package main

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

var (
	Config struct {
		Port    int
		Debug   bool
		ChatBot struct {
			SessionD  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.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.Name, r.Method, r.URL.Path, err)
	} else {
		log.Printf("%s: %s %s", cookie.Name, r.Method, r.URL.Path)
	}
}

func _handle(w http.ResponseWriter, r *http.Request) error {
	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":
		w.Write(htmlChatBot)
		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) Verify() error {
	if cookie.Name == "" {
		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 {
	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)
	default:
		return handleNotFound(w, r)
	}
}

func handleAPIChatBotPost(w http.ResponseWriter, r *http.Request) error {
	cookie, _ := ParseCookie(r)
	sessionD := path.Join(Config.ChatBot.SessionD, cookie.Name)
	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.Name)

	promptF := path.Join(sessionD, "prompt.txt")
	inputF := path.Join(sessionD, "input.txt")
	cacheF := path.Join(sessionD, "cache.bin")
	reversePrompt := cookie.Name + "///"
	if err := copyFile(inputF, promptF); err != nil {
		return err
	}
	if err := appendFile(inputF, reversePrompt+message); err != nil {
		return err
	}
	if _, err := os.Stat(cacheF); os.IsNotExist(err) {
		if err := func() error {
			commands := strings.Fields(Config.ChatBot.Command)
			commands = append(commands,
				"--batch-size", "8",
				"--prompt-cache", cacheF,
				"-f", inputF,
				"--n_predict", "1",
			)
			command := exec.CommandContext(
				r.Context(),
				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
		}(); err != nil {
			return err
		}
	}

	commands := strings.Fields(Config.ChatBot.Command)
	commands = append(commands,
		"-f", inputF,
		"--prompt-cache-all",
		"--prompt-cache", cacheF,
		"-n", strconv.Itoa(Config.ChatBot.N),
		"--reverse-prompt", reversePrompt,
	)
	command := exec.CommandContext(
		r.Context(),
		commands[0],
		commands[1:]...,
	)
	command.Dir = Config.ChatBot.WD
	command.Stderr = log.Writer()

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

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

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

	result := bytes.TrimSuffix(buff.Bytes(), []byte(reversePrompt))
	priorContent, err := os.ReadFile(inputF)
	if err != nil {
		return err
	}
	shortResult := result[len(priorContent):]
	if err := os.WriteFile(promptF, result, os.ModePerm); err != nil {
		return err
	}
	w.Write(shortResult)

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

	f.Write([]byte("\n"))
	if _, err := f.WriteString(msg); err != nil {
		return err
	}
	f.Write([]byte("\n"))
	return nil
}