/*
   Copyright The containerd Authors.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

// originally from https://github.com/moby/moby/blob/6014c1e29dc34dffa77fb5749cc3281c1b4854ac/libnetwork/resolvconf/resolvconf_linux_test.go
package resolvconf

import (
	"bytes"
	"os"
	"testing"

	"github.com/containerd/nerdctl/v2/pkg/internal/filesystem"
)

func TestGet(t *testing.T) {
	resolvConfUtils, err := Get()
	if err != nil {
		t.Fatal(err)
	}
	resolvConfSystem, err := filesystem.ReadFile("/run/systemd/resolve/resolv.conf")
	if err != nil {
		t.Fatal(err)
	}
	if string(resolvConfUtils.Content) != string(resolvConfSystem) {
		t.Fatalf("/etc/resolv.conf and GetResolvConf have different content.")
	}
	hashSystem, err := hashData(bytes.NewReader(resolvConfSystem))
	if err != nil {
		t.Fatal(err)
	}
	if resolvConfUtils.Hash != hashSystem {
		t.Fatalf("/etc/resolv.conf and GetResolvConf have different hashes.")
	}
}

func TestGetNameservers(t *testing.T) {
	for resolv, result := range map[string][]string{`
nameserver 1.2.3.4
nameserver 40.3.200.10
search example.com`: {"1.2.3.4", "40.3.200.10"},
		`search example.com`: {},
		`nameserver 1.2.3.4
search example.com
nameserver 4.30.20.100`: {"1.2.3.4", "4.30.20.100"},
		``:                        {},
		`  nameserver 1.2.3.4   `: {"1.2.3.4"},
		`search example.com
nameserver 1.2.3.4
#nameserver 4.3.2.1`: {"1.2.3.4"},
		`search example.com
nameserver 1.2.3.4 # not 4.3.2.1`: {"1.2.3.4"},
	} {
		test := GetNameservers([]byte(resolv), IP)
		if !strSlicesEqual(test, result) {
			t.Fatalf("Wrong nameserver string {%s} should be %v. Input: %s", test, result, resolv)
		}
	}
}

func TestGetNameserversAsCIDR(t *testing.T) {
	for resolv, result := range map[string][]string{`
nameserver 1.2.3.4
nameserver 40.3.200.10
search example.com`: {"1.2.3.4/32", "40.3.200.10/32"},
		`search example.com`: {},
		`nameserver 1.2.3.4
search example.com
nameserver 4.30.20.100`: {"1.2.3.4/32", "4.30.20.100/32"},
		``:                        {},
		`  nameserver 1.2.3.4   `: {"1.2.3.4/32"},
		`search example.com
nameserver 1.2.3.4
#nameserver 4.3.2.1`: {"1.2.3.4/32"},
		`search example.com
nameserver 1.2.3.4 # not 4.3.2.1`: {"1.2.3.4/32"},
	} {
		test := GetNameserversAsCIDR([]byte(resolv))
		if !strSlicesEqual(test, result) {
			t.Fatalf("Wrong nameserver string {%s} should be %v. Input: %s", test, result, resolv)
		}
	}
}

func TestGetSearchDomains(t *testing.T) {
	for resolv, result := range map[string][]string{
		`search example.com`:                                   {"example.com"},
		`search example.com # ignored`:                         {"example.com"},
		`	  search	 example.com	  `:                            {"example.com"},
		`	  search	 example.com	  # ignored`:                   {"example.com"},
		`search foo.example.com example.com`:                   {"foo.example.com", "example.com"},
		`	   search	   foo.example.com	 example.com	`:          {"foo.example.com", "example.com"},
		`	   search	   foo.example.com	 example.com	# ignored`: {"foo.example.com", "example.com"},
		``:          {},
		`# ignored`: {},
		`nameserver 1.2.3.4
search foo.example.com example.com`: {"foo.example.com", "example.com"},
		`nameserver 1.2.3.4
search dup1.example.com dup2.example.com
search foo.example.com example.com`: {"foo.example.com", "example.com"},
		`nameserver 1.2.3.4
search foo.example.com example.com
nameserver 4.30.20.100`: {"foo.example.com", "example.com"},
	} {
		test := GetSearchDomains([]byte(resolv))
		if !strSlicesEqual(test, result) {
			t.Fatalf("Wrong search domain string {%s} should be %v. Input: %s", test, result, resolv)
		}
	}
}

func TestGetOptions(t *testing.T) {
	for resolv, result := range map[string][]string{
		`options opt1`:                            {"opt1"},
		`options opt1 # ignored`:                  {"opt1"},
		`	  options	 opt1	  `:                     {"opt1"},
		`	  options	 opt1	  # ignored`:            {"opt1"},
		`options opt1 opt2 opt3`:                  {"opt1", "opt2", "opt3"},
		`options opt1 opt2 opt3 # ignored`:        {"opt1", "opt2", "opt3"},
		`	   options	 opt1	 opt2	 opt3	`:          {"opt1", "opt2", "opt3"},
		`	   options	 opt1	 opt2	 opt3	# ignored`: {"opt1", "opt2", "opt3"},
		``:                   {},
		`# ignored`:          {},
		`nameserver 1.2.3.4`: {},
		`nameserver 1.2.3.4
options opt1 opt2 opt3`: {"opt1", "opt2", "opt3"},
		`nameserver 1.2.3.4
options opt1 opt2
options opt3 opt4`: {"opt3", "opt4"},
	} {
		test := GetOptions([]byte(resolv))
		if !strSlicesEqual(test, result) {
			t.Fatalf("Wrong options string {%s} should be %v. Input: %s", test, result, resolv)
		}
	}
}

func strSlicesEqual(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}

	for i, v := range a {
		if v != b[i] {
			return false
		}
	}

	return true
}

func TestBuild(t *testing.T) {
	file, err := os.CreateTemp("", "")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove(file.Name())

	_, err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"search1"}, []string{"opt1"})
	if err != nil {
		t.Fatal(err)
	}

	content, err := filesystem.ReadFile(file.Name())
	if err != nil {
		t.Fatal(err)
	}

	if expected := "search search1\nnameserver ns1\nnameserver ns2\nnameserver ns3\noptions opt1\n"; !bytes.Contains(content, []byte(expected)) {
		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
	}
}

func TestBuildWithZeroLengthDomainSearch(t *testing.T) {
	file, err := os.CreateTemp("", "")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove(file.Name())

	_, err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"."}, []string{"opt1"})
	if err != nil {
		t.Fatal(err)
	}

	content, err := filesystem.ReadFile(file.Name())
	if err != nil {
		t.Fatal(err)
	}

	if expected := "nameserver ns1\nnameserver ns2\nnameserver ns3\noptions opt1\n"; !bytes.Contains(content, []byte(expected)) {
		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
	}
	if notExpected := "search ."; bytes.Contains(content, []byte(notExpected)) {
		t.Fatalf("Expected to not find '%s' got '%s'", notExpected, content)
	}
}

func TestBuildWithNoOptions(t *testing.T) {
	file, err := os.CreateTemp("", "")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove(file.Name())

	_, err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"search1"}, []string{})
	if err != nil {
		t.Fatal(err)
	}

	content, err := filesystem.ReadFile(file.Name())
	if err != nil {
		t.Fatal(err)
	}

	if expected := "search search1\nnameserver ns1\nnameserver ns2\nnameserver ns3\n"; !bytes.Contains(content, []byte(expected)) {
		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
	}
	if notExpected := "search ."; bytes.Contains(content, []byte(notExpected)) {
		t.Fatalf("Expected to not find '%s' got '%s'", notExpected, content)
	}
}

func TestFilterResolvDns(t *testing.T) {
	ns0 := "nameserver 10.16.60.14\nnameserver 10.16.60.21\n"

	if result, _ := FilterResolvDNS([]byte(ns0), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed No Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	ns1 := "nameserver 10.16.60.14\nnameserver 10.16.60.21\nnameserver 127.0.0.1\n"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	ns1 = "nameserver 10.16.60.14\nnameserver 127.0.0.1\nnameserver 10.16.60.21\n"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	ns1 = "nameserver 127.0.1.1\nnameserver 10.16.60.14\nnameserver 10.16.60.21\n"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	ns1 = "nameserver ::1\nnameserver 10.16.60.14\nnameserver 127.0.2.1\nnameserver 10.16.60.21\n"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	ns1 = "nameserver 10.16.60.14\nnameserver ::1\nnameserver 10.16.60.21\nnameserver ::1"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	// with IPv6 disabled (false param), the IPv6 nameserver should be removed
	ns1 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\nnameserver ::1"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost+IPv6 off: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	// with IPv6 disabled (false param), the IPv6 link-local nameserver with zone ID should be removed
	ns1 = "nameserver 10.16.60.14\nnameserver FE80::BB1%1\nnameserver FE80::BB1%eth0\nnameserver 10.16.60.21\n"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost+IPv6 off: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	// with IPv6 enabled, the IPv6 nameserver should be preserved
	ns0 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\n"
	ns1 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\nnameserver ::1"
	if result, _ := FilterResolvDNS([]byte(ns1), true); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed Localhost+IPv6 on: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	// with IPv6 enabled, and no non-localhost servers, Google defaults (both IPv4+IPv6) should be added
	ns0 = "\nnameserver 8.8.8.8\nnameserver 8.8.4.4\nnameserver 2001:4860:4860::8888\nnameserver 2001:4860:4860::8844"
	ns1 = "nameserver 127.0.0.1\nnameserver ::1\nnameserver 127.0.2.1"
	if result, _ := FilterResolvDNS([]byte(ns1), true); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}

	// with IPv6 disabled, and no non-localhost servers, Google defaults (only IPv4) should be added
	ns0 = "\nnameserver 8.8.8.8\nnameserver 8.8.4.4"
	ns1 = "nameserver 127.0.0.1\nnameserver ::1\nnameserver 127.0.2.1"
	if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
		if ns0 != string(result.Content) {
			t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result.Content))
		}
	}
}

func TestFilterResolvDnsWithLocalhostOption(t *testing.T) {
	testCases := []struct {
		name              string
		input             string
		allowLocalhostDNS bool
		ipv6Enabled       bool
		expected          string
	}{
		{
			name:              "filter_disallow_localhost_ipv6_disabled",
			input:             "nameserver 127.0.0.53\nnameserver 192.88.99.1\nnameserver ::1\nnameserver 2001:db8::1\n",
			allowLocalhostDNS: false,
			ipv6Enabled:       false,
			expected:          "nameserver 192.88.99.1\n",
		},
		{
			name:              "filter_allow_localhost_ipv6_disabled",
			input:             "nameserver 127.0.0.53\nnameserver 192.88.99.1\nnameserver ::1\nnameserver 2001:db8::1\n",
			allowLocalhostDNS: true,
			ipv6Enabled:       false,
			expected:          "nameserver 127.0.0.53\nnameserver 192.88.99.1\n",
		},
		{
			name:              "filter_disallow_localhost_ipv6_enabled",
			input:             "nameserver 127.0.0.53\nnameserver 192.88.99.1\nnameserver ::1\nnameserver 2001:db8::1\n",
			allowLocalhostDNS: false,
			ipv6Enabled:       true,
			expected:          "nameserver 192.88.99.1\nnameserver 2001:db8::1\n",
		},
		{
			name:              "filter_allow_localhost_ipv6_enabled",
			input:             "nameserver 127.0.0.53\nnameserver 192.88.99.1\nnameserver ::1\nnameserver 2001:db8::1\n",
			allowLocalhostDNS: true,
			ipv6Enabled:       true,
			expected:          "nameserver 127.0.0.53\nnameserver 192.88.99.1\nnameserver ::1\nnameserver 2001:db8::1\n",
		},
		{
			name:              "fallback_none_ipv6_disabled",
			input:             "",
			allowLocalhostDNS: false,
			ipv6Enabled:       false,
			expected:          "\nnameserver 8.8.8.8\nnameserver 8.8.4.4",
		},
		{
			name:              "fallback_none_ipv6_enabled",
			input:             "",
			allowLocalhostDNS: false,
			ipv6Enabled:       true,
			expected:          "\nnameserver 8.8.8.8\nnameserver 8.8.4.4\nnameserver 2001:4860:4860::8888\nnameserver 2001:4860:4860::8844",
		},
		{
			name:              "fallback_localhost4_ipv6_disabled",
			input:             "nameserver 127.0.0.53",
			allowLocalhostDNS: false,
			ipv6Enabled:       false,
			expected:          "\nnameserver 8.8.8.8\nnameserver 8.8.4.4",
		},
		{
			name:              "fallback_localhost4_ipv6_enabled",
			input:             "nameserver 127.0.0.53",
			allowLocalhostDNS: false,
			ipv6Enabled:       true,
			expected:          "\nnameserver 8.8.8.8\nnameserver 8.8.4.4\nnameserver 2001:4860:4860::8888\nnameserver 2001:4860:4860::8844",
		},
		{
			name:              "fallback_localhost6_ipv6_disabled",
			input:             "nameserver ::1",
			allowLocalhostDNS: false,
			ipv6Enabled:       false,
			expected:          "\nnameserver 8.8.8.8\nnameserver 8.8.4.4",
		},
		{
			name:              "fallback_localhost6_ipv6_enabled",
			input:             "nameserver ::1",
			allowLocalhostDNS: false,
			ipv6Enabled:       true,
			expected:          "\nnameserver 8.8.8.8\nnameserver 8.8.4.4\nnameserver 2001:4860:4860::8888\nnameserver 2001:4860:4860::8844",
		},
	}

	for _, tc := range testCases {
		tc := tc
		t.Run(tc.name, func(t *testing.T) {
			result, err := FilterResolvDNSWithLocalhostOption([]byte(tc.input), tc.ipv6Enabled, tc.allowLocalhostDNS)
			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}
			if result == nil {
				t.Fatal("result is nil")
			}
			if tc.expected != string(result.Content) {
				t.Fatalf("expected \n<%s> got \n<%s>", tc.expected, string(result.Content))
			}
		})
	}
}