package main

import (
	"errors"
	"io"
	"net/http"
)

type WorkerRequest struct {
	Request *http.Request
	Route string
	result chan *WorkerResponse
}

type WorkerResponse struct {
	Code int
	Headers map[string]string
	Body string
}

type Worker struct {
	read chan *WorkerRequest
	lua *Lua
	api LuaRef
	routes map[string]LuaRef
	started bool
}

func NewWorker(read chan *WorkerRequest) *Worker {
	return &Worker {
		read: read,
		routes: make(map[string]LuaRef),
		lua: &Lua{},
	}
}

func (w *Worker) Start (filename string) error {
	if w.started {
		return errors.New("already started")
	}

	w.lua.Start()
	api, err := w.lua.Require(filename)
	if err != nil {
		return err
	}
	w.api = api
	w.initRoutes()

	return nil
}

func (w *Worker) Listen () {
	for {
		r := <- w.read
		handlerRef := w.routes[r.Route]
		w.lua.PushFromRef(handlerRef)
		w.lua.PushString(r.Request.Method)
		w.lua.PushString(r.Request.URL.Path)

		fh := make(map[string]string)
		for k := range r.Request.Header {
			fh[k] = r.Request.Header.Get(k)
		}
		w.lua.PushTable(fh)
		
		body, err := io.ReadAll(r.Request.Body)
		if err != nil {
			w.lua.Pop(4);
			// TODO: 500
			return
		}
		w.lua.PushString(string(body))

		w.lua.PCall(4, 3)
		code := w.lua.ToInt(-3)
		rbody := w.lua.ToString(-1)

		// parse headers
		headers := make(map[string]string)
		w.lua.Pop(1)
		w.lua.PushNil()
		for w.lua.Next() {
			if !w.lua.IsString(-2) || !w.lua.IsString(-2) {
				w.lua.Pop(1)
				continue
			}
			v := w.lua.ToString(-1)
			w.lua.Pop(1)
			// we must not pop the item key from the stack because
			// otherwise C.lua_next won't work properly
			k := w.lua.ToString(-1)
			headers[k] = v
		}
		w.lua.Pop(2)

		r.result <- &WorkerResponse {
			Code: int(code),
			Headers: headers,
			Body: rbody,
		}
	}
}

func (w *Worker) Request (route string, r *http.Request,) chan *WorkerResponse {
	res := make(chan *WorkerResponse)
	w.read <- &WorkerRequest{
		Request: r,
		Route: route,
		result: res,
	}
	return res
}

func (w *Worker) ListRoutes() []string {
	res := []string{}
	for route, _ := range w.routes {
		res = append(res, route)
	}
	return res
}

func (w *Worker) Stop () {
	w.lua.Close()
}

func (w *Worker) initRoutes() {
	w.lua.PushFromRef(w.api)
	w.lua.PushTableItem("routes")
	// FIXME: istable?
	w.lua.PushNil()
	for w.lua.Next() {
		if !w.lua.IsString(-2) || !w.lua.IsFunction(-1) {
			w.lua.Pop(1)
			continue
		}
		handlerRef := w.lua.PopToRef()
		// we must not pop the item key from the stack because
		// otherwise C.lua_next won't work properly
		route := w.lua.ToString(-1)
		w.routes[route] = handlerRef
	}
	// FIXME: pop?
}