Moving go code to subdir.

code/.gitignore

@@ -0,0 +1,16 @@
+# Allowlisting gitignore template for GO projects prevents us
+# from adding various unwanted local files, such as generated
+# files, developer configurations or IDE-specific files etc.
+#
+# Recommended: Go.AllowList.gitignore
+
+# Ignore everything
+*
+
+.env
+# But not these files...
+!/.gitignore
+
+!*.go
+!go.sum
+!go.mod

code/functions/fibonacci.go

@@ -0,0 +1,21 @@
+package functions
+
+import(
+	"errors"
+	"fmt"
+)
+
+func MyFibonacci(count int) (fibonaccivalue int, error error) {
+	fibonaccivalue = 1
+	error = nil
+	var prev_fibonacci int = 0
+
+	if count < 1 {
+		return -1, errors.New(fmt.Sprintf("%d is not a positive integer.",count))
+	}
+	for i := 1; i < count; i++ {
+		fibonaccivalue += prev_fibonacci
+		prev_fibonacci = fibonaccivalue - prev_fibonacci
+	}
+	return
+}

code/functions/flagcheck.go

@@ -0,0 +1,15 @@
+package functions
+
+import (
+	"flag"
+)
+
+func FlagSet(name string) (found bool) {
+	found = false
+	flag.Visit(func (f *flag.Flag) {
+		if f.Name == name {
+			found = true
+		}
+	})
+	return 
+}

code/functions/functions_test.go

@@ -0,0 +1,52 @@
+package functions
+
+import (
+	"testing"
+	"fmt"
+)
+
+// Test fibonacci function
+
+func TestFibonacci(t *testing.T) {
+	var sequence = [4]int{1, 3, 5, 9}
+	var values = [4]int{1, 2, 5, 34}
+	for i := 0; i < len(sequence); i++ {
+		var seq, want = sequence[i], values[i]
+		outcome, error := MyFibonacci(seq)
+		if error != nil {
+			t.Errorf("Error trying to Fibonacci %d: %s", seq, error)
+		}
+		if outcome != want {
+			t.Errorf("Invalid outcome: Fibonacci sequence %d should be %d, got %d",
+				seq, want, outcome)
+		}
+	}
+}
+
+func TestFibBadNumber(t *testing.T) {
+	outcome,error := MyFibonacci(-4)
+	if error == nil {
+		t.Errorf("This should be an error, not a %d",outcome)
+	}
+}
+
+func TestSums(t *testing.T) {
+	var tests = []struct{
+		a, b int
+		want int
+	} {
+		{1, 2, 3},
+		{5, 3, 8},
+		{9, 4, 13},
+	}
+
+	for _, tt := range tests {
+		testname := fmt.Sprintf("%d+%d",tt.a, tt.b)
+		t.Run(testname, func(t *testing.T) {
+			result := sum(tt.a, tt.b)
+			if result != tt.want {
+				t.Errorf("Expected %d, got %d", tt.want,result)
+			}
+		})
+	}
+}

code/functions/http.go

@@ -0,0 +1,79 @@
+package functions
+
+// HTTP helper functions doing the input checking and calling the actual math functions
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+)
+
+func HttpAbort(w http.ResponseWriter, code int, message string) {
+	w.WriteHeader(code)
+	fmt.Fprint(w, message)
+}
+
+func HttpGetPostInt(request *http.Request, key string) (value int, error error) {
+	switch request.Method {
+	case "POST":
+		error = request.ParseForm()
+		if error != nil {
+			error = fmt.Errorf("unable to parse post input: %s",
+				error.Error())
+			return
+		}
+		value, error = strconv.Atoi(request.Form.Get(key))
+		if error != nil {
+			fmt.Printf("Error parsing parameter '%s'\n", key)
+			error = fmt.Errorf("unable to parse parameter '%s' as an integer: %s",
+				key, error.Error())
+		}
+		return
+	default:
+		error = fmt.Errorf("this endpoint does not support %s operations", request.Method)
+		return
+	}
+}
+
+func HttFibonacci(w http.ResponseWriter, request *http.Request) {
+	seq, error := HttpGetPostInt(request, "seq")
+	if error != nil {
+		HttpAbort(w, http.StatusBadRequest,
+			fmt.Sprintf("Could not get parameter: %s", error.Error()))
+	} else if seq < 1 {
+		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)
+		value, error := MyFibonacci(seq)
+		if error != nil {
+			fmt.Printf("Error trying to Fibonacci %d: %s", seq, error)
+			fmt.Fprintf(w, "Error trying to Fibonacci %d: %s", seq, error)
+		} else {
+		fmt.Fprintf(w, "Fibonacci sequence index [%d]: %d\n",
+			seq, value)
+		}
+	}
+}
+
+func HttSum(w http.ResponseWriter, request *http.Request) {
+	var errorstr string
+	first, error := HttpGetPostInt(request, "first")
+	if error != nil {
+		errorstr = error.Error()
+	}
+	second, error := HttpGetPostInt(request, "second")
+	if error != nil {
+		errorstr = error.Error()
+	}
+
+	if errorstr != "" {
+		HttpAbort(w, http.StatusBadRequest,
+			fmt.Sprintf("Invalid input: %s\n", errorstr))
+		return
+	}
+	fmt.Printf("Received a request to add %d and %d.\n", first, second)
+	fmt.Fprintf(w, "The sum of %d and %d is %d.\n", first, second, sum(first, second))
+
+}

code/functions/sum.go

@@ -0,0 +1,6 @@
+package functions
+
+func sum(first int, second int) (result int) {
+	result = first + second
+	return
+}

code/go.mod

@@ -0,0 +1,5 @@
+module darjeeling.systemec.nl/rhouben/fibonacci
+
+go 1.24.4
+
+require github.com/joho/godotenv v1.5.1

code/go.sum

@@ -0,0 +1,2 @@
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=

code/main.go

@@ -0,0 +1,60 @@
+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)
+		}
+	}
+}