/*
Package ldapSync provides a scheduler for syncing ldap users and groups to the database
*/
package ldapSync

import (
	"fmt"
	"git.stuve.uni-ulm.de/StuVe-IT/stuve-it-backend/logger"
	"github.com/pocketbase/pocketbase"
	"github.com/pocketbase/pocketbase/tools/cron"
	"os"
	"strconv"
	"time"
)

// ldapTimeToUnixTime converts a ldap time string to a time.Time object
func ldapTimeToUnixTime(ldapTimeStampStr string) (time.Time, error) {

	ldapTimeStamp, err := strconv.ParseInt(ldapTimeStampStr, 10, 64)

	if err != nil {
		return time.Time{}, fmt.Errorf("error parsing ldap time string: %v", err)
	}

	// convert from 100 nanosecond intervals to milliseconds
	unixTimeStamp := ldapTimeStamp/1e4 - 1.16444736e13

	if unixTimeStamp < 0 {
		return time.Time{}, fmt.Errorf("error parsing ldap time string: unixTimeStamp is negative")
	}

	// Convert milliseconds to seconds
	seconds := unixTimeStamp / 1000

	// Create a time.Time object
	t := time.Unix(seconds, 0)

	return t, nil
}

// InitLdapSync initializes the ldap sync scheduler
//
// the function syncs the ldap users and groups initially and then as defined in the LDAP_SYNC_SCHEDULE env variable (cron syntax)
//
// the function also checks for the existence of the ldapUsers and ldapGroups tables and creates them if they do not exist
func InitLdapSync(app *pocketbase.PocketBase) error {

	// check if ldapGroups table exists
	if _, err := app.Dao().FindCollectionByNameOrId(ldapGroupsTableName); err != nil {
		// create ldap_groups table if not exists
		logger.LogInfoF("creating " + ldapGroupsTableName + " table ...")
		if err := createLDAPGroupsTable(app); err != nil {
			return err
		}
	} else {
		logger.LogInfoF(ldapGroupsTableName + " table already exists ... skipping creation")
	}

	// check if ldapUsers table exists
	if _, err := app.Dao().FindCollectionByNameOrId(ldapUsersTableName); err != nil {
		// create ldap_users table if not exists
		logger.LogInfoF("creating " + ldapUsersTableName + " table ...")
		if err := createLDAPUsersTable(app); err != nil {
			return err
		}
	} else {
		logger.LogInfoF(ldapUsersTableName + " table already exists ... skipping creation")
	}

	// check if ldapSyncLogs table exists
	if _, err := app.Dao().FindCollectionByNameOrId(ldapSyncLogsTableName); err != nil {
		// create ldapSyncs table if not exists
		logger.LogInfoF("creating " + ldapSyncLogsTableName + " table ...")
		if err := createLDAPSyncLogsTable(app); err != nil {
			return err
		}
	} else {
		logger.LogInfoF(ldapSyncLogsTableName + " table already exists ... skipping creation")
	}

	// start sync
	scheduler := cron.New()

	// initial sync
	logger.LogInfoF("initial LDAP on startup")
	syncLdap(app)
	logger.LogInfoF("... initial LDAP Sync done")

	ldapSyncSchedule := os.Getenv("LDAP_SYNC_SCHEDULE")

	// syncs ldap - interval specified in the LDAP_SYNC_SCHEDULE env variable
	scheduler.MustAdd("ldapSync", ldapSyncSchedule, func() {
		logger.LogInfoF("syncing LDAP ...")
		syncLdap(app)
		logger.LogInfoF("... LDAP Sync done")
	})

	scheduler.Start()
	logger.LogInfoF("ldap sync scheduler started with schedule: %s", ldapSyncSchedule)

	return nil
}