// Copyright 2013 Prometheus Team
// 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 rules

import (
	"fmt"
	"github.com/prometheus/prometheus/model"
	"github.com/prometheus/prometheus/rules/ast"
	"github.com/prometheus/prometheus/storage/metric"
	"github.com/prometheus/prometheus/utility/test"
	"path"
	"strings"
	"testing"
	"time"
)

var (
	testEvalTime = testStartTime.Add(testSampleInterval * 10)
	fixturesPath = "fixtures"
)

func annotateWithTime(lines []string, timestamp time.Time) []string {
	annotatedLines := []string{}
	for _, line := range lines {
		annotatedLines = append(annotatedLines, fmt.Sprintf(line, timestamp))
	}
	return annotatedLines
}

func vectorComparisonString(expected []string, actual []string) string {
	separator := "\n--------------\n"
	return fmt.Sprintf("Expected:%v%v%v\nActual:%v%v%v ",
		separator,
		strings.Join(expected, "\n"),
		separator,
		separator,
		strings.Join(actual, "\n"),
		separator)
}

func newTestStorage(t test.Tester) (storage *metric.TieredStorage, closer test.Closer) {
	storage, closer = metric.NewTestTieredStorage(t)
	if storage == nil {
		t.Fatal("storage == nil")
	}
	storeMatrix(*storage, testMatrix)
	return
}

func TestExpressions(t *testing.T) {
	// Labels in expected output need to be alphabetically sorted.
	var expressionTests = []struct {
		expr           string
		output         []string
		shouldFail     bool
		checkOrder     bool
		fullRanges     int
		intervalRanges int
	}{
		{
			expr:           "SUM(http_requests)",
			output:         []string{"http_requests{} => 3600 @[%v]"},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 1000 @[%v]",
				"http_requests{job='app-server'} => 2600 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "COUNT(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 4 @[%v]",
				"http_requests{job='app-server'} => 4 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job, group)",
			output: []string{
				"http_requests{group='canary',job='api-server'} => 700 @[%v]",
				"http_requests{group='canary',job='app-server'} => 1500 @[%v]",
				"http_requests{group='production',job='api-server'} => 300 @[%v]",
				"http_requests{group='production',job='app-server'} => 1100 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "AVG(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 250 @[%v]",
				"http_requests{job='app-server'} => 650 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "MIN(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 100 @[%v]",
				"http_requests{job='app-server'} => 500 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "MAX(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 400 @[%v]",
				"http_requests{job='app-server'} => 800 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) - COUNT(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 996 @[%v]",
				"http_requests{job='app-server'} => 2596 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) - 2",
			output: []string{
				"http_requests{job='api-server'} => 998 @[%v]",
				"http_requests{job='app-server'} => 2598 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) % 3",
			output: []string{
				"http_requests{job='api-server'} => 1 @[%v]",
				"http_requests{job='app-server'} => 2 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) / 0",
			output: []string{
				"http_requests{job='api-server'} => +Inf @[%v]",
				"http_requests{job='app-server'} => +Inf @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) > 1000",
			output: []string{
				"http_requests{job='app-server'} => 2600 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) <= 1000",
			output: []string{
				"http_requests{job='api-server'} => 1000 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) != 1000",
			output: []string{
				"http_requests{job='app-server'} => 2600 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) == 1000",
			output: []string{
				"http_requests{job='api-server'} => 1000 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "SUM(http_requests) BY (job) + SUM(http_requests) BY (job)",
			output: []string{
				"http_requests{job='api-server'} => 2000 @[%v]",
				"http_requests{job='app-server'} => 5200 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "http_requests{job='api-server', group='canary'}",
			output: []string{
				"http_requests{group='canary',instance='0',job='api-server'} => 300 @[%v]",
				"http_requests{group='canary',instance='1',job='api-server'} => 400 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 2,
		}, {
			expr: "http_requests{job='api-server', group='canary'} + delta(http_requests{job='api-server'}[5m], 1)",
			output: []string{
				"http_requests{group='canary',instance='0',job='api-server'} => 330 @[%v]",
				"http_requests{group='canary',instance='1',job='api-server'} => 440 @[%v]",
			},
			fullRanges:     4,
			intervalRanges: 0,
		}, {
			expr: "delta(http_requests[25m], 1)",
			output: []string{
				"http_requests{group='canary',instance='0',job='api-server'} => 150 @[%v]",
				"http_requests{group='canary',instance='0',job='app-server'} => 350 @[%v]",
				"http_requests{group='canary',instance='1',job='api-server'} => 200 @[%v]",
				"http_requests{group='canary',instance='1',job='app-server'} => 400 @[%v]",
				"http_requests{group='production',instance='0',job='api-server'} => 50 @[%v]",
				"http_requests{group='production',instance='0',job='app-server'} => 250 @[%v]",
				"http_requests{group='production',instance='1',job='api-server'} => 100 @[%v]",
				"http_requests{group='production',instance='1',job='app-server'} => 300 @[%v]",
			},
			fullRanges:     8,
			intervalRanges: 0,
		}, {
			expr: "sort(http_requests)",
			output: []string{
				"http_requests{group='production',instance='0',job='api-server'} => 100 @[%v]",
				"http_requests{group='production',instance='1',job='api-server'} => 200 @[%v]",
				"http_requests{group='canary',instance='0',job='api-server'} => 300 @[%v]",
				"http_requests{group='canary',instance='1',job='api-server'} => 400 @[%v]",
				"http_requests{group='production',instance='0',job='app-server'} => 500 @[%v]",
				"http_requests{group='production',instance='1',job='app-server'} => 600 @[%v]",
				"http_requests{group='canary',instance='0',job='app-server'} => 700 @[%v]",
				"http_requests{group='canary',instance='1',job='app-server'} => 800 @[%v]",
			},
			checkOrder:     true,
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			expr: "sort_desc(http_requests)",
			output: []string{
				"http_requests{group='canary',instance='1',job='app-server'} => 800 @[%v]",
				"http_requests{group='canary',instance='0',job='app-server'} => 700 @[%v]",
				"http_requests{group='production',instance='1',job='app-server'} => 600 @[%v]",
				"http_requests{group='production',instance='0',job='app-server'} => 500 @[%v]",
				"http_requests{group='canary',instance='1',job='api-server'} => 400 @[%v]",
				"http_requests{group='canary',instance='0',job='api-server'} => 300 @[%v]",
				"http_requests{group='production',instance='1',job='api-server'} => 200 @[%v]",
				"http_requests{group='production',instance='0',job='api-server'} => 100 @[%v]",
			},
			checkOrder:     true,
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			// Single-letter label names and values.
			expr: "x{y='testvalue'}",
			output: []string{
				"x{y='testvalue'} => 100 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 1,
		}, {
			// Lower-cased aggregation operators should work too.
			expr: "sum(http_requests) by (job) + min(http_requests) by (job) + max(http_requests) by (job) + avg(http_requests) by (job)",
			output: []string{
				"http_requests{job='app-server'} => 4550 @[%v]",
				"http_requests{job='api-server'} => 1750 @[%v]",
			},
			fullRanges:     0,
			intervalRanges: 8,
		}, {
			// Deltas should be adjusted for target interval vs. samples under target interval.
			expr:           "delta(http_requests{group='canary',instance='1',job='app-server'}[18m], 1)",
			output:         []string{"http_requests{group='canary',instance='1',job='app-server'} => 288 @[%v]"},
			fullRanges:     1,
			intervalRanges: 0,
		}, {
			// Rates should transform per-interval deltas to per-second rates.
			expr:           "rate(http_requests{group='canary',instance='1',job='app-server'}[10m])",
			output:         []string{"http_requests{group='canary',instance='1',job='app-server'} => 0.26666666666666666 @[%v]"},
			fullRanges:     1,
			intervalRanges: 0,
		}, {
			// Empty expressions shouldn't parse.
			expr:       "",
			shouldFail: true,
		}, {
			// Subtracting a vector from a scalar is not supported.
			expr:       "1 - http_requests",
			shouldFail: true,
		}, {
			// Interval durations can't be in quotes.
			expr:       "http_requests['1m']",
			shouldFail: true,
		},
	}

	tieredStorage, closer := newTestStorage(t)
	defer closer.Close()
	tieredStorage.Flush()

	for i, exprTest := range expressionTests {
		expectedLines := annotateWithTime(exprTest.output, testEvalTime)

		testExpr, err := LoadExprFromString(exprTest.expr)

		if err != nil {
			if exprTest.shouldFail {
				continue
			}
			t.Errorf("%d. Error during parsing: %v", i, err)
			t.Errorf("%d. Expression: %v", i, exprTest.expr)
		} else {
			if exprTest.shouldFail {
				t.Errorf("%d. Test should fail, but didn't", i)
			}
			failed := false
			resultStr := ast.EvalToString(testExpr, testEvalTime, ast.TEXT, tieredStorage)
			resultLines := strings.Split(resultStr, "\n")

			if len(exprTest.output) != len(resultLines) {
				t.Errorf("%d. Number of samples in expected and actual output don't match", i)
				failed = true
			}

			if exprTest.checkOrder {
				for j, expectedSample := range expectedLines {
					if resultLines[j] != expectedSample {
						t.Errorf("%d.%d. Expected sample '%v', got '%v'", i, j, resultLines[j], expectedSample)
						failed = true
					}
				}
			} else {
				for j, expectedSample := range expectedLines {
					found := false
					for _, actualSample := range resultLines {
						if actualSample == expectedSample {
							found = true
						}
					}
					if !found {
						t.Errorf("%d.%d. Couldn't find expected sample in output: '%v'", i, j, expectedSample)
						failed = true
					}
				}
			}

			analyzer := ast.NewQueryAnalyzer(tieredStorage)
			analyzer.AnalyzeQueries(testExpr)
			if exprTest.fullRanges != len(analyzer.FullRanges) {
				t.Errorf("%d. Count of full ranges didn't match: %v vs %v", i, exprTest.fullRanges, len(analyzer.FullRanges))
				failed = true
			}
			if exprTest.intervalRanges != len(analyzer.IntervalRanges) {
				t.Errorf("%d. Count of interval ranges didn't match: %v vs %v", i, exprTest.intervalRanges, len(analyzer.IntervalRanges))
				failed = true
			}

			if failed {
				t.Errorf("%d. Expression: %v\n%v", i, exprTest.expr, vectorComparisonString(expectedLines, resultLines))
			}
		}
	}
}

var ruleTests = []struct {
	inputFile         string
	shouldFail        bool
	errContains       string
	numRecordingRules int
	numAlertingRules  int
}{
	{
		inputFile:         "empty.rules",
		numRecordingRules: 0,
		numAlertingRules:  0,
	}, {
		inputFile:         "mixed.rules",
		numRecordingRules: 2,
		numAlertingRules:  2,
	},
	{
		inputFile:   "syntax_error.rules",
		shouldFail:  true,
		errContains: "Error parsing rules at line 3",
	},
	{
		inputFile:   "non_vector.rules",
		shouldFail:  true,
		errContains: "does not evaluate to vector type",
	},
}

func TestRules(t *testing.T) {
	for i, ruleTest := range ruleTests {
		testRules, err := LoadRulesFromFile(path.Join(fixturesPath, ruleTest.inputFile))

		if err != nil {
			if !ruleTest.shouldFail {
				t.Fatalf("%d. Error parsing rules file %v: %v", i, ruleTest.inputFile, err)
			} else {
				if !strings.Contains(err.Error(), ruleTest.errContains) {
					t.Fatalf("%d. Expected error containing '%v', got: %v", i, ruleTest.errContains, err)
				}
			}
		} else {
			numRecordingRules := 0
			numAlertingRules := 0

			for j, rule := range testRules {
				switch rule.(type) {
				case *RecordingRule:
					numRecordingRules++
				case *AlertingRule:
					numAlertingRules++
				default:
					t.Fatalf("%d.%d. Unknown rule type!", i, j)
				}
			}

			if numRecordingRules != ruleTest.numRecordingRules {
				t.Fatalf("%d. Expected %d recording rules, got %d", i, ruleTest.numRecordingRules, numRecordingRules)
			}
			if numAlertingRules != ruleTest.numAlertingRules {
				t.Fatalf("%d. Expected %d alerting rules, got %d", i, ruleTest.numAlertingRules, numAlertingRules)
			}

			// TODO(julius): add more complex checks on the parsed rules here.
		}
	}
}

func TestAlertingRule(t *testing.T) {
	// Labels in expected output need to be alphabetically sorted.
	var evalOutputs = [][]string{
		{
			"ALERTS{alertname='HttpRequestRateLow',alertstate='pending',group='canary',instance='0',job='app-server'} => 1 @[%v]",
			"ALERTS{alertname='HttpRequestRateLow',alertstate='pending',group='canary',instance='1',job='app-server'} => 1 @[%v]",
		},
		{
			"ALERTS{alertname='HttpRequestRateLow',alertstate='pending',group='canary',instance='0',job='app-server'} => 0 @[%v]",
			"ALERTS{alertname='HttpRequestRateLow',alertstate='firing',group='canary',instance='0',job='app-server'} => 1 @[%v]",
			"ALERTS{alertname='HttpRequestRateLow',alertstate='pending',group='canary',instance='1',job='app-server'} => 0 @[%v]",
			"ALERTS{alertname='HttpRequestRateLow',alertstate='firing',group='canary',instance='1',job='app-server'} => 1 @[%v]",
		},
		{
			"ALERTS{alertname='HttpRequestRateLow',alertstate='firing',group='canary',instance='1',job='app-server'} => 0 @[%v]",
			"ALERTS{alertname='HttpRequestRateLow',alertstate='firing',group='canary',instance='0',job='app-server'} => 0 @[%v]",
		},
		{
		/* empty */
		},
		{
		/* empty */
		},
	}

	tieredStorage, closer := newTestStorage(t)
	defer closer.Close()
	tieredStorage.Flush()

	alertExpr, err := LoadExprFromString("http_requests{group='canary',job='app-server'} < 100")
	if err != nil {
		t.Fatalf("Unable to parse alert expression: %s", err)
	}
	alertName := "HttpRequestRateLow"
	alertLabels := model.LabelSet{
		"summary": "HTTP request rate is low",
	}
	rule := NewAlertingRule(alertName, alertExpr.(ast.VectorNode), time.Minute, alertLabels)

	for i, expected := range evalOutputs {
		evalTime := testStartTime.Add(testSampleInterval * time.Duration(i))
		actual, err := rule.Eval(evalTime, tieredStorage)
		if err != nil {
			t.Fatalf("Error during alerting rule evaluation: %s", err)
		}
		actualLines := strings.Split(actual.String(), "\n")
		expectedLines := annotateWithTime(expected, evalTime)
		if actualLines[0] == "" {
			actualLines = []string{}
		}

		failed := false
		if len(actualLines) != len(expectedLines) {
			t.Errorf("%d. Number of samples in expected and actual output don't match (%d vs. %d)", i, len(expectedLines), len(actualLines))
			failed = true
		}

		for j, expectedSample := range expectedLines {
			found := false
			for _, actualSample := range actualLines {
				if actualSample == expectedSample {
					found = true
				}
			}
			if !found {
				t.Errorf("%d.%d. Couldn't find expected sample in output: '%v'", i, j, expectedSample)
				failed = true
			}
		}

		if failed {
			t.Fatalf("%d. Expected and actual outputs don't match:\n%v", i, vectorComparisonString(expectedLines, actualLines))
		}
	}
}