package iprange

import (
	"math/rand"
	"net/netip"
	"strings"
	"testing"
)

func TestParse(t *testing.T) {
	for _, tc := range []struct {
		in, want, err string
		ok            bool
	}{
		{in: "10.0.10.101-10.0.10.199", want: "10.0.10.101-10.0.10.199", ok: true},
		{in: "10.0.10.101 - 10.0.10.199", want: "10.0.10.101-10.0.10.199", ok: true},
		{in: "2001:DB8::100-2001:db8::1ff", want: "2001:db8::100-2001:db8::1ff", ok: true},
		{in: "10.0.0.5-10.0.0.5", want: "10.0.0.5-10.0.0.5", ok: true},
		{in: "branch-office", ok: false},
		{in: "10-net", ok: false},
		{in: "10.0.0.0/24", ok: false},
		{in: "10.0.10.101-199", ok: true, err: "not a full IP address"},
		{in: "10.0.10.101-", ok: true, err: "no end address"},
		{in: "2001:db8::100-1ff", ok: true, err: "not a full IP address"},
		{in: "10.0.0.9-10.0.0.1", ok: true, err: "start is after the end"},
		{in: "10.0.0.1-2001:db8::1", ok: true, err: "mixes IPv4 and IPv6"},
		{in: "fe80::1%eth0-fe80::9%eth0", ok: true, err: "zone"},
		{in: "10.0.300.1-10.0.300.9", ok: true, err: "not a full IP address"},
		{in: "10.0.0.1-10.0.0.9-10.0.0.20", ok: true, err: "not a full IP address"},
	} {
		r, ok, err := Parse(tc.in)
		if ok != tc.ok || (err == nil) != (tc.err == "") || err != nil && !strings.Contains(err.Error(), tc.err) {
			t.Errorf("%s: ok=%v err=%v, want ok=%v err~%q", tc.in, ok, err, tc.ok, tc.err)
			continue
		}
		if err == nil && ok && r.String() != tc.want {
			t.Errorf("%s = %s, want %s", tc.in, r, tc.want)
		}
	}
}

func TestPrefixes(t *testing.T) {
	for in, want := range map[string]string{
		"10.0.10.101-10.0.10.199":                    "10.0.10.101/32 10.0.10.102/31 10.0.10.104/29 10.0.10.112/28 10.0.10.128/26 10.0.10.192/29",
		"10.0.0.0-10.0.0.255":                        "10.0.0.0/24",
		"10.0.0.5-10.0.0.5":                          "10.0.0.5/32",
		"0.0.0.0-255.255.255.255":                    "0.0.0.0/0",
		"255.255.255.254-255.255.255.255":            "255.255.255.254/31",
		"2001:db8::100-2001:db8::1ff":                "2001:db8::100/120",
		"::-ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff": "::/0",
	} {
		r, _, err := Parse(in)
		if err != nil {
			t.Fatal(err)
		}
		var got []string
		for _, p := range r.Prefixes() {
			got = append(got, p.String())
		}
		if strings.Join(got, " ") != want {
			t.Errorf("%s = %s, want %s", in, strings.Join(got, " "), want)
		}
	}
	// The worst cases stay small.
	if n := len(must(t, "0.0.0.1-255.255.255.254").Prefixes()); n != 62 {
		t.Errorf("worst IPv4 case = %d prefixes, want 62", n)
	}
	if n := len(must(t, "::1-ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe").Prefixes()); n != 254 {
		t.Errorf("worst IPv6 case = %d prefixes, want 254", n)
	}
}

// Every address of a random range is covered once, and nothing outside it.
func TestPrefixesExact(t *testing.T) {
	rnd := rand.New(rand.NewSource(1))
	for i := 0; i < 300; i++ {
		lo, hi := rnd.Intn(4096), rnd.Intn(4096)
		if hi < lo {
			lo, hi = hi, lo
		}
		base := []byte{10, 20, 0, 0}
		addr := func(n int) netip.Addr {
			return netip.AddrFrom4([4]byte{base[0], base[1], byte(n >> 8), byte(n)})
		}
		r := Range{Start: addr(lo), End: addr(hi)}
		ps := r.Prefixes()
		for n := max(lo-3, 0); n <= min(hi+3, 4095); n++ {
			c := 0
			for _, p := range ps {
				if p.Contains(addr(n)) {
					c++
				}
			}
			if in := n >= lo && n <= hi; in && c != 1 || !in && c != 0 {
				t.Fatalf("%s: %s covered %d times (%v)", r, addr(n), c, ps)
			}
		}
		if got := r.Size().Int64(); got != int64(hi-lo+1) {
			t.Fatalf("%s: size %d", r, got)
		}
	}
}

func TestSizeAndMapped(t *testing.T) {
	if s := must(t, "10.0.10.101-10.0.10.199").SizeText(); s != "99 addresses" {
		t.Errorf("size = %s", s)
	}
	if s := must(t, "2001:db8::-2001:db8:0:ffff:ffff:ffff:ffff:ffff").SizeText(); s != "about 2^80 addresses" {
		t.Errorf("size = %s", s)
	}
	if !must(t, "::ffff:10.0.0.1-::ffff:10.0.0.9").TouchesMapped4() || must(t, "2001:db8::1-2001:db8::9").TouchesMapped4() || must(t, "10.0.0.1-10.0.0.9").TouchesMapped4() {
		t.Error("TouchesMapped4")
	}
}

func must(t *testing.T, s string) Range {
	t.Helper()
	r, ok, err := Parse(s)
	if !ok || err != nil {
		t.Fatalf("%s: %v %v", s, ok, err)
	}
	return r
}