// Package storage defines streaming object storage; callers own returned bodies.
package storage

import (
	"context"
	"errors"
	"io"
	"net/url"
	"strings"
	"time"
	"unicode"
	"unicode/utf8"
)

var ErrNotFound = errors.New("storage: object not found")
var ErrTooLarge = errors.New("storage: object exceeds limit")

type Info struct {
	Key         string    `json:"key"`
	Size        int64     `json:"size"`
	ContentType string    `json:"contentType"`
	ModifiedAt  time.Time `json:"modifiedAt"`
}
type Object struct {
	Info
	Body io.ReadCloser
}
type Store interface {
	Put(context.Context, string, io.Reader, int64, string) (Info, error)
	Get(context.Context, string) (Object, error)
	Delete(context.Context, string) error
}

// Presigner is an optional capability. URLs grant temporary read access and
// must not be logged. Providers may expire them earlier when credentials expire.
type Presigner interface {
	PresignGet(context.Context, string, time.Duration) (*url.URL, error)
}

func Check(ctx context.Context, key string) error {
	if ctx == nil {
		return errors.New("storage: nil context")
	}
	if err := ctx.Err(); err != nil {
		return err
	}
	if key == "" || len(key) > 1024 || !utf8.ValidString(key) || strings.Contains(key, "\\") || strings.IndexFunc(key, unicode.IsControl) >= 0 {
		return errors.New("storage: invalid key")
	}
	for _, part := range strings.Split(key, "/") {
		if part == "" || part == "." || part == ".." {
			return errors.New("storage: invalid key path")
		}
	}
	return nil
}

type ContextReader struct {
	Context context.Context
	Reader  io.Reader
}

func (r ContextReader) Read(p []byte) (int, error) {
	if err := r.Context.Err(); err != nil {
		return 0, err
	}
	return r.Reader.Read(p)
}