package app

import (
	"context"
	"fmt"
	"time"

	"sneak.berlin/go/upaas/internal/models"
)

// BackupEnvVar represents an environment variable in a backup.
type BackupEnvVar struct {
	Key   string `json:"key"`
	Value string `json:"value"`
}

// BackupLabel represents a Docker label in a backup.
type BackupLabel struct {
	Key   string `json:"key"`
	Value string `json:"value"`
}

// BackupVolume represents a volume mount in a backup.
type BackupVolume struct {
	HostPath      string `json:"hostPath"`
	ContainerPath string `json:"containerPath"`
	ReadOnly      bool   `json:"readOnly"`
}

// BackupPort represents a port mapping in a backup.
type BackupPort struct {
	HostPort      int    `json:"hostPort"`
	ContainerPort int    `json:"containerPort"`
	Protocol      string `json:"protocol"`
}

// Backup represents the exported configuration of a single app.
type Backup struct {
	Name           string         `json:"name"`
	RepoURL        string         `json:"repoUrl"`
	Branch         string         `json:"branch"`
	DockerfilePath string         `json:"dockerfilePath"`
	DockerNetwork  string         `json:"dockerNetwork,omitempty"`
	NtfyTopic      string         `json:"ntfyTopic,omitempty"`
	SlackWebhook   string         `json:"slackWebhook,omitempty"`
	EnvVars        []BackupEnvVar `json:"envVars"`
	Labels         []BackupLabel  `json:"labels"`
	Volumes        []BackupVolume `json:"volumes"`
	Ports          []BackupPort   `json:"ports"`
}

// BackupBundle represents a complete backup of one or more apps.
type BackupBundle struct {
	Version    int      `json:"version"`
	ExportedAt string   `json:"exportedAt"`
	Apps       []Backup `json:"apps"`
}

// backupVersion is the current backup format version.
const backupVersion = 1

// ExportApp exports a single app's configuration as a BackupBundle.
func (svc *Service) ExportApp(
	ctx context.Context,
	application *models.App,
) (*BackupBundle, error) {
	appBackup, err := svc.buildAppBackup(ctx, application)
	if err != nil {
		return nil, err
	}

	return &BackupBundle{
		Version:    backupVersion,
		ExportedAt: time.Now().UTC().Format(time.RFC3339),
		Apps:       []Backup{appBackup},
	}, nil
}

// ExportAllApps exports all app configurations as a BackupBundle.
func (svc *Service) ExportAllApps(ctx context.Context) (*BackupBundle, error) {
	apps, err := models.AllApps(ctx, svc.db)
	if err != nil {
		return nil, fmt.Errorf("listing apps for export: %w", err)
	}

	backups := make([]Backup, 0, len(apps))

	for _, application := range apps {
		appBackup, buildErr := svc.buildAppBackup(ctx, application)
		if buildErr != nil {
			return nil, buildErr
		}

		backups = append(backups, appBackup)
	}

	return &BackupBundle{
		Version:    backupVersion,
		ExportedAt: time.Now().UTC().Format(time.RFC3339),
		Apps:       backups,
	}, nil
}

// ImportApps imports app configurations from a BackupBundle.
// It creates new apps (with fresh IDs, SSH keys, and webhook secrets)
// and populates their env vars, labels, volumes, and ports.
// Apps whose names conflict with existing apps are skipped and reported.
func (svc *Service) ImportApps(
	ctx context.Context,
	bundle *BackupBundle,
) ([]string, []string, error) {
	// Build a set of existing app names for conflict detection
	existingApps, listErr := models.AllApps(ctx, svc.db)
	if listErr != nil {
		return nil, nil, fmt.Errorf("listing existing apps: %w", listErr)
	}

	existingNames := make(map[string]bool, len(existingApps))
	for _, a := range existingApps {
		existingNames[a.Name] = true
	}

	var imported, skipped []string

	for _, ab := range bundle.Apps {
		if existingNames[ab.Name] {
			skipped = append(skipped, ab.Name)

			continue
		}

		importErr := svc.importSingleApp(ctx, ab)
		if importErr != nil {
			return imported, skipped, fmt.Errorf(
				"importing app %q: %w", ab.Name, importErr,
			)
		}

		imported = append(imported, ab.Name)
	}

	return imported, skipped, nil
}

// importSingleApp creates a single app from backup data.
func (svc *Service) importSingleApp(
	ctx context.Context,
	ab Backup,
) error {
	createdApp, createErr := svc.CreateApp(ctx, CreateAppInput{
		Name:           ab.Name,
		RepoURL:        ab.RepoURL,
		Branch:         ab.Branch,
		DockerfilePath: ab.DockerfilePath,
		DockerNetwork:  ab.DockerNetwork,
		NtfyTopic:      ab.NtfyTopic,
		SlackWebhook:   ab.SlackWebhook,
	})
	if createErr != nil {
		return fmt.Errorf("creating app: %w", createErr)
	}

	envErr := svc.importEnvVars(ctx, createdApp.ID, ab.EnvVars)
	if envErr != nil {
		return envErr
	}

	labelErr := svc.importLabels(ctx, createdApp.ID, ab.Labels)
	if labelErr != nil {
		return labelErr
	}

	volErr := svc.importVolumes(ctx, createdApp.ID, ab.Volumes)
	if volErr != nil {
		return volErr
	}

	portErr := svc.importPorts(ctx, createdApp.ID, ab.Ports)
	if portErr != nil {
		return portErr
	}

	svc.log.Info("app imported from backup",
		"id", createdApp.ID, "name", createdApp.Name)

	return nil
}

// importEnvVars adds env vars from backup to an app.
func (svc *Service) importEnvVars(
	ctx context.Context,
	appID string,
	envVars []BackupEnvVar,
) error {
	for _, ev := range envVars {
		addErr := svc.AddEnvVar(ctx, appID, ev.Key, ev.Value)
		if addErr != nil {
			return fmt.Errorf("adding env var %q: %w", ev.Key, addErr)
		}
	}

	return nil
}

// importLabels adds labels from backup to an app.
func (svc *Service) importLabels(
	ctx context.Context,
	appID string,
	labels []BackupLabel,
) error {
	for _, l := range labels {
		addErr := svc.AddLabel(ctx, appID, l.Key, l.Value)
		if addErr != nil {
			return fmt.Errorf("adding label %q: %w", l.Key, addErr)
		}
	}

	return nil
}

// importVolumes adds volumes from backup to an app.
func (svc *Service) importVolumes(
	ctx context.Context,
	appID string,
	volumes []BackupVolume,
) error {
	for _, v := range volumes {
		addErr := svc.AddVolume(ctx, appID, v.HostPath, v.ContainerPath, v.ReadOnly)
		if addErr != nil {
			return fmt.Errorf("adding volume %q: %w", v.ContainerPath, addErr)
		}
	}

	return nil
}

// importPorts adds ports from backup to an app.
func (svc *Service) importPorts(
	ctx context.Context,
	appID string,
	ports []BackupPort,
) error {
	for _, p := range ports {
		port := models.NewPort(svc.db)
		port.AppID = appID
		port.HostPort = p.HostPort
		port.ContainerPort = p.ContainerPort
		port.Protocol = models.PortProtocol(p.Protocol)

		if port.Protocol == "" {
			port.Protocol = models.PortProtocolTCP
		}

		saveErr := port.Save(ctx)
		if saveErr != nil {
			return fmt.Errorf("adding port %d: %w", p.HostPort, saveErr)
		}
	}

	return nil
}

// buildAppBackup collects all configuration for a single app into a Backup.
func (svc *Service) buildAppBackup(
	ctx context.Context,
	application *models.App,
) (Backup, error) {
	envVars, labels, volumes, ports, err := svc.fetchAppResources(ctx, application)
	if err != nil {
		return Backup{}, err
	}

	backup := Backup{
		Name:           application.Name,
		RepoURL:        application.RepoURL,
		Branch:         application.Branch,
		DockerfilePath: application.DockerfilePath,
		EnvVars:        convertEnvVars(envVars),
		Labels:         convertLabels(labels),
		Volumes:        convertVolumes(volumes),
		Ports:          convertPorts(ports),
	}

	if application.DockerNetwork.Valid {
		backup.DockerNetwork = application.DockerNetwork.String
	}

	if application.NtfyTopic.Valid {
		backup.NtfyTopic = application.NtfyTopic.String
	}

	if application.SlackWebhook.Valid {
		backup.SlackWebhook = application.SlackWebhook.String
	}

	return backup, nil
}

// fetchAppResources retrieves all sub-resources for an app.
func (svc *Service) fetchAppResources(
	ctx context.Context,
	application *models.App,
) ([]*models.EnvVar, []*models.Label, []*models.Volume, []*models.Port, error) {
	envVars, err := application.GetEnvVars(ctx)
	if err != nil {
		return nil, nil, nil, nil, fmt.Errorf(
			"getting env vars for %q: %w", application.Name, err,
		)
	}

	labels, err := application.GetLabels(ctx)
	if err != nil {
		return nil, nil, nil, nil, fmt.Errorf(
			"getting labels for %q: %w", application.Name, err,
		)
	}

	volumes, err := application.GetVolumes(ctx)
	if err != nil {
		return nil, nil, nil, nil, fmt.Errorf(
			"getting volumes for %q: %w", application.Name, err,
		)
	}

	ports, err := application.GetPorts(ctx)
	if err != nil {
		return nil, nil, nil, nil, fmt.Errorf(
			"getting ports for %q: %w", application.Name, err,
		)
	}

	return envVars, labels, volumes, ports, nil
}

// convertEnvVars converts model env vars to backup format.
func convertEnvVars(envVars []*models.EnvVar) []BackupEnvVar {
	result := make([]BackupEnvVar, 0, len(envVars))

	for _, ev := range envVars {
		result = append(result, BackupEnvVar{
			Key:   ev.Key,
			Value: ev.Value,
		})
	}

	return result
}

// convertLabels converts model labels to backup format.
func convertLabels(labels []*models.Label) []BackupLabel {
	result := make([]BackupLabel, 0, len(labels))

	for _, l := range labels {
		result = append(result, BackupLabel{
			Key:   l.Key,
			Value: l.Value,
		})
	}

	return result
}

// convertVolumes converts model volumes to backup format.
func convertVolumes(volumes []*models.Volume) []BackupVolume {
	result := make([]BackupVolume, 0, len(volumes))

	for _, v := range volumes {
		result = append(result, BackupVolume{
			HostPath:      v.HostPath,
			ContainerPath: v.ContainerPath,
			ReadOnly:      v.ReadOnly,
		})
	}

	return result
}

// convertPorts converts model ports to backup format.
func convertPorts(ports []*models.Port) []BackupPort {
	result := make([]BackupPort, 0, len(ports))

	for _, p := range ports {
		result = append(result, BackupPort{
			HostPort:      p.HostPort,
			ContainerPort: p.ContainerPort,
			Protocol:      string(p.Protocol),
		})
	}

	return result
}