/*
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 client

import (
	"context"
	"fmt"
	"time"

	"github.com/sirupsen/logrus"
	"github.com/tarm/serial"

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

type Client struct {
	port     *serial.Port
	logger   *logrus.Logger
	framer   protocol.Framer
	in       chan []byte
	out      chan []byte
	commands chan *protocol.Command
	handler  protocol.ClientHandler
	config   *config.ClientConfig
}

func (c *Client) Run(ctx context.Context) error {
	protocolErrors := make(chan error)
	framerErrors := make(chan error)

	go func(f protocol.Framer) {
		framerErrors <- f.ReadFrames(c.port, c.in)
	}(c.framer)

	go func(f protocol.Framer) {
		framerErrors <- f.WriteFrames(c.port, c.out)
	}(c.framer)

	go func() {
		clientProtocol := protocol.NewClient(c.handler, c.commands, c.in, c.out, c.logger)

		protocolErrors <- clientProtocol.Handle()
	}()

	ctx, cancelCommandLoop := context.WithCancel(ctx)

	go c.commandLoop(ctx)

	for {
		select {
		case <-ctx.Done():
			cancelCommandLoop()

			return nil
		case err := <-framerErrors:
			cancelCommandLoop()

			if err != nil {
				return fmt.Errorf("error from framer: %w", err)
			}

			return nil
		case err := <-protocolErrors:
			cancelCommandLoop()

			if err != nil {
				return fmt.Errorf("error from protocol: %w", err)
			}

			return nil
		}
	}
}

func (c *Client) setupConnection(serialConfig *serial.Config) error {
	s, err := serial.OpenPort(serialConfig)
	if err != nil {
		return fmt.Errorf("could not open serial port: %w", err)
	}

	c.port = s

	return nil
}

func (c *Client) Close() error {
	close(c.in)
	close(c.out)

	if c.port != nil {
		err := c.port.Close()
		if err != nil {
			return fmt.Errorf("could not close serial port: %w", err)
		}
	}

	return nil
}

func (c *Client) commandLoop(ctx context.Context) {
	healthTimer := time.NewTimer(c.config.HealthStart)

	for {
		select {
		case <-ctx.Done():
			return
		case <-healthTimer.C:
			announce, err := messages.BuildCommandAnnounce(messages.CmdHealth)
			if err != nil {
				c.logger.WithError(err).Error("could not build health command announce")
			}

			c.commands <- &protocol.Command{
				Announce: announce,
				Command:  &messages.HealthCommand{},
			}

			healthTimer.Reset(c.config.HealthInterval)
		}
	}
}

func New(
	cfg *config.ClientConfig,
	logger *logrus.Logger,
	handler protocol.ClientHandler,
	commands chan *protocol.Command,
) (*Client, error) {
	client := &Client{
		logger:   logger,
		framer:   protocol.NewCOBSFramer(logger),
		in:       make(chan []byte),
		out:      make(chan []byte),
		commands: commands,
		handler:  handler,
		config:   cfg,
	}

	err := client.setupConnection(&serial.Config{
		Name:        cfg.Serial.Device,
		Baud:        cfg.Serial.Baud,
		ReadTimeout: cfg.Serial.Timeout,
	})
	if err != nil {
		return nil, err
	}

	return client, nil
}