//TODO: Consider restructuring  this file/folder    "github.com/gorilla/handlers"

//It may make more sense to split into different files and not call it "helpers"

package functions

import (
    "fmt"
    "errors"
    "math/rand"
    "time"
    "context"
    "encoding/base64"
    "strings"
    "log"
    "net"
    "github.com/gravitl/netmaker/models"
    "github.com/gravitl/netmaker/mongoconn"
    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/bson/primitive"
    "go.mongodb.org/mongo-driver/mongo/options"
    "go.mongodb.org/mongo-driver/mongo"
)

//Takes in an arbitrary field and value for field and checks to see if any other
//node has that value for the same field within the group
func IsFieldUnique(group string,  field string, value string) bool {

	var node models.Node
	isunique := true

        collection := mongoconn.Client.Database("netmaker").Collection("nodes")
        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

	filter := bson.M{field: value, "group": group}

        err := collection.FindOne(ctx, filter).Decode(&node)

        defer cancel()

        if err != nil {
		return isunique
        }

        if (node.Name != "") {
                isunique = false
        }

        return isunique
}

func GroupExists(name string) (bool, error) {

        collection := mongoconn.Client.Database("netmaker").Collection("groups")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        filter := bson.M{"nameid": name}

	var result bson.M
        err := collection.FindOne(ctx, filter).Decode(&result)

	defer cancel()

	if err != nil {
		if err == mongo.ErrNoDocuments {
			return false, err
		}
		fmt.Println("ERROR RETRIEVING GROUP!")
		fmt.Println(err)
	}
	return true, err
}

//TODO: This is  very inefficient (N-squared). Need to find a better way.
//Takes a list of  nodes in a group and iterates through
//for each node, it gets a unique address. That requires checking against all other nodes once more
func UpdateGroupNodeAddresses(groupName string) error {

        //Connection mongoDB with mongoconn class
        collection := mongoconn.Client.Database("netmaker").Collection("nodes")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        filter := bson.M{"group": groupName}
        cur, err := collection.Find(ctx, filter)

        if err != nil {
                return err
        }

        defer cancel()

        for cur.Next(context.TODO()) {

                var node models.Node

                err := cur.Decode(&node)
		if err != nil {
			fmt.Println("error in node address assignment!")
                        return err
                }
		ipaddr, iperr := UniqueAddress(groupName)
                if iperr != nil {
			fmt.Println("error in node  address assignment!")
                        return iperr
                }

		filter := bson.M{"macaddress": node.MacAddress}
	        update := bson.D{{"$set", bson.D{{"address", ipaddr}}}}

		errN := collection.FindOneAndUpdate(ctx, filter, update).Decode(&node)

		defer cancel()
	        if errN != nil {
			return errN
		}
        }

        return err
}

//Checks to see if any other groups have the same name (id)
func IsGroupNameUnique(name string) bool {

        isunique := true

        dbs := ListGroups()

	for i := 0; i < len(dbs); i++ {

		if name == dbs[i].NameID {
			isunique = false
		}
	}

        return isunique
}

func IsGroupDisplayNameUnique(name string) bool {

        isunique := true

        dbs := ListGroups()

        for i := 0; i < len(dbs); i++ {

                if name == dbs[i].DisplayName {
                        isunique = false
                }
        }

        return isunique
}

//Kind  of a weird name. Should just be GetGroups I think. Consider changing.
//Anyway, returns all the groups
func ListGroups() []models.Group{
        var groups []models.Group

        collection := mongoconn.Client.Database("netmaker").Collection("groups")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        cur, err := collection.Find(ctx, bson.M{}, options.Find().SetProjection(bson.M{"_id": 0}))

        if err != nil {
                return groups
        }

        defer cancel()

        for cur.Next(context.TODO()) {

                var group models.Group
                err := cur.Decode(&group)
                if err != nil {
                        log.Fatal(err)
                }

                // add group our array
                groups = append(groups, group)
        }

        if err := cur.Err(); err != nil {
                log.Fatal(err)
        }

        return groups
}

//Checks to see if access key is valid
//Does so by checking against all keys and seeing if any have the same value
//may want to hash values before comparing...consider this
//TODO: No error handling!!!!
func IsKeyValid(groupname string, keyvalue string) bool{

	group, _ := GetParentGroup(groupname)
	var key models.AccessKey
	foundkey := false
	isvalid := false

	for i := len(group.AccessKeys) - 1; i >= 0; i-- {
              currentkey:= group.AccessKeys[i]
              if currentkey.Value == keyvalue {
			key = currentkey
			foundkey = true
		}
	}
	if foundkey {
		if key.Uses > 0 {
			isvalid  = true
		}
	}
	return isvalid
}
//TODO: Contains a fatal error return. Need to change
//This just gets a group object from a group name
//Should probably just be GetGroup. kind of a dumb name. 
//Used in contexts where it's not the Parent group.
func GetParentGroup(groupname string) (models.Group, error) {

        var group models.Group

        collection := mongoconn.Client.Database("netmaker").Collection("groups")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        filter := bson.M{"nameid": groupname}
        err := collection.FindOne(ctx, filter).Decode(&group)

        defer cancel()

        if err != nil {
                return group, err
        }

        return group, nil
}

//Check for valid IPv4 address
//Note: We dont handle IPv6 AT ALL!!!!! This definitely is needed at some point
//But for iteration 1, lets just stick to IPv4. Keep it simple stupid.
func IsIpv4Net(host string) bool {
   return net.ParseIP(host) != nil
}

//Similar to above but checks if Cidr range is valid
//At least this guy's got some print statements
//still not good error handling
func IsIpv4CIDR(host string) bool {

   ip, ipnet, err := net.ParseCIDR(host)

	if err != nil {
                fmt.Println(err)
                fmt.Println("Address Range is not valid!")
                return false
        }

   return ip != nil && ipnet != nil
}

//This is used to validate public keys (make sure they're base64 encoded like all public keys should be).
func IsBase64(s string) bool {
	_, err := base64.StdEncoding.DecodeString(s)
	return err == nil
}

//This should probably just be called GetNode
//It returns a node based on the ID of the node.
//Why do we need this?
//TODO: Check references. This seems unnecessary.
func GetNodeObj(id primitive.ObjectID) models.Node {

        var node models.Node

	collection := mongoconn.Client.Database("netmaker").Collection("nodes")
        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        filter := bson.M{"_id": id}
        err := collection.FindOne(ctx, filter).Decode(&node)

	defer cancel()

        if err != nil {
                fmt.Println(err)
		fmt.Println("Did not get the node...")
                return node
        }
	fmt.Println("Got node " + node.Name)
        return node
}

//This  checks to  make sure a group name is valid.
//Switch to REGEX?
func NameInGroupCharSet(name string) bool{

	charset := "abcdefghijklmnopqrstuvwxyz1234567890-_"

	for _, char := range name {
		if !strings.Contains(charset, strings.ToLower(string(char))) {
			return false
		}
	}
	return true
}

func NameInNodeCharSet(name string) bool{

        charset := "abcdefghijklmnopqrstuvwxyz1234567890-"

        for _, char := range name {
                if !strings.Contains(charset, strings.ToLower(string(char))) {
                        return false
                }
        }
        return true
}


//This returns a node based on its mac address.
//The mac address acts as the Unique ID for nodes.
//Is this a dumb thing to do? I thought it was cool but maybe it's dumb.
//It doesn't really provide a tangible benefit over a random ID
func GetNodeByMacAddress(group string, macaddress string) (models.Node, error) {

        var node models.Node

	filter := bson.M{"macaddress": macaddress, "group": group}

	collection := mongoconn.Client.Database("netmaker").Collection("nodes")

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        err := collection.FindOne(ctx, filter).Decode(&node)

        defer cancel()

        if err != nil {
                return node, err
        }
        return node, nil
}

//This returns a unique address for a node to use
//it iterates through the list of IP's in the subnet
//and checks against all nodes to see if it's taken, until it finds one.
//TODO: We do not handle a case where we run out of addresses.
//We will need to handle that eventually
func UniqueAddress(groupName string) (string, error){

	var group models.Group
	group, err := GetParentGroup(groupName)
        if err != nil {
                fmt.Println("UniqueAddress encountered  an error")
                return "666", err
        }

	offset := true
	ip, ipnet, err := net.ParseCIDR(group.AddressRange)
	if err != nil {
		fmt.Println("UniqueAddress encountered  an error")
		return "666", err
	}
	for ip := ip.Mask(ipnet.Mask); ipnet.Contains(ip); Inc(ip) {
		if offset {
			offset = false
			continue
		}
		if IsIPUnique(groupName, ip.String()){
			return ip.String(), err
		}
	}
	//TODO
	err1 := errors.New("ERROR: No unique addresses available. Check group subnet.")
	return "W1R3: NO UNIQUE ADDRESSES AVAILABLE", err1
}

//pretty simple get
func GetGlobalConfig() ( models.GlobalConfig, error) {

        filter := bson.M{}

        var globalconf models.GlobalConfig

        collection := mongoconn.Client.Database("netmaker").Collection("config")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        err := collection.FindOne(ctx, filter).Decode(&globalconf)

        defer cancel()

        if err != nil {
                fmt.Println(err)
                fmt.Println("Could not get global config")
                return globalconf, err
        }
	return globalconf, err
}



//generate an access key value
func GenKey() string {

  var seededRand *rand.Rand = rand.New(
  rand.NewSource(time.Now().UnixNano()))

  length := 16
  charset := "abcdefghijklmnopqrstuvwxyz" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

  b := make([]byte, length)
  for i := range b {
    b[i] = charset[seededRand.Intn(len(charset))]
  }
  return string(b)
}

//generate a key value
//we should probably just have 1 random string generator
//that  can be used across all functions
//have a "base string" a "length" and a "charset"
func GenKeyName() string {

  var seededRand *rand.Rand = rand.New(
  rand.NewSource(time.Now().UnixNano()))

  length := 5
  charset := "abcdefghijklmnopqrstuvwxyz" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

  b := make([]byte, length)
  for i := range b {
    b[i] = charset[seededRand.Intn(len(charset))]
  }
  return "key-" + string(b)
}

//checks if IP is unique in the address range
//used by UniqueAddress
func IsIPUnique(group string, ip string) bool {

	var node models.Node

	isunique := true

        collection := mongoconn.Client.Database("netmaker").Collection("nodes")
        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

	filter := bson.M{"address": ip, "group": group}

        err := collection.FindOne(ctx, filter).Decode(&node)

	defer cancel()

        if err != nil {
                fmt.Println(err)
                return isunique
        }

	if (node.Address == ip) {
		isunique = false
	}
	return isunique
}

//called once key has been used by createNode
//reduces value by one and deletes if necessary
func DecrimentKey(groupName string, keyvalue string) {

        var group models.Group

	group, err := GetParentGroup(groupName)
        if err != nil {
                return
        }

        for i := len(group.AccessKeys) - 1; i >= 0; i-- {

                currentkey := group.AccessKeys[i]
                if currentkey.Value == keyvalue {
                        group.AccessKeys[i].Uses--
			if group.AccessKeys[i].Uses < 1 {
				//this is the part where it will call the delete
				//not sure if there's edge cases I'm missing
				DeleteKey(group, i)
				return
			}
                }
        }

        collection := mongoconn.Client.Database("netmaker").Collection("groups")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        filter := bson.M{"nameid": group.NameID}

        update := bson.D{
                {"$set", bson.D{
                        {"accesskeys", group.AccessKeys},
                }},
        }
        errN := collection.FindOneAndUpdate(ctx, filter, update).Decode(&group)

        defer cancel()

        if errN != nil {
                return
        }
}
//takes the logic from controllers.deleteKey
func DeleteKey(group models.Group, i int) {

	group.AccessKeys = append(group.AccessKeys[:i],
                                group.AccessKeys[i+1:]...)

        collection := mongoconn.Client.Database("netmaker").Collection("groups")

        ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)

        // Create filter
        filter := bson.M{"nameid": group.NameID}

        // prepare update model.
        update := bson.D{
                {"$set", bson.D{
                        {"accesskeys", group.AccessKeys},
                }},
        }

        errN := collection.FindOneAndUpdate(ctx, filter, update).Decode(&group)

        defer cancel()

        if errN != nil {
                return
        }
}
//increments an IP over the previous
func Inc(ip net.IP) {
	for j := len(ip)-1; j>=0; j-- {
		ip[j]++
		if ip[j] > 0 {
			break
		}
	}
}