package cache

import (
	"errors"
	"fmt"
	"path/filepath"

	"github.com/minio/minio-go/v7/pkg/credentials"

	"github.com/opencloud-eu/opencloud/pkg/config/defaults"
)

var ErrCacheMiss = errors.New("thumbnail cache miss")

// DefaultFileCacheDir is the on-disk location of file-backend thumbnails:
// $OC_BASE_DATA_PATH/thumbnails/cache. It is not the files directory the old
// thumbnails service wrote to: the keys changed, nothing in there is read again,
// and keeping the two apart lets that directory be deleted as a whole.
func DefaultFileCacheDir() string {
	return filepath.Join(defaults.BaseDataPath(), "thumbnails", "cache")
}

// ThumbnailCache provides cached storage for generated thumbnails.
type ThumbnailCache interface {
	Get(key string) ([]byte, error)
	Put(key string, data []byte) error
}

// NewThumbnailCache creates a cache instance based on the configured backend. A
// backend nobody can serve is an error, not a silently disabled cache.
func NewThumbnailCache(backend string, cacheDir string, s3cfg *S3CacheConfig) (ThumbnailCache, error) {
	switch backend {
	case "none":
		return NoopCache{}, nil
	case "memory":
		return NewInMemoryCache(), nil
	case "file":
		dir := cacheDir
		if dir == "" {
			dir = DefaultFileCacheDir()
		}
		return NewFileCache(dir), nil
	case "s3":
		if s3cfg == nil || !s3cfg.IsComplete() {
			return nil, errors.New("s3 thumbnail cache needs a bucket, a region and credentials")
		}
		return NewS3Cache(*s3cfg), nil
	default:
		return nil, fmt.Errorf("unknown thumbnail cache backend %q, expected none, memory, file or s3", backend)
	}
}

// BuildS3CacheConfig creates an S3CacheConfig from raw config fields.
func BuildS3CacheConfig(bucket, region, endpoint, accessKey, secretKey string) *S3CacheConfig {
	cfg := &S3CacheConfig{
		Bucket:   bucket,
		Region:   region,
		Endpoint: endpoint,
		Secure:   true,
	}
	if accessKey != "" && secretKey != "" {
		cfg.Credentials = credentials.NewStaticV4(accessKey, secretKey, "")
	}
	return cfg
}