package dhcp4

import (
	"bytes"
	"net"
	"net/netip"
	"strings"
	"testing"
)

func TestRoundTrip(t *testing.T) {
	mac, _ := net.ParseMAC("aa:bb:cc:00:11:22")
	p := NewRequest(Discover, mac, 0x12345678)
	p.Flags = FlagBroadcast
	p.Set(OptHostName, []byte("laptop"))
	p.Set(OptParamRequest, []byte{1, 3, 6, 15})
	p.Set(OptClientID, append([]byte{1}, mac...))
	b := p.Marshal()
	if len(b) < MinLen {
		t.Fatalf("message is %d bytes, under %d", len(b), MinLen)
	}
	if p.Len() != len(b) {
		t.Errorf("Len() = %d, Marshal gave %d", p.Len(), len(b))
	}
	q, err := Parse(b)
	if err != nil {
		t.Fatal(err)
	}
	if q.Type() != Discover || q.XID != 0x12345678 || !q.Broadcast() || q.MAC().String() != mac.String() {
		t.Errorf("parsed %+v", q)
	}
	if q.HostName() != "laptop" || q.ClientID() != "01aabbcc001122" {
		t.Errorf("host %q client id %q", q.HostName(), q.ClientID())
	}
	if !bytes.Equal(q.ParamRequest(), []byte{1, 3, 6, 15}) {
		t.Errorf("PRL %v", q.ParamRequest())
	}
	r := q.Reply(Offer)
	r.YIAddr = netip.MustParseAddr("10.0.10.57")
	if r.Op != BootReply || r.XID != q.XID || r.Type() != Offer || r.CHAddr != q.CHAddr {
		t.Errorf("reply %+v", r)
	}
	r2, err := Parse(r.Marshal())
	if err != nil || r2.YIAddr != r.YIAddr {
		t.Fatalf("reply round trip: %v %v", r2, err)
	}
}

func TestLongOptionsAreSplitAndJoined(t *testing.T) {
	p := NewRequest(Inform, net.HardwareAddr{1, 2, 3, 4, 5, 6}, 1)
	long := bytes.Repeat([]byte{7}, 600)
	p.Set(43, long)
	b := p.Marshal()
	q, err := Parse(b)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(q.Get(43), long) {
		t.Errorf("got %d bytes back, want 600", len(q.Get(43)))
	}
	if p.Len() != len(b) {
		t.Errorf("Len() = %d, Marshal gave %d", p.Len(), len(b))
	}
}

func TestOverload(t *testing.T) {
	p := NewRequest(Request, net.HardwareAddr{1, 2, 3, 4, 5, 6}, 1)
	p.Set(OptOverload, []byte{1})
	b := p.Marshal()
	// Put option 12 in the file field (bytes 108..236).
	copy(b[108:], []byte{12, 3, 'p', 'c', '1', 255})
	q, err := Parse(b)
	if err != nil {
		t.Fatal(err)
	}
	if q.HostName() != "pc1" || q.File != "" {
		t.Errorf("host %q file %q", q.HostName(), q.File)
	}
}

func TestParseErrors(t *testing.T) {
	if _, err := Parse(make([]byte, 100)); err == nil {
		t.Error("short message accepted")
	}
	b := NewRequest(Discover, net.HardwareAddr{1, 2, 3, 4, 5, 6}, 1).Marshal()
	b[236] = 0
	if _, err := Parse(b); err == nil || !strings.Contains(err.Error(), "cookie") {
		t.Errorf("missing cookie: %v", err)
	}
	b = NewRequest(Discover, net.HardwareAddr{1, 2, 3, 4, 5, 6}, 1).Marshal()
	b[240+1] = 200 // message type option claims 200 bytes
	if _, err := Parse(b); err == nil {
		t.Error("overlong option accepted")
	}
}

func TestHostNameFromFQDN(t *testing.T) {
	p := NewRequest(Request, net.HardwareAddr{1, 2, 3, 4, 5, 6}, 1)
	wire, _ := encodeNames([]string{"desk.example.com"})
	p.Set(OptClientFQDN, append([]byte{0x04, 0, 0}, wire...))
	if got := p.HostName(); got != "desk" {
		t.Errorf("wire FQDN: %q", got)
	}
	p.Set(OptClientFQDN, append([]byte{0, 0, 0}, "tv.lan"...))
	if got := p.HostName(); got != "tv" {
		t.Errorf("ASCII FQDN: %q", got)
	}
}

func TestEncodeDecode(t *testing.T) {
	cases := []struct {
		typ, in, out string
		hex          string
	}{
		{TypeIP, " 10.0.0.1 ", "10.0.0.1", "0a000001"},
		{TypeIPs, "10.0.0.1,10.0.0.2", "10.0.0.1, 10.0.0.2", "0a0000010a000002"},
		{TypeU8, "8", "8", "08"},
		{TypeU16, "1500", "1500", "05dc"},
		{TypeU32, "86400", "86400", "00015180"},
		{TypeI32, "-3600", "-3600", "fffff1f0"},
		{TypeBool, "yes", "true", "01"},
		{TypeHex, "01:02:0A", "01:02:0a", "01020a"},
		{TypeHex, "0x0102", "01:02", "0102"},
		{TypeDomains, "lan, Example.com.", "lan, example.com", "036c616e00076578616d706c6503636f6d00"},
		{TypeRoutes, "10.20.0.0/16 via 10.0.10.1, 0.0.0.0/0 - 10.0.10.1", "10.20.0.0/16 via 10.0.10.1, 0.0.0.0/0 via 10.0.10.1", "100a140a000a01000a000a01"},
	}
	for _, c := range cases {
		b, err := Encode(c.typ, c.in)
		if err != nil {
			t.Errorf("%s %q: %v", c.typ, c.in, err)
			continue
		}
		if got := Decode(c.typ, b); got != c.out {
			t.Errorf("%s %q decodes as %q, want %q", c.typ, c.in, got, c.out)
		}
		if got := Decode(TypeHex, b); strings.ReplaceAll(got, ":", "") != c.hex {
			t.Errorf("%s %q encodes as %s, want %s", c.typ, c.in, got, c.hex)
		}
	}
	bad := []struct{ typ, in string }{
		{TypeIP, "10.0.0.256"}, {TypeIP, "::1"}, {TypeIPs, ""}, {TypeU8, "256"}, {TypeU16, "-1"},
		{TypeBool, "maybe"}, {TypeHex, "zz"}, {TypeDomains, "a..b"}, {TypeDomains, "bad!name"},
		{TypeRoutes, "10.20.0.0/16"}, {TypeRoutes, "10.20.0.1/16 via 10.0.0.1"}, {TypeString, ""}, {"nope", "x"},
	}
	for _, c := range bad {
		if _, err := Encode(c.typ, c.in); err == nil {
			t.Errorf("%s %q accepted", c.typ, c.in)
		}
	}
}

func TestDecodeCompressedNames(t *testing.T) {
	// "lan" then "example.lan" written with a pointer to the first "lan".
	b := []byte{3, 'l', 'a', 'n', 0, 7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 0xc0, 0}
	if got := Decode(TypeDomains, b); got != "lan, example.lan" {
		t.Errorf("got %q", got)
	}
}

func TestLookup(t *testing.T) {
	if d, ok := Lookup("routers"); !ok || d.Code != 3 {
		t.Errorf("routers: %v %v", d, ok)
	}
	if d, ok := Lookup("42"); !ok || d.Name != "ntp-servers" {
		t.Errorf("42: %v %v", d, ok)
	}
	if d, ok := Lookup("224"); !ok || d.Type != TypeHex || d.Name != "option-224" {
		t.Errorf("224: %v %v", d, ok)
	}
	if _, ok := Lookup("no-such-option"); ok {
		t.Error("unknown name found")
	}
	for _, d := range Catalog {
		if _, ok := Reserved[d.Code]; ok {
			t.Errorf("%s (%d) is in the catalog and reserved", d.Name, d.Code)
		}
	}
}