %v", err)
+		return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
+	}
+
+	db := dynamodb.NewFromConfig(cfg)
+
+	// Simple Scan as requested for the initial version
+	scanInput := &dynamodb.ScanInput{
+		TableName: &tableName,
+	}
+
+	scanOutput, err := db.Scan(ctx, scanInput)
+	if err != nil {
+		log.Printf("dynamodb scan error: %v", err)
+		return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
+	}
+
+	readings := make([]Reading, 0, len(scanOutput.Items))
+	for _, item := range scanOutput.Items {
+		var r Reading
+		err := attributevalue.UnmarshalMap(item, &r)
+		if err != nil {
+			// skip items that fail to unmarshal but log them
+			log.Printf("failed to unmarshal item: %v", err)
+			continue
+		}
+		readings = append(readings, r)
+	}
+
+	body := ResponseBody{Data: readings}
+	b, err := json.Marshal(body)
+	if err != nil {
+		log.Printf("failed to marshal response: %v", err)
+		return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
+	}
+
+	return events.APIGatewayV2HTTPResponse{
+		StatusCode: http.StatusOK,
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+		},
+		Body: string(b),
+	}, nil
+}
+
+func main() {
+	lambda.Start(handler)
+}