// Copyright (C) 2018 LEAP
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package bitmask

import (
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"os"
	"time"

	"github.com/pebbe/zmq4"
)

const (
	// On win should be: tcp://127.0.0.1:5001
	coreEndpoint = "ipc://%s/bitmask.core.sock"
	timeout      = time.Second * 40
)

// Bitmask holds the bitmask client data
type Bitmask struct {
	coresoc  *zmq4.Socket
	eventsoc *zmq4.Socket
	statusCh chan string
}

// Init the connection to bitmask
func Init() (*Bitmask, error) {
	statusCh := make(chan string)
	coresoc, err := initCore()
	if err != nil {
		return nil, err
	}
	eventsoc, err := initEvents()
	if err != nil {
		return nil, err
	}

	coresoc.SetRcvtimeo(timeout)

	b := Bitmask{coresoc, eventsoc, statusCh}
	go b.eventsHandler()
	return &b, nil
}

// GetStatusCh returns a channel that will recieve VPN status changes
func (b *Bitmask) GetStatusCh() chan string {
	return b.statusCh
}

// Close the connection to bitmask
func (b *Bitmask) Close() {
	_, err := b.send("core", "stop")
	if err != nil {
		log.Printf("Got an error stopping bitmaskd: %v", err)
	}
	b.coresoc.Close()
}

func (b *Bitmask) send(parts ...interface{}) (map[string]interface{}, error) {
	_, err := b.coresoc.SendMessage(parts...)
	if err != nil {
		return nil, err
	}
	resJSON, err := b.coresoc.RecvBytes(0)
	if err != nil {
		return nil, err
	}
	return parseResponse(resJSON)
}

func parseResponse(resJSON []byte) (map[string]interface{}, error) {
	var response struct {
		Result map[string]interface{}
		Error  string
	}
	err := json.Unmarshal(resJSON, &response)
	if response.Error != "" {
		return nil, errors.New(response.Error)
	}
	return response.Result, err
}

func initCore() (*zmq4.Socket, error) {
	socket, err := zmq4.NewSocket(zmq4.REQ)
	if err != nil {
		return nil, err
	}

	endpointPwd := "/tmp"
	if os.Getenv("SNAP") != "" {
        endpointPwd = "/var/tmp"
	}
	err = socket.Connect(fmt.Sprintf(coreEndpoint, endpointPwd))
	return socket, err
}