package docker

import (
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strconv"
	"strings"

	"gitea.thegux.fr/hmdeploy/connection"
	"gitea.thegux.fr/hmdeploy/models"
	"gitea.thegux.fr/hmdeploy/utils"
)

const (
	appPartsLength     = 2
	imagePartsLength   = 2
	portPartsLength    = 2
	portOutPartsLength = 2
	replicasPartLength = 2
)

var (
	ErrDockerClientSave = errors.New("unable to save image into tar")

	ErrDockerClientExtractServicesInputLength = errors.New("bad input length")
	ErrDockerClientExtractServicesParse       = errors.New("parse error")
)

type Port struct {
	In  int
	Out int
}

type Service struct {
	App   string
	Name  string
	Image struct {
		Name string
		Tag  string
	}
	Ports    []Port
	Replicas int
}

func (s Service) String() string {
	return fmt.Sprintf(
		"%-20s | %-20s | %-30s | %-10s | %-5d",
		s.App,
		s.Name,
		s.Image.Name,
		s.Image.Tag,
		s.Replicas,
	)
}

type Services []Service

func (s Services) String() string {
	data := []string{}
	header := fmt.Sprintf(
		"%-20s | %-20s | %-30s | %-10s | %-5s",
		"Service name",
		"App name",
		"Image name",
		"Image Tag",
		"Replicas",
	)
	hr := ""
	for i := 0; i < len(header); i++ {
		hr += "-"
	}
	data = append(data, hr)
	data = append(data, header)
	data = append(data, hr)
	for idx := range s {
		data = append(data, s[idx].String())
	}
	return strings.Join(data, "\n")
}

type serviceDetailsHeader map[string]int

func (h serviceDetailsHeader) getPos(value string) int {
	v, ok := h[value]
	if !ok {
		return -1
	}
	return v
}

// serviceFromString instantiates a new service from the `docker service ls` command output.
// TODO: it's ugly... To rework, if i'm not too lazy
func serviceFromString( //nolint:all // todo
	header serviceDetailsHeader,
	value string,
) (Service, error) {
	var srv Service

	parts := strings.Split(value, " ")
	parts = slices.DeleteFunc(parts, func(e string) bool { return e == "" })

	if pos := header.getPos("name"); pos != -1 {
		appParts := strings.Split(parts[pos], "_")
		if len(appParts) >= appPartsLength {
			srv.App = appParts[len(appParts)-1]
			srv.Name = appParts[0]
		}
	}

	if pos := header.getPos("image"); pos != -1 {
		imageParts := strings.Split(parts[pos], ":")
		if len(imageParts) >= imagePartsLength {
			srv.Image.Name = imageParts[0]
			srv.Image.Tag = imageParts[1]
		}
	}

	if pos := header.getPos("replicas"); pos != -1 {
		replicasParts := strings.Split(parts[pos], "/")
		if len(replicasParts) >= replicasPartLength {
			replicas, err := strconv.Atoi(replicasParts[1])
			if err != nil {
				return srv, fmt.Errorf(
					"%w, replicas conversion failed: %s",
					ErrDockerClientExtractServicesParse,
					string(replicasParts[1]),
				)
			}
			srv.Replicas = replicas
		}
	}

	srv.Ports = []Port{}

	if pos := header.getPos("ports"); pos != -1 && pos < len(parts) {
		// ports parts must exceed the header pos so, to find missing ports
		// the pos difference is computed in order to retrieve them
		portsParts := []string{}
		diff := len(parts) - pos
		for i := 0; i < diff; i++ {
			portsParts = append(portsParts, parts[pos+i])
		}

		for _, port := range portsParts {
			servicePort := Port{}
			// port in/out are displayed like "out->in"
			portParts := strings.Split(port, "->")
			if len(portParts) >= portPartsLength {
				// out port is displayed like "ip:port"
				portOutParts := strings.Split(portParts[0], ":")
				if len(portOutParts) == portOutPartsLength {
					portOut, err := utils.CatchAndConvertNumber(portOutParts[1])
					if err != nil {
						return srv, fmt.Errorf(
							"%w, out port conversion failed: %s",
							ErrDockerClientExtractServicesParse,
							string(portOutParts[1]),
						)
					}
					servicePort.Out = portOut
				}

				portIn, err := utils.CatchAndConvertNumber(portParts[1])
				if err != nil {
					return srv, fmt.Errorf(
						"%w, in port conversion failed: %s",
						ErrDockerClientExtractServicesParse,
						string(portParts[1]),
					)
				}
				servicePort.In = portIn

				srv.Ports = append(srv.Ports, servicePort)
			}
		}
	}

	return srv, nil
}

// Parse the `docker service ls` header (ID NAME MODE REPLICAS IMAGE PORTS)
func parseServiceDetailsHeader(value string) serviceDetailsHeader {
	header := serviceDetailsHeader{}

	parts := strings.Split(value, " ")
	parts = slices.DeleteFunc(parts, func(e string) bool { return e == "" })

	for idx, part := range parts {
		header[part] = idx
	}

	return header
}

func parseServiceDetails(cmdOutput string) (Services, error) {
	services := Services{}
	var header serviceDetailsHeader

	bufLine := []rune{}
	isHeaderCatched := false
	for _, c := range cmdOutput {
		if c == '\n' {
			if !isHeaderCatched {
				header = parseServiceDetailsHeader(strings.ToLower(string(bufLine)))
				bufLine = bufLine[:0]
				isHeaderCatched = true
				continue
			}

			service, err := serviceFromString(header, string(bufLine))
			if err != nil {
				return services, fmt.Errorf(
					"%w, err=%v",
					ErrDockerClientExtractServicesParse,
					err,
				)
			}
			services = append(services, service)
			bufLine = bufLine[:0]

			continue
		}
		bufLine = append(bufLine, c)
	}

	return services, nil
}

type IClient interface {
	Save(imageName, dest string) (string, error)
}

// LocalClient is a simple Docker client wrapping the local Docker daemon.
// It does not use the Docker API but instead shell command and collect the output.
//
// NOTE: for now, it's ok, it only needs one command so, no need to add a fat dedicated
// library with full Docker client API.
type LocalClient struct{}

var _ IClient = (*LocalClient)(nil)

func NewLocalClient() LocalClient {
	return LocalClient{}
}

// Save saves the `imageName` (tag included) in tar format in the target directory: `dest`.
// The `dest` directory must exist with correct permissions.
func (c *LocalClient) Save(imageName, dest string) (string, error) {
	destInfo, err := os.Stat(dest)
	if err != nil {
		return "", fmt.Errorf("unable to stat file, dir=%s, err=%v", dest, err)
	}

	if !destInfo.IsDir() {
		return "", fmt.Errorf("dest file must be a directory, dir=%s, err=%v", dest, err)
	}

	tarFile := fmt.Sprintf("%s.tar", imageName)

	cmd := exec.Command("docker", "save", "-o", tarFile, imageName)
	cmd.Dir = dest
	if _, err := cmd.Output(); err != nil {
		return "", fmt.Errorf(
			"%w, dir=%s, image=%s, err=%v",
			ErrDockerClientSave,
			dest,
			imageName,
			err,
		)
	}

	return filepath.Join(dest, tarFile), nil
}

// RemoteClient is a simple Docker client for remote daemon.
// It does not use the Docker API but instead shell command over an SSH connection and collect the output.
//
// NOTE: for now, it's ok, it only needs one command so, no need to add a fat dedicated
// library with full Docker client API.
type RemoteClient struct {
	conn connection.SSHConn
}

func NewRemoteClient(netInfo *models.HMNetInfo) (RemoteClient, error) {
	var rc RemoteClient
	conn, err := connection.NewSSHConn(
		netInfo.IP.String(),
		netInfo.SSH.User,
		netInfo.SSH.Port,
		netInfo.SSH.PrivKey,
	)
	if err != nil {
		return rc, nil
	}

	rc.conn = conn
	return rc, nil
}

func (c *RemoteClient) ExtractServicesDetails() (Services, error) {
	output, err := c.conn.Execute("docker service ls")
	if err != nil {
		return nil, err
	}

	services, err := parseServiceDetails(output)
	if err != nil {
		return nil, err
	}

	return services, nil
}