package main

import (
    "bufio"
    "fmt"
    "net"
    "strconv"
    "os"
    //"time"
)

func check(err error, message string) {
    if err != nil {
        panic(err)
    }
}

func FiboLoop1(n int) uint64 {
    f := make([]uint64, n+1, n+2)
    if n < 2 {
        f = f[0:2]
    }
    f[0] = 0
    f[1] = 1
    for i := 2; i <= n; i++ {
        f[i] = f[i-1] + f[i-2]
    }
    return uint64(f[n])
}

func FiboLoop2(n int) uint64 {
    a := 0
    b := 1
    // Iterate until desired position in sequence.
    for i := 0; i < n; i++ {
        // Use temporary variable to swap values.
        temp := a
        a = b
        b = temp + a
    }
    return uint64(a)
}


func FiboRecursive(n int) int{
    if n <= 1 {
        return n
    }
    return FiboRecursive(n-1) + FiboRecursive(n-2)
}


func makeFibo(n int) string {
    result := " "
    for i:=0; i<=n; i++ {
        result += strconv.FormatUint(FiboLoop1(i), 10) + " "
    }
    return result + "\r\n"
}


func main() {
    if (len(os.Args) != 2 ) {
        fmt.Println("Port number must be the 1st and only argument!")
        return
    }
    ln, err := net.Listen("tcp", ":"+os.Args[1])
    check(err, "Server is ready.")

    for {
        conn, err := ln.Accept()
        check(err, "Accepted connection.")

        go func() {
            buf := bufio.NewReader(conn)

            //for {
            num, err := buf.ReadString('\n')
            if err != nil {
                conn.Write([]byte("Invalid input\r\n"))
                conn.Close()
                return
            }
            //fmt.Println(num[:len(num)-2])
            //fmt.Println(len(num))

            numFib, err := strconv.Atoi(num[:len(num)-2])
            if err != nil {
                conn.Write([]byte("Invalid input\r\n"))
                conn.Close()
                return
            }
            //fmt.Printf("Fibonacchi number: %d\n", numFib)

            //startLoop := time.Now()
    //      result := makeFibo(numFib)

            result := FiboRecursive(numFib)
            fmt.Println(result)



            //fmt.Printf("\nIt took %s to make FIBO\n", time.Since(startLoop))

            conn.Write([]byte(strconv.Itoa(result)))
            conn.Close()
            //}
        }()
    }
}