package http

import (
	"fmt"
	"net/http"
	"reflect"
	"strings"
)

type HTTPAdapter struct {
}

// ServeHTTP
func (a *HTTPAdapter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		WriteError(w, 405, "rpc: POST method required, received "+r.Method)
		return
	}
	contentType := r.Header.Get("Content-Type")
	idx := strings.Index(contentType, ";")
	if idx != -1 {
		contentType = contentType[:idx]
	}
	var codec Codec
	if contentType == "" && len(s.codecs) == 1 {
		// If Content-Type is not set and only one codec has been registered,
		// then default to that codec.
		for _, c := range s.codecs {
			codec = c
		}
	} else if codec = s.codecs[strings.ToLower(contentType)]; codec == nil {
		WriteError(w, 415, "rpc: unrecognized Content-Type: "+contentType)
		return
	}
	// Create a new codec request.
	codecReq := codec.NewRequest(r)
	// Get service method to be called.
	method, errMethod := codecReq.Method()
	if errMethod != nil {
		codecReq.WriteError(w, 400, errMethod)
		return
	}
	serviceSpec, methodSpec, errGet := s.services.get(method)
	if errGet != nil {
		codecReq.WriteError(w, 400, errGet)
		return
	}
	// Decode the args.
	args := reflect.New(methodSpec.argsType)
	if errRead := codecReq.ReadRequest(args.Interface()); errRead != nil {
		codecReq.WriteError(w, 400, errRead)
		return
	}
	// Call the service method.
	reply := reflect.New(methodSpec.replyType)
	errValue := methodSpec.method.Func.Call([]reflect.Value{
		serviceSpec.rcvr,
		reflect.ValueOf(r),
		args,
		reply,
	})
	// Cast the result to error if needed.
	var errResult error
	errInter := errValue[0].Interface()
	if errInter != nil {
		errResult = errInter.(error)
	}
	// Prevents Internet Explorer from MIME-sniffing a response away
	// from the declared content-type
	w.Header().Set("x-content-type-options", "nosniff")
	// Encode the response.
	if errResult == nil {
		codecReq.WriteResponse(w, reply.Interface())
	} else {
		codecReq.WriteError(w, 400, errResult)
	}
}

func WriteError(w http.ResponseWriter, status int, msg string) {
	w.WriteHeader(status)
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	fmt.Fprint(w, msg)
}