package useCases

import (
	"RenewCMS/internal/domain/update"
	"strings"
	"time"
)

type ManageBrowserUpdatesDependencies struct {
	Probe   update.MachineProbe
	Locator update.ServiceLocator
	Units   update.UnitWriter
	Manager update.UnitManager
	Status  update.HelperStatusWriter
	Now     func() time.Time
}

type EnableBrowserUpdatesUseCase struct {
	dependencies ManageBrowserUpdatesDependencies
}

type DisableBrowserUpdatesUseCase struct {
	dependencies ManageBrowserUpdatesDependencies
}

func NewEnableBrowserUpdatesUseCase(dependencies ManageBrowserUpdatesDependencies) *EnableBrowserUpdatesUseCase {
	return &EnableBrowserUpdatesUseCase{dependencies: dependencies}
}

func NewDisableBrowserUpdatesUseCase(dependencies ManageBrowserUpdatesDependencies) *DisableBrowserUpdatesUseCase {
	return &DisableBrowserUpdatesUseCase{dependencies: dependencies}
}

func (e *EnableBrowserUpdatesUseCase) Enable(options update.InstallOptions) (string, error) {
	d := e.dependencies
	if err := update.CheckInstallEnvironment(d.Probe); err != nil {
		return "", err
	}
	resolved, err := e.resolve(options)
	if err != nil {
		return "", err
	}
	if err := e.install(resolved); err != nil {
		e.undo()
		return "", err
	}
	status := update.HelperStatus{
		Version:     update.HelperStatusVersion,
		Service:     resolved.Service,
		Binary:      resolved.Binary,
		DataDir:     resolved.DataDir,
		InstalledAt: d.Now().UTC(),
	}
	if err := d.Status.Write(resolved.DataDir, status); err != nil {
		e.undo()
		return "", err
	}
	return enabledMessage(resolved), nil
}

func (e *EnableBrowserUpdatesUseCase) resolve(options update.InstallOptions) (update.InstallOptions, error) {
	service := firstNonEmpty(options.Service, update.DefaultService)
	description, found := e.dependencies.Locator.Locate(service)
	resolved := update.InstallOptions{
		Service: service,
		Binary:  firstNonEmpty(options.Binary, description.BinaryPath),
		DataDir: firstNonEmpty(options.DataDir, description.DataDir),
	}
	if resolved.Binary == "" || (resolved.DataDir == "" && !found) {
		return resolved, update.ErrServiceNotFound
	}
	if resolved.DataDir == "" {
		return resolved, update.ErrDataDirNotFound
	}
	resolved.Port = e.port(options.Port, description)
	return resolved, update.ValidatePort(resolved.Port)
}

func (e *EnableBrowserUpdatesUseCase) port(flag string, description update.ServiceDescription) string {
	if flag != "" {
		return flag
	}
	if port, found := e.dependencies.Locator.PortFromEnvironmentFile(description.EnvironmentFile); found {
		return port
	}
	return update.DefaultPort
}

func (e *EnableBrowserUpdatesUseCase) install(options update.InstallOptions) error {
	d := e.dependencies
	layout := update.HelperLayout{DataDir: options.DataDir, BinaryPath: options.Binary}
	if err := d.Units.Write(update.ServiceUnitName, update.RenderServiceUnit(options)); err != nil {
		return err
	}
	if err := d.Units.Write(update.PathUnitName, update.RenderPathUnit(layout)); err != nil {
		return err
	}
	if err := d.Manager.DaemonReload(); err != nil {
		return err
	}
	return d.Manager.EnableNow(update.PathUnitName)
}

func (e *EnableBrowserUpdatesUseCase) undo() {
	d := e.dependencies
	_ = d.Manager.DisableNow(update.PathUnitName)
	_, _ = d.Units.Remove(update.ServiceUnitName)
	_, _ = d.Units.Remove(update.PathUnitName)
	_ = d.Manager.DaemonReload()
}

func enabledMessage(options update.InstallOptions) string {
	lines := []string{
		"Browser updates are enabled for " + options.Service + ".",
		"Installed " + update.PathUnitName + " and " + update.ServiceUnitName + " (port " + options.Port + ") and wrote " + update.HelperStatusFileName + " in " + options.DataDir + ".",
		"To undo it, run: renewcms disable-browser-updates",
	}
	return strings.Join(lines, "\n")
}

func (u *DisableBrowserUpdatesUseCase) Disable(options update.InstallOptions) (string, error) {
	d := u.dependencies
	if d.Probe.OS() != update.OSLinux || !d.Probe.SystemdRunning() {
		return notEnabledMessage, nil
	}
	if err := update.CheckInstallEnvironment(d.Probe); err != nil {
		return "", err
	}
	dataDir := firstNonEmpty(options.DataDir, u.locatedDataDir(options.Service))

	_ = d.Manager.DisableNow(update.PathUnitName)
	removed := u.removeUnits()
	if dataDir == "" {
		return "", update.ErrDataDirNotFound
	}
	statusRemoved, err := d.Status.Remove(dataDir)
	if err != nil {
		return "", err
	}
	if !removed && !statusRemoved {
		return notEnabledMessage, nil
	}
	if err := d.Manager.DaemonReload(); err != nil {
		return "", err
	}
	return disabledMessage, nil
}

func (u *DisableBrowserUpdatesUseCase) locatedDataDir(service string) string {
	description, _ := u.dependencies.Locator.Locate(firstNonEmpty(service, update.DefaultService))
	return description.DataDir
}

func (u *DisableBrowserUpdatesUseCase) removeUnits() bool {
	removedAny := false
	for _, name := range []string{update.PathUnitName, update.ServiceUnitName} {
		removed, err := u.dependencies.Units.Remove(name)
		removedAny = removedAny || (removed && err == nil)
	}
	return removedAny
}

const (
	notEnabledMessage = "Browser updates were not enabled, nothing to remove."
	disabledMessage   = "Browser updates are disabled. The restart request, the result, the staged files and the backups were left in place."
)

func firstNonEmpty(values ...string) string {
	for _, value := range values {
		if value != "" {
			return value
		}
	}
	return ""
}