package main

import (
	"encoding/json"
	"io"
	"log/slog"
	"math/rand"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"text/template"
	"time"

	"git.andreafazzi.eu/andrea/probo/lib/models"
	"git.andreafazzi.eu/andrea/probo/lib/store"
	"git.andreafazzi.eu/andrea/probo/lib/store/file"
	"github.com/lmittmann/tint"
)

var (
	DefaultAssetDir    = "assets"
	DefaultDataDir     = "data"
	DefaultSessionDir  = "sessions"
	DefaultResponseDir = "responses"
	DefaultTemplateDir = "templates"
	DefaultStaticDir   = "static"
)

type Config struct {
	SessionDir  string
	ResponseDir string
	TemplateDir string
	StaticDir   string
}

type ExamTemplateData struct {
	*models.Exam

	SessionID string
}

type Server struct {
	config *Config
	mux    *http.ServeMux

	sessionFileStore  *file.SessionFileStore
	responseFileStore *file.ResponseFileStore
}

func GetDefaultTemplateDir() string {
	return filepath.Join(DefaultAssetDir, DefaultTemplateDir)
}

func GetDefaultStaticDir() string {
	return filepath.Join(DefaultAssetDir, DefaultStaticDir)
}

func GetDefaultSessionDir() string {
	return filepath.Join(DefaultDataDir, DefaultSessionDir)
}

func GetDefaultResponseDir() string {
	return filepath.Join(DefaultDataDir, DefaultResponseDir)
}

func NewServer(config *Config) (*Server, error) {
	_, err := os.Stat(config.SessionDir)
	if err != nil {
		return nil, err
	}

	_, err = os.Stat(config.TemplateDir)
	if err != nil {
		return nil, err
	}

	_, err = os.Stat(config.StaticDir)
	if err != nil {
		return nil, err
	}

	sStore, err := file.NewSessionFileStore(
		&file.FileStoreConfig[*models.Session, *store.SessionStore]{
			FilePathConfig: file.FilePathConfig{Dir: config.SessionDir, FilePrefix: "session", FileSuffix: ".json"},
			IndexDirFunc:   file.DefaultIndexDirFunc[*models.Session, *store.SessionStore],
			CreateEntityFunc: func() *models.Session {
				return &models.Session{}
			},
		},
	)
	if err != nil {
		return nil, err
	}

	rStore, err := file.NewResponseFileStore(
		&file.FileStoreConfig[*models.Response, *store.ResponseStore]{
			FilePathConfig: file.FilePathConfig{Dir: config.ResponseDir, FilePrefix: "response", FileSuffix: ".json"},
			IndexDirFunc:   file.DefaultIndexDirFunc[*models.Response, *store.ResponseStore],
			CreateEntityFunc: func() *models.Response {
				return &models.Response{}
			},
		},
	)
	if err != nil {
		return nil, err
	}

	rStore.FilePathConfig = file.FilePathConfig{
		Dir:        config.ResponseDir,
		FilePrefix: "response",
		FileSuffix: ".json",
	}

	s := &Server{
		config,
		http.NewServeMux(),
		sStore,
		rStore,
	}

	s.mux.Handle("/static/", http.StripPrefix("/static", http.FileServer(http.Dir(config.StaticDir))))
	s.mux.HandleFunc("/create", s.createExamSessionHandler)
	s.mux.HandleFunc("/responses/", s.getResponsesHandler)
	s.mux.HandleFunc("/", s.getExamHandler)

	return s, nil
}

func NewDefaultServer() (*Server, error) {
	return NewServer(&Config{
		SessionDir:  GetDefaultSessionDir(),
		ResponseDir: GetDefaultResponseDir(),
		TemplateDir: GetDefaultTemplateDir(),
		StaticDir:   GetDefaultStaticDir(),
	})
}

func (s *Server) getResponsesHandler(w http.ResponseWriter, r *http.Request) {
	result := make([]*models.Response, 0)

	urlParts := strings.Split(r.URL.Path, "/")

	sessionID := urlParts[2]

	if r.Method == "GET" {
		session, err := s.sessionFileStore.Read(sessionID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		for _, exam := range session.Exams {
			responses := s.responseFileStore.ReadAll()
			for _, r := range responses {
				if r.ID == exam.ID {
					result = append(result, r)
				}
			}
		}
		err = json.NewEncoder(w).Encode(result)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}
}

func (s *Server) createExamSessionHandler(w http.ResponseWriter, r *http.Request) {
	session := new(models.Session)

	data, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	err = session.Unmarshal(data)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	memorySession, err := s.sessionFileStore.Create(session)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	err = json.NewEncoder(w).Encode(memorySession)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	slog.Info("Received a new session", "session", memorySession)

}

func (s *Server) getExamHandler(w http.ResponseWriter, r *http.Request) {
	urlParts := strings.Split(r.URL.Path, "/")

	sessionID := urlParts[1]
	token := urlParts[2]

	session, err := s.sessionFileStore.Read(sessionID)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	exam := session.Exams[token]

	if r.Method == "GET" {
		w.Header().Set("Content-Type", "text/html")

		tplData, err := os.ReadFile(filepath.Join(GetDefaultTemplateDir(), "exam.tpl"))
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return

		}
		tmpl := template.Must(template.New("exam").Parse(string(tplData)))

		err = tmpl.Execute(w, ExamTemplateData{exam, session.ID})
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}

	if r.Method == "POST" {
		err := r.ParseForm()
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		response := new(models.Response)
		response.UniqueIDFunc = func() string {
			return exam.GetID()
		}

		response.Questions = make(map[string]string)
		for qID, values := range r.Form {
			for _, aID := range values {
				response.Questions[qID] = aID
			}
		}

		_, err = s.responseFileStore.Create(response)
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		w.Write([]byte("<p>Thank you for your response.</p>"))
		return
	}

}

func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	s.mux.ServeHTTP(w, r)
}

func generateRandomID() string {
	id := ""
	for i := 0; i < 6; i++ {
		id += strconv.Itoa(rand.Intn(9) + 1)
	}
	return id
}

func main() {
	slog.SetDefault(slog.New(
		tint.NewHandler(os.Stdout, &tint.Options{
			Level:      slog.LevelInfo,
			TimeFormat: time.Kitchen,
		}),
	))

	server, err := NewDefaultServer()
	if err != nil {
		panic(err)
	}

	slog.Info("Probo server started.")
	http.ListenAndServe(":8080", server)
}