package service

import (
	"strings"
	"testing"
)

func TestGenerateKey_Format(t *testing.T) {
	prefixes := []string{"ESIR-", "ARV-", "LT-"}

	for _, prefix := range prefixes {
		key, err := GenerateKey(prefix)
		if err != nil {
			t.Fatalf("GenerateKey(%q) error: %v", prefix, err)
		}

		if !strings.HasPrefix(key, prefix) {
			t.Errorf("key %q nema prefix %q", key, prefix)
		}

		// Remove prefix, check 4 groups of 4 chars separated by dashes
		rest := strings.TrimPrefix(key, prefix)
		groups := strings.Split(rest, "-")
		if len(groups) != 4 {
			t.Errorf("key %q: ocekivano 4 grupe, dobijeno %d", key, len(groups))
		}
		for i, g := range groups {
			if len(g) != 4 {
				t.Errorf("key %q: grupa %d ima %d karaktera umesto 4", key, i, len(g))
			}
		}
	}
}

func TestGenerateKey_ValidChars(t *testing.T) {
	key, err := GenerateKey("TEST-")
	if err != nil {
		t.Fatal(err)
	}

	rest := strings.TrimPrefix(key, "TEST-")
	rest = strings.ReplaceAll(rest, "-", "")

	for _, c := range rest {
		if !strings.ContainsRune(keyChars, c) {
			t.Errorf("key sadrzi nedozvoljen karakter: %c", c)
		}
	}
}

func TestGenerateKey_NoConfusingChars(t *testing.T) {
	// Generate multiple keys and check none contain O, 0, I, 1, L, Z
	confusing := "OIL01Z"
	for i := 0; i < 50; i++ {
		key, err := GenerateKey("T-")
		if err != nil {
			t.Fatal(err)
		}
		rest := strings.TrimPrefix(key, "T-")
		rest = strings.ReplaceAll(rest, "-", "")
		for _, c := range rest {
			if strings.ContainsRune(confusing, c) {
				t.Errorf("key sadrzi konfuzan karakter %c: %s", c, key)
			}
		}
	}
}

func TestGenerateKey_Uniqueness(t *testing.T) {
	seen := make(map[string]bool)
	for i := 0; i < 100; i++ {
		key, err := GenerateKey("U-")
		if err != nil {
			t.Fatal(err)
		}
		if seen[key] {
			t.Errorf("duplikat kljuca: %s", key)
		}
		seen[key] = true
	}
}