package main

import (
	"fmt"
	"net/http"
	"github.com/mattermost/mattermost-server/plugin"
	"github.com/mattermost/mattermost-server/model"
	"github.com/pkg/errors"
	"sync"
	"reflect"
	_ "github.com/google/go-cmp/cmp"
	"os"
	_ "github.com/fatih/structs"
	"github.com/hashicorp/go-multierror"
	_ "github.com/kr/pretty"
	"strings"
	"regexp"
	"strconv"
	"time"
	"github.com/fsnotify/fsnotify"
	"io/ioutil"
	"html"
	"encoding/json"
	"encoding/pem"
	"crypto/rsa"
	"crypto/x509"
	"crypto/rand"
	"crypto/sha1"
	"path"
	"encoding/base64"
)

const DO_LOGGING = false

var userSplit *regexp.Regexp = regexp.MustCompile(`\s+(^|[^,])|\s*,\s*`)

const (
	Unknown = uint(iota)
	Open
	Closed
)

func statusName(status uint) (string, error) {
	switch status {
	case Unknown:
		return "unknown", nil
	case Open:
		return "open", nil
	case Closed:
		return "closed", nil
	}

	return "", errors.New(fmt.Sprintf("Invalid status %d", status))
}

type DoorRequest struct {
	ip string
	time int64
	verify string
	status uint
}

type Door struct {
	id uint8
	status uint
	pubKey *rsa.PublicKey
	lastRequest *DoorRequest
}

type Config struct {
	NumDoors string
	numDoors uint8

	WatchPath string

	AdminUsers string
	adminUsers []string

	KeyPath string
}

type BathroomMonitorPlugin struct {
	plugin.MattermostPlugin
	
	config *Config
	configLock sync.RWMutex
	configChanged chan struct{}
	configUpdates int

	doorLock sync.RWMutex
	doors map[uint8]*Door

	lastReport *string
}

func (p *BathroomMonitorPlugin) getKeyFile(id uint8) (*rsa.PublicKey, error) {
	keyFile, err := ioutil.ReadFile(path.Join(p.config.KeyPath, fmt.Sprintf("public%d.pem", id)))
	if err != nil {
		return nil, err
	}

	data, _ := pem.Decode(keyFile)
	if data == nil {
		return nil, errors.New("No PEM formatted data in file")
	}

	key, err := x509.ParsePKIXPublicKey(data.Bytes)
	if err != nil {
		return nil, err
	}

	switch pub := key.(type) {
	case *rsa.PublicKey:
		return pub, nil
	}

	return nil, errors.New(fmt.Sprintf("Keyfile wasn't a public RSA PKIX key, it was %T", key))
}

func (p *BathroomMonitorPlugin) initDoors() {
	p.doorLock.Lock()
	defer p.doorLock.Unlock()

	p.doors = make(map[uint8]*Door)
	for i := uint8(0); i < p.config.numDoors; i++ {
		id := i + 1
		var pub *rsa.PublicKey = nil
		if !USE_FSNOTIFY {
			var err error
			pub, err = p.getKeyFile(id)
			if err != nil {
				p.API.LogError(errors.Wrap(err, fmt.Sprintf("Unable to load key file for id %d", id)).Error())
				pub = nil
			}
		}
		p.doors[i] = &Door {
			id: id,
			status: Unknown,
			pubKey: pub,
		}
	}
}

func (p *BathroomMonitorPlugin) log(log string) {
	if DO_LOGGING {
		p.API.LogInfo(log)
	}
}

func (p *BathroomMonitorPlugin) setDoorStatus(id uint8, status uint, report bool) error {
	if id < 1 || id > p.config.numDoors {
		return errors.New(fmt.Sprintf("Invalid door id %d", id))
	}

	if status < Unknown || status > Closed {
		return errors.New(fmt.Sprintf("Invalid door status %d", status))
	}

	if p.doors == nil || len(p.doors) < int(p.config.numDoors) {
		return errors.New("Doors not inited yet")
	}

	if p.doors[id - 1].status != status {
		p.doors[id - 1].status = status
		if report {
			statusStr, _ := statusName(status)
			_ = statusStr
			//p.postAdminChannel(fmt.Sprintf("STATUS: door %d = %s", id, statusStr))
			p.API.PublishWebSocketEvent("updated", map[string]interface{}{}, &model.WebsocketBroadcast{})
		}
	} else {
		p.log(fmt.Sprintf("Asked to change status from %d to %d ?", p.doors[id - 1].status, status))
	}

	return nil
}

func (p *BathroomMonitorPlugin) init() *BathroomMonitorPlugin {
	p.config = &Config {
		NumDoors: "1", 
		numDoors: 1, 

		WatchPath: "./", 

		KeyPath: "./",

		AdminUsers: "",
	}

	p.configChanged = make(chan struct{})

	return p;
}

func (p *BathroomMonitorPlugin) validateRequestDoorId(r *http.Request) (uint8, error) {
	p.configLock.Lock()
	numDoors := p.config.numDoors
	p.configLock.Unlock()


	doorStr, ok := r.Form["door_id"]
	if !ok || len(doorStr) == 0 {
		return 0, errors.New("Please send door id")
	}

	doorId, err := strconv.ParseUint(doorStr[0], 10, 8)
	if err != nil {
		return 0, errors.New(fmt.Sprintf("Couldn't parse door_id: %s", err.Error()))
	}
	doorId8 := uint8(doorId)

	if doorId8 < 1 || doorId8 > numDoors {
		return 0, errors.New("Invalid door id")
	}

	return doorId8, nil
}

func (p *BathroomMonitorPlugin) ServeHTTP(c *plugin.Context, w http.ResponseWriter, r *http.Request) {
	p.log(fmt.Sprintf("Requested path: %s %s", r.URL.Path, c.IpAddress))
	if r.URL.Path == "/status" {
		p.doorLock.Lock()
		defer p.doorLock.Unlock()

		var write map[string]string = make(map[string]string)
		for d, s := range p.doors {
			statusStr, _ := statusName(s.status)
			write[fmt.Sprintf("%d", d + 1)] = statusStr
		}
		if output, err := json.Marshal(write); err == nil {
			fmt.Fprint(w, string(output))
		} else {
			fmt.Fprint(w, html.EscapeString(err.Error()))
		}
		return
	}
	if r.URL.Path == "/status-update" {
		r.ParseForm()
		p.log("Contacted by " + r.RemoteAddr)

		doorId8, err := p.validateRequestDoorId(r)
		if err != nil {
			fmt.Fprint(w, err.Error())
			return
		}

		statusStr, ok := r.Form["status"]
		if !ok || len(statusStr) == 0 {
			fmt.Fprint(w, "Please send door status")
			return
		}

		status, err := strconv.ParseUint(statusStr[0], 10, 8)
		if err != nil {
			fmt.Fprintf(w, "Couldn't parse status: %s", err.Error())
			return
		}

		if status != 0 && status != 1 {
			fmt.Fprint(w, "Invalid status")
			return
		}

		statusVal := Open
		if status == 1 {
			statusVal = Closed
		}

		p.doorLock.Lock()
		defer p.doorLock.Unlock()

		if p.doors[doorId8 - 1].pubKey == nil {
			fmt.Fprintf(w, "No public key found for door %d", doorId8)
			return
		}

		p.log("Getting random bytes")
		var verifyBytes [50]byte
		rand.Read(verifyBytes[:])
		p.log("Encoding random bytes")

		verifyB64 := base64.StdEncoding.EncodeToString(verifyBytes[:])

		p.log("Encryping random bytes")
		encrypted, err := rsa.EncryptOAEP(sha1.New(), rand.Reader, p.doors[doorId8 - 1].pubKey, verifyBytes[:], []byte{})
		if err != nil {
			fmt.Fprintf(w, "Couldn't encrypt verification: %s", err.Error())
			return
		}

		p.log("Encoding encrypted bytes")
		encryptedB64 := base64.StdEncoding.EncodeToString(encrypted)


		req := &DoorRequest {
			ip:c.IpAddress,
			time:time.Now().Unix(),
			verify:verifyB64,
			status: statusVal,
		}

		p.doors[doorId8 - 1].lastRequest = req

		p.log(fmt.Sprintf("NEW REQUEST SAVED: %s %d %s", req.ip, req.time, req.verify))

		fmt.Fprint(w, encryptedB64)


		return
	}
	if r.URL.Path == "/verify-status" {
		r.ParseForm()
		p.log("Contacted by " + r.RemoteAddr)
		doorId8, err := p.validateRequestDoorId(r)
		if err != nil {
			fmt.Fprint(w, err.Error())
			return
		}

		verifyB64, ok := r.Form["verify"]
		if !ok || len(verifyB64) <= 0 {
			fmt.Fprint(w, "Please send the verification code")
			return
		}

		p.log("Verify locking")
		p.doorLock.Lock()
		defer p.doorLock.Unlock()
		p.log("Verify done locking")

		if p.doors[doorId8 - 1].lastRequest == nil {
			fmt.Fprint(w, "Invalid request")
			return
		}

		req := p.doors[doorId8 - 1].lastRequest
		if req.ip != c.IpAddress {
			fmt.Fprintf(w, "Not your request %s %s", req.ip, r.RemoteAddr)
			return
		}

		diff := time.Now().Unix() - req.time
		if diff < 0 || diff > 10 {
			fmt.Fprint(w, "Request expired")
			return
		}


		if req.verify != verifyB64[0] {
			p.log(fmt.Sprintf("Failed verification %s %s", req.verify, verifyB64[0]))
			fmt.Fprint(w, "Unauthorized request")
			return
		}


		p.doors[doorId8 - 1].lastRequest = nil

		p.log("Changing")
		err = p.setDoorStatus(doorId8, req.status, true)
		p.log("Changed")
		if err != nil {
			fmt.Fprintf(w, "Couldn't set status %d %d: %s", doorId8, req.status, err.Error())
		}

		return

	}
	http.NotFound(w, r)
}

func (p *BathroomMonitorPlugin) confChangedEvent() {
	select {
	case p.configChanged <- struct{}{}:
	default:
	}
}

func (p *BathroomMonitorPlugin) postAdminChannel(text string) {
	p.API.LogError(text)
	if p.lastReport != nil && *p.lastReport == text {
		return
	}
	p.lastReport = &text
	var users []*model.User = make([]*model.User, 0, len(p.config.adminUsers))
	for _, un := range(p.config.adminUsers) {
		u, _ := p.API.GetUserByUsername(un)
		if u != nil {
			users = append(users, u)
		}
	}
	
	if len(users) > 0 {
		admin := users[0]
		bots, _ := p.API.GetBots(&model.BotGetOptions{Page:0, PerPage:1000})
		var bathroom_bot *model.Bot = nil
		if bots != nil {
			for _, b := range(bots) {
				if b.Username == "bathroom-bot" {
					bathroom_bot = b
					break
				}
			}
		}

		if bathroom_bot == nil {
			created_bathroom_bot, err := p.API.CreateBot(&model.Bot{Username:"bathroom-bot", OwnerId:admin.Id, DisplayName:"Bathroom Bot", Description:"Tracks Bathroom Status"})
			if err != nil {
				p.API.LogError(errors.Wrap(err, "Couldn't create bathroom-bot bot").Error())
				return
			}
			bathroom_bot = created_bathroom_bot
		}

		if bathroom_bot == nil {
			p.API.LogError("Really couldn't create bathroom-bot bot")
			return
		}
		
		for _, u := range(users) {
			channel, err := p.API.GetDirectChannel(bathroom_bot.UserId, u.Id);
			if err != nil {
				p.API.LogError(errors.Wrap(err, fmt.Sprintf("Couldn't get direct channel to user %s", u.Username)).Error())
				continue
			}
			p.API.CreatePost(&model.Post{UserId: bathroom_bot.UserId, ChannelId:channel.Id, Message:text, MessageSource:text})
		}
	} else {
		p.API.LogError("No admin users?")
	}
}

func (p *BathroomMonitorPlugin) OnConfigurationChange() error {
	p.configLock.Lock()
	defer p.configLock.Unlock()

	var newConfig *Config = new(Config);
	if err := p.API.LoadPluginConfiguration(newConfig); err != nil {
		newErr := errors.Wrap(err, fmt.Sprintf("%d: Failed to load configuration", p.configUpdates))
		p.postAdminChannel(newErr.Error())
		return newErr
	}

	if newConfig == nil || newConfig == p.config || reflect.ValueOf(*newConfig).NumField() == 0 {
		p.API.LogInfo("Passed same config, or empty?")
		return nil;
	}

	var configErr error = nil


	if USE_FSNOTIFY {
		if info, err := os.Stat(newConfig.WatchPath); err != nil || info.Mode() & os.ModeDir != os.ModeDir {
			newConfig.WatchPath = "./"
			configErr = multierror.Append(configErr, errors.Wrap(err, "Invalid watch path"))
		}
	} else {
		if info, err := os.Stat(newConfig.KeyPath); err != nil || info.Mode() & os.ModeDir != os.ModeDir {
			newConfig.KeyPath = "./"
			configErr = multierror.Append(configErr, errors.Wrap(err, "Invalid key path"))
		}
	}


	numDoors, err := strconv.ParseUint(newConfig.NumDoors, 10, 8)
	if err != nil {
		newConfig.NumDoors = "1"
		newConfig.numDoors = 1
		configErr = multierror.Append(configErr, errors.Wrap(err, "Invalid number of doors"))
	} else {
		newConfig.numDoors = uint8(numDoors)
	}

	newConfig.adminUsers = make([]string, 0, 4)
	
	split := userSplit.Split(newConfig.AdminUsers, -1)
	for _, un := range split {
		trimmed := strings.Trim(un, ", \t\n")
		if trimmed != "" {
			newConfig.adminUsers = append(newConfig.adminUsers, trimmed)
		}
	}

	p.config = newConfig
	p.configUpdates++

	p.initDoors()

	p.log(fmt.Sprintf("%d: Config: %d %s", p.configUpdates, p.config.numDoors, p.config.WatchPath))

	if configErr != nil {
		p.postAdminChannel(configErr.Error())
	}

	p.confChangedEvent()

	return configErr
}

func fileNotifyBasedLoop(p *BathroomMonitorPlugin) {
	doorFile, err := regexp.Compile(`(^|/)door(\d+)$`)
	if err != nil {
		p.API.LogError(errors.Wrap(err, "Couldn't compile regex").Error())
		return
	}

	for {
		p.configLock.Lock()
		numDoors := p.config.numDoors
		watchPath := p.config.WatchPath
		p.configLock.Unlock()

		_ = numDoors

		watcher, err := fsnotify.NewWatcher()
		if err != nil {
			p.API.LogError(errors.Wrap(err, "Couldn't make watcher").Error())
			time.Sleep(60)
			continue
		}

		err = watcher.Add(watchPath)

		if err != nil {
			p.API.LogError(errors.Wrap(err, "Couldn't watch WatchPath").Error())
		}

		run := true
		for ;run; {
			select {
			case event, ok := <- watcher.Events:
				if (!ok) {
					p.API.LogError(errors.Wrap(err, "Couldn't get fsnotify event").Error())
					time.Sleep(60)
					run = false
				} else {
					match := doorFile.FindStringSubmatch(event.Name)
					if match == nil {
						continue
					}

					id64, err := strconv.ParseUint(match[2], 10, 8)
					if err != nil {
						p.API.LogError(errors.Wrap(err, "ParseUint error").Error())
						continue
					}

					id := uint8(id64)
					if id < 1 || id > numDoors {
						continue
					}

					if event.Op & fsnotify.Write != fsnotify.Write && event.Op & fsnotify.Create != fsnotify.Create {
						continue
					}

					statusBytes, err := ioutil.ReadFile(event.Name)
					if err != nil {
						p.API.LogError(errors.Wrap(err, "Couldn't read door file").Error())
					}

					status := strings.Trim(string(statusBytes), " \n\t")
					if len(status) <= 0 {
						continue
					}

					statusInt, err := strconv.ParseUint(status, 10, 32)
					if err != nil {
						p.API.LogError(errors.Wrap(err, "Status invalid " + status).Error())
						continue
					}

					newStatus := Open
					if statusInt == 1 {
						newStatus = Closed
					}

					p.doorLock.Lock()
					err = p.setDoorStatus(id, newStatus, true)
					p.doorLock.Unlock()

					if err != nil {
						p.API.LogError(errors.Wrap(err, fmt.Sprintf("Couldn't set door status %d %d", id, statusInt)).Error())
						continue
					}
				}
			case <- p.configChanged:
				p.log(fmt.Sprintf("CONFIG CHANGED, RESTARTING %d", p.configUpdates))
				run = false
			}
		}

		watcher.Close()
	}
}


func (p *BathroomMonitorPlugin) OnActivate() error {
	if USE_FSNOTIFY {
		go fileNotifyBasedLoop(p)
	} else {
	}

	return nil
}

func main() {
	plugin.ClientMain((&BathroomMonitorPlugin{}).init())
}