package main

import (
	"bytes"
	"context"
	"fmt"
	"io"

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

var s3Client *s3.Client

func initS3() error {
	cfg, err := config.LoadDefaultConfig(context.Background(), config.WithRegion("us-east-1"))
	if err != nil {
		return err
	}
	s3Client = s3.NewFromConfig(cfg)
	return nil
}

// s3Download fetches an object from S3.
func s3Download(ctx context.Context, bucket, key string) ([]byte, error) {
	resp, err := s3Client.GetObject(ctx, &s3.GetObjectInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
	})
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	return io.ReadAll(resp.Body)
}

// s3UploadBundle uploads a bundle JSON to S3.
func s3UploadBundle(ctx context.Context, bucket, key string, data []byte) error {
	_, err := s3Client.PutObject(ctx, &s3.PutObjectInput{
		Bucket:      aws.String(bucket),
		Key:         aws.String(key),
		Body:        bytes.NewReader(data),
		ContentType: aws.String("application/json"),
	})
	return err
}

// s3DeletePrefix deletes all objects under a prefix in S3.
func s3DeletePrefix(ctx context.Context, bucket, prefix string) error {
	paginator := s3.NewListObjectsV2Paginator(s3Client, &s3.ListObjectsV2Input{
		Bucket: aws.String(bucket),
		Prefix: aws.String(prefix),
	})

	for paginator.HasMorePages() {
		page, err := paginator.NextPage(ctx)
		if err != nil {
			return err
		}
		if len(page.Contents) == 0 {
			continue
		}

		var objects []types.ObjectIdentifier
		for _, obj := range page.Contents {
			objects = append(objects, types.ObjectIdentifier{Key: obj.Key})
		}

		_, err = s3Client.DeleteObjects(ctx, &s3.DeleteObjectsInput{
			Bucket: aws.String(bucket),
			Delete: &types.Delete{Objects: objects},
		})
		if err != nil {
			return fmt.Errorf("delete batch: %w", err)
		}
	}
	return nil
}