package acimpl

import (
	"context"
	"fmt"
	"time"

	"github.com/grafana/grafana/pkg/api/routing"
	"github.com/grafana/grafana/pkg/infra/localcache"
	"github.com/grafana/grafana/pkg/infra/log"
	"github.com/grafana/grafana/pkg/infra/metrics"
	"github.com/grafana/grafana/pkg/services/accesscontrol"
	"github.com/grafana/grafana/pkg/services/accesscontrol/api"
	"github.com/grafana/grafana/pkg/services/accesscontrol/database"
	"github.com/grafana/grafana/pkg/services/accesscontrol/ossaccesscontrol"
	"github.com/grafana/grafana/pkg/services/sqlstore"
	"github.com/grafana/grafana/pkg/services/user"
	"github.com/grafana/grafana/pkg/setting"
	"github.com/prometheus/client_golang/prometheus"
)

const (
	cacheTTL = 10 * time.Second
)

func ProvideService(cfg *setting.Cfg, store sqlstore.Store, routeRegister routing.RouteRegister, cache *localcache.CacheService) (*Service, error) {
	service := ProvideOSSService(cfg, database.ProvideService(store), cache)

	if !accesscontrol.IsDisabled(cfg) {
		api.NewAccessControlAPI(routeRegister, service).RegisterAPIEndpoints()
		if err := accesscontrol.DeclareFixedRoles(service); err != nil {
			return nil, err
		}
	}

	return service, nil
}

func ProvideOSSService(cfg *setting.Cfg, store store, cache *localcache.CacheService) *Service {
	s := &Service{
		cfg:   cfg,
		store: store,
		log:   log.New("accesscontrol.service"),
		cache: cache,
		roles: accesscontrol.BuildBasicRoleDefinitions(),
	}

	return s
}

type store interface {
	GetUserPermissions(ctx context.Context, query accesscontrol.GetUserPermissionsQuery) ([]accesscontrol.Permission, error)
	DeleteUserPermissions(ctx context.Context, orgID, userID int64) error
}

// Service is the service implementing role based access control.
type Service struct {
	log           log.Logger
	cfg           *setting.Cfg
	store         store
	cache         *localcache.CacheService
	registrations accesscontrol.RegistrationList
	roles         map[string]*accesscontrol.RoleDTO
}

func (s *Service) GetUsageStats(_ context.Context) map[string]interface{} {
	enabled := 0
	if !accesscontrol.IsDisabled(s.cfg) {
		enabled = 1
	}

	return map[string]interface{}{
		"stats.oss.accesscontrol.enabled.count": enabled,
	}
}

var actionsToFetch = append(
	ossaccesscontrol.TeamAdminActions, append(ossaccesscontrol.DashboardAdminActions, ossaccesscontrol.FolderAdminActions...)...,
)

// GetUserPermissions returns user permissions based on built-in roles
func (s *Service) GetUserPermissions(ctx context.Context, user *user.SignedInUser, options accesscontrol.Options) ([]accesscontrol.Permission, error) {
	timer := prometheus.NewTimer(metrics.MAccessPermissionsSummary)
	defer timer.ObserveDuration()

	if !s.cfg.RBACPermissionCache || !user.HasUniqueId() {
		return s.getUserPermissions(ctx, user, options)
	}

	return s.getCachedUserPermissions(ctx, user, options)
}

func (s *Service) getUserPermissions(ctx context.Context, user *user.SignedInUser, options accesscontrol.Options) ([]accesscontrol.Permission, error) {
	permissions := make([]accesscontrol.Permission, 0)
	for _, builtin := range accesscontrol.GetOrgRoles(user) {
		if basicRole, ok := s.roles[builtin]; ok {
			permissions = append(permissions, basicRole.Permissions...)
		}
	}

	dbPermissions, err := s.store.GetUserPermissions(ctx, accesscontrol.GetUserPermissionsQuery{
		OrgID:   user.OrgID,
		UserID:  user.UserID,
		Roles:   accesscontrol.GetOrgRoles(user),
		TeamIDs: user.Teams,
		Actions: actionsToFetch,
	})
	if err != nil {
		return nil, err
	}

	return append(permissions, dbPermissions...), nil
}

func (s *Service) getCachedUserPermissions(ctx context.Context, user *user.SignedInUser, options accesscontrol.Options) ([]accesscontrol.Permission, error) {
	key, err := permissionCacheKey(user)
	if err != nil {
		return nil, err
	}

	if !options.ReloadCache {
		permissions, ok := s.cache.Get(key)
		if ok {
			s.log.Debug("using cached permissions", "key", key)
			return permissions.([]accesscontrol.Permission), nil
		}
	}

	s.log.Debug("fetch permissions from store", "key", key)
	permissions, err := s.getUserPermissions(ctx, user, options)
	if err != nil {
		return nil, err
	}

	s.log.Debug("cache permissions", "key", key)
	s.cache.Set(key, permissions, cacheTTL)

	return permissions, nil
}

func (s *Service) DeleteUserPermissions(ctx context.Context, orgID int64, userID int64) error {
	return s.store.DeleteUserPermissions(ctx, orgID, userID)
}

// DeclareFixedRoles allow the caller to declare, to the service, fixed roles and their assignments
// to organization roles ("Viewer", "Editor", "Admin") or "Grafana Admin"
func (s *Service) DeclareFixedRoles(registrations ...accesscontrol.RoleRegistration) error {
	// If accesscontrol is disabled no need to register roles
	if accesscontrol.IsDisabled(s.cfg) {
		return nil
	}

	for _, r := range registrations {
		err := accesscontrol.ValidateFixedRole(r.Role)
		if err != nil {
			return err
		}

		err = accesscontrol.ValidateBuiltInRoles(r.Grants)
		if err != nil {
			return err
		}

		s.registrations.Append(r)
	}

	return nil
}

// RegisterFixedRoles registers all declared roles in RAM
func (s *Service) RegisterFixedRoles(ctx context.Context) error {
	// If accesscontrol is disabled no need to register roles
	if accesscontrol.IsDisabled(s.cfg) {
		return nil
	}
	s.registrations.Range(func(registration accesscontrol.RoleRegistration) bool {
		for br := range accesscontrol.BuiltInRolesWithParents(registration.Grants) {
			if basicRole, ok := s.roles[br]; ok {
				basicRole.Permissions = append(basicRole.Permissions, registration.Role.Permissions...)
			} else {
				s.log.Error("Unknown builtin role", "builtInRole", br)
			}
		}
		return true
	})
	return nil
}

func (s *Service) IsDisabled() bool {
	return accesscontrol.IsDisabled(s.cfg)
}

func permissionCacheKey(user *user.SignedInUser) (string, error) {
	key, err := user.GetCacheKey()
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("rbac-permissions-%s", key), nil
}