// peerChatKeys provides functions to store user chat keys

package peerChatKeys

// We need to keep their keys in a seperate location, as opposed to reading user chat keys from the database
// We do this because if a user's profile expires/is banned, the person chatting with them may want to continue talking to them.
// If we prevented deleting their profile from the database, that could pose a fingerprinting risk when contacting hosts
// Hosts would know that the requestor had been chatting with the profiles which were expired, because they would normally be deleted
// Therefore, we store the user's chat keys in peerChatKeys, so we can delete their expired profile and still keep their chat keys
// Their profile will be deleted from the database when the identity expires/is banned.

// Active keys are keys that are a maximum of 1 day older than any any known peer latestChatKeysUpdateTime

// TODO: create updateStoredChatKeys to refresh all chat keys for all saved identities
// TODO: Delete chat keys for users who are not chatting partners

import "seekia/internal/encoding"
import "seekia/internal/helpers"
import "seekia/internal/identity"
import "seekia/internal/messaging/peerDevices"
import "seekia/internal/myDatastores/myMap"
import "seekia/internal/myDatastores/myMapList"
import "seekia/internal/profiles/profileStorage"
import "seekia/internal/profiles/readProfiles"
import "seekia/internal/unixTime"

import "strings"
import "sync"
import "errors"

// This mutex will be locked whenever we are updating the peer chat keys MyMapList
var updatingPeerChatKeysMutex sync.Mutex

// This mutex will be locked whenever we are updating the peer chat keys latest update time MyMap
var updatingPeerChatKeysLatestUpdateTimeMutex sync.Mutex

var peerChatKeysMapListDatastore *myMapList.MyMapList

// Map Structure: Peer Identity Hash + "@" + networkType -> Latest update unix time 
var peerChatKeysLatestUpdateTimeMapDatastore *myMap.MyMap

// This function must be called whenever an app user signs in
func InitializePeerChatKeysDatastores()error{

	updatingPeerChatKeysMutex.Lock()
	defer updatingPeerChatKeysMutex.Unlock()

	updatingPeerChatKeysLatestUpdateTimeMutex.Lock()
	defer updatingPeerChatKeysLatestUpdateTimeMutex.Unlock()

	newPeerChatKeysMapListDatastore, err := myMapList.CreateNewMapList("PeerChatKeys")
	if (err != nil) { return err }

	newPeerChatKeysLatestUpdateTimeMapDatastore, err := myMap.CreateNewMap("PeerChatKeysLatestUpdateTime")
	if (err != nil) { return err }

	peerChatKeysMapListDatastore = newPeerChatKeysMapListDatastore
	peerChatKeysLatestUpdateTimeMapDatastore = newPeerChatKeysLatestUpdateTimeMapDatastore

	return nil
}


// This function will return true if we need to download a user's newest chat keys
// It determines this by comparing a user's saved chat keys to their latest chat keys update time
//Outputs:
//	-bool: User's chat keys are missing (will return false if their newest profile is disabled)
//	-error
func CheckIfUsersChatKeysAreMissing(userIdentityHash [16]byte, networkType byte)(bool, error){

	isValid := helpers.VerifyNetworkType(networkType)
	if (isValid == false){
		networkTypeString := helpers.ConvertByteToString(networkType)
		return false, errors.New("CheckIfUsersChatKeysAreMissing called with invalid networkType: " + networkTypeString)
	}

	profileIsDisabled, chatKeysExist, _, _, err := GetPeerNewestActiveChatKeys(userIdentityHash, networkType)
	if (err != nil) { return false, err }
	if (profileIsDisabled == true){
		// We treat this as the chat keys not being missing
		return false, nil
	}
	if (chatKeysExist == true){
		return false, nil
	}

	return true, nil
}

// This function saves a user's chat key latest update time from a message
// It is used to keep track of when peer updates their key set, so the app knows to retrieve new chat keys
// This information could be wrong, if newer keys have been shared since the user sent their message
func SavePeerMessageLatestChatKeysUpdateTime(peerIdentityHash [16]byte, networkType byte, theirLatestChatKeysUpdateTime int64, theirMessageCreationTime int64)error{

	updatingPeerChatKeysLatestUpdateTimeMutex.Lock()
	defer updatingPeerChatKeysLatestUpdateTimeMutex.Unlock()

	peerIdentityHashString, _, err := identity.EncodeIdentityHashBytesToString(peerIdentityHash)
	if (err != nil){
		peerIdentityHashHex := encoding.EncodeBytesToHexString(peerIdentityHash[:])
		return errors.New("SavePeerMessageLatestChatKeysUpdateTime called with invalid peerIdentityHash: " + peerIdentityHashHex)
	}

	isValid := helpers.VerifyNetworkType(networkType)
	if (isValid == false){
		networkTypeString := helpers.ConvertByteToString(networkType)
		return errors.New("SavePeerMessageLatestChatKeysUpdateTime called with invalid networkType: " + networkTypeString)
	}

	existingLatestUpdateTimeExists, existingLatestUpdateTime, existingLatestUpdateTimeCreationTime, err := getSavedPeerMessageLatestChatKeysUpdateTime(peerIdentityHash, networkType)
	if (err != nil){ return err }
	if (existingLatestUpdateTimeExists == true){

		if (existingLatestUpdateTimeCreationTime > theirMessageCreationTime){
			// We already have a latest update time which was sent at later time
			// Nothing to do
			return nil
		}

		// We have a latest update time that was created earler
		// We see if the newer created latest update time is actually newer
		if (existingLatestUpdateTime > theirLatestChatKeysUpdateTime){
			// They are sending a latestUpdateTime that is older than one they have previously sent
			// The user has probably moved to a different device, and then moved back to their previous device
			// This should not happen
			// To avoid this happening we should make sure there is an option in the GUI to reinitialize the application as if it is a new device
			// This will require sharing a new LatestChatKeysUpdateTime in our profile
			//
			// We will delete our stored chatKeys and update our datastore latestChatKeysUpdateTime
			// This will allow their older chat keys to be used if and when they created a profile from their device.

			networkTypeString := helpers.ConvertByteToString(networkType)

			mapToDelete := map[string]string{
				"PeerIdentityHash": peerIdentityHashString,
				"NetworkType": networkTypeString,
			}

			err := peerChatKeysMapListDatastore.DeleteMapListItems(mapToDelete)
			if (err != nil) { return err }
		}
	}

	theirLatestChatKeysUpdateTimeString := helpers.ConvertInt64ToString(theirLatestChatKeysUpdateTime)
	theirMessageCreationTimeString := helpers.ConvertInt64ToString(theirMessageCreationTime)

	networkTypeString := helpers.ConvertByteToString(networkType)

	newMapKey := peerIdentityHashString + "@" + networkTypeString
	newMapValue := theirLatestChatKeysUpdateTimeString + "$" + theirMessageCreationTimeString

	err = peerChatKeysLatestUpdateTimeMapDatastore.SetMapEntry(newMapKey, newMapValue)
	if (err != nil) { return err }

	return nil
}


// This function retrieves our saved peer latest chat keys update time that we received in a message
//Outputs:
//	-bool: Latest update time info exists
//	-int64: Latest Update Time
//	-int64: Latest update time creation time (the time when the user shared this latestUpdateTime)
//	-error
func getSavedPeerMessageLatestChatKeysUpdateTime(peerIdentityHash [16]byte, networkType byte)(bool, int64, int64, error){

	peerIdentityHashString, _, err := identity.EncodeIdentityHashBytesToString(peerIdentityHash)
	if (err != nil){
		peerIdentityHashHex := encoding.EncodeBytesToHexString(peerIdentityHash[:])
		return false, 0, 0, errors.New("getSavedPeerMessageLatestChatKeysUpdateTime called with invalid peerIdentityHash: " + peerIdentityHashHex)
	}

	isValid := helpers.VerifyNetworkType(networkType)
	if (isValid == false){
		networkTypeString := helpers.ConvertByteToString(networkType)
		return false, 0, 0, errors.New("getSavedPeerMessageLatestChatKeysUpdateTime called with invalid networkType: " + networkTypeString)
	}

	networkTypeString := helpers.ConvertByteToString(networkType)

	mapKey := peerIdentityHashString + "@" + networkTypeString

	entryExists, mapValue, err := peerChatKeysLatestUpdateTimeMapDatastore.GetMapEntry(mapKey)
	if (err != nil) { return false, 0, 0, err }
	if (entryExists == false){
		return false, 0, 0, nil
	}

	latestUpdateTime, latestUpdateTimeCreationTime, delimiterFound := strings.Cut(mapValue, "$")
	if (delimiterFound == false){
		return false, 0, 0, errors.New("peerChatKeysLatestUpdateTimeMapDatastore entry is malformed: Map value missing $: " + mapValue)
	}

	latestUpdateTimeInt64, err := helpers.ConvertStringToInt64(latestUpdateTime)
	if (err != nil){
		return false, 0, 0, errors.New("peerChatKeysLatestUpdateTimeMapDatastore entry value is malformed: Invalid latestUpdateTime: " + latestUpdateTime)
	}

	latestUpdateTimeCreationTimeInt64, err := helpers.ConvertStringToInt64(latestUpdateTimeCreationTime)
	if (err != nil){
		return false, 0, 0, errors.New("peerChatKeysLatestUpdateTimeMapDatastore entry value is malformed: Invalid latestUpdateTimeCreationTime: " + latestUpdateTimeCreationTime)
	}

	return true, latestUpdateTimeInt64, latestUpdateTimeCreationTimeInt64, nil
}


// This function returns the newest saved device chat keys list for a user 
// It also checks saved profiles to update saved keys.
//Outputs:
//	-bool: Peer newest profile is known to be disabled
//	-bool: Peer active chat keys found
//	-[32]byte: Nacl Key
//	-[1568]byte: Kyber key
//	-error
func GetPeerNewestActiveChatKeys(peerIdentityHash [16]byte, networkType byte)(bool, bool, [32]byte, [1568]byte, error){

	peerIdentityHashString, userIdentityType, err := identity.EncodeIdentityHashBytesToString(peerIdentityHash)
	if (err != nil) {
		peerIdentityHashHex := encoding.EncodeBytesToHexString(peerIdentityHash[:])
		return false, false, [32]byte{}, [1568]byte{}, errors.New("GetPeerNewestActiveChatKeys called with invalid peerIdentityHash: " + peerIdentityHashHex)
	}

	if (userIdentityType != "Mate" && userIdentityType != "Moderator"){
		return false, false, [32]byte{}, [1568]byte{}, errors.New("Trying to get peer chat keys for host identity")
	}

	isValid := helpers.VerifyNetworkType(networkType)
	if (isValid == false){
		networkTypeString := helpers.ConvertByteToString(networkType)
		return false, false, [32]byte{}, [1568]byte{}, errors.New("GetPeerNewestActiveChatKeys called with invalid networkType: " + networkTypeString)
	}

	updatingPeerChatKeysMutex.Lock()
	defer updatingPeerChatKeysMutex.Unlock()

	//Outputs:
	//	-bool: Peer newest profile is known to be disabled
	//	-bool: Any keys found
	//	-[32]byte: User Nacl key
	//	-[1568]byte: User Kyber key
	//	-int64: Time keys were created
	//	-error
	getPeerNewestKnownChatKeys := func()(bool, bool, [32]byte, [1568]byte, int64, error){

		// We get newest known user chat keys
		// We check database and storage, and return whichever are newer

		// Database = Profiles within the badger database
		// Storage = myMapList datastore

		//Outputs:
		//	-bool: Profile found
		//	-bool: Profile is disabled
		//	-int64: Profile creation time
		//	-[32]byte: Peer Nacl key
		//	-[1568]byte: Peer Kyber key
		//	-error
		getPeerChatKeysMapFromDatabase := func()(bool, bool, int64, [32]byte, [1568]byte, error){

			profileExists, _, _, _, profileCreationTime, rawProfileMap, err := profileStorage.GetNewestUserProfile(peerIdentityHash, networkType)
			if (err != nil) { return false, false, 0, [32]byte{}, [1568]byte{}, err }
			if (profileExists == false) {
				return false, false, 0, [32]byte{}, [1568]byte{}, nil
			}

			profileIsDisabled, _, err := readProfiles.GetFormattedProfileAttributeFromRawProfileMap(rawProfileMap, "Disabled")
			if (err != nil) { return false, false, 0, [32]byte{}, [1568]byte{}, err }
			if (profileIsDisabled == true){
				return true, true, profileCreationTime, [32]byte{}, [1568]byte{}, nil
			}

			exists, peerNaclKey, err := readProfiles.GetFormattedProfileAttributeFromRawProfileMap(rawProfileMap, "NaclKey")
			if (err != nil) { return false, false, 0, [32]byte{}, [1568]byte{}, err }
			if (exists == false){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Database corrupt: Contains Mate/Moderator profile missing NaclKey")
			}

			exists, peerKyberKey, err := readProfiles.GetFormattedProfileAttributeFromRawProfileMap(rawProfileMap, "KyberKey")
			if (err != nil) { return false, false, 0, [32]byte{}, [1568]byte{}, err }
			if (exists == false){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Database corrupt: Contains Mate/Moderator profile missing KyberKey")
			}

			peerNaclKeyBytes, err := encoding.DecodeBase64StringToBytes(peerNaclKey)
			if (err != nil){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Database corrupt: Contains Mate/Moderator profile with invalid NaclKey: Not Base64: " + peerNaclKey)
			}

			if (len(peerNaclKeyBytes) != 32){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Database corrupt: Contains Mate/Moderator profile with invalid NaclKey: Invalid length: " + peerNaclKey)
			}

			peerNaclKeyArray := [32]byte(peerNaclKeyBytes)

			peerKyberKeyBytes, err := encoding.DecodeBase64StringToBytes(peerKyberKey)
			if (err != nil){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Database corrupt: Contains Mate/Moderator profile with invalid KyberKey: Not Base64: " + peerKyberKey)
			}

			if (len(peerKyberKeyBytes) != 1568){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Database corrupt: Contains Mate/Moderator profile with invalid KyberKey: Invalid length: " + peerKyberKey)
			}

			peerKyberKeyArray := [1568]byte(peerKyberKeyBytes)

			return true, false, profileCreationTime, peerNaclKeyArray, peerKyberKeyArray, nil
		}

		//Outputs:
		//	-bool: Peer stored keys found
		//	-bool: Peer is disabled
		//	-int64: Creation time of these keys/disabled status
		//	-[32]byte: Peer Nacl Key
		//	-[1568]byte: Peer Kyber key
		//	-error
		getPeerChatKeysMapListFromMyMapListStorage := func()(bool, bool, int64, [32]byte, [1568]byte, error){

			networkTypeString := helpers.ConvertByteToString(networkType)

			lookupMap := map[string]string{
				"PeerIdentityHash": peerIdentityHashString,
				"NetworkType": networkTypeString,
			}

			exists, retrievedMapListItems, err := peerChatKeysMapListDatastore.GetMapListItems(lookupMap)
			if (err != nil) { return false, false, 0, [32]byte{}, [1568]byte{}, err }
			if (exists == false){
				return false, false, 0, [32]byte{}, [1568]byte{}, nil
			}

			if (len(retrievedMapListItems) != 1) {
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: multiple entries found.")
			}

			peerChatKeysMap := retrievedMapListItems[0]

			keysCreationTime, exists := peerChatKeysMap["CreationTime"]
			if (exists == false) {
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item missing CreationTime")
			}

			keysCreationTimeInt64, err := helpers.ConvertCreationTimeStringToInt64(keysCreationTime)
			if (err != nil) {
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item contains invalid CreationTime: " + keysCreationTime)
			}

			peerIsDisabled, exists := peerChatKeysMap["PeerIsDisabled"]
			if (exists == true && peerIsDisabled == "Yes"){
				return true, true, keysCreationTimeInt64, [32]byte{}, [1568]byte{}, nil
			}
			
			peerNaclKey, exists := peerChatKeysMap["NaclKey"]
			if (exists == false) {
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item missing NaclKey")
			}

			peerKyberKey, exists := peerChatKeysMap["KyberKey"]
			if (exists == false) {
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item missing KyberKey")
			}

			peerNaclKeyBytes, err := encoding.DecodeBase64StringToBytes(peerNaclKey)
			if (err != nil){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item contains invalid NaclKey: Not Base64: " + peerNaclKey)
			}

			if (len(peerNaclKeyBytes) != 32){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item contains invalid NaclKey: Invalid length: " + peerNaclKey)
			}

			peerNaclKeyArray := [32]byte(peerNaclKeyBytes)

			peerKyberKeyBytes, err := encoding.DecodeBase64StringToBytes(peerKyberKey)
			if (err != nil){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item contains invalid KyberKey: Not Base64: " + peerKyberKey)
			}

			if (len(peerKyberKeyBytes) != 1568){
				return false, false, 0, [32]byte{}, [1568]byte{}, errors.New("Malformed peer chat keys maplist: Item contains invalid KyberKey: Invalid length: " + peerKyberKey)
			}

			peerKyberKeyArray := [1568]byte(peerKyberKeyBytes)

			return true, false, keysCreationTimeInt64, peerNaclKeyArray, peerKyberKeyArray, nil
		}

		databaseUserProfileExists, databaseProfileIsDisabled, databaseUserProfileCreationTime, databaseUserNaclKey, databaseUserKyberKey, err := getPeerChatKeysMapFromDatabase()
		if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, 0, err }

		storageUserChatKeysInfoExists, storageProfileIsDisabled, storageUserProfileCreationTime, storageUserNaclKey, storageUserKyberKey, err := getPeerChatKeysMapListFromMyMapListStorage()
		if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, 0, err }

		if (databaseUserProfileExists == false){

			if (storageUserChatKeysInfoExists == false){
				return false, false, [32]byte{}, [1568]byte{}, 0, nil
			}

			if (storageProfileIsDisabled == true){
				return true, false, [32]byte{}, [1568]byte{}, 0, nil
			}

			return false, true, storageUserNaclKey, storageUserKyberKey, storageUserProfileCreationTime, nil
		}
		// Database chat keys exist

		if (storageUserChatKeysInfoExists == true){

			// Both the database profile and the datastore info exist
			// We see which contains newer information

			if (databaseUserProfileCreationTime <= storageUserProfileCreationTime){
				// myMapList storage is up to date, or even more recent than the stored profile
				// The latter would occur if a newer profile was deleted at some point, and an older profile was downloaded
				// We return the myMapList stored data

				if (storageProfileIsDisabled == true){
					return true, false, [32]byte{}, [1568]byte{}, 0, nil
				}
				return false, true, storageUserNaclKey, storageUserKyberKey, storageUserProfileCreationTime, nil
			}
		}

		// MyMapList chat keys entry is either missing or out of date.
		// Update them with database profile keys, and return the database profile chat keys
		// Note that just because the created profile is newer does not mean the chat keys are any different.

		networkTypeString := helpers.ConvertByteToString(networkType)

		deleteLookupMap := map[string]string{
			"PeerIdentityHash": peerIdentityHashString,
			"NetworkType": networkTypeString,
		}

		err = peerChatKeysMapListDatastore.DeleteMapListItems(deleteLookupMap)
		if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, 0, err }

		creationTimeString := helpers.ConvertInt64ToString(databaseUserProfileCreationTime)

		newChatKeysMap := map[string]string{
			"PeerIdentityHash": peerIdentityHashString,
			"NetworkType": networkTypeString,
			"CreationTime": creationTimeString,
		}

		if (databaseProfileIsDisabled == true){
			newChatKeysMap["PeerIsDisabled"] = "Yes"
		} else {

			databaseUserNaclKeyString := encoding.EncodeBytesToBase64String(databaseUserNaclKey[:])
			databaseUserKyberKeyString := encoding.EncodeBytesToBase64String(databaseUserKyberKey[:])

			newChatKeysMap["NaclKey"] = databaseUserNaclKeyString
			newChatKeysMap["KyberKey"] = databaseUserKyberKeyString
		}

		err = peerChatKeysMapListDatastore.AddMapListItem(newChatKeysMap)
		if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, 0, err }

		if (databaseProfileIsDisabled == true){
			return true, false, [32]byte{}, [1568]byte{}, 0, nil
		}

		return false, true, databaseUserNaclKey, databaseUserKyberKey, databaseUserProfileCreationTime, nil
	}

	peerProfileIsDisabled, peerChatKeysExist, peerNewestKnownNaclKey, peerNewestKnownKyberKey, peerNewestKnownKeysCreationTime, err := getPeerNewestKnownChatKeys()
	if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, err }
	if (peerProfileIsDisabled == true){
		return true, false, [32]byte{}, [1568]byte{}, nil
	}
	if (peerChatKeysExist == false){
		return false, false, [32]byte{}, [1568]byte{}, nil
	}

	// We check to see if user has updated their device since they created these keys

	deviceInfoFound, _, deviceFirstSeenTime, err := peerDevices.GetPeerNewestDeviceInfo(peerIdentityHash, networkType)
	if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, err }
	if (deviceInfoFound == true){
		if (deviceFirstSeenTime > peerNewestKnownKeysCreationTime){
			// User has changed their device since they created these keys
			// We do not have access to the user's chat keys
			return false, false, [32]byte{}, [1568]byte{}, nil
		}
	}

	// Now we check to see if user has sent a newer ChatKeysLatestUpdateTime
	// We allow a 1 day grace period where old keys will still work

	newestUpdateTimeIsKnown, newestUpdateTime, _, err := getSavedPeerMessageLatestChatKeysUpdateTime(peerIdentityHash, networkType)
	if (err != nil) { return false, false, [32]byte{}, [1568]byte{}, err }
	if (newestUpdateTimeIsKnown == true){

		dayUnix := unixTime.GetDayUnix()

		keysExpirationTime := newestUpdateTime - dayUnix

		if (peerNewestKnownKeysCreationTime < keysExpirationTime){
			return false, false, [32]byte{}, [1568]byte{}, nil
		}
	}

	return false, true, peerNewestKnownNaclKey, peerNewestKnownKyberKey, nil
}