// Copyright (c) 2020, Objective Security Corporation

// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.

// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"strconv"
	"time"

	"github.com/docker/go-plugins-helpers/volume"
	log "github.com/sirupsen/logrus"
)

type ofsVolume struct {
	volume  *volume.Volume
	fs      string
	opts    string
	env     []string
	use     map[string]bool
	mounted bool
	asap    bool
}

type ofsDriver struct {
	//sync.RWMutex
	volumes map[string]*ofsVolume
	defEnv  map[string]string
}

var version = "1.0"

func (d ofsDriver) Create(r *volume.CreateRequest) error {
	log.WithFields(log.Fields{"name": r.Name}).Info("Create ObjectiveFS Volume")
	//d.Lock()
	//defer d.Unlock()

	if _, ok := d.volumes[r.Name]; ok {
		return fmt.Errorf("volume '%s' already exists", r.Name)
	}
	v := &ofsVolume{}
	v.volume = &volume.Volume{Name: r.Name, Mountpoint: filepath.Join(volume.DefaultDockerRootDirectory, "objectivefs", r.Name), CreatedAt: time.Now().Format(time.RFC3339Nano)}
	v.use = make(map[string]bool)
	v.opts = ""
	v.fs = r.Name
	env := make(map[string]string)
	for id, val := range d.defEnv {
		env[id] = val
	}
	for key, val := range r.Options {
		switch key {
		case "fs":
			v.fs = val
		case "options", "ptions":
			v.opts = v.opts + "," + val
		case "asap":
			v.asap = true
		default:
			env[key] = val
		}
	}
	for id, val := range env {
		v.env = append(v.env, id+"="+val)
	}

	d.volumes[r.Name] = v
	return nil
}

func (d ofsDriver) List() (*volume.ListResponse, error) {
	//d.Lock()
	//defer d.Unlock()

	var vs []*volume.Volume
	for _, v := range d.volumes {
		vs = append(vs, v.volume)
	}
	return &volume.ListResponse{Volumes: vs}, nil
}

func (d ofsDriver) Get(r *volume.GetRequest) (*volume.GetResponse, error) {
	//d.Lock()
	//defer d.Unlock()

	v, ok := d.volumes[r.Name]
	if !ok {
		return &volume.GetResponse{}, fmt.Errorf("volume '%s' not found", r.Name)
	}
	return &volume.GetResponse{Volume: v.volume}, nil
}

func umount(v *ofsVolume) error {
	log.WithFields(log.Fields{"name": v.volume.Name}).Info("Unmount ObjectiveFS Volume")
	if !v.mounted {
		return nil
	}
	if err := exec.Command("umount", v.volume.Mountpoint).Run(); err != nil {
		return err
	}
	if err := os.Remove(v.volume.Mountpoint); err != nil {
		return err
	}
	v.mounted = false
	return nil
}

func (d ofsDriver) Remove(r *volume.RemoveRequest) error {
	//d.Lock()
	//defer d.Unlock()

	v, ok := d.volumes[r.Name]
	if !ok {
		return fmt.Errorf("volume '%s' not found", r.Name)
	}
	if len(v.use) != 0 {
		return fmt.Errorf("volume '%s' currently in use (%d unique)", r.Name, len(v.use))
	}
	if err := umount(v); err != nil {
		return err
	}
	delete(d.volumes, r.Name)
	return nil
}

func (d ofsDriver) Path(r *volume.PathRequest) (*volume.PathResponse, error) {
	//d.Lock()
	//defer d.Unlock()

	v, ok := d.volumes[r.Name]
	if !ok {
		return &volume.PathResponse{}, fmt.Errorf("volume '%s' not found", r.Name)
	}
	return &volume.PathResponse{Mountpoint: v.volume.Mountpoint}, nil
}

func (d ofsDriver) Mount(r *volume.MountRequest) (*volume.MountResponse, error) {
	//d.Lock()
	//defer d.Unlock()

	v, ok := d.volumes[r.Name]
	if !ok {
		return &volume.MountResponse{}, fmt.Errorf("volume '%s' not found", r.Name)
	}
	log.WithFields(log.Fields{"name": r.Name, "id": r.ID}).Info("Attach ObjectiveFS Volume")
	if !v.mounted {
		if err := os.MkdirAll(v.volume.Mountpoint, 0755); err != nil {
			return &volume.MountResponse{}, err
		}

		// Note: The first argument ("mount") causes running in the foreground, its absence in the background
		var cmd *exec.Cmd
		if len(v.opts) == 0 {
			cmd = exec.Command("/sbin/mount.objectivefs", "mount", v.fs, v.volume.Mountpoint)
		} else {
			cmd = exec.Command("/sbin/mount.objectivefs", "mount", "-o"+v.opts, v.fs, v.volume.Mountpoint)
		}

		cmd.Env = v.env
		cmdReader, _ := cmd.StderrPipe()
		log.WithFields(log.Fields{
			"name": r.Name,
			"cmd":  cmd,
			//"env":  v.env, // for security reasons disabled
		}).Info("Mount ObjectiveFS Volume")
		scanner := bufio.NewScanner(cmdReader)
		go func() {
			for scanner.Scan() {
				log.WithFields(log.Fields{"name": r.Name}).Info(scanner.Text())
			}
			log.WithFields(log.Fields{"name": r.Name}).Info("Completing mount process")
			cmd.Wait()
			log.WithFields(log.Fields{"name": r.Name}).Info("Completed mount process")
		}()
		if err := cmd.Start(); err != nil {
			return &volume.MountResponse{}, fmt.Errorf("unexpected error mounting '%s' error: %s", r.Name, err.Error())
		}
		log.WithFields(log.Fields{"name": r.Name}).Info("Process starting")

		// The drawback of running the mount in the foreground is there is no way to tell if it failed
		// to initially connect. So we just wait a fixed amount of time and check for process exit.
		time.Sleep(1 * time.Second)
		log.WithFields(log.Fields{"name": r.Name}).Info("Process started")
		if cmd.ProcessState.Exited() {
			log.WithFields(log.Fields{"name": r.Name, "exitStatus": cmd.ProcessState.ExitCode()}).Error("Volume mount failed")
			return &volume.MountResponse{}, fmt.Errorf("unexpected error mounting '%s' exist status: %v", r.Name, cmd.ProcessState.ExitCode())
		}

		log.WithFields(log.Fields{"name": r.Name}).Info("Volume mounted")
		v.mounted = true
	}
	v.use[r.ID] = true
	return &volume.MountResponse{Mountpoint: v.volume.Mountpoint}, nil
}

func (d ofsDriver) Unmount(r *volume.UnmountRequest) error {
	//d.Lock()
	//defer d.Unlock()

	v, ok := d.volumes[r.Name]
	if !ok {
		return fmt.Errorf("volume '%s' not found", r.Name)
	}
	log.WithFields(log.Fields{"name": r.Name, "id": r.ID}).Info("Detach ObjectiveFS Volume")
	delete(v.use, r.ID)
	if len(v.use) == 0 && v.asap {
		if err := umount(v); err != nil {
			return err
		}
	}
	return nil
}

func (d ofsDriver) Capabilities() *volume.CapabilitiesResponse {
	//d.Lock()
	//defer d.Unlock()

	return &volume.CapabilitiesResponse{Capabilities: volume.Capability{Scope: "local"}}
}

var (
	logLevel    = flag.String("log", "", "log level")
	logFilePath = flag.String("logfile", "", "log file")
)

func main() {
	flag.Parse()

	if *logLevel == "" {
		if *logLevel = os.Getenv("LOG_LEVEL"); *logLevel == "" {
			*logLevel = "info"
		}
	}

	level, err := log.ParseLevel(*logLevel)
	if err != nil {
		log.WithError(err).Fatal("Failed to parse log level")
	}
	log.SetLevel(level)

	if *logFilePath != "" {
		f, err := os.OpenFile(*logFilePath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
		if err != nil {
			log.WithError(err).Fatal("Failed to open log file for writing")
		}
		defer f.Close()

		log.StandardLogger().Out = f
	}
	log.Info("Starting ObjectiveFS Volume Driver, version " + version)

	defEnv := make(map[string]string)
	for _, i := range []string{"ACCESS_KEY", "SECRET_KEY", "OBJECTIVEFS_LICENSE", "OBJECTSTORE", "ENDPOINT", "CACHESIZE", "DISKCACHE_SIZE", "DISKCACHE_PATH", "OBJECTIVEFS_PASSPHRASE"} {
		if a := os.Getenv(i); a != "" {
			defEnv[i] = a
		}
	}

	d := ofsDriver{volumes: make(map[string]*ofsVolume), defEnv: defEnv}
	h := volume.NewHandler(d)
	u, _ := user.Lookup("root")
	gid, _ := strconv.Atoi(u.Gid)
	if err := h.ServeUnix("/run/docker/plugins/objectivefs", gid); err != nil {
		log.Fatal(err)
	}
}