package blob

import (
	"context"
	"fmt"
	"io"
	"strings"

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

// Uploader stores public avatar objects.
type Uploader interface {
	Enabled() bool
	Upload(ctx context.Context, key string, body io.Reader, contentType string, size int64) (publicURL string, err error)
}

// Disabled is a no-op uploader used when Spaces is not configured.
type Disabled struct{}

func (Disabled) Enabled() bool { return false }

func (Disabled) Upload(context.Context, string, io.Reader, string, int64) (string, error) {
	return "", fmt.Errorf("avatar uploads are not configured")
}

// SpacesConfig holds DigitalOcean Spaces settings.
type SpacesConfig struct {
	Key      string
	Secret   string
	Region   string
	Bucket   string
	Endpoint string // e.g. https://nyc3.digitaloceanspaces.com
	CDNBase  string // optional public base URL without trailing slash
}

// NewSpaces returns an Uploader when required env is present; otherwise Disabled.
func NewSpaces(cfg SpacesConfig) Uploader {
	cfg.Key = strings.TrimSpace(cfg.Key)
	cfg.Secret = strings.TrimSpace(cfg.Secret)
	cfg.Region = strings.TrimSpace(cfg.Region)
	cfg.Bucket = strings.TrimSpace(cfg.Bucket)
	cfg.Endpoint = strings.TrimSpace(cfg.Endpoint)
	cfg.CDNBase = strings.TrimRight(strings.TrimSpace(cfg.CDNBase), "/")
	if cfg.Key == "" || cfg.Secret == "" || cfg.Region == "" || cfg.Bucket == "" || cfg.Endpoint == "" {
		return Disabled{}
	}
	client := s3.New(s3.Options{
		Region: cfg.Region,
		Credentials: credentials.NewStaticCredentialsProvider(cfg.Key, cfg.Secret, ""),
		BaseEndpoint: aws.String(cfg.Endpoint),
	})
	return &spaces{client: client, cfg: cfg}
}

type spaces struct {
	client *s3.Client
	cfg    SpacesConfig
}

func (s *spaces) Enabled() bool { return true }

func (s *spaces) Upload(ctx context.Context, key string, body io.Reader, contentType string, size int64) (string, error) {
	key = strings.TrimPrefix(key, "/")
	input := &s3.PutObjectInput{
		Bucket:      aws.String(s.cfg.Bucket),
		Key:         aws.String(key),
		Body:        body,
		ContentType: aws.String(contentType),
		ACL:         types.ObjectCannedACLPublicRead,
	}
	if size > 0 {
		input.ContentLength = aws.Int64(size)
	}
	if _, err := s.client.PutObject(ctx, input); err != nil {
		return "", err
	}
	if s.cfg.CDNBase != "" {
		return s.cfg.CDNBase + "/" + key, nil
	}
	// Virtual-hosted–style Spaces URL.
	host := strings.TrimPrefix(s.cfg.Endpoint, "https://")
	host = strings.TrimPrefix(host, "http://")
	return fmt.Sprintf("https://%s.%s/%s", s.cfg.Bucket, host, key), nil
}