package provisioning

import (
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"sort"
	"strings"

	alertingNotify "github.com/grafana/alerting/notify"
	"github.com/prometheus/alertmanager/config"

	"github.com/grafana/grafana/pkg/apimachinery/identity"
	"github.com/grafana/grafana/pkg/components/simplejson"
	"github.com/grafana/grafana/pkg/infra/log"
	ac "github.com/grafana/grafana/pkg/services/accesscontrol"
	apimodels "github.com/grafana/grafana/pkg/services/ngalert/api/tooling/definitions"
	"github.com/grafana/grafana/pkg/services/ngalert/models"
	"github.com/grafana/grafana/pkg/services/ngalert/notifier/channels_config"
	"github.com/grafana/grafana/pkg/services/ngalert/notifier/legacy_storage"
	"github.com/grafana/grafana/pkg/services/ngalert/store"
	"github.com/grafana/grafana/pkg/services/secrets"
	"github.com/grafana/grafana/pkg/util"
)

type AlertRuleNotificationSettingsStore interface {
	RenameReceiverInNotificationSettings(ctx context.Context, orgID int64, oldReceiver, newReceiver string, validateProvenance func(models.Provenance) bool, dryRun bool) ([]models.AlertRuleKey, []models.AlertRuleKey, error)
	RenameTimeIntervalInNotificationSettings(ctx context.Context, orgID int64, oldTimeInterval, newTimeInterval string, validateProvenance func(models.Provenance) bool, dryRun bool) ([]models.AlertRuleKey, []models.AlertRuleKey, error)
	ListNotificationSettings(ctx context.Context, q models.ListNotificationSettingsQuery) (map[models.AlertRuleKey][]models.NotificationSettings, error)
}

type ContactPointService struct {
	configStore               alertmanagerConfigStore
	encryptionService         secrets.Service
	provenanceStore           ProvisioningStore
	notificationSettingsStore AlertRuleNotificationSettingsStore
	xact                      TransactionManager
	receiverService           receiverService
	log                       log.Logger
	resourcePermissions       ac.ReceiverPermissionsService
}

type receiverService interface {
	GetReceivers(ctx context.Context, query models.GetReceiversQuery, user identity.Requester) ([]*models.Receiver, error)
	RenameReceiverInDependentResources(ctx context.Context, orgID int64, route *apimodels.Route, oldName, newName string, receiverProvenance models.Provenance) error
}

func NewContactPointService(
	store alertmanagerConfigStore,
	encryptionService secrets.Service,
	provenanceStore ProvisioningStore,
	xact TransactionManager,
	receiverService receiverService,
	log log.Logger,
	nsStore AlertRuleNotificationSettingsStore,
	resourcePermissions ac.ReceiverPermissionsService,
) *ContactPointService {
	return &ContactPointService{
		configStore:               store,
		receiverService:           receiverService,
		encryptionService:         encryptionService,
		provenanceStore:           provenanceStore,
		xact:                      xact,
		log:                       log,
		notificationSettingsStore: nsStore,
		resourcePermissions:       resourcePermissions,
	}
}

type ContactPointQuery struct {
	// Optionally filter by name.
	Name  string
	OrgID int64
	// Optionally decrypt secure settings, requires OrgAdmin.
	Decrypt bool
}

// GetContactPoints returns contact points. If q.Decrypt is true and the user is an OrgAdmin, decrypted secure settings are included instead of redacted ones.
func (ecp *ContactPointService) GetContactPoints(ctx context.Context, q ContactPointQuery, u identity.Requester) ([]apimodels.EmbeddedContactPoint, error) {
	receiverQuery := models.GetReceiversQuery{
		OrgID:   q.OrgID,
		Decrypt: q.Decrypt,
	}
	if q.Name != "" {
		receiverQuery.Names = []string{q.Name}
	}

	res, err := ecp.receiverService.GetReceivers(ctx, receiverQuery, u)
	if err != nil {
		return nil, convertRecSvcErr(err)
	}
	if q.Name != "" && len(res) > 0 {
		res = []*models.Receiver{res[0]} // we only expect one receiver group
	}

	contactPoints := make([]apimodels.EmbeddedContactPoint, 0, len(res))
	for _, recv := range res {
		for _, gr := range recv.Integrations {
			if !q.Decrypt {
				// Provisioning API redacts by default.
				gr.Redact(func(value string) string {
					return apimodels.RedactedValue
				})
			}
			contactPoints = append(contactPoints, GrafanaIntegrationConfigToEmbeddedContactPoint(gr, recv.Provenance))
		}
	}

	sort.SliceStable(contactPoints, func(i, j int) bool {
		switch strings.Compare(contactPoints[i].Name, contactPoints[j].Name) {
		case -1:
			return true
		case 1:
			return false
		}
		return contactPoints[i].UID < contactPoints[j].UID
	})

	return contactPoints, nil
}

// getContactPointDecrypted is an internal-only function that gets full contact point info, included encrypted fields.
// nil is returned if no matching contact point exists.
func (ecp *ContactPointService) getContactPointDecrypted(ctx context.Context, orgID int64, uid string) (apimodels.EmbeddedContactPoint, error) {
	revision, err := ecp.configStore.Get(ctx, orgID)
	if err != nil {
		return apimodels.EmbeddedContactPoint{}, err
	}
	for _, receiver := range revision.Config.GetGrafanaReceiverMap() {
		if receiver.UID != uid {
			continue
		}
		embeddedContactPoint, err := PostableGrafanaReceiverToEmbeddedContactPoint(
			receiver,
			models.ProvenanceNone, // TODO should be correct provenance?
			ecp.decryptValueOrRedacted(true, receiver.UID),
		)
		if err != nil {
			return apimodels.EmbeddedContactPoint{}, err
		}
		return embeddedContactPoint, nil
	}
	return apimodels.EmbeddedContactPoint{}, fmt.Errorf("%w: contact point with uid '%s' not found", ErrNotFound, uid)
}

func (ecp *ContactPointService) CreateContactPoint(
	ctx context.Context,
	orgID int64,
	user identity.Requester,
	contactPoint apimodels.EmbeddedContactPoint,
	provenance models.Provenance,
) (apimodels.EmbeddedContactPoint, error) {
	if err := ValidateContactPoint(ctx, contactPoint, ecp.encryptionService.GetDecryptedValue); err != nil {
		return apimodels.EmbeddedContactPoint{}, fmt.Errorf("%w: %s", ErrValidation, err.Error())
	}

	revision, err := ecp.configStore.Get(ctx, orgID)
	if err != nil {
		return apimodels.EmbeddedContactPoint{}, err
	}

	extractedSecrets, err := RemoveSecretsForContactPoint(&contactPoint)
	if err != nil {
		return apimodels.EmbeddedContactPoint{}, err
	}

	for k, v := range extractedSecrets {
		encryptedValue, err := ecp.encryptValue(v)
		if err != nil {
			return apimodels.EmbeddedContactPoint{}, err
		}
		extractedSecrets[k] = encryptedValue
	}

	if contactPoint.UID == "" {
		contactPoint.UID = util.GenerateShortUID()
	} else if err := util.ValidateUID(contactPoint.UID); err != nil {
		return apimodels.EmbeddedContactPoint{}, errors.Join(ErrValidation, fmt.Errorf("cannot create contact point with UID '%s': %w", contactPoint.UID, err))
	}

	jsonData, err := contactPoint.Settings.MarshalJSON()
	if err != nil {
		return apimodels.EmbeddedContactPoint{}, err
	}

	grafanaReceiver := &apimodels.PostableGrafanaReceiver{
		UID:                   contactPoint.UID,
		Name:                  contactPoint.Name,
		Type:                  contactPoint.Type,
		DisableResolveMessage: contactPoint.DisableResolveMessage,
		Settings:              jsonData,
		SecureSettings:        extractedSecrets,
	}

	receiverFound := false
	for _, receiver := range revision.Config.AlertmanagerConfig.Receivers {
		// check if uid is already used in receiver
		for _, rec := range receiver.PostableGrafanaReceivers.GrafanaManagedReceivers {
			if grafanaReceiver.UID == rec.UID {
				return apimodels.EmbeddedContactPoint{}, MakeErrContactPointUidExists(rec.UID, rec.Name)
			}
		}
		if receiver.Name == contactPoint.Name {
			receiver.PostableGrafanaReceivers.GrafanaManagedReceivers = append(receiver.PostableGrafanaReceivers.GrafanaManagedReceivers, grafanaReceiver)
			receiverFound = true
		}
	}

	if !receiverFound {
		revision.Config.AlertmanagerConfig.Receivers = append(revision.Config.AlertmanagerConfig.Receivers, &apimodels.PostableApiReceiver{
			Receiver: config.Receiver{
				Name: grafanaReceiver.Name,
			},
			PostableGrafanaReceivers: apimodels.PostableGrafanaReceivers{
				GrafanaManagedReceivers: []*apimodels.PostableGrafanaReceiver{grafanaReceiver},
			},
		})
	}

	err = ecp.xact.InTransaction(ctx, func(ctx context.Context) error {
		if err := ecp.configStore.Save(ctx, revision, orgID); err != nil {
			return err
		}
		if !receiverFound {
			// Compatibility with new receiver resource permissions.
			// Since this is a new receiver, we need to set default resource permissions so that viewers and editors can see and edit it.
			ecp.resourcePermissions.SetDefaultPermissions(ctx, orgID, user, legacy_storage.NameToUid(contactPoint.Name))
		}
		return ecp.provenanceStore.SetProvenance(ctx, &contactPoint, orgID, provenance)
	})
	if err != nil {
		return apimodels.EmbeddedContactPoint{}, err
	}
	for k := range extractedSecrets {
		contactPoint.Settings.Set(k, apimodels.RedactedValue)
	}
	return contactPoint, nil
}

func (ecp *ContactPointService) UpdateContactPoint(ctx context.Context, orgID int64, contactPoint apimodels.EmbeddedContactPoint, provenance models.Provenance) error {
	// set all redacted values with the latest known value from the store
	if contactPoint.Settings == nil {
		return fmt.Errorf("%w: %s", ErrValidation, "settings should not be empty")
	}
	rawContactPoint, err := ecp.getContactPointDecrypted(ctx, orgID, contactPoint.UID)
	if err != nil {
		return err
	}
	secretKeys, err := channels_config.GetSecretKeysForContactPointType(contactPoint.Type)
	if err != nil {
		return fmt.Errorf("%w: %s", ErrValidation, err.Error())
	}
	for _, secretKey := range secretKeys {
		secretValue := contactPoint.Settings.Get(secretKey).MustString()
		if secretValue == apimodels.RedactedValue {
			contactPoint.Settings.Set(secretKey, rawContactPoint.Settings.Get(secretKey).MustString())
		}
	}

	// validate merged values
	if err := ValidateContactPoint(ctx, contactPoint, ecp.encryptionService.GetDecryptedValue); err != nil {
		return fmt.Errorf("%w: %s", ErrValidation, err.Error())
	}

	// check that provenance is not changed in an invalid way
	storedProvenance, err := ecp.provenanceStore.GetProvenance(ctx, &contactPoint, orgID)
	if err != nil {
		return err
	}
	if storedProvenance != provenance && storedProvenance != models.ProvenanceNone {
		return fmt.Errorf("cannot change provenance from '%s' to '%s'", storedProvenance, provenance)
	}
	// transform to internal model
	extractedSecrets, err := RemoveSecretsForContactPoint(&contactPoint)
	if err != nil {
		return err
	}
	for k, v := range extractedSecrets {
		encryptedValue, err := ecp.encryptValue(v)
		if err != nil {
			return err
		}
		extractedSecrets[k] = encryptedValue
	}

	jsonData, err := contactPoint.Settings.MarshalJSON()
	if err != nil {
		return err
	}
	mergedReceiver := &apimodels.PostableGrafanaReceiver{
		UID:                   contactPoint.UID,
		Name:                  contactPoint.Name,
		Type:                  contactPoint.Type,
		DisableResolveMessage: contactPoint.DisableResolveMessage,
		Settings:              jsonData,
		SecureSettings:        extractedSecrets,
	}
	// save to store
	revision, err := ecp.configStore.Get(ctx, orgID)
	if err != nil {
		return err
	}

	oldReceiverName, fullRemoval, newReceiverCreated := stitchReceiver(revision.Config, mergedReceiver)
	if oldReceiverName == "" {
		return fmt.Errorf("contact point with uid '%s' not found", mergedReceiver.UID)
	}

	err = ecp.xact.InTransaction(ctx, func(ctx context.Context) error {
		if mergedReceiver.Name != oldReceiverName {
			if newReceiverCreated {
				// Copy receiver permissions
				permissionsUpdated, err := ecp.resourcePermissions.CopyPermissions(ctx, orgID, nil, legacy_storage.NameToUid(oldReceiverName), legacy_storage.NameToUid(mergedReceiver.Name))
				if err != nil {
					return err
				}
				if permissionsUpdated > 0 {
					ecp.log.FromContext(ctx).Debug("Moved custom receiver permissions", "oldName", oldReceiverName, "newName", mergedReceiver.Name, "count", permissionsUpdated)
				}
			}

			if fullRemoval {
				if err := ecp.receiverService.RenameReceiverInDependentResources(ctx, orgID, revision.Config.AlertmanagerConfig.Route, oldReceiverName, mergedReceiver.Name, provenance); err != nil {
					return err
				}
				if err := ecp.resourcePermissions.DeleteResourcePermissions(ctx, orgID, legacy_storage.NameToUid(oldReceiverName)); err != nil {
					return err
				}
			}
		}
		if err := ecp.configStore.Save(ctx, revision, orgID); err != nil {
			return err
		}
		return ecp.provenanceStore.SetProvenance(ctx, &contactPoint, orgID, provenance)
	})
	if err != nil {
		return err
	}
	return nil
}

func (ecp *ContactPointService) DeleteContactPoint(ctx context.Context, orgID int64, uid string) error {
	revision, err := ecp.configStore.Get(ctx, orgID)
	if err != nil {
		return err
	}
	// Indicates if the full contact point is removed or just one of the
	// configurations, as a contactpoint can consist of any number of
	// configurations.
	fullRemoval := false
	// Name of the contact point that will be removed, might be used if a
	// full removal is done to check if it's referenced in any route.
	name := ""
	for i, receiver := range revision.Config.AlertmanagerConfig.Receivers {
		for j, grafanaReceiver := range receiver.GrafanaManagedReceivers {
			if grafanaReceiver.UID == uid {
				name = grafanaReceiver.Name
				receiver.GrafanaManagedReceivers = append(receiver.GrafanaManagedReceivers[:j], receiver.GrafanaManagedReceivers[j+1:]...)
				// if this was the last receiver we removed, we remove the whole receiver
				if len(receiver.GrafanaManagedReceivers) == 0 {
					fullRemoval = true
					revision.Config.AlertmanagerConfig.Receivers = append(revision.Config.AlertmanagerConfig.Receivers[:i], revision.Config.AlertmanagerConfig.Receivers[i+1:]...)
				}
				break
			}
		}
	}
	if fullRemoval && revision.ReceiverNameUsedByRoutes(name) {
		return ErrContactPointReferenced.Errorf("")
	}

	return ecp.xact.InTransaction(ctx, func(ctx context.Context) error {
		if fullRemoval {
			used, err := ecp.notificationSettingsStore.ListNotificationSettings(ctx, models.ListNotificationSettingsQuery{OrgID: orgID, ReceiverName: name})
			if err != nil {
				return fmt.Errorf("failed to query alert rules for reference to the contact point '%s': %w", name, err)
			}
			if len(used) > 0 {
				uids := make([]string, 0, len(used))
				for key := range used {
					uids = append(uids, key.UID)
				}
				ecp.log.Error("Cannot delete contact point because it is used in rule's notification settings", "receiverName", name, "rulesUid", strings.Join(uids, ","))
				return ErrContactPointUsedInRule.Errorf("")
			}

			// Compatibility with new receiver resource permissions.
			// We need to cleanup resource permissions.
			if err := ecp.resourcePermissions.DeleteResourcePermissions(ctx, orgID, legacy_storage.NameToUid(name)); err != nil {
				ecp.log.Error("Could not delete receiver permissions", "receiverName", name, "error", err)
			}
		}

		if err := ecp.configStore.Save(ctx, revision, orgID); err != nil {
			return err
		}
		target := &apimodels.EmbeddedContactPoint{
			UID: uid,
		}
		return ecp.provenanceStore.DeleteProvenance(ctx, target, orgID)
	})
}

// decryptValueOrRedacted returns a function that decodes a string from Base64 and then decrypts using secrets.Service.
// If argument 'decrypt' is false, then returns definitions.RedactedValue regardless of the decrypted value.
// Otherwise, it returns the decoded and decrypted value. The function returns empty string in the case of errors, which are logged
func (ecp *ContactPointService) decryptValueOrRedacted(decrypt bool, integrationUID string) func(v string) string {
	return func(value string) string {
		decodeValue, err := base64.StdEncoding.DecodeString(value)
		if err != nil {
			ecp.log.Warn("Failed to decode secret value from Base64", "error", err.Error(), "integrationUid", integrationUID)
			return ""
		}
		decryptedValue, err := ecp.encryptionService.Decrypt(context.Background(), decodeValue)
		if err != nil {
			ecp.log.Warn("Failed to decrypt secret value", "error", err.Error(), "integrationUid", integrationUID)
			return ""
		}
		if decrypt {
			return string(decryptedValue)
		} else {
			return apimodels.RedactedValue
		}
	}
}

func (ecp *ContactPointService) encryptValue(value string) (string, error) {
	encryptedData, err := ecp.encryptionService.Encrypt(context.Background(), []byte(value), secrets.WithoutScope())
	if err != nil {
		return "", fmt.Errorf("failed to encrypt secure settings: %w", err)
	}
	return base64.StdEncoding.EncodeToString(encryptedData), nil
}

// stitchReceiver modifies a receiver, target, in an alertmanager configStore. It modifies the given configStore in-place.
// Returns true if the configStore was altered in any way, and false otherwise.
// If integration was moved to another group and it was the last in the previous group, the second parameter contains the name of the old group that is gone
func stitchReceiver(cfg *apimodels.PostableUserConfig, target *apimodels.PostableGrafanaReceiver) (oldReceiverName string, fullRemoval bool, newReceiverCreated bool) {
	// Algorithm to fix up receivers. Receivers are very complex and depend heavily on internal consistency.
	// All receivers in a given receiver group have the same name. We must maintain this across renames.
groupLoop:
	for groupIdx, receiverGroup := range cfg.AlertmanagerConfig.Receivers {
		// Does the current group contain the grafana receiver we're interested in?
		for i, grafanaReceiver := range receiverGroup.GrafanaManagedReceivers {
			if grafanaReceiver.UID == target.UID {
				oldReceiverName = receiverGroup.Name
				// If it's a basic field change, simply replace it. Done!
				//
				// NOTE:
				// In a "normal" database, receiverGroup.Name should always == grafanaReceiver.Name.
				// Check it regardless.
				// If these values are out of sync due to some bug elsewhere in the code, let's fix it up.
				// Our receiver group fixing logic below will handle it.
				if grafanaReceiver.Name == target.Name && receiverGroup.Name == grafanaReceiver.Name {
					receiverGroup.GrafanaManagedReceivers[i] = target
					break groupLoop
				}

				// If we're renaming, we'll need to fix up the macro receiver group for consistency.
				// Firstly, if we're the only receiver in the group, simply rename the group to match. Done!
				if len(receiverGroup.GrafanaManagedReceivers) == 1 {
					fullRemoval = true
				}

				// Otherwise, we only want to rename the receiver we are touching... NOT all of them.
				// Check to see whether a different group with the name we want already exists.
				for _, candidateExistingGroup := range cfg.AlertmanagerConfig.Receivers {
					// If so, put our modified receiver into that group. Done!
					if candidateExistingGroup.Name == target.Name {
						// Drop it from the old group...
						receiverGroup.GrafanaManagedReceivers = append(receiverGroup.GrafanaManagedReceivers[:i], receiverGroup.GrafanaManagedReceivers[i+1:]...)
						// Add the modified receiver to the new group...
						candidateExistingGroup.GrafanaManagedReceivers = append(candidateExistingGroup.GrafanaManagedReceivers, target)

						// if the old receiver group turns out to be empty. Remove it.
						if len(receiverGroup.GrafanaManagedReceivers) == 0 {
							cfg.AlertmanagerConfig.Receivers = append(cfg.AlertmanagerConfig.Receivers[:groupIdx], cfg.AlertmanagerConfig.Receivers[groupIdx+1:]...)
						}
						break groupLoop
					}
				}

				newReceiverCreated = true
				if fullRemoval {
					// Since we're going to remove the receiver group anyways, we reuse the old group to retain order.
					receiverGroup.Name = target.Name
					receiverGroup.GrafanaManagedReceivers[i] = target
					break groupLoop
				}

				// Doesn't exist? Create a new group just for the receiver.
				newGroup := &apimodels.PostableApiReceiver{
					Receiver: config.Receiver{
						Name: target.Name,
					},
					PostableGrafanaReceivers: apimodels.PostableGrafanaReceivers{
						GrafanaManagedReceivers: []*apimodels.PostableGrafanaReceiver{
							target,
						},
					},
				}
				cfg.AlertmanagerConfig.Receivers = append(cfg.AlertmanagerConfig.Receivers, newGroup)
				// Drop it from the old spot.
				receiverGroup.GrafanaManagedReceivers = append(receiverGroup.GrafanaManagedReceivers[:i], receiverGroup.GrafanaManagedReceivers[i+1:]...)
				break groupLoop
			}
		}
	}

	return oldReceiverName, fullRemoval, newReceiverCreated
}

func ValidateContactPoint(ctx context.Context, e apimodels.EmbeddedContactPoint, decryptFunc alertingNotify.GetDecryptedValueFn) error {
	integration, err := EmbeddedContactPointToGrafanaIntegrationConfig(e)
	if err != nil {
		return err
	}
	return models.ValidateIntegration(ctx, integration, decryptFunc)
}

// RemoveSecretsForContactPoint removes all secrets from the contact point's settings and returns them as a map. Returns error if contact point type is not known.
func RemoveSecretsForContactPoint(e *apimodels.EmbeddedContactPoint) (map[string]string, error) {
	s := map[string]string{}
	secretKeys, err := channels_config.GetSecretKeysForContactPointType(e.Type)
	if err != nil {
		return nil, err
	}
	for _, secretKey := range secretKeys {
		secretValue, err := extractCaseInsensitive(e.Settings, secretKey)
		if err != nil {
			return nil, err
		}
		if secretValue == "" {
			continue
		}
		s[secretKey] = secretValue
	}
	return s, nil
}

// extractCaseInsensitive returns the value of the specified key, preferring an exact match but accepting a case-insensitive match.
// If no key matches, the second return value is an empty string.
func extractCaseInsensitive(jsonObj *simplejson.Json, key string) (string, error) {
	if key == "" {
		return "", nil
	}
	path := strings.Split(key, ".")
	getNodeCaseInsensitive := func(n *simplejson.Json, field string) (string, *simplejson.Json, error) {
		// Check for an exact key match first.
		if value, ok := n.CheckGet(field); ok {
			return field, value, nil
		}

		// If no exact match is found, look for a case-insensitive match.
		settingsMap, err := n.Map()
		if err != nil {
			return "", nil, err
		}

		for k := range settingsMap {
			if strings.EqualFold(k, field) {
				return k, n.GetPath(k), nil
			}
		}
		return "", nil, nil
	}

	node := jsonObj
	for idx, segment := range path {
		_, value, err := getNodeCaseInsensitive(node, segment)
		if err != nil {
			return "", err
		}
		if value == nil {
			return "", nil
		}
		if idx == len(path)-1 {
			resultValue := value.MustString()
			node.Del(segment)
			return resultValue, nil
		}
		node = value
	}
	return "", nil
}

// convertRecSvcErr converts errors from notifier.ReceiverService to errors expected from ContactPointService.
func convertRecSvcErr(err error) error {
	if errors.Is(err, store.ErrNoAlertmanagerConfiguration) {
		return legacy_storage.ErrNoAlertmanagerConfiguration.Errorf("")
	}
	return err
}