// Copyright 2016 The Prometheus 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 main

import (
	"fmt"
	"io/ioutil"
	"net/http"

	"github.com/golang/protobuf/proto"
	"github.com/golang/snappy"
	"github.com/prometheus/common/model"
	"golang.org/x/net/context"

	"github.com/prometheus/prometheus/storage/remote"
)

type server struct{}

func (server *server) Write(ctx context.Context, req *remote.WriteRequest) (*remote.WriteResponse, error) {
	for _, ts := range req.Timeseries {
		m := make(model.Metric, len(ts.Labels))
		for _, l := range ts.Labels {
			m[model.LabelName(l.Name)] = model.LabelValue(l.Value)
		}
		fmt.Println(m)

		for _, s := range ts.Samples {
			fmt.Printf("  %f %d\n", s.Value, s.TimestampMs)
		}
	}

	return &remote.WriteResponse{}, nil
}

func main() {
	http.Handle("/push", AppenderHandler(&server{}))
	http.ListenAndServe(":1234", nil)
}

type WriteServer interface {
	Write(context.Context, *remote.WriteRequest) (*remote.WriteResponse, error)
}

// AppenderHandler returns a http.Handler that accepts proto encoded samples.
func AppenderHandler(s WriteServer) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		reqBuf, err := ioutil.ReadAll(snappy.NewReader(r.Body))
		if err != nil {
			return
		}

		var req remote.WriteRequest
		if err := proto.Unmarshal(reqBuf, &req); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		if _, err := s.Write(context.Background(), &req); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		w.WriteHeader(http.StatusOK)
	})
}