package docker

import (
	"context"
	"errors"
	"io"
	"io/ioutil"
	"log"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/container"
	"github.com/docker/docker/api/types/network"
	dockerClient "github.com/docker/docker/client"
	"github.com/docker/go-connections/nat"
)

// Docker timeout
const dockerTimeout = 10

// DOCKER_SOCK tells where to connect to docker, it will be always local sock
const dockerSock = "unix:///var/run/docker.sock"

// DOCKER_API_VERSION set API version of Docker, 1.40 belongs to Docker 19.03.11
const dockerAPIVersion = "1.40"

// Driver keeps everything for connection to Docker
type Driver struct{}

func (d *Driver) getClient() (*dockerClient.Client, error) {
	cli, err := dockerClient.NewClient(dockerSock, dockerAPIVersion, nil, nil)
	return cli, err
}

// ConnectionStatus checks connection to the Docker daemon
func (d *Driver) ConnectionStatus() (bool, error) {
	cli, err := d.getClient()
	if err != nil {
		return false, err
	}

	_, err = cli.ServerVersion(context.TODO())
	if err != nil {
		return false, err
	}

	return true, nil
}

func (d *Driver) nameToID(name string) (string, error) {
	containerIDs, err := d.IsExist(name)
	if err != nil {
		return "", err
	}

	if len(containerIDs) == 0 {
		return "", errors.New("no container found")
	}
	if len(containerIDs) > 1 {
		return "", errors.New("multiple containers with the same name")
	}

	return containerIDs[0], nil
}

// Status return current status of container with given name
func (d *Driver) Status(name string) (string, error) {
	status := "unknown"

	cli, err := d.getClient()
	if err != nil {
		return status, err
	}

	containerID, err := d.nameToID(name)
	if err != nil {
		status = "no-container"
		return status, err
	}

	info, err := cli.ContainerInspect(context.TODO(), containerID)
	if err != nil {
		return status, err
	}

	if info.State.Running {
		status = "running"
	} else {
		status = "stopped"
	}

	return status, nil

}

// Stats returns current CPU and memory usage
func (d *Driver) Stats(name string) (float64, int, error) {
	cli, err := d.getClient()
	if err != nil {
		return 0.0, 0, err
	}

	containerID, err := d.nameToID(name)
	if err != nil {
		return 0.0, 0, err
	}

	stats, err := cli.ContainerStats(context.TODO(), containerID, false)
	if err != nil {
		return 0.0, 0, nil
	}

	data, err := ioutil.ReadAll(stats.Body)
	if err != nil {
		return 0.0, 0, err
	}
	log.Println(data)

	return 0.0, 0, nil
}

// Remove removes container represented by containerID
func (d *Driver) Remove(name string) error {
	log.Println("Removing container " + name)
	cli, err := d.getClient()
	if err != nil {
		return err
	}

	containerID, err := d.nameToID(name)
	if err != nil {
		return err
	}

	timeout := time.Duration(dockerTimeout * time.Second)
	err = cli.ContainerStop(context.TODO(), containerID, &timeout)
	if err != nil {
		return err
	}

	err = cli.ContainerRemove(context.TODO(), containerID, types.ContainerRemoveOptions{})

	return err
}

// Start starts container represented by containerID
func (d *Driver) Start(name string) error {
	log.Println("Starting container " + name)
	cli, err := d.getClient()
	if err != nil {
		return err
	}

	containerID, err := d.nameToID(name)
	if err != nil {
		return err
	}

	err = cli.ContainerStart(context.TODO(), containerID, types.ContainerStartOptions{})

	return err
}

// Stop stops container represented by containerID
func (d *Driver) Stop(name string) error {
	log.Println("Stopping container " + name)
	cli, err := d.getClient()
	if err != nil {
		return err
	}

	containerID, err := d.nameToID(name)
	if err != nil {
		return err
	}

	timeout := time.Duration(dockerTimeout * time.Second)
	err = cli.ContainerStop(context.TODO(), containerID, &timeout)

	return err
}

// IsExist checks existence of the container based on container name
// Returns container IDs in case of existence. Otherwise
// empty slice.
func (d *Driver) IsExist(name string) ([]string, error) {
	var containerIDs = make([]string, 0)

	cli, err := d.getClient()
	if err != nil {
		return containerIDs, err
	}

	containers, err := cli.ContainerList(context.TODO(), types.ContainerListOptions{All: true})
	if err != nil {
		return containerIDs, err
	}

	// We go through the containers and pick the ones which match the task name
	for _, containerObject := range containers {
		for _, containerName := range containerObject.Names {
			containerName = strings.TrimLeft(containerName, "/")
			if containerName == name {
				containerIDs = append(containerIDs, containerObject.ID)
			}
		}
	}

	return containerIDs, nil
}

// pullImage pulls image into local docker instance
func (d *Driver) pullImage(image string) error {
	log.Println("Pulling image " + image)
	cli, err := d.getClient()
	if err != nil {
		return err
	}

	stream, err := cli.ImagePull(context.TODO(), image, types.ImagePullOptions{})
	if err != nil {
		return err
	}
	defer stream.Close()

	io.Copy(os.Stdout, stream)

	return nil
}

// Create creates the container
// image - docker image
// cmd - string slice of command and its arguments
// volumePath - host's directory to mount into the container
// returns container ID
func (d *Driver) Create(name string, image string, volumePath string, HTTPPort int, SSHPort int, CPU int, memory int, cmd []string) (string, error) {
	log.Println("Creating container " + name)
	cli, err := d.getClient()
	if err != nil {
		return "", err
	}

	err = d.pullImage(image)
	if err != nil {
		return "", err
	}

	portmaps := make(nat.PortMap, 1)

	portbindingsHTTP := make([]nat.PortBinding, 1)
	portbindingsHTTP[0] = nat.PortBinding{
		HostPort: strconv.Itoa(HTTPPort) + "/tcp",
	}
	portmaps["8000/tcp"] = portbindingsHTTP

	if SSHPort != 0 {
		portbindingsSSH := make([]nat.PortBinding, 1)
		portbindingsSSH[0] = nat.PortBinding{
			HostPort: strconv.Itoa(SSHPort) + "/tcp",
		}
		portmaps["22/tcp"] = portbindingsSSH
	}

	createdContainer, err := cli.ContainerCreate(
		context.TODO(),
		&container.Config{
			Hostname: name,
			Env:      []string{},
			Image:    image,
			Cmd:      cmd,
		},
		&container.HostConfig{
			Resources: container.Resources{
				CPUPeriod:         100000,
				CPUQuota:          int64(CPU) * 1000,
				Memory:            int64(memory*110/100)*1024 ^ 2, // Allow 10 % more memory so we have space for MemoryReservation
				MemoryReservation: int64(memory)*1024 ^ 2,         // This should provide softer way how to limit the memory of our containers
			},
			PortBindings: portmaps,
			AutoRemove:   false,
			RestartPolicy: container.RestartPolicy{
				Name:              "on-failure",
				MaximumRetryCount: 3,
			},
			Binds: []string{
				volumePath + ":/srv",
			},
		},
		&network.NetworkingConfig{},
		name,
	)
	if err != nil {
		return "", err
	}

	containerID := createdContainer.ID

	// I dunno if we want this
	// err = cli.ContainerStart(context.TODO(), createdContainer.ID, types.ContainerStartOptions{})

	return containerID, nil
}