package services

import (
	"context"
	"fmt"
	"strings"
	"time"

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

var S3Client S3

type S3 interface {
	GetPresignedURL(ctx context.Context, key, contentType string, expiry time.Duration) (string, error)
	DoesFileExist(ctx context.Context, key string) (bool, error)
}

type S3Concrete struct {
	S3Client *s3.Client
	Bucket   string
}

func (svc S3Concrete) GetPresignedURL(ctx context.Context, key, contentType string, expiry time.Duration) (string, error) {
	presignClient := s3.NewPresignClient(svc.S3Client)

	request, err := presignClient.PresignPutObject(ctx, &s3.PutObjectInput{
		Bucket:      &svc.Bucket,
		Key:         &key,
		ContentType: &contentType,
	}, s3.WithPresignExpires(expiry))
	if err != nil {
		return "", err
	}

	return request.URL, nil
}

func (svc S3Concrete) DoesFileExist(ctx context.Context, key string) (bool, error) {
	_, error := svc.S3Client.HeadObject(ctx, &s3.HeadObjectInput{
		Bucket: &svc.Bucket,
		Key:    &key,
	})

	if error != nil {
		return false, error
	}

	return true, nil
}

// AssertSuccessfulConnection verifies that the bucket is reachable and that
// the configured credentials can get, put, and presign objects in it. It
// panics with a descriptive message on the first check that fails, since the
// service cannot function without these permissions.
func (svc S3Concrete) AssertSuccessfulConnection(ctx context.Context) {
	if _, err := svc.S3Client.HeadBucket(ctx, &s3.HeadBucketInput{
		Bucket: &svc.Bucket,
	}); err != nil {
		panic(fmt.Errorf("s3: cannot connect to bucket %q: %w", svc.Bucket, err))
	}

	const probeKey = ".s3-connectivity-check"

	if _, err := svc.S3Client.PutObject(ctx, &s3.PutObjectInput{
		Bucket: &svc.Bucket,
		Key:    aws.String(probeKey),
		Body:   strings.NewReader("ok"),
	}); err != nil {
		panic(fmt.Errorf("s3: missing permission to put objects in bucket %q: %w", svc.Bucket, err))
	}

	object, err := svc.S3Client.GetObject(ctx, &s3.GetObjectInput{
		Bucket: &svc.Bucket,
		Key:    aws.String(probeKey),
	})
	if err != nil {
		panic(fmt.Errorf("s3: missing permission to get objects from bucket %q: %w", svc.Bucket, err))
	}
	object.Body.Close()

	if _, err := svc.GetPresignedURL(ctx, probeKey, "text/plain", time.Minute); err != nil {
		panic(fmt.Errorf("s3: cannot create presigned urls for bucket %q: %w", svc.Bucket, err))
	}
}