package http

import (
	"crypto/rand"
	_ "embed"
	"encoding/base64"
	"fmt"
	"mime/multipart"
	"strings"
	"sync"
	"time"

	"Moonshark/http/router"
	"Moonshark/http/sessions"

	luajit "git.sharkk.net/Sky/LuaJIT-to-Go"
	"github.com/goccy/go-json"
	"github.com/valyala/fasthttp"
)

//go:embed http.lua
var httpLuaCode string

type Server struct {
	server      *fasthttp.Server
	router      *router.Router
	sessions    *sessions.SessionManager
	state       *luajit.State
	stateMu     sync.Mutex
	funcCounter int
}

type RequestContext struct {
	Method  string
	Path    string
	Headers map[string]string
	Query   map[string]string
	Form    map[string]any
	Cookies map[string]string
	Session *sessions.Session
	Body    string
	Params  map[string]string
}

var globalServer *Server

func NewServer(state *luajit.State) *Server {
	return &Server{
		router:   router.New(),
		sessions: sessions.NewSessionManager(10000),
		state:    state,
	}
}

func RegisterHTTPFunctions(L *luajit.State) error {
	globalServer = NewServer(L)

	functions := map[string]luajit.GoFunction{
		"__http_listen":       globalServer.httpListen,
		"__http_route":        globalServer.httpRoute,
		"__http_set_status":   httpSetStatus,
		"__http_set_header":   httpSetHeader,
		"__http_redirect":     httpRedirect,
		"__session_get":       globalServer.sessionGet,
		"__session_set":       globalServer.sessionSet,
		"__session_flash":     globalServer.sessionFlash,
		"__session_get_flash": globalServer.sessionGetFlash,
		"__cookie_set":        cookieSet,
		"__cookie_get":        cookieGet,
		"__csrf_generate":     globalServer.csrfGenerate,
		"__csrf_validate":     globalServer.csrfValidate,
	}

	for name, fn := range functions {
		if err := L.RegisterGoFunction(name, fn); err != nil {
			return err
		}
	}

	return L.DoString(httpLuaCode)
}

func (s *Server) httpListen(state *luajit.State) int {
	port, err := state.SafeToNumber(1)
	if err != nil {
		return state.PushError("listen: port must be number")
	}

	s.server = &fasthttp.Server{
		Handler: s.requestHandler,
		Name:    "Moonshark/1.0",
	}

	addr := fmt.Sprintf(":%d", int(port))
	go func() {
		if err := s.server.ListenAndServe(addr); err != nil {
			fmt.Printf("Server error: %v\n", err)
		}
	}()

	fmt.Printf("Server listening on port %d\n", int(port))
	state.PushBoolean(true)
	return 1
}

func (s *Server) httpRoute(state *luajit.State) int {
	method, err := state.SafeToString(1)
	if err != nil {
		return state.PushError("route: method must be string")
	}

	path, err := state.SafeToString(2)
	if err != nil {
		return state.PushError("route: path must be string")
	}

	if !state.IsFunction(3) {
		return state.PushError("route: handler must be function")
	}

	// Store function and get reference
	state.PushCopy(3)
	funcRef := s.storeFunction()

	// Add route to router
	if err := s.router.AddRoute(strings.ToUpper(method), path, funcRef); err != nil {
		return state.PushError("route: failed to add route: %s", err.Error())
	}

	state.PushBoolean(true)
	return 1
}

func (s *Server) storeFunction() int {
	s.state.GetGlobal("__moonshark_functions")
	if s.state.IsNil(-1) {
		s.state.Pop(1)
		s.state.NewTable()
		s.state.PushCopy(-1)
		s.state.SetGlobal("__moonshark_functions")
	}

	s.funcCounter++
	s.state.PushNumber(float64(s.funcCounter))
	s.state.PushCopy(-3)
	s.state.SetTable(-3)
	s.state.Pop(2)

	return s.funcCounter
}

func (s *Server) getFunction(ref int) bool {
	s.state.GetGlobal("__moonshark_functions")
	if s.state.IsNil(-1) {
		s.state.Pop(1)
		return false
	}

	s.state.PushNumber(float64(ref))
	s.state.GetTable(-2)
	isFunc := s.state.IsFunction(-1)
	if !isFunc {
		s.state.Pop(2)
		return false
	}

	s.state.Remove(-2)
	return true
}

func (s *Server) requestHandler(ctx *fasthttp.RequestCtx) {
	method := string(ctx.Method())
	path := string(ctx.Path())

	// Look up route in router
	handlerRef, params, found := s.router.Lookup(method, path)
	if !found {
		ctx.SetStatusCode(404)
		ctx.SetBodyString("Not Found")
		return
	}

	reqCtx := s.buildRequestContext(ctx, params)
	reqCtx.Session.AdvanceFlash()

	s.stateMu.Lock()
	defer s.stateMu.Unlock()

	s.setupRequestEnvironment(reqCtx)

	if !s.getFunction(handlerRef) {
		ctx.SetStatusCode(500)
		ctx.SetBodyString("Handler not found")
		return
	}

	if err := s.state.PushValue(s.requestToTable(reqCtx)); err != nil {
		ctx.SetStatusCode(500)
		ctx.SetBodyString("Failed to create request object")
		return
	}

	if err := s.state.Call(1, 1); err != nil {
		ctx.SetStatusCode(500)
		ctx.SetBodyString(fmt.Sprintf("Handler error: %v", err))
		return
	}

	var responseBody string
	if s.state.GetTop() > 0 && !s.state.IsNil(-1) {
		responseBody = s.state.ToString(-1)
		s.state.Pop(1)
	}

	s.updateSessionFromLua(reqCtx.Session)
	s.applyResponse(ctx, responseBody)
	s.sessions.ApplySessionCookie(ctx, reqCtx.Session)
}

func (s *Server) setupRequestEnvironment(reqCtx *RequestContext) {
	s.state.PushValue(s.requestToTable(reqCtx))
	s.state.SetGlobal("__request")

	s.state.PushValue(s.sessionToTable(reqCtx.Session))
	s.state.SetGlobal("__session")

	s.state.NewTable()
	s.state.SetGlobal("__response")
}

func (s *Server) requestToTable(reqCtx *RequestContext) map[string]any {
	return map[string]any{
		"method":  reqCtx.Method,
		"path":    reqCtx.Path,
		"headers": reqCtx.Headers,
		"query":   reqCtx.Query,
		"form":    reqCtx.Form,
		"cookies": reqCtx.Cookies,
		"body":    reqCtx.Body,
		"params":  reqCtx.Params,
	}
}

func (s *Server) sessionToTable(session *sessions.Session) map[string]any {
	return map[string]any{
		"id":   session.ID,
		"data": session.GetAll(),
	}
}

func (s *Server) updateSessionFromLua(session *sessions.Session) {
	s.state.GetGlobal("__session")
	if s.state.IsNil(-1) {
		s.state.Pop(1)
		return
	}

	s.state.GetField(-1, "data")
	if s.state.IsTable(-1) {
		if data, err := s.state.ToTable(-1); err == nil {
			if dataMap, ok := data.(map[string]any); ok {
				session.Clear()
				for k, v := range dataMap {
					session.Set(k, v)
				}
			}
		}
	}
	s.state.Pop(2)
}

func (s *Server) applyResponse(ctx *fasthttp.RequestCtx, body string) {
	s.state.GetGlobal("__response")
	if s.state.IsNil(-1) {
		s.state.Pop(1)
		if body != "" {
			ctx.SetBodyString(body)
		}
		return
	}

	s.state.GetField(-1, "status")
	if s.state.IsNumber(-1) {
		ctx.SetStatusCode(int(s.state.ToNumber(-1)))
	}
	s.state.Pop(1)

	s.state.GetField(-1, "headers")
	if s.state.IsTable(-1) {
		s.state.ForEachTableKV(-1, func(key, value string) bool {
			ctx.Response.Header.Set(key, value)
			return true
		})
	}
	s.state.Pop(1)

	s.state.GetField(-1, "cookies")
	if s.state.IsTable(-1) {
		s.applyCookies(ctx)
	}
	s.state.Pop(1)

	s.state.Pop(1)

	if body != "" {
		ctx.SetBodyString(body)
	}
}

func (s *Server) applyCookies(ctx *fasthttp.RequestCtx) {
	s.state.ForEachArray(-1, func(i int, state *luajit.State) bool {
		if !state.IsTable(-1) {
			return true
		}

		name := state.GetFieldString(-1, "name", "")
		value := state.GetFieldString(-1, "value", "")
		if name == "" {
			return true
		}

		cookie := fasthttp.AcquireCookie()
		defer fasthttp.ReleaseCookie(cookie)

		cookie.SetKey(name)
		cookie.SetValue(value)
		cookie.SetPath(state.GetFieldString(-1, "path", "/"))

		if domain := state.GetFieldString(-1, "domain", ""); domain != "" {
			cookie.SetDomain(domain)
		}

		if state.GetFieldBool(-1, "secure", false) {
			cookie.SetSecure(true)
		}

		if state.GetFieldBool(-1, "http_only", true) {
			cookie.SetHTTPOnly(true)
		}

		if maxAge := state.GetFieldNumber(-1, "max_age", 0); maxAge > 0 {
			cookie.SetExpire(time.Now().Add(time.Duration(maxAge) * time.Second))
		}

		ctx.Response.Header.SetCookie(cookie)
		return true
	})
}

func (s *Server) buildRequestContext(ctx *fasthttp.RequestCtx, params *router.Params) *RequestContext {
	reqCtx := &RequestContext{
		Method:  string(ctx.Method()),
		Path:    string(ctx.Path()),
		Headers: make(map[string]string),
		Query:   make(map[string]string),
		Cookies: make(map[string]string),
		Body:    string(ctx.PostBody()),
		Params:  make(map[string]string),
	}

	ctx.Request.Header.VisitAll(func(key, value []byte) {
		reqCtx.Headers[string(key)] = string(value)
	})

	ctx.Request.Header.VisitAllCookie(func(key, value []byte) {
		reqCtx.Cookies[string(key)] = string(value)
	})

	ctx.QueryArgs().VisitAll(func(key, value []byte) {
		reqCtx.Query[string(key)] = string(value)
	})

	// Convert router params to map
	for i, key := range params.Keys {
		if i < len(params.Values) {
			reqCtx.Params[key] = params.Values[i]
		}
	}

	reqCtx.Form = s.parseForm(ctx)
	reqCtx.Session = s.sessions.GetSessionFromRequest(ctx)

	return reqCtx
}

func (s *Server) parseForm(ctx *fasthttp.RequestCtx) map[string]any {
	contentType := string(ctx.Request.Header.ContentType())
	form := make(map[string]any)

	if strings.Contains(contentType, "application/json") {
		var data map[string]any
		if err := json.Unmarshal(ctx.PostBody(), &data); err == nil {
			return data
		}
	} else if strings.Contains(contentType, "application/x-www-form-urlencoded") {
		ctx.PostArgs().VisitAll(func(key, value []byte) {
			form[string(key)] = string(value)
		})
	} else if strings.Contains(contentType, "multipart/form-data") {
		if multipartForm, err := ctx.MultipartForm(); err == nil {
			for key, values := range multipartForm.Value {
				if len(values) == 1 {
					form[key] = values[0]
				} else {
					form[key] = values
				}
			}

			if len(multipartForm.File) > 0 {
				files := make(map[string]any)
				for fieldName, fileHeaders := range multipartForm.File {
					if len(fileHeaders) == 1 {
						files[fieldName] = s.fileToMap(fileHeaders[0])
					} else {
						fileList := make([]map[string]any, len(fileHeaders))
						for i, fh := range fileHeaders {
							fileList[i] = s.fileToMap(fh)
						}
						files[fieldName] = fileList
					}
				}
				form["_files"] = files
			}
		}
	}

	return form
}

func (s *Server) fileToMap(fh *multipart.FileHeader) map[string]any {
	return map[string]any{
		"filename": fh.Filename,
		"size":     fh.Size,
		"mimetype": fh.Header.Get("Content-Type"),
	}
}

func (s *Server) generateCSRFToken() string {
	bytes := make([]byte, 32)
	rand.Read(bytes)
	return base64.URLEncoding.EncodeToString(bytes)
}

// Lua function implementations
func httpSetStatus(state *luajit.State) int {
	code, _ := state.SafeToNumber(1)
	state.GetGlobal("__response")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__response")
		state.GetGlobal("__response")
	}
	state.PushNumber(code)
	state.SetField(-2, "status")
	state.Pop(1)
	return 0
}

func httpSetHeader(state *luajit.State) int {
	name, _ := state.SafeToString(1)
	value, _ := state.SafeToString(2)

	state.GetGlobal("__response")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__response")
		state.GetGlobal("__response")
	}

	state.GetField(-1, "headers")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.PushCopy(-1)
		state.SetField(-3, "headers")
	}

	state.PushString(value)
	state.SetField(-2, name)
	state.Pop(2)
	return 0
}

func httpRedirect(state *luajit.State) int {
	url, _ := state.SafeToString(1)
	status := 302.0
	if state.GetTop() >= 2 {
		status, _ = state.SafeToNumber(2)
	}

	state.GetGlobal("__response")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__response")
		state.GetGlobal("__response")
	}

	state.PushNumber(status)
	state.SetField(-2, "status")

	state.GetField(-1, "headers")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.PushCopy(-1)
		state.SetField(-3, "headers")
	}

	state.PushString(url)
	state.SetField(-2, "Location")
	state.Pop(2)
	return 0
}

func (s *Server) sessionGet(state *luajit.State) int {
	key, _ := state.SafeToString(1)

	state.GetGlobal("__session")
	if state.IsNil(-1) {
		state.Pop(1)
		state.PushNil()
		return 1
	}

	state.GetField(-1, "data")
	if state.IsNil(-1) {
		state.Pop(2)
		state.PushNil()
		return 1
	}

	state.GetField(-1, key)
	return 1
}

func (s *Server) sessionSet(state *luajit.State) int {
	key, _ := state.SafeToString(1)

	state.GetGlobal("__session")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__session")
		state.GetGlobal("__session")
	}

	state.GetField(-1, "data")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.PushCopy(-1)
		state.SetField(-3, "data")
	}

	value, err := state.ToValue(2)
	if err == nil {
		state.PushValue(value)
		state.SetField(-2, key)
	}
	state.Pop(2)
	return 0
}

func (s *Server) sessionFlash(state *luajit.State) int {
	key, _ := state.SafeToString(1)

	state.GetGlobal("__session")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__session")
		state.GetGlobal("__session")
	}

	state.GetField(-1, "flash")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.PushCopy(-1)
		state.SetField(-3, "flash")
	}

	value, err := state.ToValue(2)
	if err == nil {
		state.PushValue(value)
		state.SetField(-2, key)
	}
	state.Pop(2)
	return 0
}

func (s *Server) sessionGetFlash(state *luajit.State) int {
	key, _ := state.SafeToString(1)

	state.GetGlobal("__session")
	if state.IsNil(-1) {
		state.Pop(1)
		state.PushNil()
		return 1
	}

	state.GetField(-1, "flash")
	if state.IsNil(-1) {
		state.Pop(2)
		state.PushNil()
		return 1
	}

	state.GetField(-1, key)
	return 1
}

func cookieSet(state *luajit.State) int {
	name, _ := state.SafeToString(1)
	value, _ := state.SafeToString(2)

	maxAge := 0
	path := "/"
	domain := ""
	secure := false
	httpOnly := true

	if state.GetTop() >= 3 && state.IsTable(3) {
		maxAge = int(state.GetFieldNumber(3, "max_age", 0))
		path = state.GetFieldString(3, "path", "/")
		domain = state.GetFieldString(3, "domain", "")
		secure = state.GetFieldBool(3, "secure", false)
		httpOnly = state.GetFieldBool(3, "http_only", true)
	}

	state.GetGlobal("__response")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__response")
		state.GetGlobal("__response")
	}

	state.GetField(-1, "cookies")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.PushCopy(-1)
		state.SetField(-3, "cookies")
	}

	cookieData := map[string]any{
		"name":      name,
		"value":     value,
		"path":      path,
		"secure":    secure,
		"http_only": httpOnly,
	}
	if domain != "" {
		cookieData["domain"] = domain
	}
	if maxAge > 0 {
		cookieData["max_age"] = maxAge
	}

	state.PushValue(cookieData)

	length := globalServer.getTableLength(-2)
	state.PushNumber(float64(length + 1))
	state.PushCopy(-2)
	state.SetTable(-4)

	state.Pop(3)
	return 0
}

func cookieGet(state *luajit.State) int {
	name, _ := state.SafeToString(1)

	state.GetGlobal("__request")
	if state.IsNil(-1) {
		state.Pop(1)
		state.PushNil()
		return 1
	}

	state.GetField(-1, "cookies")
	if state.IsNil(-1) {
		state.Pop(2)
		state.PushNil()
		return 1
	}

	state.GetField(-1, name)
	return 1
}

func (s *Server) csrfGenerate(state *luajit.State) int {
	token := s.generateCSRFToken()

	state.GetGlobal("__session")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.SetGlobal("__session")
		state.GetGlobal("__session")
	}

	state.GetField(-1, "data")
	if state.IsNil(-1) {
		state.Pop(1)
		state.NewTable()
		state.PushCopy(-1)
		state.SetField(-3, "data")
	}

	state.PushString(token)
	state.SetField(-2, "_csrf_token")
	state.Pop(2)

	state.PushString(token)
	return 1
}

func (s *Server) csrfValidate(state *luajit.State) int {
	state.GetGlobal("__session")
	if state.IsNil(-1) {
		state.Pop(1)
		state.PushBoolean(false)
		return 1
	}

	sessionToken := state.GetFieldString(-1, "data._csrf_token", "")
	state.Pop(1)

	state.GetGlobal("__request")
	if state.IsNil(-1) {
		state.Pop(1)
		state.PushBoolean(false)
		return 1
	}

	requestToken := state.GetFieldString(-1, "form._csrf_token", "")
	state.Pop(1)

	state.PushBoolean(sessionToken != "" && sessionToken == requestToken)
	return 1
}

func (s *Server) getTableLength(index int) int {
	length := 0
	s.state.PushNil()
	for s.state.Next(index - 1) {
		length++
		s.state.Pop(1)
	}
	return length
}