package objectstorage

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"go.uber.org/zap"

	"github.com/geo-platform/tenant-api/internal/shared/config"
)

var ErrNotConfigured = errors.New("object storage is not configured")
var ErrObjectNotFound = errors.New("object storage object not found")
var ErrObjectNotPublic = errors.New("object storage object is not publicly readable")
var ErrUsageUnsupported = errors.New("object storage usage stat is not supported")

type Client interface {
	Validate() error
	PutBytes(ctx context.Context, objectKey string, content []byte, contentType string) error
	GetBytes(ctx context.Context, objectKey string) ([]byte, error)
	Exists(ctx context.Context, objectKey string) (bool, error)
	Delete(ctx context.Context, objectKey string) error
	PublicURL(objectKey string) (string, error)
	DownloadURL(objectKey string) (string, error)
}

type ReaderClient interface {
	PutReader(ctx context.Context, objectKey string, reader io.Reader, size int64, contentType string) error
}

type ObjectReaderClient interface {
	GetReader(ctx context.Context, objectKey string) (io.ReadCloser, error)
}

type PresignedPutResult struct {
	URL       string
	Headers   http.Header
	ExpiresAt time.Time
}

type PresignedPutClient interface {
	PresignedPutURL(ctx context.Context, objectKey string, contentType string, contentMD5Base64 string, ttl time.Duration) (*PresignedPutResult, error)
}

type ManagementClient interface {
	Client
	List(ctx context.Context, in ListInput) (*ListResult, error)
	Stat(ctx context.Context, objectKey string) (*ObjectInfo, error)
	Copy(ctx context.Context, sourceKey, destinationKey string) error
}

type UsageClient interface {
	Usage(ctx context.Context) (*UsageInfo, error)
}

type PublicReadableClient interface {
	PublicReadableURL(objectKey string) (string, error)
}

type ListInput struct {
	Prefix            string
	ContinuationToken string
	StartAfter        string
	Delimiter         string
	Limit             int
	Recursive         bool
}

type ListResult struct {
	Objects               []ObjectInfo `json:"objects"`
	CommonPrefixes        []string     `json:"common_prefixes"`
	ContinuationToken     string       `json:"continuation_token,omitempty"`
	NextContinuationToken string       `json:"next_continuation_token,omitempty"`
	IsTruncated           bool         `json:"is_truncated"`
	Prefix                string       `json:"prefix"`
	Delimiter             string       `json:"delimiter"`
}

type ObjectInfo struct {
	Key          string    `json:"key"`
	Size         int64     `json:"size"`
	ETag         string    `json:"etag,omitempty"`
	LastModified time.Time `json:"last_modified"`
	ContentType  string    `json:"content_type,omitempty"`
	StorageClass string    `json:"storage_class,omitempty"`
}

type UsageInfo struct {
	Available   bool   `json:"available"`
	Provider    string `json:"provider"`
	StorageSize int64  `json:"storage_size"`
	ObjectCount int64  `json:"object_count"`
}

func New(cfg config.ObjectStorageConfig, logger *zap.Logger) Client {
	provider := strings.ToLower(strings.TrimSpace(cfg.Provider))
	switch provider {
	case "", "disabled":
		return disabledClient{reason: "object storage is disabled"}
	case "minio", "mino", "r2", "cloudflare_r2", "cloudflare-r2", "s3", "aws_s3", "aws-s3", "custom", "custom_s3", "custom-s3":
		return NewMinIOClient(cfg, logger)
	case "aliyun", "aliyun_oss", "aliyun-oss", "oss":
		return NewAliyunClient(cfg, logger)
	default:
		return disabledClient{reason: fmt.Sprintf("unsupported object storage provider %q", cfg.Provider)}
	}
}

type disabledClient struct {
	reason string
}

func (c disabledClient) Validate() error {
	if c.reason == "" {
		c.reason = "missing object storage configuration"
	}
	return fmt.Errorf("%w: %s", ErrNotConfigured, c.reason)
}

func (c disabledClient) PutBytes(context.Context, string, []byte, string) error {
	return c.Validate()
}

func (c disabledClient) PutReader(context.Context, string, io.Reader, int64, string) error {
	return c.Validate()
}

func (c disabledClient) GetBytes(context.Context, string) ([]byte, error) {
	return nil, c.Validate()
}

func (c disabledClient) Exists(context.Context, string) (bool, error) {
	return false, c.Validate()
}

func (c disabledClient) Delete(context.Context, string) error {
	return c.Validate()
}

func (c disabledClient) PublicURL(string) (string, error) {
	return "", c.Validate()
}

func (c disabledClient) DownloadURL(string) (string, error) {
	return "", c.Validate()
}

func (c disabledClient) List(context.Context, ListInput) (*ListResult, error) {
	return nil, c.Validate()
}

func (c disabledClient) Stat(context.Context, string) (*ObjectInfo, error) {
	return nil, c.Validate()
}

func (c disabledClient) Copy(context.Context, string, string) error {
	return c.Validate()
}

func (c disabledClient) Usage(context.Context) (*UsageInfo, error) {
	return nil, c.Validate()
}