package docker

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"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"
	"github.com/rosti-cz/node-api/detector"
)

// Stats delay in seconds
const statsDelay = 1

// Docker timeout
const dockerTimeout = 10

// DOCKER_SOCK tells where to connect to docker, it will be always local sock
const dockerSock = "/var/run/docker.sock"
const podmanSock = "/run/user/1000/podman/podman.sock"

// DOCKER_API_VERSION set API version of Docker, 1.40 belongs to Docker 19.03.11
const dockerAPIVersion = "1.38"

// Driver keeps everything for connection to Docker
type Driver struct {
	BindIPHTTP string // IP to which containers are bound
	BindIPSSH  string // IP to which containers are bound
}

func (d *Driver) getClient() (*dockerClient.Client, error) {
	var connectTo string
	if _, err := os.Stat(podmanSock); !os.IsNotExist(err) {
		connectTo = podmanSock
	} else {
		connectTo = dockerSock
	}

	cli, err := dockerClient.NewClient("unix://"+connectTo, dockerAPIVersion, nil, nil)
	if err != nil {
		return cli, fmt.Errorf("get docker client error: %v", err)
	}
	return cli, nil
}

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

	_, 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
	}
	defer cli.Close()

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

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

	return info.State.Status, nil

}

// RawStats returns snapshot of current cpu and memory usage, CPU cannot be used
// for % usage because it's number of used tics. Call this twice to get the % usage.
// One second is 10 000 000 ticks.
func (d *Driver) RawStats(name string) (int64, int, error) {
	cli, err := d.getClient()
	if err != nil {
		return 0.0, 0, err
	}
	defer cli.Close()

	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, err
	}

	row := ContainerStats{}

	data, err := ioutil.ReadAll(stats.Body)
	if err != nil {
		return 0.0, 0, err
	}
	err = json.Unmarshal(data, &row)
	if err != nil {
		return 0.0, 0, err
	}

	return row.CPU.Usage.Total, row.Memory.Usage, 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
	}
	defer cli.Close()

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

	rows := make([]ContainerStats, 2)

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

		data, err := ioutil.ReadAll(stats.Body)
		if err != nil {
			return 0.0, 0, err
		}
		// It returns one JSON:
		// {"read":"2020-07-11T20:42:31.486726241Z","preread":"2020-07-11T20:42:30.484048602Z","pids_stats":{"current":7},"blkio_stats":{"io_service_bytes_recursive":[{"major":253,"minor":0,"op":"Read","value":0},{"major":253,"minor":0,"op":"Write","value":20480},{"major":253,"minor":0,"op":"Sync","value":12288},{"major":253,"minor":0,"op":"Async","value":8192},{"major":253,"minor":0,"op":"Discard","value":0},{"major":253,"minor":0,"op":"Total","value":20480}],"io_serviced_recursive":[{"major":253,"minor":0,"op":"Read","value":0},{"major":253,"minor":0,"op":"Write","value":5},{"major":253,"minor":0,"op":"Sync","value":3},{"major":253,"minor":0,"op":"Async","value":2},{"major":253,"minor":0,"op":"Discard","value":0},{"major":253,"minor":0,"op":"Total","value":5}],"io_queue_recursive":[],"io_service_time_recursive":[],"io_wait_time_recursive":[],"io_merged_recursive":[],"io_time_recursive":[],"sectors_recursive":[]},"num_procs":0,"storage_stats":{},"cpu_stats":{"cpu_usage":{"total_usage":758392753,"percpu_usage":[302688474,0,11507116,124238500,222136766,5656446,3009320,0,19406386,1397028,6201423,62151294,0,0,0,0],"usage_in_kernelmode":100000000,"usage_in_usermode":640000000},"system_cpu_usage":119385810000000,"online_cpus":12,"throttling_data":{"periods":21,"throttled_periods":1,"throttled_time":2995938}},"precpu_stats":{"cpu_usage":{"total_usage":758282347,"percpu_usage":[302688474,0,11507116,124238500,222026360,5656446,3009320,0,19406386,1397028,6201423,62151294,0,0,0,0],"usage_in_kernelmode":100000000,"usage_in_usermode":640000000},"system_cpu_usage":119373720000000,"online_cpus":12,"throttling_data":{"periods":21,"throttled_periods":1,"throttled_time":2995938}},"memory_stats":{"usage":21626880,"max_usage":22630400,"stats":{"active_anon":15949824,"active_file":0,"cache":0,"dirty":0,"hierarchical_memory_limit":144179200,"hierarchical_memsw_limit":288358400,"inactive_anon":0,"inactive_file":0,"mapped_file":0,"pgfault":13167,"pgmajfault":0,"pgpgin":7293,"pgpgout":3406,"rss":15900672,"rss_huge":0,"total_active_anon":15949824,"total_active_file":0,"total_cache":0,"total_dirty":0,"total_inactive_anon":0,"total_inactive_file":0,"total_mapped_file":0,"total_pgfault":13167,"total_pgmajfault":0,"total_pgpgin":7293,"total_pgpgout":3406,"total_rss":15900672,"total_rss_huge":0,"total_unevictable":0,"total_writeback":0,"unevictable":0,"writeback":0},"limit":144179200},"name":"/test_1234","id":"576878d645efecc8e5e2a57b88351f7b5c551e3fc72dc8473fd965d10dfddbec","networks":{"eth0":{"rx_bytes":6150,"rx_packets":37,"rx_errors":0,"rx_dropped":0,"tx_bytes":0,"tx_packets":0,"tx_errors":0,"tx_dropped":0}}}

		err = json.Unmarshal(data, &rows[idx])
		if err != nil {
			return 0.0, 0, err
		}

		if idx == 0 {
			time.Sleep(statsDelay * time.Second)
		}
	}

	cpuUsage := (float64(rows[1].CPU.Usage.Total) - float64(rows[0].CPU.Usage.Total)) / statsDelay / 10000000

	return cpuUsage, rows[1].Memory.Usage, 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
	}
	defer cli.Close()

	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
	}
	defer cli.Close()

	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
	}
	defer cli.Close()

	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
	}
	defer cli.Close()

	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
	}
	defer cli.Close()

	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
	}
	defer cli.Close()

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

	portBindings := nat.PortMap{
		"8000/tcp": []nat.PortBinding{
			{
				HostIP:   d.BindIPHTTP,
				HostPort: strconv.Itoa(HTTPPort),
			},
		},
	}

	if SSHPort != 0 {
		portBindings["22/tcp"] = []nat.PortBinding{
			{
				HostIP:   d.BindIPSSH,
				HostPort: strconv.Itoa(SSHPort),
			},
		}
	}

	createdContainer, err := cli.ContainerCreate(
		context.Background(),
		&container.Config{
			Hostname: name,
			Env:      []string{},
			Image:    image,
			Cmd:      cmd,
			ExposedPorts: nat.PortSet{
				nat.Port("22/tcp"):   struct{}{},
				nat.Port("8000/tcp"): struct{}{},
			},
		},
		&container.HostConfig{
			Resources: container.Resources{
				CPUPeriod:         100000,
				CPUQuota:          int64(CPU) * 1000,
				Memory:            int64(memory*110/100) * 1024 * 1024, // Allow 10 % more memory so we have space for MemoryReservation
				MemoryReservation: int64(memory) * 1024 * 1024,         // This should provide softer way how to limit the memory of our containers
			},
			PortBindings: portBindings,
			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
}

// Exec runs command cmd with stdin if it's not empty.
func (d *Driver) Exec(name string, cmd []string, stdin string, env []string, attachStdout bool) (*[]byte, error) {
	if len(cmd) == 0 {
		return &[]byte{}, errors.New("cmd needs at least one string in the slice")
	}

	ctx := context.Background()

	stdinEnabled := false
	if len(stdin) > 0 {
		stdinEnabled = true
	}

	log.Println("Command running in " + name)
	cli, err := d.getClient()
	if err != nil {
		return &[]byte{}, err
	}
	defer cli.Close()

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

	execOpts := types.ExecConfig{
		AttachStdin:  stdinEnabled,
		AttachStdout: attachStdout,
		AttachStderr: false,
		Tty:          attachStdout,
		Cmd:          cmd,
	}

	resp, err := cli.ContainerExecCreate(ctx, containerID, execOpts)
	if err != nil {
		return &[]byte{}, err
	}

	respAttach, err := cli.ContainerExecAttach(ctx, resp.ID, types.ExecConfig{
		AttachStdin:  stdinEnabled,
		AttachStdout: attachStdout,
		AttachStderr: false,
		Tty:          attachStdout,
	})
	if err != nil {
		return &[]byte{}, err
	}
	defer respAttach.Close()

	err = cli.ContainerExecStart(ctx, resp.ID, types.ExecStartCheck{})
	if err != nil {
		return &[]byte{}, err
	}

	if stdinEnabled {
		_, err = respAttach.Conn.Write([]byte(stdin))
		if err != nil {
			return &[]byte{}, err
		}
	}

	stdouterr := []byte{}
	if attachStdout {
		stdouterr, err = ioutil.ReadAll(respAttach.Reader)
	}

	return &stdouterr, err
}

// GetProcesses return list of processes running under this container
func (d *Driver) GetProcesses(name string) ([]string, error) {
	processes := []string{}

	ctx := context.Background()

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

	processList, err := cli.ContainerTop(ctx, name, []string{"-eo", "args"})
	if err != nil {
		return processes, fmt.Errorf("docker container top call error: %v", err)
	}

	for _, process := range processList.Processes {
		if len(process) > 0 {
			processes = append(processes, process[0])
		}
	}

	return processes, nil
}

// GetFlags returns list of flags with problems found in the container, mainly used to detect miners or viruses
func (d *Driver) GetFlags(name string) (detector.Flags, error) {
	processes, err := d.GetProcesses(name)
	if err != nil {
		return detector.Flags{}, err
	}
	flags, err := detector.Check(processes)
	if err != nil {
		return flags, err
	}

	return flags, nil
}