package core

import (
	"bufio"
	"context"
	"fmt"
	"log/slog"
	"net"

	"github.com/google/uuid"
)

type Server struct {
	l        *slog.Logger
	port     string
	ctx      context.Context
	Sessions chan *Session
	ln       net.Listener
}

func NewServer(ctx context.Context, l *slog.Logger, port string) *Server {
	var s Server

	// TODO: Check for context cancellation and cleanup

	c := make(chan *Session)
	s.Sessions = c
	ln, err := net.Listen("tcp", port)
	if err != nil {
		s.l.With(
			slog.Any("error", err),
		).Error("could not start tcp listener")
		return &s
	}

	s.ctx = ctx
	s.ln = ln
	s.l = l
	s.port = port

	return &s
}

func (s *Server) Start() {
	s.l.Debug("starting telnet server")
	// TODO: Check for context cancellation and cleanup
	for {
		conn, err := s.ln.Accept()
		if err != nil {
			s.l.With(
				slog.Any("error", err),
			).Error("could not accept tcp connection")
		}
		s.Sessions <- NewSession(s.ctx, conn, Printer{}, s.l)

	}
}

type Session struct {
	c   net.Conn
	ctx context.Context
	p   Printer
	l   *slog.Logger

	userID uint64
}

func NewSession(ctx context.Context, c net.Conn, p Printer, l *slog.Logger) *Session {
	sid := uuid.New()
	return &Session{
		ctx: ctx,
		l:   l.With(slog.String("sid", sid.String())),
		c:   c,
	}
}

func (s *Session) bufferInput(commands chan string) {
	scanner := bufio.NewScanner(s.c)
	defer close(commands)

	for scanner.Scan() {
		err := scanner.Err()
		switch err {
		case nil:
			commands <- scanner.Text()
		default:
			s.l.With(slog.Any("error", scanner.Err())).Error("error scanning input")
			return
		}
	}

	s.l.Debug("session terminated")
}

func (s *Session) Start() {
	s.l.Debug("starting telnet session")
	fmt.Fprint(s.c, "Welcome to Bing Bong.\n")

	commands := make(chan string)
	go s.bufferInput(commands)

	for command := range commands {
		s.l.With(slog.String("command", command)).Debug("command recieved")
		_, err := fmt.Fprintf(s.c, "> %q\n", command)
		if err != nil {
			s.l.With(
				slog.Any("error", err),
			).Error("connection closed on write")
			return
		}
	}
}