package crdt

import (
	"errors"
	"net"
	"strings"

	"github.com/automerge/automerge-go"
	logging "github.com/tim-beatham/wgmesh/pkg/log"
	"golang.zx2c4.com/wireguard/wgctrl"
	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
)

// CrdtNodeManager manages nodes in the crdt mesh
type CrdtNodeManager struct {
	MeshId string
	IfName string
	NodeId string
	Client *wgctrl.Client
	doc    *automerge.Doc
}

const maxFails = 5

func (c *CrdtNodeManager) AddNode(crdt MeshNodeCrdt) {
	crdt.FailedMap = automerge.NewMap()
	c.doc.Path("nodes").Map().Set(crdt.HostEndpoint, crdt)
}

func (c *CrdtNodeManager) ApplyWg() error {
	snapshot, err := c.GetCrdt()

	if err != nil {
		return err
	}

	c.updateWgConf(c.IfName, snapshot.Nodes, *c.Client)
	return nil
}

// GetCrdt(): Converts the document into a struct
func (c *CrdtNodeManager) GetCrdt() (*MeshCrdt, error) {
	return automerge.As[*MeshCrdt](c.doc.Root())
}

// Load: Load an entire mesh network
func (c *CrdtNodeManager) Load(bytes []byte) error {
	doc, err := automerge.Load(bytes)

	if err != nil {
		return err
	}

	c.doc = doc
	return nil
}

// Save: Save an entire mesh network
func (c *CrdtNodeManager) Save() []byte {
	return c.doc.Save()
}

func (c *CrdtNodeManager) LoadChanges(changes []byte) error {
	err := c.doc.LoadIncremental(changes)

	if err != nil {
		return err
	}

	return nil
}

func (c *CrdtNodeManager) SaveChanges() []byte {
	return c.doc.SaveIncremental()
}

// NewCrdtNodeManager: Create a new crdt node manager
func NewCrdtNodeManager(meshId, hostId, devName string, client *wgctrl.Client) *CrdtNodeManager {
	var manager CrdtNodeManager
	manager.MeshId = meshId
	manager.doc = automerge.New()
	manager.IfName = devName
	manager.Client = client
	manager.NodeId = hostId
	return &manager
}

func (m *CrdtNodeManager) convertMeshNode(node MeshNodeCrdt) (*wgtypes.PeerConfig, error) {
	peerEndpoint, err := net.ResolveUDPAddr("udp", node.WgEndpoint)

	if err != nil {
		return nil, err
	}

	peerPublic, err := wgtypes.ParseKey(node.PublicKey)

	if err != nil {
		return nil, err
	}

	allowedIps := make([]net.IPNet, 1)
	_, ipnet, err := net.ParseCIDR(node.WgHost)

	if err != nil {
		return nil, err
	}

	allowedIps[0] = *ipnet

	peerConfig := wgtypes.PeerConfig{
		PublicKey:  peerPublic,
		Remove:     m.HasFailed(node.HostEndpoint),
		Endpoint:   peerEndpoint,
		AllowedIPs: allowedIps,
	}

	return &peerConfig, nil
}

func (m1 *MeshNodeCrdt) Compare(m2 *MeshNodeCrdt) int {
	return strings.Compare(m1.PublicKey, m2.PublicKey)
}

func (c *CrdtNodeManager) changeFailedCount(meshId, endpoint string, incAmount int64) error {
	node, err := c.doc.Path("nodes").Map().Get(endpoint)

	if err != nil {
		return err
	}

	counterMap, err := node.Map().Get("failedMap")

	if counterMap.Kind() == automerge.KindVoid {
		return errors.New("Something went wrong map does not exist")
	}

	counter, _ := counterMap.Map().Get(c.NodeId)

	if counter.Kind() == automerge.KindVoid {
		err = counterMap.Map().Set(c.NodeId, incAmount)
	} else {
		if counter.Int64()+incAmount < 0 {
			return nil
		}

		err = counterMap.Map().Set(c.NodeId, counter.Int64()+1)
	}

	return err
}

// Increment failed count increments the number of times we have attempted
// to contact the node and it's failed
func (c *CrdtNodeManager) IncrementFailedCount(endpoint string) error {
	return c.changeFailedCount(c.MeshId, endpoint, +1)
}

func (c *CrdtNodeManager) removeNode(endpoint string) error {
	err := c.doc.Path("nodes").Map().Delete(endpoint)

	if err != nil {
		return err
	}

	return nil
}

// Decrement failed count decrements the number of times we have attempted to
// contact the node and it's failed
func (c *CrdtNodeManager) DecrementFailedCount(endpoint string) error {
	return c.changeFailedCount(c.MeshId, endpoint, -1)
}

// GetNode: returns a mesh node crdt.
func (m *CrdtNodeManager) GetNode(endpoint string) (*MeshNodeCrdt, error) {
	node, err := m.doc.Path("nodes").Map().Get(endpoint)

	if err != nil {
		return nil, err
	}

	meshNode, err := automerge.As[*MeshNodeCrdt](node)

	if err != nil {
		return nil, err
	}

	return meshNode, nil
}

const threshold = 2
const thresholdVotes = 0.1

func (m *CrdtNodeManager) Length() int {
	return m.doc.Path("nodes").Map().Len()
}

func (m *CrdtNodeManager) HasFailed(endpoint string) bool {
	node, err := m.GetNode(endpoint)

	if err != nil {
		logging.InfoLog.Printf("Cannot get node node: %s\n", endpoint)
		return true
	}

	values, err := node.FailedMap.Values()

	if err != nil {
		return true
	}

	countFailed := 0

	for _, value := range values {
		count := value.Int64()

		if count >= threshold {
			countFailed++
		}
	}

	logging.InfoLog.Printf("Count Failed Value: %d\n", countFailed)
	logging.InfoLog.Printf("Threshold Value: %d\n", int(thresholdVotes*float64(m.Length())+1))
	return countFailed >= int(thresholdVotes*float64(m.Length())+1)
}

func (m *CrdtNodeManager) updateWgConf(devName string, nodes map[string]MeshNodeCrdt, client wgctrl.Client) error {
	peerConfigs := make([]wgtypes.PeerConfig, len(nodes))

	var count int = 0

	for _, n := range nodes {
		peer, err := m.convertMeshNode(n)
		logging.InfoLog.Println(n.HostEndpoint)

		if err != nil {
			return err
		}

		peerConfigs[count] = *peer
		count++
	}

	cfg := wgtypes.Config{
		Peers:        peerConfigs,
		ReplacePeers: true,
	}

	client.ConfigureDevice(devName, cfg)
	return nil
}