package main

import (
	"bytes"
	"context"
	_ "embed"
	"encoding/base64"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"os/signal"
	"path"
	"regexp"
	"strconv"
	"strings"
	"sync"
	"syscall"
)

var (
	Config struct {
		Port    int
		Debug   bool
		ChatBot struct {
			SessionD        string
			PromptDelimiter string
			semaphore       sync.Mutex
			WD              string
			Command         string
			N               int
		}
	}

	//go:embed template.d/login.html
	htmlLogin []byte
	//go:embed template.d/index.html
	htmlIndex []byte
	//go:embed template.d/chatbot.html
	htmlChatBot []byte
)

func main() {
	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
	defer can()

	ctx, cleanup := contextWithCleanup(ctx)
	defer cleanup()

	config(ctx)
	log.Printf("%+v", Config)

	listenAndServe(ctx)
	log.Println("done")
}

func contextWithCleanup(ctx context.Context) (context.Context, func()) {
	m := map[int]func(){}
	ctx = context.WithValue(ctx, "__cleanup__", m)
	return ctx, func() {
		defer func() {
			recover()
		}()
		for _, v := range m {
			v()
		}
	}
}

func contextWithCleanupFunc(ctx context.Context, foo func()) {
	v := ctx.Value("__cleanup__")
	if v == nil {
		panic("cannot get context with cleanup func that doesnt have cleanup init")
	}
	m := v.(map[int]func())
	m[len(m)] = foo
}

func config(ctx context.Context) {
	d, err := os.MkdirTemp(os.TempDir(), "ai.*")
	if err != nil {
		panic(err)
	}
	contextWithCleanupFunc(ctx, func() { os.RemoveAll(d) })

	flag.IntVar(&Config.Port, "p", 37070, "port to listen on")
	flag.StringVar(&Config.ChatBot.SessionD, "chatbot-session-d", d, "dir to store chat bot sessions")
	flag.StringVar(&Config.ChatBot.PromptDelimiter, "chatbot-rp", "> ", "prompt delimiter prefixed by NAME/YOU")
	flag.StringVar(&Config.ChatBot.WD, "chatbot-working-d", "./llama.cpp", "working directory for chatbot")
	flag.StringVar(&Config.ChatBot.Command, "chatbot-cmd", "./main -m ./models/ggml-vic7b-uncensored-q5_1.bin --repeat_penalty 1.0", "chatbot cmd prefix")
	flag.IntVar(&Config.ChatBot.N, "chatbot-n", 256, "chatbot items to gen")
	flag.BoolVar(&Config.Debug, "debug", false, "debug mode")
	flag.Parse()
}

func listenAndServe(ctx context.Context) {
	wg := &sync.WaitGroup{}
	s := &http.Server{
		Addr:    fmt.Sprintf(":%d", Config.Port),
		Handler: http.HandlerFunc(handle),
	}
	wg.Add(1)
	go func() {
		defer wg.Done()
		if err := s.ListenAndServe(); err != nil && ctx.Err() == nil {
			panic(err)
		}
	}()

	<-ctx.Done()
	s.Close()
	wg.Wait()
}

func handle(w http.ResponseWriter, r *http.Request) {
	cookie, _ := ParseCookie(r)
	if err := _handle(w, r); err != nil {
		log.Printf("%s: %s %s: %v", cookie.MyName(), r.Method, r.URL.Path, err)
	} else {
		log.Printf("%s: %s %s", cookie.MyName(), r.Method, r.URL.Path)
	}
}

func _handle(w http.ResponseWriter, r *http.Request) error {
	//ctx, can := context.WithTimeout(r.Context(), time.Minute)
	//defer can()
	//r = r.WithContext(ctx)

	first := strings.Split(strings.TrimLeft(r.URL.Path, "/"), "/")[0]
	switch first {
	case "login":
		return handleLogin(w, r)
	case "api":
		return handleAPI(w, r)
	default:
		return handleUI(w, r)
	}
}

func handleLogin(w http.ResponseWriter, r *http.Request) error {
	switch r.Method {
	case http.MethodGet:
		w.Write(htmlLogin)
		return nil
	case http.MethodPost:
		err := r.ParseForm()
		if err != nil {
			return err
		}
		cookie, err := ParseCookie(r)
		if err != nil {
			return err
		}
		cookie.Inject(w)
		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
		return nil
	default:
		return handleNotFound(w, r)
	}
}

func handleUI(w http.ResponseWriter, r *http.Request) error {
	if _, err := ParseCookie(r); err != nil {
		http.Redirect(w, r, "/login", http.StatusTemporaryRedirect)
		return err
	}

	switch r.URL.Path {
	case "/":
		w.Write(htmlIndex)
		return nil
	case "/chatbot":
		if !Config.Debug {
			w.Write(htmlChatBot)
		} else {
			b, _ := os.ReadFile("./template.d/chatbot.html")
			w.Write(b)
		}
		return nil
	default:
		return handleNotFound(w, r)
	}
}

type Cookie struct {
	Name string
}

func ParseCookie(r *http.Request) (Cookie, error) {
	if r.URL.Path != "/login" {
		return parseCookieFromCookie(r)
	}
	cookie := Cookie{
		Name: r.PostForm.Get("Name"),
	}
	return cookie, cookie.Verify()
}

func parseCookieFromCookie(r *http.Request) (Cookie, error) {
	cookie, err := r.Cookie("root")
	if err != nil {
		return Cookie{}, err
	}

	decoded, err := base64.URLEncoding.DecodeString(cookie.Value)
	if err != nil {
		return Cookie{}, err
	}

	var result Cookie
	if err := json.Unmarshal(decoded, &result); err != nil {
		return Cookie{}, err
	}

	return result, result.Verify()
}

func (cookie Cookie) MyName() string {
	return string(bytes.Join(
		regexp.MustCompile(`[a-zA-Z]`).FindAll([]byte(cookie.Name), -1),
		[]byte(""),
	))
}

func (cookie Cookie) Verify() error {
	if cookie.MyName() == "" {
		return fmt.Errorf("incomplete cookie")
	}
	return nil
}

func (cookie Cookie) Inject(w http.ResponseWriter) {
	c := &http.Cookie{
		Name:  "root",
		Value: cookie.Serialize(),
	}
	http.SetCookie(w, c)
}

func (cookie Cookie) Serialize() string {
	b, _ := json.Marshal(cookie)
	return base64.URLEncoding.EncodeToString(b)
}

func handleAPI(w http.ResponseWriter, r *http.Request) error {
	if _, err := ParseCookie(r); err != nil {
		http.Redirect(w, r, "/login", http.StatusTemporaryRedirect)
		return err
	}

	switch r.URL.Path {
	case "/api/v0/chatbot":
		return handleAPIChatBot(w, r)
	default:
		return handleNotFound(w, r)
	}
}

func handleNotFound(w http.ResponseWriter, r *http.Request) error {
	http.NotFound(w, r)
	return fmt.Errorf("not found: %s %s", r.Method, r.URL.Path)
}

func handleAPIChatBot(w http.ResponseWriter, r *http.Request) error {
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	err := r.ParseForm()
	if err != nil {
		return err
	}

	switch r.Method {
	case http.MethodPost:
		return handleAPIChatBotPost(w, r)
	case http.MethodPut:
		return handleAPIChatBotPut(w, r)
	case http.MethodGet:
		return handleAPIChatBotGet(w, r)
	default:
		return handleNotFound(w, r)
	}
}

func handleAPIChatBotGet(w http.ResponseWriter, r *http.Request) error {
	cookie, _ := ParseCookie(r)
	sessionD := path.Join(Config.ChatBot.SessionD, cookie.MyName())
	f, err := os.Open(path.Join(sessionD, "prompt.txt"))
	if err != nil {
		return err
	}
	defer f.Close()

	io.Copy(w, f)
	return nil
}

func handleAPIChatBotPost(w http.ResponseWriter, r *http.Request) error {
	cookie, _ := ParseCookie(r)
	sessionD := path.Join(Config.ChatBot.SessionD, cookie.MyName())
	if _, err := os.Stat(path.Join(sessionD)); err == nil {
		if err := os.RemoveAll(path.Join(sessionD)); err != nil {
			return err
		}
	}
	if err := os.MkdirAll(path.Join(sessionD, "chat.d"), os.ModePerm); err != nil {
		return err
	}

	prompt := r.PostForm.Get("Prompt")
	if len(prompt) == 0 {
		return errors.New("no prompt")
	}
	if err := os.WriteFile(path.Join(sessionD, "prompt.txt"), []byte(prompt), os.ModePerm); err != nil {
		return err
	}

	return handleAPIChatBotPut(w, r)
}

func handleAPIChatBotPut(w http.ResponseWriter, r *http.Request) error {
	message := r.PostForm.Get("Message")
	if len(message) == 0 {
		return errors.New("empty Message")
	}

	cookie, _ := ParseCookie(r)
	sessionD := path.Join(Config.ChatBot.SessionD, cookie.MyName())

	promptF := path.Join(sessionD, "prompt.txt")
	inputF := path.Join(sessionD, "input.txt")
	cacheF := path.Join(sessionD, "cache.bin")
	reversePrompt := cookie.MyName()
	if len(reversePrompt) > 8 {
		reversePrompt = reversePrompt[:8]
	}
	reversePrompt = reversePrompt + Config.ChatBot.PromptDelimiter
	forwardPrompt := "YOU" + Config.ChatBot.PromptDelimiter
	if err := copyFile(inputF, promptF); err != nil {
		return err
	}
	if err := chatBotGenerateInitCacheF(r.Context(), cacheF, inputF); err != nil {
		return err
	}
	if err := appendFile(inputF, reversePrompt+message+"\n"+forwardPrompt); err != nil {
		return err
	}

	justNew, err := chatBotGenerateAndFillInputF(r.Context(), cacheF, inputF, reversePrompt, 0)
	if err != nil {
		return err
	}
	//log.Printf("generated for %s via %s: [%s]", cookie.MyName(), r.URL.Path, justNew)
	if err := os.Rename(inputF, promptF); err != nil {
		return err
	}
	w.Write(bytes.TrimSuffix(justNew, []byte(reversePrompt)))

	return nil
}

func chatBotGenerateInitCacheF(ctx context.Context, cacheF, inputF string) error {
	if _, err := os.Stat(cacheF); !os.IsNotExist(err) {
		return nil
	}
	commands := strings.Fields(Config.ChatBot.Command)
	commands = append(commands,
		"--batch-size", "8",
		"--prompt-cache", cacheF,
		"-f", inputF,
		"--n_predict", "1",
	)
	command := exec.CommandContext(
		ctx,
		commands[0],
		commands[1:]...,
	)
	command.Dir = Config.ChatBot.WD

	Config.ChatBot.semaphore.Lock()
	defer Config.ChatBot.semaphore.Unlock()

	if b, err := command.CombinedOutput(); err != nil {
		return fmt.Errorf("error generating cache with '%s': %w: %s", command.String(), err, b)
	}
	return nil
}

func chatBotGenerateAndFillInputF(ctx context.Context, cacheF, inputF, reversePrompt string, depth int) ([]byte, error) {
	if depth >= 3 {
		justNew := []byte("...\n" + reversePrompt)
		return justNew, _appendFile(inputF, string(justNew))
	}

	commands := strings.Fields(Config.ChatBot.Command)
	commands = append(commands,
		"-f", inputF,
		"--prompt-cache-all",
		"--prompt-cache", cacheF,
		"-n", strconv.Itoa(Config.ChatBot.N),
	)
	if len(reversePrompt) > 0 {
		commands = append(commands,
			"--reverse-prompt", reversePrompt,
		)
	}
	command := exec.CommandContext(
		ctx,
		commands[0],
		commands[1:]...,
	)
	command.Dir = Config.ChatBot.WD
	command.Stderr = io.Discard
	command.Stderr = log.Writer()

	stdout, err := command.StdoutPipe()
	if err != nil {
		return nil, err
	}
	buff := bytes.NewBuffer(nil)
	go func() {
		stdout.Read(make([]byte, 1)) //1 BOS byte
		io.Copy(buff, stdout)
	}()

	if err := func() error {
		Config.ChatBot.semaphore.Lock()
		defer Config.ChatBot.semaphore.Unlock()

		return command.Run()
	}(); err != nil {
		return nil, err

	}

	oldAndNew := buff.Bytes()
	priorContent, err := os.ReadFile(inputF)
	if err != nil {
		return nil, err
	}
	justNew := oldAndNew[len(priorContent):]

	if idx := bytes.Index(justNew, []byte(reversePrompt)); idx > 0 {
		justNew = justNew[:idx]
	} else if idx := bytes.LastIndex(
		append(priorContent, justNew...),
		[]byte(reversePrompt),
	); idx+len(reversePrompt) > len(priorContent) {
		justNew = justNew[:idx+len(reversePrompt)-len(priorContent)]
	}
	if err := _appendFile(inputF, string(justNew)); err != nil {
		return nil, err
	}

	if !bytes.HasSuffix(append(priorContent, justNew...), []byte(reversePrompt)) {
		more, err := chatBotGenerateAndFillInputF(ctx, cacheF, inputF, reversePrompt, depth+1)
		if err != nil {
			return nil, err
		}
		justNew = append(justNew, more...)
	}
	return justNew, nil
}

func copyFile(toF, fromF string) error {
	from, err := os.Open(fromF)
	if err != nil {
		return err
	}
	defer from.Close()

	to, err := os.Create(toF)
	if err != nil {
		return err
	}
	defer to.Close()

	io.Copy(to, from)
	return nil
}

func appendFile(toF, msg string) error {
	return _appendFile(toF, "\n"+msg+"\n")
}

func _appendFile(toF, msg string) error {
	f, err := os.OpenFile(toF, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
	if err != nil {
		return err
	}
	defer f.Close()

	if _, err := f.WriteString(msg); err != nil {
		return err
	}
	return nil
}