package ldap

import (
	"fmt"
	"strconv"
	"strings"
	"time"
)

// DecodeSID decodes a SID string
func DecodeSID(s string) string {
	b := []byte(s)
	revisionLvl := int(b[0])
	subAuthorityCount := int(b[1]) & 0xFF

	var authority int
	for i := 2; i <= 7; i++ {
		authority = authority | int(b[i])<<(8*(5-(i-2)))
	}

	var size = 4
	var offset = 8
	var subAuthorities []int
	for i := 0; i < subAuthorityCount; i++ {
		var subAuthority int
		for k := 0; k < size; k++ {
			subAuthority = subAuthority | (int(b[offset+k])&0xFF)<<(8*k)
		}
		subAuthorities = append(subAuthorities, subAuthority)
		offset += size
	}

	var builder strings.Builder
	builder.WriteString("S-")
	builder.WriteString(fmt.Sprintf("%d-", revisionLvl))
	builder.WriteString(fmt.Sprintf("%d", authority))
	for _, v := range subAuthorities {
		builder.WriteString(fmt.Sprintf("-%d", v))
	}
	return builder.String()
}

// DecodeADTimestamp decodes an Active Directory timestamp
func DecodeADTimestamp(timestamp string) string {
	adtime, _ := strconv.ParseInt(timestamp, 10, 64)
	if (adtime == 9223372036854775807) || (adtime == 0) {
		return "Not Set"
	}
	unixtime_int64 := adtime/(10*1000*1000) - 11644473600
	unixtime := time.Unix(unixtime_int64, 0)
	return unixtime.Format("2006-01-02 3:4:5 pm")
}

// DecodeZuluTimestamp decodes a Zulu timestamp
// example: 2021-08-25T14:00:00Z
func DecodeZuluTimestamp(timestamp string) string {
	zulu, err := time.Parse(time.RFC3339, timestamp)
	if err != nil {
		return ""
	}
	return zulu.Format("2006-01-02 3:4:5 pm")
}