package ssh

import (
	"context"
	"errors"
	"net"
	"path"
	"strconv"
	"sync"

	"github.com/Neur0toxine/sshpoke/internal/config"
	"github.com/Neur0toxine/sshpoke/internal/server/driver/base"
	"github.com/Neur0toxine/sshpoke/internal/server/driver/ssh/sshtun"
	"github.com/Neur0toxine/sshpoke/internal/server/driver/ssh/types"
	"github.com/Neur0toxine/sshpoke/internal/server/driver/util"
	"github.com/Neur0toxine/sshpoke/pkg/dto"
	"github.com/Neur0toxine/sshpoke/pkg/proto/ssh"
)

var ErrAlreadyInUse = errors.New("domain is already in use")

type SSH struct {
	base.Base
	params Params
	auth   []ssh.AuthMethod
	conns  map[string]conn
	rw     sync.RWMutex
	wg     sync.WaitGroup
}

type conn struct {
	ctx    context.Context
	cancel func()
	tun    *sshtun.Tunnel
}

func New(ctx context.Context, name string, params config.DriverParams) (base.Driver, error) {
	drv := &SSH{
		Base:  base.New(ctx, name),
		conns: make(map[string]conn),
	}
	if err := util.UnmarshalParams(params, &drv.params); err != nil {
		return nil, err
	}
	drv.populateFromSSHConfig()
	drv.auth = drv.authenticators()
	return drv, nil
}

func (d *SSH) forward(val sshtun.Forward) conn {
	tun := sshtun.New(d.params.Address,
		d.params.Auth.User,
		d.params.FakeRemoteHost,
		val,
		d.auth,
		d.Log())
	ctx, cancel := context.WithCancel(d.Context())
	tunDbgLog := d.Log().With("ssh-output", val.Remote.String())
	go tun.Connect(ctx,
		sshtun.StdoutPrinterBannerCallback(tunDbgLog),
		sshtun.StdoutPrinterSessionCallback(tunDbgLog))
	return conn{ctx: ctx, cancel: cancel, tun: tun}
}

func (d *SSH) populateFromSSHConfig() {
	if d.params.Auth.Directory == "" {
		return
	}
	cfg, err := parseSSHConfig(types.SmartPath(path.Join(string(d.params.Auth.Directory), "config")))
	if err != nil {
		return
	}
	if user, err := cfg.Get(d.params.Address, "User"); err == nil && user != "" {
		d.params.Auth.User = user
	}
	if usePass, err := cfg.Get(d.params.Address, "PasswordAuthentication"); err == nil && usePass == "yes" {
		d.params.Auth.Type = types.AuthTypePassword
	}
	if keyfile, err := cfg.Get(d.params.Address, "IdentityFile"); err == nil && keyfile != "" {
		resolvedKeyFile, err := types.SmartPath(keyfile).Resolve(false)
		if err == nil {
			d.params.Auth.Type = types.AuthTypeKey
			d.params.Auth.Keyfile = resolvedKeyFile
		}
	}
}

func (d *SSH) Handle(event dto.Event) error {
	defer d.rw.Unlock()
	d.rw.Lock()
	switch event.Type {
	case dto.EventStart:
		if d.params.Mode == types.DomainModeSingle && len(d.conns) > 0 {
			return ErrAlreadyInUse
		}
		conn := d.forward(sshtun.Forward{
			Local:  sshtun.AddrToEndpoint(net.JoinHostPort(event.Container.IP.String(), strconv.Itoa(int(event.Container.Port)))),
			Remote: d.remoteEndpoint(event.Container.RemoteHost),
		})
		d.conns[event.Container.ID] = conn
		d.wg.Add(1)
	case dto.EventStop:
		conn, found := d.conns[event.Container.ID]
		if !found {
			return nil
		}
		conn.cancel()
		delete(d.conns, event.Container.ID)
		d.wg.Done()
	case dto.EventShutdown:
		for id, conn := range d.conns {
			conn.cancel()
			delete(d.conns, id)
			d.wg.Done()
		}
	}
	return nil
}

func (d *SSH) remoteEndpoint(remoteHost string) sshtun.Endpoint {
	port := int(d.params.ForwardPort)
	if port == 0 {
		port = 80
	}
	return sshtun.Endpoint{
		Host: remoteHost,
		Port: port,
	}
}

func (d *SSH) Driver() config.DriverType {
	return config.DriverSSH
}

func (d *SSH) WaitForShutdown() {
	go d.Handle(dto.Event{Type: dto.EventShutdown})
	d.wg.Wait()
}

func (d *SSH) authenticators() []ssh.AuthMethod {
	auth := d.authenticator()
	if auth == nil {
		return nil
	}
	return []ssh.AuthMethod{auth}
}

func (d *SSH) authenticator() ssh.AuthMethod {
	switch d.params.Auth.Type {
	case types.AuthTypePasswordless:
		return sshtun.AuthPassword("")
	case types.AuthTypePassword:
		return sshtun.AuthPassword(d.params.Auth.Password)
	case types.AuthTypeKey:
		if d.params.Auth.Keyfile != "" {
			keyAuth, err := sshtun.AuthKeyFile(
				types.SmartPath(path.Join(d.params.Auth.Directory.String(), d.params.Auth.Keyfile)))
			if err != nil {
				return nil
			}
			return keyAuth
		}
		dirAuth, err := sshtun.AuthKeyDir(d.params.Auth.Directory)
		if err != nil {
			return nil
		}
		return dirAuth
	}
	return nil
}