// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package dav

import (
	"bytes"
	"context"
	"encoding/xml"
)

// Proppatch describes a property update instruction as defined in RFC 4918.
// See http://www.webdav.org/specs/rfc4918.html#METHOD_PROPPATCH
type Proppatch struct {
	// Remove specifies whether this patch removes properties. If it does not
	// remove them, it sets them.
	Remove bool
	// Props contains the properties to be set or removed.
	Props []Property
}

// Propstat describes a XML propstat element as defined in RFC 4918.
// See http://www.webdav.org/specs/rfc4918.html#ELEMENT_propstat
type Propstat struct {
	// Props contains the properties for which Status applies.
	Props []Property

	// Status defines the HTTP status code of the properties in Prop.
	// Allowed values include, but are not limited to the WebDAV status
	// code extensions for HTTP/1.1.
	// http://www.webdav.org/specs/rfc4918.html#status.code.extensions.to.http11
	Status int

	// XMLError contains the XML representation of the optional error element.
	// XML content within this field must not rely on any predefined
	// namespace declarations or prefixes. If empty, the XML error element
	// is omitted.
	XMLError string

	// ResponseDescription contains the contents of the optional
	// responsedescription field. If empty, the XML element is omitted.
	ResponseDescription string
}


// DeadPropsHolder holds the dead properties of a resource.
//
// Dead properties are those properties that are explicitly defined. In
// comparison, live properties, such as DAV:getcontentlength, are implicitly
// defined by the underlying resource, and cannot be explicitly overridden or
// removed. See the Terminology section of
// http://www.webdav.org/specs/rfc4918.html#rfc.section.3
//
// There is a whitelist of the names of live properties. This package handles
// all live properties, and will only pass non-whitelisted names to the Patch
// method of DeadPropsHolder implementations.
type DeadPropsHolder interface {
	// DeadProps returns a copy of the dead properties held.
	DeadProps() (map[xml.Name]Property, error)

	// Patch patches the dead properties held.
	//
	// Patching is atomic; either all or no patches succeed. It returns (nil,
	// non-nil) if an internal server error occurred, otherwise the Propstats
	// collectively contain one Property for each proposed patch Property. If
	// all patches succeed, Patch returns a slice of length one and a Propstat
	// element with a 200 OK HTTP status code. If none succeed, for reasons
	// other than an internal server error, no Propstat has status 200 OK.
	//
	// For more details on when various HTTP status codes apply, see
	// http://www.webdav.org/specs/rfc4918.html#PROPPATCH-status
	Patch([]Proppatch) ([]Propstat, error)
}


func EscapeXML(s string) string {
	for i := 0; i < len(s); i++ {
		// As an optimization, if s contains only ASCII letters, digits or a
		// few special characters, the escaped value is s itself and we don't
		// need to allocate a buffer and convert between string and []byte.
		switch c := s[i]; {
		case c == ' ' || c == '_' ||
			('+' <= c && c <= '9') || // Digits as well as + , - . and /
			('A' <= c && c <= 'Z') ||
			('a' <= c && c <= 'z'):
			continue
		}
		// Otherwise, go through the full escaping process.
		var buf bytes.Buffer
		xml.EscapeText(&buf, []byte(s))
		return buf.String()
	}
	return s
}



// ContentTyper is an optional interface for the os.FileInfo
// objects returned by the FileSystem.
//
// If this interface is defined then it will be used to read the
// content type from the object.
//
// If this interface is not defined the file will be opened and the
// content type will be guessed from the initial contents of the file.
type ContentTyper interface {
	// ContentType returns the content type for the file.
	//
	// If this returns error ErrNotImplemented then the error will
	// be ignored and the base implementation will be used
	// instead.
	ContentType(ctx context.Context) (string, error)
}