// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package etcdhttp

import (
	"errors"
	"log"
	"math"
	"net/http"
	"strings"
	"time"

	etcdErr "github.com/coreos/etcd/error"
	"github.com/coreos/etcd/etcdserver/etcdhttp/httptypes"
)

const (
	// time to wait for response from EtcdServer requests
	// 5s for disk and network delay + 10*heartbeat for commit and possible
	// leader switch
	// TODO: use heartbeat set in etcdserver
	defaultServerTimeout = 5*time.Second + 10*(100*time.Millisecond)

	// time to wait for a Watch request
	defaultWatchTimeout = time.Duration(math.MaxInt64)
)

var errClosed = errors.New("etcdhttp: client closed connection")

// writeError logs and writes the given Error to the ResponseWriter
// If Error is an etcdErr, it is rendered to the ResponseWriter
// Otherwise, it is assumed to be an InternalServerError
func writeError(w http.ResponseWriter, err error) {
	if err == nil {
		return
	}
	switch e := err.(type) {
	case *etcdErr.Error:
		e.WriteTo(w)
	case *httptypes.HTTPError:
		e.WriteTo(w)
	default:
		log.Printf("etcdhttp: unexpected error: %v", err)
		herr := httptypes.NewHTTPError(http.StatusInternalServerError, "Internal Server Error")
		herr.WriteTo(w)
	}
}

// allowMethod verifies that the given method is one of the allowed methods,
// and if not, it writes an error to w.  A boolean is returned indicating
// whether or not the method is allowed.
func allowMethod(w http.ResponseWriter, m string, ms ...string) bool {
	for _, meth := range ms {
		if m == meth {
			return true
		}
	}
	w.Header().Set("Allow", strings.Join(ms, ","))
	http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
	return false
}