/*
 * Mini Object Storage, (C) 2015 Minio, 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 minioapi

import (
	"net/http"
	"strings"

	"github.com/minio-io/minio/pkg/utils/config"
	"github.com/minio-io/minio/pkg/utils/crypto/signers"
)

type vHandler struct {
	conf    config.Config
	handler http.Handler
}

type rHandler struct {
	handler http.Handler
}

// grab AccessKey from authorization header
func stripAccessKey(r *http.Request) string {
	fields := strings.Fields(r.Header.Get("Authorization"))
	if len(fields) < 2 {
		return ""
	}
	splits := strings.Split(fields[1], ":")
	if len(splits) < 2 {
		return ""
	}
	return splits[0]
}

func validateHandler(conf config.Config, h http.Handler) http.Handler {
	return vHandler{conf, h}
}

func (h vHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	accessKey := stripAccessKey(r)
	acceptsContentType := getContentType(r)
	if accessKey != "" {
		if err := h.conf.ReadConfig(); err != nil {
			error := errorCodeError(InternalError)
			errorResponse := getErrorResponse(error, "")
			w.WriteHeader(error.HttpStatusCode)
			w.Write(writeErrorResponse(w, errorResponse, acceptsContentType))
		} else {
			user := h.conf.GetKey(accessKey)
			ok, _ := signers.ValidateRequest(user, r)
			if ok {
				h.handler.ServeHTTP(w, r)
			} else {
				error := errorCodeError(AccessDenied)
				errorResponse := getErrorResponse(error, "")
				w.WriteHeader(error.HttpStatusCode)
				w.Write(writeErrorResponse(w, errorResponse, acceptsContentType))
			}
		}
	} else {
		//No access key found, handle this more appropriately
		//TODO: Remove this after adding tests to support signature
		//request
		h.handler.ServeHTTP(w, r)
		//Add this line, to reply back for invalid requests
		//w.WriteHeader(http.StatusUnauthorized)
		//w.Write([]byte("Authorization header malformed")
	}
}

func ignoreResourcesHandler(h http.Handler) http.Handler {
	return rHandler{h}
}

func (h rHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	acceptsContentType := getContentType(r)
	if ignoreUnImplementedObjectResources(r) || ignoreUnImplementedBucketResources(r) {
		error := errorCodeError(NotImplemented)
		errorResponse := getErrorResponse(error, "")
		w.WriteHeader(error.HttpStatusCode)
		w.Write(writeErrorResponse(w, errorResponse, acceptsContentType))
	} else {
		h.handler.ServeHTTP(w, r)
	}
}

//// helpers

// Checks requests for unimplemented resources
func ignoreUnImplementedBucketResources(req *http.Request) bool {
	q := req.URL.Query()
	for name := range q {
		if unimplementedBucketResourceNames[name] {
			return true
		}
	}
	return false
}

func ignoreUnImplementedObjectResources(req *http.Request) bool {
	q := req.URL.Query()
	for name := range q {
		if unimplementedObjectResourceNames[name] {
			return true
		}
	}
	return false
}