package functions

import (
	"fmt"
	"net/http"
	"strconv"
)

func HttpAbort(w http.ResponseWriter, code int, message string) {
	w.WriteHeader(code)
	fmt.Fprint(w, message)
}

func MyFibonacci(count int) (fibonaccivalue int) {
	fibonaccivalue = 1
	var prev_fibonacci int = 0

	for i := 1; i < count; i++ {
		fibonaccivalue += prev_fibonacci
		prev_fibonacci = fibonaccivalue - prev_fibonacci
	}
	return
}

func HttFibonacci(w http.ResponseWriter, request *http.Request) {
	switch request.Method {
	case "POST":
		error := request.ParseForm()
		if error != nil {
			fmt.Printf("Error parsing POST request: %s\n", error)
			HttpAbort(w, http.StatusUnprocessableEntity,
				"Unable to parse your POST request.\n")
		} else {
			s_seq := request.Form.Get("seq")
			seq, error := strconv.Atoi(s_seq)
			if error != nil {
				fmt.Printf("Error parsing integer value out of %s: %s\n",
					s_seq,
					error)
				HttpAbort(w, http.StatusExpectationFailed,
					fmt.Sprintf("[%s] is not a number.\n", s_seq))
			} else if seq < 1 {
				fmt.Printf("Invalid sequence number: %d\n", seq)
				HttpAbort(w, http.StatusBadRequest,
					"Please provide a positive integer as the sequence number.\n")
			} else {
				fmt.Printf("Received request for Fibonacci Sequence Number %d\n",
					seq)
				fmt.Fprintf(w, "Fibonacci sequence index [%d]: %d\n",
					seq, MyFibonacci(seq))
			}
		}
	default:
		HttpAbort(w, http.StatusMethodNotAllowed,
			fmt.Sprintf("Operation %s not implemented for this URL", request.Method))
	}
}