// Package pac implements Microsoft Privilege Attribute Certificate (PAC) processing.
package pac

import (
	"bytes"
	"fmt"

	"gopkg.in/jcmturner/rpc.v1/mstypes"
	"gopkg.in/jcmturner/rpc.v1/ndr"
)

// KERB_VALIDATION_INFO flags.
const (
	USERFLAG_GUEST                                    = 31 // Authentication was done via the GUEST account; no password was used.
	USERFLAG_NO_ENCRYPTION_AVAILABLE                  = 30 // No encryption is available.
	USERFLAG_LAN_MANAGER_KEY                          = 28 // LAN Manager key was used for authentication.
	USERFLAG_SUB_AUTH                                 = 25 // Sub-authentication used; session key came from the sub-authentication package.
	USERFLAG_EXTRA_SIDS                               = 26 // Indicates that the ExtraSids field is populated and contains additional SIDs.
	USERFLAG_MACHINE_ACCOUNT                          = 24 // Indicates that the account is a machine account.
	USERFLAG_DC_NTLM2                                 = 23 // Indicates that the domain controller understands NTLMv2.
	USERFLAG_RESOURCE_GROUPIDS                        = 22 // Indicates that the ResourceGroupIds field is populated.
	USERFLAG_PROFILEPATH                              = 21 // Indicates that ProfilePath is populated.
	USERFLAG_NTLM2_NTCHALLENGERESP                    = 20 // The NTLMv2 response from the NtChallengeResponseFields ([MS-NLMP] section 2.2.1.3) was used for authentication and session key generation.
	USERFLAG_LM2_LMCHALLENGERESP                      = 19 // The LMv2 response from the LmChallengeResponseFields ([MS-NLMP] section 2.2.1.3) was used for authentication and session key generation.
	USERFLAG_AUTH_LMCHALLENGERESP_KEY_NTCHALLENGERESP = 18 // The LMv2 response from the LmChallengeResponseFields ([MS-NLMP] section 2.2.1.3) was used for authentication and the NTLMv2 response from the NtChallengeResponseFields ([MS-NLMP] section 2.2.1.3) was used session key generation.
)

// KerbValidationInfo implement https://msdn.microsoft.com/en-us/library/cc237948.aspx
// The KERB_VALIDATION_INFO structure defines the user's logon and authorization information
// provided by the DC. The KERB_VALIDATION_INFO structure is a subset of the
// NETLOGON_VALIDATION_SAM_INFO4 structure ([MS-NRPC] section 2.2.1.4.13).
// It is a subset due to historical reasons and to the use of the common Active Directory to generate this information.
// The KERB_VALIDATION_INFO structure is marshaled by RPC [MS-RPCE].
type KerbValidationInfo struct {
	LogOnTime              mstypes.FileTime
	LogOffTime             mstypes.FileTime
	KickOffTime            mstypes.FileTime
	PasswordLastSet        mstypes.FileTime
	PasswordCanChange      mstypes.FileTime
	PasswordMustChange     mstypes.FileTime
	EffectiveName          mstypes.RPCUnicodeString
	FullName               mstypes.RPCUnicodeString
	LogonScript            mstypes.RPCUnicodeString
	ProfilePath            mstypes.RPCUnicodeString
	HomeDirectory          mstypes.RPCUnicodeString
	HomeDirectoryDrive     mstypes.RPCUnicodeString
	LogonCount             uint16
	BadPasswordCount       uint16
	UserID                 uint32
	PrimaryGroupID         uint32
	GroupCount             uint32
	GroupIDs               []mstypes.GroupMembership `ndr:"pointer,conformant"`
	UserFlags              uint32
	UserSessionKey         mstypes.UserSessionKey
	LogonServer            mstypes.RPCUnicodeString
	LogonDomainName        mstypes.RPCUnicodeString
	LogonDomainID          mstypes.RPCSID `ndr:"pointer"`
	Reserved1              [2]uint32      // Has 2 elements
	UserAccountControl     uint32
	SubAuthStatus          uint32
	LastSuccessfulILogon   mstypes.FileTime
	LastFailedILogon       mstypes.FileTime
	FailedILogonCount      uint32
	Reserved3              uint32
	SIDCount               uint32
	ExtraSIDs              []mstypes.KerbSidAndAttributes `ndr:"pointer,conformant"`
	ResourceGroupDomainSID mstypes.RPCSID                 `ndr:"pointer"`
	ResourceGroupCount     uint32
	ResourceGroupIDs       []mstypes.GroupMembership `ndr:"pointer,conformant"`
}

// Unmarshal bytes into the DeviceInfo struct
func (k *KerbValidationInfo) Unmarshal(b []byte) (err error) {
	dec := ndr.NewDecoder(bytes.NewReader(b))
	err = dec.Decode(k)
	if err != nil {
		err = fmt.Errorf("error unmarshaling KerbValidationInfo: %v", err)
	}
	return
}

// GetGroupMembershipSIDs returns a slice of strings containing the group membership SIDs found in the PAC.
func (k *KerbValidationInfo) GetGroupMembershipSIDs() []string {
	var g []string
	lSID := k.LogonDomainID.String()
	for i := range k.GroupIDs {
		g = append(g, fmt.Sprintf("%s-%d", lSID, k.GroupIDs[i].RelativeID))
	}
	for _, s := range k.ExtraSIDs {
		var exists = false
		for _, es := range g {
			if es == s.SID.String() {
				exists = true
				break
			}
		}
		if !exists {
			g = append(g, s.SID.String())
		}
	}
	for _, r := range k.ResourceGroupIDs {
		var exists = false
		s := fmt.Sprintf("%s-%d", k.ResourceGroupDomainSID.String(), r.RelativeID)
		for _, es := range g {
			if es == s {
				exists = true
				break
			}
		}
		if !exists {
			g = append(g, s)
		}
	}
	return g
}