fibonacci/code/main.go

package main

import (
	"fmt"
	"net/http"
	"os"
	"strconv"
        "flag"

	"github.com/joho/godotenv"

	"darjeeling.systemec.nl/rhouben/fibonacci/functions"
)

func main() {
	var port_number int = 8098 // hard default
	var error error
	var bind_socket string
	var seq, port int

	error = godotenv.Load() // Load .env file
	if error != nil {
		fmt.Printf("Error trying to load .env file: %s\n", error)
	}
	port_arg := os.Getenv("FIB_PORT")
	if port_arg != "" {
		fmt.Printf("Loaded port value '%s' from environment.\n",port_arg)
		port_number, error = strconv.Atoi(port_arg)
		if error != nil {
			fmt.Printf("I had an error trying to parse '%s' into a number: %s\n",
				port_arg,
				error)
			os.Exit(0)
		}
	}
	flag.IntVar(&port, "port", 8098, 
		fmt.Sprintf("Port number to bind to, default %d", port_number))
	flag.IntVar(&seq, "number", 0, 
		"Fibonacci sequence value to calculate")
	flag.Parse()

	if functions.FlagSet("port") { // Command line overrides env
		port_number = port
	}

	if !functions.FlagSet("number") {
		fmt.Printf("Listening on port %d...\n", port_number)
		bind_socket = fmt.Sprintf(":%d", port_number)
		http.HandleFunc("/fibonacci", functions.HttFibonacci)
		http.HandleFunc("/sum", functions.HttSum)
		http.ListenAndServe(bind_socket, nil)
	} else {
		value, error := functions.MyFibonacci(seq)
		if error != nil {
			fmt.Printf("Failed to Fibonacci %d: %s", seq, error)
		} else {
			fmt.Printf("%d", value)
		}
	}
}