package app

import (
	"bytes"
	"encoding/json"
	"html/template"
	"io/fs"
	"log"
	"net/http"
	"net/url"
	"strconv"

	"git.atik.me/basicweb/models"
)

type App struct {
	LabsFS fs.FS
	WebFS  fs.FS
	Labs   map[int]models.Lab
}

func New(labsFS fs.FS, webFS fs.FS) App {
	return App{
		LabsFS: labsFS,
		WebFS:  webFS,
		Labs:   getLabsList(labsFS),
	}
}

func (a *App) MainPageHandler(writer http.ResponseWriter, request *http.Request) {
	html, err := template.ParseFS(a.WebFS, "templates/index.html")
	if err != nil {
		log.Fatal(err)
	}

	if err := html.Execute(writer, a.Labs); err != nil {
		log.Fatal(err)
	}
}

func (a *App) LabPageHandler(writer http.ResponseWriter, request *http.Request) {
	html, err := template.ParseFS(a.WebFS, "templates/lab.html")
	if err != nil {
		log.Fatal(err)
	}

	parsedURL, err := url.Parse(request.URL.String())
	if err != nil {
		writer.WriteHeader(http.StatusInternalServerError)
		writer.Write([]byte("Internal server error"))
		return
	}

	strNumber := parsedURL.Query().Get("number")
	if strNumber == "" {
		writer.WriteHeader(http.StatusNotFound)
		writer.Write([]byte("Не указан номер лабораторной работы!"))
		return
	}

	number, err := strconv.Atoi(strNumber)
	if err != nil {
		writer.WriteHeader(http.StatusNotFound)
		writer.Write([]byte("Некорректный номер лабораторной работы!"))
		return
	}

	lab, ok := a.Labs[number]
	if !ok || !lab.Complete {
		writer.WriteHeader(http.StatusNotFound)
		writer.Write([]byte("Лаборатораня работа с номером " + strconv.Itoa(number) + " не найдена!"))
		return
	}

	if err := html.Execute(writer, lab); err != nil {
		log.Fatal(err)
	}
}

func getLabsList(labsFS fs.FS) map[int]models.Lab {

	var result = make(map[int]models.Lab)

	folders, err := fs.ReadDir(labsFS, "labs")
	if err != nil {
		log.Fatal(err)
	}

	for _, folder := range folders {
		if folder.IsDir() {
			fileData, err := fs.ReadFile(labsFS, "labs/"+folder.Name()+"/desc.json")
			if err != nil {
				log.Fatal(err)
			}

			reader := bytes.NewReader(fileData)
			decoder := json.NewDecoder(reader)
			lab := models.Lab{}
			if err := decoder.Decode(&lab); err != nil {
				log.Fatal(err)
			}

			result[lab.Number] = lab
		}
	}

	return result
}