/*
Copyright 2021 The Dapr Authors
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 http

import (
	"errors"
	"io"
	"net/http"
	"strings"

	"github.com/dapr/go-sdk/service/common"
)

// AddBindingInvocationHandler appends provided binding invocation handler with its route to the service.
func (s *Server) AddBindingInvocationHandler(route string, fn common.BindingInvocationHandler) error {
	if route == "" {
		return errors.New("binding route required")
	}
	if fn == nil {
		return errors.New("binding handler required")
	}

	if !strings.HasPrefix(route, "/") {
		route = "/" + route
	}

	s.mux.Handle(route, optionsHandler(http.HandlerFunc(
		func(w http.ResponseWriter, r *http.Request) {
			var (
				content []byte
				err     error
			)
			if r.Body != nil {
				content, err = io.ReadAll(r.Body)
				if err != nil {
					http.Error(w, err.Error(), http.StatusBadRequest)
					return
				}
			}

			// assuming Dapr doesn't pass multiple values for key
			meta := map[string]string{}
			for k, values := range r.Header {
				// TODO: Need to figure out how to parse out only the headers set in the binding + Traceparent
				// if k == "raceparent" || strings.HasPrefix(k, "dapr") {
				for _, v := range values {
					meta[k] = v
				}
				// }
			}

			// execute handler
			in := &common.BindingEvent{
				Data:     content,
				Metadata: meta,
			}
			out, err := fn(r.Context(), in)
			if err != nil {
				http.Error(w, err.Error(), http.StatusInternalServerError)
				return
			}

			if out == nil {
				out = []byte("{}")
			}

			w.Header().Add("Content-Type", "application/json")
			if _, err := w.Write(out); err != nil {
				http.Error(w, err.Error(), http.StatusInternalServerError)
				return
			}
		})))

	return nil
}
