// Copyright 2015 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 promql

import (
	"fmt"
	"reflect"
	"testing"
)

var tests = []struct {
	input      string
	expected   []item
	fail       bool
	seriesDesc bool // Whether to lex a series description.
}{
	// Test common stuff.
	{
		input:    ",",
		expected: []item{{itemComma, 0, ","}},
	}, {
		input:    "()",
		expected: []item{{itemLeftParen, 0, `(`}, {itemRightParen, 1, `)`}},
	}, {
		input:    "{}",
		expected: []item{{itemLeftBrace, 0, `{`}, {itemRightBrace, 1, `}`}},
	}, {
		input: "[5m]",
		expected: []item{
			{itemLeftBracket, 0, `[`},
			{itemDuration, 1, `5m`},
			{itemRightBracket, 3, `]`},
		},
	}, {
		input:    "\r\n\r",
		expected: []item{},
	},
	// Test numbers.
	{
		input:    "1",
		expected: []item{{itemNumber, 0, "1"}},
	}, {
		input:    "4.23",
		expected: []item{{itemNumber, 0, "4.23"}},
	}, {
		input:    ".3",
		expected: []item{{itemNumber, 0, ".3"}},
	}, {
		input:    "5.",
		expected: []item{{itemNumber, 0, "5."}},
	}, {
		input:    "NaN",
		expected: []item{{itemNumber, 0, "NaN"}},
	}, {
		input:    "nAN",
		expected: []item{{itemNumber, 0, "nAN"}},
	}, {
		input:    "NaN 123",
		expected: []item{{itemNumber, 0, "NaN"}, {itemNumber, 4, "123"}},
	}, {
		input:    "NaN123",
		expected: []item{{itemIdentifier, 0, "NaN123"}},
	}, {
		input:    "iNf",
		expected: []item{{itemNumber, 0, "iNf"}},
	}, {
		input:    "Inf",
		expected: []item{{itemNumber, 0, "Inf"}},
	}, {
		input:    "+Inf",
		expected: []item{{itemADD, 0, "+"}, {itemNumber, 1, "Inf"}},
	}, {
		input:    "+Inf 123",
		expected: []item{{itemADD, 0, "+"}, {itemNumber, 1, "Inf"}, {itemNumber, 5, "123"}},
	}, {
		input:    "-Inf",
		expected: []item{{itemSUB, 0, "-"}, {itemNumber, 1, "Inf"}},
	}, {
		input:    "Infoo",
		expected: []item{{itemIdentifier, 0, "Infoo"}},
	}, {
		input:    "-Infoo",
		expected: []item{{itemSUB, 0, "-"}, {itemIdentifier, 1, "Infoo"}},
	}, {
		input:    "-Inf 123",
		expected: []item{{itemSUB, 0, "-"}, {itemNumber, 1, "Inf"}, {itemNumber, 5, "123"}},
	}, {
		input:    "0x123",
		expected: []item{{itemNumber, 0, "0x123"}},
	},
	// Test strings.
	{
		input:    "\"test\\tsequence\"",
		expected: []item{{itemString, 0, `"test\tsequence"`}},
	},
	{
		input:    "\"test\\\\.expression\"",
		expected: []item{{itemString, 0, `"test\\.expression"`}},
	},
	{
		input: "\"test\\.expression\"",
		expected: []item{
			{itemError, 0, "unknown escape sequence U+002E '.'"},
			{itemString, 0, `"test\.expression"`},
		},
	},
	{
		input:    "`test\\.expression`",
		expected: []item{{itemString, 0, "`test\\.expression`"}},
	},
	{
		// See https://github.com/prometheus/prometheus/issues/939.
		input: ".٩",
		fail:  true,
	},
	// Test duration.
	{
		input:    "5s",
		expected: []item{{itemDuration, 0, "5s"}},
	}, {
		input:    "123m",
		expected: []item{{itemDuration, 0, "123m"}},
	}, {
		input:    "1h",
		expected: []item{{itemDuration, 0, "1h"}},
	}, {
		input:    "3w",
		expected: []item{{itemDuration, 0, "3w"}},
	}, {
		input:    "1y",
		expected: []item{{itemDuration, 0, "1y"}},
	},
	// Test identifiers.
	{
		input:    "abc",
		expected: []item{{itemIdentifier, 0, "abc"}},
	}, {
		input:    "a:bc",
		expected: []item{{itemMetricIdentifier, 0, "a:bc"}},
	}, {
		input:    "abc d",
		expected: []item{{itemIdentifier, 0, "abc"}, {itemIdentifier, 4, "d"}},
	}, {
		input:    ":bc",
		expected: []item{{itemMetricIdentifier, 0, ":bc"}},
	}, {
		input: "0a:bc",
		fail:  true,
	},
	// Test comments.
	{
		input:    "# some comment",
		expected: []item{{itemComment, 0, "# some comment"}},
	}, {
		input: "5 # 1+1\n5",
		expected: []item{
			{itemNumber, 0, "5"},
			{itemComment, 2, "# 1+1"},
			{itemNumber, 8, "5"},
		},
	},
	// Test operators.
	{
		input:    `=`,
		expected: []item{{itemAssign, 0, `=`}},
	}, {
		// Inside braces equality is a single '=' character.
		input:    `{=}`,
		expected: []item{{itemLeftBrace, 0, `{`}, {itemEQL, 1, `=`}, {itemRightBrace, 2, `}`}},
	}, {
		input:    `==`,
		expected: []item{{itemEQL, 0, `==`}},
	}, {
		input:    `!=`,
		expected: []item{{itemNEQ, 0, `!=`}},
	}, {
		input:    `<`,
		expected: []item{{itemLSS, 0, `<`}},
	}, {
		input:    `>`,
		expected: []item{{itemGTR, 0, `>`}},
	}, {
		input:    `>=`,
		expected: []item{{itemGTE, 0, `>=`}},
	}, {
		input:    `<=`,
		expected: []item{{itemLTE, 0, `<=`}},
	}, {
		input:    `+`,
		expected: []item{{itemADD, 0, `+`}},
	}, {
		input:    `-`,
		expected: []item{{itemSUB, 0, `-`}},
	}, {
		input:    `*`,
		expected: []item{{itemMUL, 0, `*`}},
	}, {
		input:    `/`,
		expected: []item{{itemDIV, 0, `/`}},
	}, {
		input:    `^`,
		expected: []item{{itemPOW, 0, `^`}},
	}, {
		input:    `%`,
		expected: []item{{itemMOD, 0, `%`}},
	}, {
		input:    `AND`,
		expected: []item{{itemLAND, 0, `AND`}},
	}, {
		input:    `or`,
		expected: []item{{itemLOR, 0, `or`}},
	}, {
		input:    `unless`,
		expected: []item{{itemLUnless, 0, `unless`}},
	},
	// Test aggregators.
	{
		input:    `sum`,
		expected: []item{{itemSum, 0, `sum`}},
	}, {
		input:    `AVG`,
		expected: []item{{itemAvg, 0, `AVG`}},
	}, {
		input:    `MAX`,
		expected: []item{{itemMax, 0, `MAX`}},
	}, {
		input:    `min`,
		expected: []item{{itemMin, 0, `min`}},
	}, {
		input:    `count`,
		expected: []item{{itemCount, 0, `count`}},
	}, {
		input:    `stdvar`,
		expected: []item{{itemStdvar, 0, `stdvar`}},
	}, {
		input:    `stddev`,
		expected: []item{{itemStddev, 0, `stddev`}},
	},
	// Test keywords.
	{
		input:    "offset",
		expected: []item{{itemOffset, 0, "offset"}},
	}, {
		input:    "by",
		expected: []item{{itemBy, 0, "by"}},
	}, {
		input:    "without",
		expected: []item{{itemWithout, 0, "without"}},
	}, {
		input:    "on",
		expected: []item{{itemOn, 0, "on"}},
	}, {
		input:    "ignoring",
		expected: []item{{itemIgnoring, 0, "ignoring"}},
	}, {
		input:    "group_left",
		expected: []item{{itemGroupLeft, 0, "group_left"}},
	}, {
		input:    "group_right",
		expected: []item{{itemGroupRight, 0, "group_right"}},
	}, {
		input:    "bool",
		expected: []item{{itemBool, 0, "bool"}},
	},
	// Test Selector.
	{
		input: `台北`,
		fail:  true,
	}, {
		input: `{台北='a'}`,
		fail:  true,
	}, {
		input: `{0a='a'}`,
		fail:  true,
	}, {
		input: `{foo='bar'}`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemIdentifier, 1, `foo`},
			{itemEQL, 4, `=`},
			{itemString, 5, `'bar'`},
			{itemRightBrace, 10, `}`},
		},
	}, {
		input: `{foo="bar"}`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemIdentifier, 1, `foo`},
			{itemEQL, 4, `=`},
			{itemString, 5, `"bar"`},
			{itemRightBrace, 10, `}`},
		},
	}, {
		input: `{foo="bar\"bar"}`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemIdentifier, 1, `foo`},
			{itemEQL, 4, `=`},
			{itemString, 5, `"bar\"bar"`},
			{itemRightBrace, 15, `}`},
		},
	}, {
		input: `{NaN	!= "bar" }`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemIdentifier, 1, `NaN`},
			{itemNEQ, 5, `!=`},
			{itemString, 8, `"bar"`},
			{itemRightBrace, 14, `}`},
		},
	}, {
		input: `{alert=~"bar" }`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemIdentifier, 1, `alert`},
			{itemEQLRegex, 6, `=~`},
			{itemString, 8, `"bar"`},
			{itemRightBrace, 14, `}`},
		},
	}, {
		input: `{on!~"bar"}`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemIdentifier, 1, `on`},
			{itemNEQRegex, 3, `!~`},
			{itemString, 5, `"bar"`},
			{itemRightBrace, 10, `}`},
		},
	}, {
		input: `{alert!#"bar"}`, fail: true,
	}, {
		input: `{foo:a="bar"}`, fail: true,
	},
	// Test common errors.
	{
		input: `=~`, fail: true,
	}, {
		input: `!~`, fail: true,
	}, {
		input: `!(`, fail: true,
	}, {
		input: "1a", fail: true,
	},
	// Test mismatched parens.
	{
		input: `(`, fail: true,
	}, {
		input: `())`, fail: true,
	}, {
		input: `(()`, fail: true,
	}, {
		input: `{`, fail: true,
	}, {
		input: `}`, fail: true,
	}, {
		input: "{{", fail: true,
	}, {
		input: "{{}}", fail: true,
	}, {
		input: `[`, fail: true,
	}, {
		input: `[[`, fail: true,
	}, {
		input: `[]]`, fail: true,
	}, {
		input: `[[]]`, fail: true,
	}, {
		input: `]`, fail: true,
	},
	// Test encoding issues.
	{
		input: "\"\xff\"", fail: true,
	},
	{
		input: "`\xff`", fail: true,
	},
	// Test series description.
	{
		input: `{} _ 1 x .3`,
		expected: []item{
			{itemLeftBrace, 0, `{`},
			{itemRightBrace, 1, `}`},
			{itemSpace, 2, ` `},
			{itemBlank, 3, `_`},
			{itemSpace, 4, ` `},
			{itemNumber, 5, `1`},
			{itemSpace, 6, ` `},
			{itemTimes, 7, `x`},
			{itemSpace, 8, ` `},
			{itemNumber, 9, `.3`},
		},
		seriesDesc: true,
	},
	{
		input: `metric +Inf Inf NaN`,
		expected: []item{
			{itemIdentifier, 0, `metric`},
			{itemSpace, 6, ` `},
			{itemADD, 7, `+`},
			{itemNumber, 8, `Inf`},
			{itemSpace, 11, ` `},
			{itemNumber, 12, `Inf`},
			{itemSpace, 15, ` `},
			{itemNumber, 16, `NaN`},
		},
		seriesDesc: true,
	},
	{
		input: `metric 1+1x4`,
		expected: []item{
			{itemIdentifier, 0, `metric`},
			{itemSpace, 6, ` `},
			{itemNumber, 7, `1`},
			{itemADD, 8, `+`},
			{itemNumber, 9, `1`},
			{itemTimes, 10, `x`},
			{itemNumber, 11, `4`},
		},
		seriesDesc: true,
	},
	// Test subquery.
	{
		input: `test_name{on!~"bar"}[4m:4s]`,
		expected: []item{
			{itemIdentifier, 0, `test_name`},
			{itemLeftBrace, 9, `{`},
			{itemIdentifier, 10, `on`},
			{itemNEQRegex, 12, `!~`},
			{itemString, 14, `"bar"`},
			{itemRightBrace, 19, `}`},
			{itemLeftBracket, 20, `[`},
			{itemDuration, 21, `4m`},
			{itemColon, 23, `:`},
			{itemDuration, 24, `4s`},
			{itemRightBracket, 26, `]`},
		},
	},
	{
		input: `test:name{on!~"bar"}[4m:4s]`,
		expected: []item{
			{itemMetricIdentifier, 0, `test:name`},
			{itemLeftBrace, 9, `{`},
			{itemIdentifier, 10, `on`},
			{itemNEQRegex, 12, `!~`},
			{itemString, 14, `"bar"`},
			{itemRightBrace, 19, `}`},
			{itemLeftBracket, 20, `[`},
			{itemDuration, 21, `4m`},
			{itemColon, 23, `:`},
			{itemDuration, 24, `4s`},
			{itemRightBracket, 26, `]`},
		},
	}, {
		input: `test:name{on!~"b:ar"}[4m:4s]`,
		expected: []item{
			{itemMetricIdentifier, 0, `test:name`},
			{itemLeftBrace, 9, `{`},
			{itemIdentifier, 10, `on`},
			{itemNEQRegex, 12, `!~`},
			{itemString, 14, `"b:ar"`},
			{itemRightBrace, 20, `}`},
			{itemLeftBracket, 21, `[`},
			{itemDuration, 22, `4m`},
			{itemColon, 24, `:`},
			{itemDuration, 25, `4s`},
			{itemRightBracket, 27, `]`},
		},
	}, {
		input: `test:name{on!~"b:ar"}[4m:]`,
		expected: []item{
			{itemMetricIdentifier, 0, `test:name`},
			{itemLeftBrace, 9, `{`},
			{itemIdentifier, 10, `on`},
			{itemNEQRegex, 12, `!~`},
			{itemString, 14, `"b:ar"`},
			{itemRightBrace, 20, `}`},
			{itemLeftBracket, 21, `[`},
			{itemDuration, 22, `4m`},
			{itemColon, 24, `:`},
			{itemRightBracket, 25, `]`},
		},
	}, { // Nested Subquery.
		input: `min_over_time(rate(foo{bar="baz"}[2s])[5m:])[4m:3s]`,
		expected: []item{

			{itemIdentifier, 0, `min_over_time`},
			{itemLeftParen, 13, `(`},
			{itemIdentifier, 14, `rate`},
			{itemLeftParen, 18, `(`},
			{itemIdentifier, 19, `foo`},
			{itemLeftBrace, 22, `{`},
			{itemIdentifier, 23, `bar`},
			{itemEQL, 26, `=`},
			{itemString, 27, `"baz"`},
			{itemRightBrace, 32, `}`},
			{itemLeftBracket, 33, `[`},
			{itemDuration, 34, `2s`},
			{itemRightBracket, 36, `]`},
			{itemRightParen, 37, `)`},
			{itemLeftBracket, 38, `[`},
			{itemDuration, 39, `5m`},
			{itemColon, 41, `:`},
			{itemRightBracket, 42, `]`},
			{itemRightParen, 43, `)`},
			{itemLeftBracket, 44, `[`},
			{itemDuration, 45, `4m`},
			{itemColon, 47, `:`},
			{itemDuration, 48, `3s`},
			{itemRightBracket, 50, `]`},
		},
	},
	// Subquery with offset.
	{
		input: `test:name{on!~"b:ar"}[4m:4s] offset 10m`,
		expected: []item{
			{itemMetricIdentifier, 0, `test:name`},
			{itemLeftBrace, 9, `{`},
			{itemIdentifier, 10, `on`},
			{itemNEQRegex, 12, `!~`},
			{itemString, 14, `"b:ar"`},
			{itemRightBrace, 20, `}`},
			{itemLeftBracket, 21, `[`},
			{itemDuration, 22, `4m`},
			{itemColon, 24, `:`},
			{itemDuration, 25, `4s`},
			{itemRightBracket, 27, `]`},
			{itemOffset, 29, "offset"},
			{itemDuration, 36, "10m"},
		},
	}, {
		input: `min_over_time(rate(foo{bar="baz"}[2s])[5m:] offset 6m)[4m:3s]`,
		expected: []item{

			{itemIdentifier, 0, `min_over_time`},
			{itemLeftParen, 13, `(`},
			{itemIdentifier, 14, `rate`},
			{itemLeftParen, 18, `(`},
			{itemIdentifier, 19, `foo`},
			{itemLeftBrace, 22, `{`},
			{itemIdentifier, 23, `bar`},
			{itemEQL, 26, `=`},
			{itemString, 27, `"baz"`},
			{itemRightBrace, 32, `}`},
			{itemLeftBracket, 33, `[`},
			{itemDuration, 34, `2s`},
			{itemRightBracket, 36, `]`},
			{itemRightParen, 37, `)`},
			{itemLeftBracket, 38, `[`},
			{itemDuration, 39, `5m`},
			{itemColon, 41, `:`},
			{itemRightBracket, 42, `]`},
			{itemOffset, 44, `offset`},
			{itemDuration, 51, `6m`},
			{itemRightParen, 53, `)`},
			{itemLeftBracket, 54, `[`},
			{itemDuration, 55, `4m`},
			{itemColon, 57, `:`},
			{itemDuration, 58, `3s`},
			{itemRightBracket, 60, `]`},
		},
	},
	{
		input: `test:name{o:n!~"bar"}[4m:4s]`,
		fail:  true,
	},
	{
		input: `test:name{on!~"bar"}[4m:4s:4h]`,
		fail:  true,
	},
	{
		input: `test:name{on!~"bar"}[4m:4s:]`,
		fail:  true,
	},
	{
		input: `test:name{on!~"bar"}[4m::]`,
		fail:  true,
	},
	{
		input: `test:name{on!~"bar"}[:4s]`,
		fail:  true,
	},
}

// TestLexer tests basic functionality of the lexer. More elaborate tests are implemented
// for the parser to avoid duplicated effort.
func TestLexer(t *testing.T) {
	for i, test := range tests {
		l := &lexer{
			input:      test.input,
			items:      make(chan item),
			seriesDesc: test.seriesDesc,
		}
		go l.run()

		out := []item{}
		for it := range l.items {
			out = append(out, it)
		}

		lastItem := out[len(out)-1]
		if test.fail {
			if lastItem.typ != itemError {
				t.Logf("%d: input %q", i, test.input)
				t.Fatalf("expected lexing error but did not fail")
			}
			continue
		}
		if lastItem.typ == itemError {
			t.Logf("%d: input %q", i, test.input)
			t.Fatalf("unexpected lexing error at position %d: %s", lastItem.pos, lastItem)
		}

		if !reflect.DeepEqual(lastItem, item{itemEOF, Pos(len(test.input)), ""}) {
			t.Logf("%d: input %q", i, test.input)
			t.Fatalf("lexing error: expected output to end with EOF item.\ngot:\n%s", expectedList(out))
		}
		out = out[:len(out)-1]
		if !reflect.DeepEqual(out, test.expected) {
			t.Logf("%d: input %q", i, test.input)
			t.Fatalf("lexing mismatch:\nexpected:\n%s\ngot:\n%s", expectedList(test.expected), expectedList(out))
		}
	}
}

func expectedList(exp []item) string {
	s := ""
	for _, it := range exp {
		s += fmt.Sprintf("\t%#v\n", it)
	}
	return s
}