/*
Copyright IBM Corp. 2017 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 main

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

	"github.com/hyperledger/fabric/common/tools/configtxlator/metadata"
	"github.com/hyperledger/fabric/common/tools/configtxlator/rest"
	"github.com/hyperledger/fabric/common/tools/configtxlator/update"
	"github.com/hyperledger/fabric/common/tools/protolator"
	cb "github.com/hyperledger/fabric/protos/common"

	"github.com/golang/protobuf/proto"
	"github.com/op/go-logging"
	"github.com/pkg/errors"
	"gopkg.in/alecthomas/kingpin.v2"
)

var logger = logging.MustGetLogger("configtxlator")

// command line flags
var (
	app = kingpin.New("configtxlator", "Utility for generating Hyperledger Fabric channel configurations")

	start    = app.Command("start", "Start the configtxlator REST server")
	hostname = start.Flag("hostname", "The hostname or IP on which the REST server will listen").Default("0.0.0.0").String()
	port     = start.Flag("port", "The port on which the REST server will listen").Default("7059").Int()

	protoEncode       = app.Command("proto_encode", "Converts a JSON document to protobuf.")
	protoEncodeType   = protoEncode.Flag("type", "The type of protobuf structure to encode to.  For example, 'common.Config'.").Required().String()
	protoEncodeSource = protoEncode.Flag("input", "A file containing the JSON document.").Default(os.Stdin.Name()).File()
	protoEncodeDest   = protoEncode.Flag("output", "A file to write the output to.").Default(os.Stdout.Name()).OpenFile(os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)

	protoDecode       = app.Command("proto_decode", "Converts a proto message to JSON.")
	protoDecodeType   = protoDecode.Flag("type", "The type of protobuf structure to decode from.  For example, 'common.Config'.").Required().String()
	protoDecodeSource = protoDecode.Flag("input", "A file containing the proto message.").Default(os.Stdin.Name()).File()
	protoDecodeDest   = protoDecode.Flag("output", "A file to write the JSON document to.").Default(os.Stdout.Name()).OpenFile(os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)

	computeUpdate          = app.Command("compute_update", "Takes two marshaled common.Config messages and computes the config update which transitions between the two.")
	computeUpdateOriginal  = computeUpdate.Flag("original", "The original config message.").File()
	computeUpdateUpdated   = computeUpdate.Flag("updated", "The updated config message.").File()
	computeUpdateChannelID = computeUpdate.Flag("channel_id", "The name of the channel for this update.").Required().String()
	computeUpdateDest      = computeUpdate.Flag("output", "A file to write the JSON document to.").Default(os.Stdout.Name()).OpenFile(os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)

	version = app.Command("version", "Show version information")
)

func main() {
	kingpin.Version("0.0.1")
	switch kingpin.MustParse(app.Parse(os.Args[1:])) {
	// "start" command
	case start.FullCommand():
		startServer(fmt.Sprintf("%s:%d", *hostname, *port))
	// "proto_encode" command
	case protoEncode.FullCommand():
		defer (*protoEncodeSource).Close()
		defer (*protoEncodeDest).Close()
		err := encodeProto(*protoEncodeType, *protoEncodeSource, *protoEncodeDest)
		if err != nil {
			app.Fatalf("Error decoding: %s", err)
		}
	case protoDecode.FullCommand():
		defer (*protoDecodeSource).Close()
		defer (*protoDecodeDest).Close()
		err := decodeProto(*protoDecodeType, *protoDecodeSource, *protoDecodeDest)
		if err != nil {
			app.Fatalf("Error decoding: %s", err)
		}
	case computeUpdate.FullCommand():
		defer (*computeUpdateOriginal).Close()
		defer (*computeUpdateUpdated).Close()
		defer (*computeUpdateDest).Close()
		err := computeUpdt(*computeUpdateOriginal, *computeUpdateUpdated, *computeUpdateDest, *computeUpdateChannelID)
		if err != nil {
			app.Fatalf("Error computing update: %s", err)
		}
	// "version" command
	case version.FullCommand():
		printVersion()
	}

}

func startServer(address string) {
	logger.Infof("Serving HTTP requests on %s", address)
	err := http.ListenAndServe(address, rest.NewRouter())

	app.Fatalf("Error starting server:[%s]\n", err)
}

func printVersion() {
	fmt.Println(metadata.GetVersionInfo())
}

func encodeProto(msgName string, input, output *os.File) error {
	msgType := proto.MessageType(msgName)
	if msgType == nil {
		return errors.Errorf("message of type %s unknown", msgType)
	}
	msg := reflect.New(msgType.Elem()).Interface().(proto.Message)

	err := protolator.DeepUnmarshalJSON(input, msg)
	if err != nil {
		return errors.Wrapf(err, "error decoding input")
	}

	out, err := proto.Marshal(msg)
	if err != nil {
		return errors.Wrapf(err, "error marshaling")
	}

	_, err = output.Write(out)
	if err != nil {
		return errors.Wrapf(err, "error writing output")
	}

	return nil
}

func decodeProto(msgName string, input, output *os.File) error {
	msgType := proto.MessageType(msgName)
	if msgType == nil {
		return errors.Errorf("message of type %s unknown", msgType)
	}
	msg := reflect.New(msgType.Elem()).Interface().(proto.Message)

	in, err := ioutil.ReadAll(input)
	if err != nil {
		return errors.Wrapf(err, "error reading input")
	}

	err = proto.Unmarshal(in, msg)
	if err != nil {
		return errors.Wrapf(err, "error unmarshaling")
	}

	err = protolator.DeepMarshalJSON(output, msg)
	if err != nil {
		return errors.Wrapf(err, "error encoding output")
	}

	return nil
}

func computeUpdt(original, updated, output *os.File, channelID string) error {
	origIn, err := ioutil.ReadAll(original)
	if err != nil {
		return errors.Wrapf(err, "error reading original config")
	}

	origConf := &cb.Config{}
	err = proto.Unmarshal(origIn, origConf)
	if err != nil {
		return errors.Wrapf(err, "error unmarshaling original config")
	}

	updtIn, err := ioutil.ReadAll(updated)
	if err != nil {
		return errors.Wrapf(err, "error reading updated config")
	}

	updtConf := &cb.Config{}
	err = proto.Unmarshal(updtIn, updtConf)
	if err != nil {
		return errors.Wrapf(err, "error unmarshaling updated config")
	}

	cu, err := update.Compute(origConf, updtConf)
	if err != nil {
		return errors.Wrapf(err, "error computing config update")
	}

	cu.ChannelId = channelID

	outBytes, err := proto.Marshal(cu)
	if err != nil {
		return errors.Wrapf(err, "error marshaling computed config update")
	}

	_, err = output.Write(outBytes)
	if err != nil {
		return errors.Wrapf(err, "error writing config update to output")
	}

	return nil
}