// Copyright 2020 The Prometheus 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.

package labels

import (
	"math/rand"
	"regexp"
	"regexp/syntax"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

var (
	letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	regexes     = []string{
		"(foo|bar)",
		"foo.*",
		".*foo",
		"^.*foo$",
		"^.+foo$",
		".*",
		".+",
		"foo.+",
		".+foo",
		"foo\n.+",
		"foo\n.*",
		".*foo.*",
		".+foo.+",
		"",
		"(?s:.*)",
		"(?s:.+)",
		"(?s:^.*foo$)",
		"((.*)(bar|b|buzz)(.+)|foo)$",
		"^$",
		"(prometheus|api_prom)_api_v1_.+",
		"10\\.0\\.(1|2)\\.+",
	}
	values = []string{
		"foo", " foo bar", "bar", "buzz\nbar", "bar foo", "bfoo", "\n", "\nfoo", "foo\n", "hello foo world", "hello foo\n world", "",
		"\nfoo\n", strings.Repeat("f", 20), "prometheus", "prometheus_api_v1", "prometheus_api_v1_foo",
		"10.0.1.20", "10.0.2.10", "10.0.3.30", "10.0.4.40",
	}
)

func TestNewFastRegexMatcher(t *testing.T) {
	for _, r := range regexes {
		r := r
		for _, v := range values {
			v := v
			t.Run(r+` on "`+v+`"`, func(t *testing.T) {
				t.Parallel()
				m, err := NewFastRegexMatcher(r)
				require.NoError(t, err)
				re, err := regexp.Compile("^(?:" + r + ")$")
				require.NoError(t, err)
				require.Equal(t, re.MatchString(v), m.MatchString(v))
			})
		}

	}
}

func BenchmarkNewFastRegexMatcher(b *testing.B) {
	benchValues := append(values,
		RandStringRunes(128), RandStringRunes(256), RandStringRunes(1024))
	for _, r := range regexes {
		r := r
		b.Run(r, func(b *testing.B) {
			m, err := NewFastRegexMatcher(r)
			require.NoError(b, err)
			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				for _, v := range benchValues {
					_ = m.MatchString(v)
				}
			}
		})

	}
}

func TestOptimizeConcatRegex(t *testing.T) {
	cases := []struct {
		regex    string
		prefix   string
		suffix   string
		contains string
	}{
		{regex: "foo(hello|bar)", prefix: "foo", suffix: "", contains: ""},
		{regex: "foo(hello|bar)world", prefix: "foo", suffix: "world", contains: ""},
		{regex: "foo.*", prefix: "foo", suffix: "", contains: ""},
		{regex: "foo.*hello.*bar", prefix: "foo", suffix: "bar", contains: "hello"},
		{regex: ".*foo", prefix: "", suffix: "foo", contains: ""},
		{regex: "^.*foo$", prefix: "", suffix: "foo", contains: ""},
		{regex: ".*foo.*", prefix: "", suffix: "", contains: "foo"},
		{regex: ".*foo.*bar.*", prefix: "", suffix: "", contains: "foo"},
		{regex: ".*(foo|bar).*", prefix: "", suffix: "", contains: ""},
		{regex: ".*[abc].*", prefix: "", suffix: "", contains: ""},
		{regex: ".*((?i)abc).*", prefix: "", suffix: "", contains: ""},
		{regex: ".*(?i:abc).*", prefix: "", suffix: "", contains: ""},
		{regex: "(?i:abc).*", prefix: "", suffix: "", contains: ""},
		{regex: ".*(?i:abc)", prefix: "", suffix: "", contains: ""},
		{regex: ".*(?i:abc)def.*", prefix: "", suffix: "", contains: "def"},
		{regex: "(?i).*(?-i:abc)def", prefix: "", suffix: "", contains: "abc"},
		{regex: ".*(?msU:abc).*", prefix: "", suffix: "", contains: "abc"},
		{regex: "[aA]bc.*", prefix: "", suffix: "", contains: "bc"},
	}

	for _, c := range cases {
		parsed, err := syntax.Parse(c.regex, syntax.Perl)
		require.NoError(t, err)

		prefix, suffix, contains := optimizeConcatRegex(parsed)
		require.Equal(t, c.prefix, prefix)
		require.Equal(t, c.suffix, suffix)
		require.Equal(t, c.contains, contains)
	}
}

// Refer to https://github.com/prometheus/prometheus/issues/2651.
func TestFindSetMatches(t *testing.T) {
	for _, c := range []struct {
		pattern string
		exp     []string
	}{
		// Single value, coming from a `bar=~"foo"` selector.
		{"foo", []string{"foo"}},
		{"^foo", []string{"foo"}},
		{"^foo$", []string{"foo"}},
		// Simple sets alternates.
		{"foo|bar|zz", []string{"foo", "bar", "zz"}},
		// Simple sets alternate and concat (bar|baz is parsed as "ba[rz]").
		{"foo|bar|baz", []string{"foo", "bar", "baz"}},
		// Simple sets alternate and concat and capture
		{"foo|bar|baz|(zz)", []string{"foo", "bar", "baz", "zz"}},
		// Simple sets alternate and concat and alternates with empty matches
		// parsed as  b(ar|(?:)|uzz) where b(?:) means literal b.
		{"bar|b|buzz", []string{"bar", "b", "buzz"}},
		// Skip anchors it's enforced anyway at the root.
		{"(^bar$)|(b$)|(^buzz)", []string{"bar", "b", "buzz"}},
		// Simple sets containing escaped characters.
		{"fo\\.o|bar\\?|\\^baz", []string{"fo.o", "bar?", "^baz"}},
		// using charclass
		{"[abc]d", []string{"ad", "bd", "cd"}},
		// high low charset different => A(B[CD]|EF)|BC[XY]
		{"ABC|ABD|AEF|BCX|BCY", []string{"ABC", "ABD", "AEF", "BCX", "BCY"}},
		// triple concat
		{"api_(v1|prom)_push", []string{"api_v1_push", "api_prom_push"}},
		// triple concat with multiple alternates
		{"(api|rpc)_(v1|prom)_push", []string{"api_v1_push", "api_prom_push", "rpc_v1_push", "rpc_prom_push"}},
		{"(api|rpc)_(v1|prom)_(push|query)", []string{"api_v1_push", "api_v1_query", "api_prom_push", "api_prom_query", "rpc_v1_push", "rpc_v1_query", "rpc_prom_push", "rpc_prom_query"}},
		// class starting with "-"
		{"[-1-2][a-c]", []string{"-a", "-b", "-c", "1a", "1b", "1c", "2a", "2b", "2c"}},
		{"[1^3]", []string{"1", "3", "^"}},
		// OpPlus with concat
		{"(.+)/(foo|bar)", nil},
		// Simple sets containing special characters without escaping.
		{"fo.o|bar?|^baz", nil},
		// case sensitive wrapper.
		{"(?i)foo", nil},
		// case sensitive wrapper on alternate.
		{"(?i)foo|bar|baz", nil},
		// case sensitive wrapper on concat.
		{"(api|rpc)_(v1|prom)_((?i)push|query)", nil},
		// too high charset combination
		{"(api|rpc)_[^0-9]", nil},
		// too many combinations
		{"[a-z][a-z]", nil},
	} {
		c := c
		t.Run(c.pattern, func(t *testing.T) {
			t.Parallel()
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)
			matches := findSetMatches(parsed, "")
			require.Equal(t, c.exp, matches)
		})

	}
}

func Test_OptimizeRegex(t *testing.T) {
	for _, c := range []struct {
		pattern string
		exp     StringMatcher
	}{
		{".*", anyStringMatcher{allowEmpty: true, matchNL: false}},
		{"(?s:.*)", anyStringMatcher{allowEmpty: true, matchNL: true}},
		{"(.*)", anyStringMatcher{allowEmpty: true, matchNL: false}},
		{"^.*$", anyStringMatcher{allowEmpty: true, matchNL: false}},
		{".+", anyStringMatcher{allowEmpty: false, matchNL: false}},
		{"(?s:.+)", anyStringMatcher{allowEmpty: false, matchNL: true}},
		{"^.+$", anyStringMatcher{allowEmpty: false, matchNL: false}},
		{"(.+)", anyStringMatcher{allowEmpty: false, matchNL: false}},
		{"", emptyStringMatcher{}},
		{"^$", emptyStringMatcher{}},
		{"^foo$", equalStringMatcher{s: "foo", caseSensitive: true}},
		{"^(?i:foo)$", equalStringMatcher{s: "FOO", caseSensitive: false}},
		{"^(?i:foo)|(bar)$", orStringMatcher([]StringMatcher{equalStringMatcher{s: "FOO", caseSensitive: false}, equalStringMatcher{s: "bar", caseSensitive: true}})},
		{"^(?i:foo|oo)|(bar)$", orStringMatcher([]StringMatcher{orStringMatcher([]StringMatcher{equalStringMatcher{s: "FOO", caseSensitive: false}, equalStringMatcher{s: "OO", caseSensitive: false}}), equalStringMatcher{s: "bar", caseSensitive: true}})},
		{".*foo.*", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"(.*)foo.*", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"(.*)foo(.*)", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"(.+)foo(.*)", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: false, matchNL: false}, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"^.+foo.+", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: false, matchNL: false}, right: anyStringMatcher{allowEmpty: false, matchNL: false}}},
		{"^(.*)(foo)(.*)$", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"^(.*)(foo|foobar)(.*)$", containsStringMatcher{substr: []string{"foo", "foobar"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"^(.*)(foo|foobar)(.+)$", containsStringMatcher{substr: []string{"foo", "foobar"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: false, matchNL: false}}},
		{"^(.*)(bar|b|buzz)(.+)$", containsStringMatcher{substr: []string{"bar", "b", "buzz"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: false, matchNL: false}}},
		{"10\\.0\\.(1|2)\\.+", containsStringMatcher{substr: []string{"10.0.1", "10.0.2"}, left: nil, right: anyStringMatcher{allowEmpty: false, matchNL: false}}},
		{"^.+foo", containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: false, matchNL: false}, right: nil}},
		{"foo-.*$", containsStringMatcher{substr: []string{"foo-"}, left: nil, right: anyStringMatcher{allowEmpty: true, matchNL: false}}},
		{"(prometheus|api_prom)_api_v1_.+", containsStringMatcher{substr: []string{"prometheus_api_v1_", "api_prom_api_v1_"}, left: nil, right: anyStringMatcher{allowEmpty: false, matchNL: false}}},
		{"^((.*)(bar|b|buzz)(.+)|foo)$", orStringMatcher([]StringMatcher{containsStringMatcher{substr: []string{"bar", "b", "buzz"}, left: anyStringMatcher{allowEmpty: true, matchNL: false}, right: anyStringMatcher{allowEmpty: false, matchNL: false}}, equalStringMatcher{s: "foo", caseSensitive: true}})},
		{"((fo(bar))|.+foo)", orStringMatcher([]StringMatcher{orStringMatcher([]StringMatcher{equalStringMatcher{s: "fobar", caseSensitive: true}}), containsStringMatcher{substr: []string{"foo"}, left: anyStringMatcher{allowEmpty: false, matchNL: false}, right: nil}})},
		{"(.+)/(gateway|cortex-gw|cortex-gw-internal)", containsStringMatcher{substr: []string{"/gateway", "/cortex-gw", "/cortex-gw-internal"}, left: anyStringMatcher{allowEmpty: false, matchNL: false}, right: nil}},
		// we don't support case insensitive matching for contains.
		// This is because there's no strings.IndexOfFold function.
		// We can revisit later if this is really popular by using strings.ToUpper.
		{"^(.*)((?i)foo|foobar)(.*)$", nil},
		{"(api|rpc)_(v1|prom)_((?i)push|query)", nil},
		{"[a-z][a-z]", nil},
		{"[1^3]", nil},
		// This one is not supported because  `stringMatcherFromRegexp` is not reentrant for syntax.OpConcat.
		// It would make the code too complex to handle it.
		{"/|/bar.*", nil},
		{"(.+)/(foo.*|bar$)", nil},
	} {
		c := c
		t.Run(c.pattern, func(t *testing.T) {
			t.Parallel()
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)
			matches := stringMatcherFromRegexp(parsed)
			require.Equal(t, c.exp, matches)
		})
	}
}

func RandStringRunes(n int) string {
	b := make([]rune, n)
	for i := range b {
		b[i] = letterRunes[rand.Intn(len(letterRunes))]
	}
	return string(b)
}