package server

import (
	"context"
	"fmt"
	"log"
	"net"

	"codeberg.org/snonux/gorum/internal/config"
	"codeberg.org/snonux/gorum/internal/iorw"
)

type handlerCb func(message string) string

func tcpServerRun(ctx context.Context, conf config.Config, cb handlerCb) error {
	listener, err := net.Listen("tcp", conf.Address)
	if err != nil {
		return fmt.Errorf("error starting TCP server: %w", err)
	}
	defer listener.Close()

	log.Println("server: listening on", conf.Address)

	for {
		conn, err := listener.Accept()
		if err != nil {
			log.Println("server: error accepting connection:", err)
			continue
		}

		if !conf.RelaxedMode &&
			!conf.IsNodeWithLookup(conn.RemoteAddr().String(), net.LookupIP) {

			log.Println("server: denying connection, peer not a node:", conn.RemoteAddr().String())
			conn.Close()
			continue
		}

		log.Println("server: client connected:", conn.RemoteAddr().String())
		go handleConnection(ctx, conn, cb)
	}
}

func handleConnection(ctx context.Context, conn net.Conn, cb handlerCb) {
	defer conn.Close()
	remoteAddr := conn.RemoteAddr().String()

	for {
		select {
		case <-ctx.Done():
			log.Println("server: context done, disconnecting client:", remoteAddr)
			return
		default:
			message, err := iorw.ReadStr(conn)
			if err != nil {
				log.Println("server: unable to read message", remoteAddr, err)
				return
			}

			log.Println("server: received message", message, "from", remoteAddr)
			response := cb(message)

			if err := iorw.WriteStr(conn, response); err != nil {
				log.Println("error:", err)
			}
		}
	}
}