package main

import (
	"context"
	"fmt"
	"io"
	"log"
	"os"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/service/s3"
)

func main() {
	ctx := context.Background()

	// Create AWS config with anonymous credentials
	cfg, err := config.LoadDefaultConfig(ctx,
		config.WithRegion("us-east-1"),
		config.WithCredentialsProvider(aws.AnonymousCredentials{}),
	)
	if err != nil {
		log.Fatalf("Failed to load config: %v", err)
	}

	client := s3.NewFromConfig(cfg)

	// Try to download a single file
	bucket := "noaa-gfs-bdp-pds"
	key := "gfs.20251020/00/atmos/gfs.t00z.pgrb2.0p50.f000"

	fmt.Printf("Downloading: s3://%s/%s\n", bucket, key)

	input := &s3.GetObjectInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
	}

	result, err := client.GetObject(ctx, input)
	if err != nil {
		log.Fatalf("Failed to get object: %v", err)
	}
	defer result.Body.Close()

	// Create output file
	outFile := "/tmp/test_grib.part"
	f, err := os.Create(outFile)
	if err != nil {
		log.Fatalf("Failed to create file: %v", err)
	}
	defer f.Close()

	// Copy data
	written, err := io.Copy(f, result.Body)
	if err != nil {
		log.Fatalf("Failed to copy data: %v (wrote %d bytes)", err, written)
	}

	fmt.Printf("Successfully downloaded %d bytes\n", written)

	// Rename
	if err := os.Rename(outFile, "/tmp/test_grib"); err != nil {
		log.Fatalf("Failed to rename: %v", err)
	}

	fmt.Println("Download complete!")
}