/*
Copyright 2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0

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 handler

import (
	"fmt"
	"time"

	"github.com/shamaton/msgpackgen/msgpack"
	"github.com/sirupsen/logrus"

	"git.cacert.org/cacert-gosignerclient/internal/client"

	"git.cacert.org/cacert-gosigner/pkg/messages"

	"git.cacert.org/cacert-gosigner/pkg/protocol"
	"git.cacert.org/cacert-gosignerclient/internal/config"
)

type SignerClientHandler struct {
	logger         *logrus.Logger
	commands       chan *protocol.Command
	config         *config.ClientConfig
	clientCallback chan interface{}
}

func (s *SignerClientHandler) Send(command *protocol.Command, out chan []byte) error {
	var (
		frame []byte
		err   error
	)

	frame, err = msgpack.Marshal(command.Announce)
	if err != nil {
		return fmt.Errorf("could not marshal command annoucement: %w", err)
	}

	s.logger.WithField("announcement", command.Announce).Debug("write command announcement")

	s.logger.Trace("writing command announcement")

	out <- frame

	frame, err = msgpack.Marshal(command.Command)
	if err != nil {
		return fmt.Errorf("could not marshal command data: %w", err)
	}

	s.logger.WithField("command", command.Command).Debug("write command data")

	out <- frame

	return nil
}

func (s *SignerClientHandler) ResponseAnnounce(in chan []byte) (*protocol.Response, error) {
	response := &protocol.Response{}

	var announce messages.ResponseAnnounce

	select {
	case frame := <-in:
		if err := msgpack.Unmarshal(frame, &announce); err != nil {
			return nil, fmt.Errorf("could not unmarshal response announcement: %w", err)
		}

		response.Announce = &announce

		s.logger.WithField("announcement", response.Announce).Debug("received response announcement")

		return response, nil
	case <-time.After(s.config.ResponseAnnounceTimeout):
		return nil, protocol.ErrResponseAnnounceTimeoutExpired
	}
}

func (s *SignerClientHandler) ResponseData(in chan []byte, response *protocol.Response) error {
	select {
	case frame := <-in:
		switch response.Announce.Code {
		case messages.RespHealth:
			var resp messages.HealthResponse
			if err := msgpack.Unmarshal(frame, &resp); err != nil {
				return fmt.Errorf("could not unmarshal health response data: %w", err)
			}

			response.Response = &resp
		case messages.RespFetchCRL:
			var resp messages.FetchCRLResponse
			if err := msgpack.Unmarshal(frame, &resp); err != nil {
				return fmt.Errorf("could not unmarshal fetch CRL response data: %w", err)
			}

			response.Response = &resp
		case messages.RespError:
			var resp messages.ErrorResponse
			if err := msgpack.Unmarshal(frame, &resp); err != nil {
				return fmt.Errorf("could not unmarshal error response data: %w", err)
			}

			response.Response = &resp
		default:
			return fmt.Errorf("unhandled response code %s", response.Announce.Code)
		}
	case <-time.After(s.config.ResponseDataTimeout):
		return protocol.ErrResponseDataTimeoutExpired
	}

	return nil
}

func (s *SignerClientHandler) HandleResponse(response *protocol.Response) error {
	s.logger.WithField("response", response.Announce).Info("handled response")
	s.logger.WithField("response", response).Debug("full response")

	switch r := response.Response.(type) {
	case *messages.ErrorResponse:
		s.logger.WithField("message", r.Message).Error("error from signer")
	case *messages.HealthResponse:
		s.handleHealthResponse(r)
	case *messages.FetchCRLResponse:
		s.handleFetchCRLResponse(r)
	default:
		s.logger.WithField("response", response).Warnf("unhandled response of type %T", response.Response)
	}

	return nil
}

func (s *SignerClientHandler) handleHealthResponse(r *messages.HealthResponse) {
	signerInfo := client.SignerInfo{}

	signerInfo.SignerHealth = r.Healthy
	signerInfo.SignerVersion = r.Version

	if !r.Healthy {
		// it might be a good idea to notify monitoring if the signer is not OK
		s.logger.Error("signer is not healthy")
	}

	for _, item := range r.Info {
		if !item.Healthy {
			s.logger.WithField("component", item.Source).Error("signer component is not healthy")
		}

		switch item.Source {
		case "HSM":
			signerInfo.CACertificates = make([]client.CertInfo, 0)
			signerInfo.UsableProfiles = make(map[string][]client.Profile)

			for certName, value := range item.MoreInfo {
				certInfo, err := messages.ParseCertificateInfo(value)
				if err != nil {
					s.logger.WithError(err).Error("could not parse certificate information")

					break
				}

				s.logger.WithFields(map[string]interface{}{
					"certificate": certName,
					"signing":     certInfo.Signing,
					"profiles":    certInfo.Profiles,
					"status":      certInfo.Status,
					"valid-until": certInfo.ValidUntil,
				}).Trace("certificate info")

				signerInfo.CACertificates = append(
					signerInfo.CACertificates,
					client.CertInfo{Name: certName, FetchCRL: certInfo.Signing},
				)

				if certInfo.Signing {
					for _, profile := range certInfo.Profiles {
						signerInfo.UsableProfiles[certName] = append(
							signerInfo.UsableProfiles[certName],
							client.Profile{Name: profile.Name, UseFor: string(profile.UseFor)},
						)
					}
				}
			}
		default:
			s.logger.WithField("source", item.Source).Warn("unhandled health source")
		}
	}

	s.clientCallback <- signerInfo
}

func (s *SignerClientHandler) handleFetchCRLResponse(r *messages.FetchCRLResponse) {
	s.clientCallback <- r
}

func New(
	config *config.ClientConfig,
	logger *logrus.Logger,
	commands chan *protocol.Command,
	clientCallback chan interface{},
) (protocol.ClientHandler, error) {
	return &SignerClientHandler{
		logger:         logger,
		config:         config,
		commands:       commands,
		clientCallback: clientCallback,
	}, nil
}