/*
   Copyright (c) 2016 VMware, Inc. All Rights Reserved.
   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 test

import (
	"bytes"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
)

// RequestHandlerMapping is a mapping between request and its handler
type RequestHandlerMapping struct {
	// Method is the method the request used
	Method string
	// Pattern is the pattern the request must match
	Pattern string
	// Handler is the handler which handles the request
	Handler func(http.ResponseWriter, *http.Request)
}

// ServeHTTP ...
func (rhm *RequestHandlerMapping) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if len(rhm.Method) != 0 && r.Method != strings.ToUpper(rhm.Method) {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	rhm.Handler(w, r)
}

// Response is a response used for unit test
type Response struct {
	// StatusCode is the status code of the response
	StatusCode int
	// Headers are the headers of the response
	Headers map[string]string
	// Boby is the body of the response
	Body []byte
}

// Handler returns a handler function which handle requst according to
// the response provided
func Handler(resp *Response) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		if resp == nil {
			return
		}

		for k, v := range resp.Headers {
			w.Header().Add(http.CanonicalHeaderKey(k), v)
		}

		if resp.StatusCode == 0 {
			resp.StatusCode = http.StatusOK
		}
		w.WriteHeader(resp.StatusCode)

		if len(resp.Body) != 0 {
			io.Copy(w, bytes.NewReader(resp.Body))
		}
	}
}

// NewServer creates a HTTP server for unit test
func NewServer(mappings ...*RequestHandlerMapping) *httptest.Server {
	mux := http.NewServeMux()

	for _, mapping := range mappings {
		mux.Handle(mapping.Pattern, mapping)
	}

	return httptest.NewServer(mux)
}