package mesh

import (
	"errors"
	"fmt"
	"sync"

	"github.com/tim-beatham/wgmesh/pkg/cmd"
	"github.com/tim-beatham/wgmesh/pkg/conf"
	"github.com/tim-beatham/wgmesh/pkg/ip"
	"github.com/tim-beatham/wgmesh/pkg/lib"
	"github.com/tim-beatham/wgmesh/pkg/wg"
	"golang.zx2c4.com/wireguard/wgctrl"
	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
)

type MeshManager interface {
	CreateMesh(params *CreateMeshParams) (string, error)
	AddMesh(params *AddMeshParams) error
	HasChanges(meshid string) bool
	GetMesh(meshId string) MeshProvider
	GetPublicKey() *wgtypes.Key
	AddSelf(params *AddSelfParams) error
	LeaveMesh(meshId string) error
	GetSelf(meshId string) (MeshNode, error)
	ApplyConfig() error
	SetDescription(description string) error
	SetAlias(alias string) error
	SetService(service string, value string) error
	RemoveService(service string) error
	UpdateTimeStamp() error
	GetClient() *wgctrl.Client
	GetMeshes() map[string]MeshProvider
	Close() error
	GetNode(string, string) MeshNode
	GetRouteManager() RouteManager
}

type MeshManagerImpl struct {
	lock         sync.RWMutex
	Meshes       map[string]MeshProvider
	RouteManager RouteManager
	Client       *wgctrl.Client
	// HostParameters contains information that uniquely locates
	// the node in the mesh network.
	HostParameters       *HostParameters
	conf                 *conf.DaemonConfiguration
	meshProviderFactory  MeshProviderFactory
	nodeFactory          MeshNodeFactory
	configApplyer        MeshConfigApplyer
	idGenerator          lib.IdGenerator
	ipAllocator          ip.IPAllocator
	interfaceManipulator wg.WgInterfaceManipulator
	cmdRunner            cmd.CmdRunner
	OnDelete             func(MeshProvider)
}

// GetRouteManager implements MeshManager.
func (m *MeshManagerImpl) GetRouteManager() RouteManager {
	return m.RouteManager
}

// RemoveService implements MeshManager.
func (m *MeshManagerImpl) RemoveService(service string) error {
	for _, mesh := range m.Meshes {
		err := mesh.RemoveService(m.HostParameters.GetPublicKey(), service)

		if err != nil {
			return err
		}
	}

	return nil
}

// SetService implements MeshManager.
func (m *MeshManagerImpl) SetService(service string, value string) error {
	for _, mesh := range m.Meshes {
		err := mesh.AddService(m.HostParameters.GetPublicKey(), service, value)

		if err != nil {
			return err
		}
	}

	return nil
}

func (m *MeshManagerImpl) GetNode(meshid, nodeId string) MeshNode {
	mesh, ok := m.Meshes[meshid]

	if !ok {
		return nil
	}

	node, err := mesh.GetNode(nodeId)

	if err != nil {
		return nil
	}

	return node
}

// CreateMeshParams contains the parameters required to create a mesh
type CreateMeshParams struct {
	Port int
	Conf *conf.WgConfiguration
}

// getConf: gets the new configuration with the base configuration overriden
// from the recent
func (m *MeshManagerImpl) getConf(override *conf.WgConfiguration) (*conf.WgConfiguration, error) {
	meshConfiguration := m.conf.BaseConfiguration

	if override != nil {
		newConf, err := conf.MergeMeshConfiguration(meshConfiguration, *override)

		if err != nil {
			return nil, err
		}

		meshConfiguration = newConf
	}

	return &meshConfiguration, nil
}

// CreateMesh: Creates a new mesh, stores it and returns the mesh id
func (m *MeshManagerImpl) CreateMesh(args *CreateMeshParams) (string, error) {
	meshConfiguration, err := m.getConf(args.Conf)

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

	if *meshConfiguration.Role == conf.CLIENT_ROLE {
		return "", fmt.Errorf("cannot create mesh as a client")
	}

	meshId, err := m.idGenerator.GetId()

	var ifName string = ""

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

	m.cmdRunner.RunCommands(m.conf.BaseConfiguration.PreUp...)

	if !m.conf.StubWg {
		ifName, err = m.interfaceManipulator.CreateInterface(args.Port, m.HostParameters.PrivateKey)

		if err != nil {
			return "", fmt.Errorf("error creating mesh: %w", err)
		}
	}

	nodeManager, err := m.meshProviderFactory.CreateMesh(&MeshProviderFactoryParams{
		DevName:    ifName,
		Port:       args.Port,
		Conf:       meshConfiguration,
		Client:     m.Client,
		MeshId:     meshId,
		DaemonConf: m.conf,
		NodeID:     m.HostParameters.GetPublicKey(),
	})

	if err != nil {
		return "", fmt.Errorf("error creating mesh: %w", err)
	}

	m.lock.Lock()
	m.Meshes[meshId] = nodeManager
	m.lock.Unlock()

	m.cmdRunner.RunCommands(m.conf.BaseConfiguration.PostUp...)

	return meshId, nil
}

type AddMeshParams struct {
	MeshId    string
	WgPort    int
	MeshBytes []byte
	Conf      *conf.WgConfiguration
}

// AddMesh: Add the mesh to the list of meshes
func (m *MeshManagerImpl) AddMesh(params *AddMeshParams) error {
	var ifName string
	var err error

	meshConfiguration, err := m.getConf(params.Conf)

	if err != nil {
		return err
	}

	m.cmdRunner.RunCommands(meshConfiguration.PreUp...)

	if !m.conf.StubWg {
		ifName, err = m.interfaceManipulator.CreateInterface(params.WgPort, m.HostParameters.PrivateKey)

		if err != nil {
			return err
		}
	}

	meshProvider, err := m.meshProviderFactory.CreateMesh(&MeshProviderFactoryParams{
		DevName:    ifName,
		Port:       params.WgPort,
		Conf:       meshConfiguration,
		Client:     m.Client,
		MeshId:     params.MeshId,
		DaemonConf: m.conf,
		NodeID:     m.HostParameters.GetPublicKey(),
	})

	m.cmdRunner.RunCommands(meshConfiguration.PostUp...)

	if err != nil {
		return err
	}

	err = meshProvider.Load(params.MeshBytes)

	if err != nil {
		return err
	}

	m.lock.Lock()
	m.Meshes[params.MeshId] = meshProvider
	m.lock.Unlock()
	return nil
}

// HasChanges returns true if the mesh has changes
func (m *MeshManagerImpl) HasChanges(meshId string) bool {
	return m.Meshes[meshId].HasChanges()
}

// GetMesh returns the mesh with the given meshid
func (m *MeshManagerImpl) GetMesh(meshId string) MeshProvider {
	theMesh := m.Meshes[meshId]
	return theMesh
}

// GetPublicKey: Gets the public key of the WireGuard mesh
func (s *MeshManagerImpl) GetPublicKey() *wgtypes.Key {
	key := s.HostParameters.PrivateKey.PublicKey()
	return &key
}

type AddSelfParams struct {
	// MeshId is the ID of the mesh to add this instance to
	MeshId string
	// WgPort is the WireGuard port to advertise
	WgPort int
	// Endpoint is the alias of the machine to send routable packets
	Endpoint string
}

// AddSelf adds this host to the mesh
func (s *MeshManagerImpl) AddSelf(params *AddSelfParams) error {
	mesh := s.GetMesh(params.MeshId)

	if mesh == nil {
		return fmt.Errorf("addself: mesh %s does not exist", params.MeshId)
	}

	if params.WgPort == 0 && !s.conf.StubWg {
		device, err := mesh.GetDevice()

		if err != nil {
			return err
		}

		params.WgPort = device.ListenPort
	}

	pubKey := s.HostParameters.PrivateKey.PublicKey()

	nodeIP, err := s.ipAllocator.GetIP(pubKey, params.MeshId)

	if err != nil {
		return err
	}

	node := s.nodeFactory.Build(&MeshNodeFactoryParams{
		PublicKey:  &pubKey,
		NodeIP:     nodeIP,
		WgPort:     params.WgPort,
		Endpoint:   params.Endpoint,
		MeshConfig: mesh.GetConfiguration(),
	})

	if !s.conf.StubWg {
		device, err := mesh.GetDevice()

		if err != nil {
			return fmt.Errorf("failed to get device %w", err)
		}

		err = s.interfaceManipulator.AddAddress(device.Name, fmt.Sprintf("%s/64", nodeIP))

		if err != nil {
			return fmt.Errorf("addSelf: failed to add address to dev %w", err)
		}
	}

	s.Meshes[params.MeshId].AddNode(node)
	return nil
}

// LeaveMesh leaves the mesh network
func (s *MeshManagerImpl) LeaveMesh(meshId string) error {
	mesh := s.GetMesh(meshId)

	if mesh == nil {
		return fmt.Errorf("mesh %s does not exist", meshId)
	}

	err := mesh.RemoveNode(s.HostParameters.GetPublicKey())

	if err != nil {
		return err
	}

	if s.OnDelete != nil {
		s.OnDelete(mesh)
	}

	s.lock.Lock()
	delete(s.Meshes, meshId)
	s.lock.Unlock()

	s.cmdRunner.RunCommands(s.conf.BaseConfiguration.PreDown...)

	if !s.conf.StubWg {
		device, err := mesh.GetDevice()

		if err != nil {
			return err
		}

		err = s.interfaceManipulator.RemoveInterface(device.Name)

		if err != nil {
			return err
		}
	}

	s.cmdRunner.RunCommands(s.conf.BaseConfiguration.PostDown...)

	return err
}

func (s *MeshManagerImpl) GetSelf(meshId string) (MeshNode, error) {
	meshInstance, ok := s.Meshes[meshId]

	if !ok {
		return nil, fmt.Errorf("mesh %s does not exist", meshId)
	}

	node, err := meshInstance.GetNode(s.HostParameters.GetPublicKey())

	if err != nil {
		return nil, errors.New("the node doesn't exist in the mesh")
	}

	return node, nil
}

func (s *MeshManagerImpl) ApplyConfig() error {
	if s.conf.StubWg {
		return nil
	}

	err := s.configApplyer.ApplyConfig()

	if err != nil {
		return err
	}

	return nil
}

func (s *MeshManagerImpl) SetDescription(description string) error {
	meshes := s.GetMeshes()
	for _, mesh := range meshes {
		if mesh.NodeExists(s.HostParameters.GetPublicKey()) {
			err := mesh.SetDescription(s.HostParameters.GetPublicKey(), description)

			if err != nil {
				return err
			}
		}
	}

	return nil
}

// SetAlias implements MeshManager.
func (s *MeshManagerImpl) SetAlias(alias string) error {
	meshes := s.GetMeshes()
	for _, mesh := range meshes {
		if mesh.NodeExists(s.HostParameters.GetPublicKey()) {
			err := mesh.SetAlias(s.HostParameters.GetPublicKey(), alias)

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

// UpdateTimeStamp updates the timestamp of this node in all meshes
func (s *MeshManagerImpl) UpdateTimeStamp() error {
	meshes := s.GetMeshes()
	for _, mesh := range meshes {
		if mesh.NodeExists(s.HostParameters.GetPublicKey()) {
			err := mesh.UpdateTimeStamp(s.HostParameters.GetPublicKey())

			if err != nil {
				return err
			}
		}
	}

	return nil
}

func (s *MeshManagerImpl) GetClient() *wgctrl.Client {
	return s.Client
}

func (s *MeshManagerImpl) GetMeshes() map[string]MeshProvider {
	meshes := make(map[string]MeshProvider)

	s.lock.RLock()

	for id, mesh := range s.Meshes {
		meshes[id] = mesh
	}

	s.lock.RUnlock()
	return meshes
}

// Close the mesh manager
func (s *MeshManagerImpl) Close() error {
	if s.conf.StubWg {
		return nil
	}

	for _, mesh := range s.Meshes {
		dev, err := mesh.GetDevice()

		if err != nil {
			return err
		}

		err = s.interfaceManipulator.RemoveInterface(dev.Name)

		if err != nil {
			return err
		}
	}

	return nil
}

// NewMeshManagerParams params required to create an instance of a mesh manager
type NewMeshManagerParams struct {
	Conf                 conf.DaemonConfiguration
	Client               *wgctrl.Client
	MeshProvider         MeshProviderFactory
	NodeFactory          MeshNodeFactory
	IdGenerator          lib.IdGenerator
	IPAllocator          ip.IPAllocator
	InterfaceManipulator wg.WgInterfaceManipulator
	ConfigApplyer        MeshConfigApplyer
	RouteManager         RouteManager
	CommandRunner        cmd.CmdRunner
	OnDelete             func(MeshProvider)
}

// Creates a new instance of a mesh manager with the given parameters
func NewMeshManager(params *NewMeshManagerParams) MeshManager {
	privateKey, _ := wgtypes.GeneratePrivateKey()
	hostParams := HostParameters{
		PrivateKey: &privateKey,
	}

	m := &MeshManagerImpl{
		Meshes:              make(map[string]MeshProvider),
		HostParameters:      &hostParams,
		meshProviderFactory: params.MeshProvider,
		nodeFactory:         params.NodeFactory,
		Client:              params.Client,
		conf:                &params.Conf,
	}

	m.configApplyer = params.ConfigApplyer
	m.RouteManager = params.RouteManager

	if m.RouteManager == nil {
		m.RouteManager = NewRouteManager(m)
	}

	if params.CommandRunner == nil {
		m.cmdRunner = &cmd.UnixCmdRunner{}
	}

	m.idGenerator = params.IdGenerator
	m.ipAllocator = params.IPAllocator
	m.interfaceManipulator = params.InterfaceManipulator

	m.OnDelete = params.OnDelete
	return m
}