package memory

import (
	"errors"
	"fmt"
	"strings"

	"github.com/getsentry/sentry-go"
	"github.com/nmcclain/ldap"
	"github.com/prometheus/client_golang/prometheus"
	log "github.com/sirupsen/logrus"
	"goauthentik.io/api"
	"goauthentik.io/internal/outpost/ldap/constants"
	"goauthentik.io/internal/outpost/ldap/group"
	"goauthentik.io/internal/outpost/ldap/metrics"
	"goauthentik.io/internal/outpost/ldap/search"
	"goauthentik.io/internal/outpost/ldap/server"
	"goauthentik.io/internal/outpost/ldap/utils"
)

type MemorySearcher struct {
	si  server.LDAPServerInstance
	log *log.Entry

	users  []api.User
	groups []api.Group
}

func NewMemorySearcher(si server.LDAPServerInstance) *MemorySearcher {
	ms := &MemorySearcher{
		si:  si,
		log: log.WithField("logger", "authentik.outpost.ldap.searcher.memory"),
	}
	ms.log.Info("initialised memory searcher")
	ms.users = ms.FetchUsers()
	ms.groups = ms.FetchGroups()
	return ms
}

func (ms *MemorySearcher) Search(req *search.Request) (ldap.ServerSearchResult, error) {
	accsp := sentry.StartSpan(req.Context(), "authentik.providers.ldap.search.check_access")
	baseDN := strings.ToLower(ms.si.GetBaseDN())

	filterOC, err := ldap.GetFilterObjectClass(req.Filter)
	if err != nil {
		metrics.RequestsRejected.With(prometheus.Labels{
			"outpost_name": ms.si.GetOutpostName(),
			"type":         "search",
			"reason":       "filter_parse_fail",
			"dn":           req.BindDN,
			"client":       req.RemoteAddr(),
		}).Inc()
		return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, fmt.Errorf("Search Error: error parsing filter: %s", req.Filter)
	}
	if len(req.BindDN) < 1 {
		metrics.RequestsRejected.With(prometheus.Labels{
			"outpost_name": ms.si.GetOutpostName(),
			"type":         "search",
			"reason":       "empty_bind_dn",
			"dn":           req.BindDN,
			"client":       req.RemoteAddr(),
		}).Inc()
		return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultInsufficientAccessRights}, fmt.Errorf("Search Error: Anonymous BindDN not allowed %s", req.BindDN)
	}
	if !strings.HasSuffix(req.BindDN, ","+baseDN) {
		metrics.RequestsRejected.With(prometheus.Labels{
			"outpost_name": ms.si.GetOutpostName(),
			"type":         "search",
			"reason":       "invalid_bind_dn",
			"dn":           req.BindDN,
			"client":       req.RemoteAddr(),
		}).Inc()
		return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultInsufficientAccessRights}, fmt.Errorf("Search Error: BindDN %s not in our BaseDN %s", req.BindDN, ms.si.GetBaseDN())
	}

	flags, ok := ms.si.GetFlags(req.BindDN)
	if !ok {
		req.Log().Debug("User info not cached")
		metrics.RequestsRejected.With(prometheus.Labels{
			"outpost_name": ms.si.GetOutpostName(),
			"type":         "search",
			"reason":       "user_info_not_cached",
			"dn":           req.BindDN,
			"client":       req.RemoteAddr(),
		}).Inc()
		return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultInsufficientAccessRights}, errors.New("access denied")
	}
	accsp.Finish()

	entries := make([]*ldap.Entry, 0)

	scope := req.SearchRequest.Scope
	needUsers, needGroups := ms.si.GetNeededObjects(scope, req.BaseDN, filterOC)

	if scope >= 0 && req.BaseDN == baseDN {
		if utils.IncludeObjectClass(filterOC, constants.GetDomainOCs()) {
			entries = append(entries, ms.si.GetBaseEntry())
		}

		scope -= 1 // Bring it from WholeSubtree to SingleLevel and so on
	}

	var users *[]api.User
	var groups []*group.LDAPGroup

	if needUsers {
		if flags.CanSearch {
			users = &ms.users
		} else {
			if flags.UserInfo == nil {
				for i, u := range ms.users {
					if u.Pk == flags.UserPk {
						flags.UserInfo = &ms.users[i]
					}
				}

				if flags.UserInfo == nil {
					req.Log().WithField("pk", flags.UserPk).Warning("User with pk is not in local cache")
					err = fmt.Errorf("failed to get userinfo")
				}
			}

			u := make([]api.User, 1)
			u[0] = *flags.UserInfo

			users = &u
		}
	}

	if needGroups {
		groups = make([]*group.LDAPGroup, 0)

		for _, g := range ms.groups {
			if flags.CanSearch {
				groups = append(groups, group.FromAPIGroup(g, ms.si))
			} else {
				// If the user cannot search, we're going to only return
				// the groups they're in _and_ only return themselves
				// as a member.
				for _, u := range g.UsersObj {
					if flags.UserPk == u.Pk {
						//TODO: Is there a better way to clone this object?
						fg := api.NewGroup(g.Pk, g.Name, g.Parent, g.ParentName, []int32{flags.UserPk}, []api.GroupMember{u})
						fg.SetAttributes(*g.Attributes)
						fg.SetIsSuperuser(*g.IsSuperuser)
						groups = append(groups, group.FromAPIGroup(*fg, ms.si))
						break
					}
				}
			}
		}
	}

	if err != nil {
		return ldap.ServerSearchResult{ResultCode: ldap.LDAPResultOperationsError}, err
	}

	if scope >= 0 && (req.BaseDN == ms.si.GetBaseDN() || strings.HasSuffix(req.BaseDN, ms.si.GetBaseUserDN())) {
		singleu := strings.HasSuffix(req.BaseDN, ","+ms.si.GetBaseUserDN())

		if !singleu && utils.IncludeObjectClass(filterOC, constants.GetContainerOCs()) {
			entries = append(entries, utils.GetContainerEntry(filterOC, ms.si.GetBaseUserDN(), constants.OUUsers))
			scope -= 1
		}

		if scope >= 0 && users != nil && utils.IncludeObjectClass(filterOC, constants.GetUserOCs()) {
			for _, u := range *users {
				entry := ms.si.UserEntry(u)
				if req.BaseDN == entry.DN || !singleu {
					entries = append(entries, entry)
				}
			}
		}

		scope += 1 // Return the scope to what it was before we descended
	}

	if scope >= 0 && (req.BaseDN == ms.si.GetBaseDN() || strings.HasSuffix(req.BaseDN, ms.si.GetBaseGroupDN())) {
		singleg := strings.HasSuffix(req.BaseDN, ","+ms.si.GetBaseGroupDN())

		if !singleg && utils.IncludeObjectClass(filterOC, constants.GetContainerOCs()) {
			entries = append(entries, utils.GetContainerEntry(filterOC, ms.si.GetBaseGroupDN(), constants.OUGroups))
			scope -= 1
		}

		if scope >= 0 && groups != nil && utils.IncludeObjectClass(filterOC, constants.GetGroupOCs()) {
			for _, g := range groups {
				if req.BaseDN == g.DN || !singleg {
					entries = append(entries, g.Entry())
				}
			}
		}

		scope += 1 // Return the scope to what it was before we descended
	}

	if scope >= 0 && (req.BaseDN == ms.si.GetBaseDN() || strings.HasSuffix(req.BaseDN, ms.si.GetBaseVirtualGroupDN())) {
		singlevg := strings.HasSuffix(req.BaseDN, ","+ms.si.GetBaseVirtualGroupDN())

		if !singlevg && utils.IncludeObjectClass(filterOC, constants.GetContainerOCs()) {
			entries = append(entries, utils.GetContainerEntry(filterOC, ms.si.GetBaseVirtualGroupDN(), constants.OUVirtualGroups))
			scope -= 1
		}

		if scope >= 0 && users != nil && utils.IncludeObjectClass(filterOC, constants.GetVirtualGroupOCs()) {
			for _, u := range *users {
				entry := group.FromAPIUser(u, ms.si).Entry()
				if req.BaseDN == entry.DN || !singlevg {
					entries = append(entries, entry)
				}
			}
		}
	}

	return ldap.ServerSearchResult{Entries: entries, Referrals: []string{}, Controls: []ldap.Control{}, ResultCode: ldap.LDAPResultSuccess}, nil
}