// Copyright 2018 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 dispatch

import (
	"reflect"
	"sort"
	"sync"
	"testing"
	"time"

	"github.com/go-kit/kit/log"
	"github.com/prometheus/common/model"
	"golang.org/x/net/context"

	"github.com/prometheus/alertmanager/notify"
	"github.com/prometheus/alertmanager/types"
)

func TestAggrGroup(t *testing.T) {
	lset := model.LabelSet{
		"a": "v1",
		"b": "v2",
	}
	opts := &RouteOpts{
		Receiver:       "n1",
		GroupBy:        map[model.LabelName]struct{}{},
		GroupWait:      1 * time.Second,
		GroupInterval:  300 * time.Millisecond,
		RepeatInterval: 1 * time.Hour,
	}
	route := &Route{
		RouteOpts: *opts,
	}

	var (
		a1 = &types.Alert{
			Alert: model.Alert{
				Labels: model.LabelSet{
					"a": "v1",
					"b": "v2",
					"c": "v3",
				},
				StartsAt: time.Now().Add(time.Minute),
				EndsAt:   time.Now().Add(time.Hour),
			},
			UpdatedAt: time.Now(),
		}
		a2 = &types.Alert{
			Alert: model.Alert{
				Labels: model.LabelSet{
					"a": "v1",
					"b": "v2",
					"c": "v4",
				},
				StartsAt: time.Now().Add(-time.Hour),
				EndsAt:   time.Now().Add(2 * time.Hour),
			},
			UpdatedAt: time.Now(),
		}
		a3 = &types.Alert{
			Alert: model.Alert{
				Labels: model.LabelSet{
					"a": "v1",
					"b": "v2",
					"c": "v5",
				},
				StartsAt: time.Now().Add(time.Minute),
				EndsAt:   time.Now().Add(5 * time.Minute),
			},
			UpdatedAt: time.Now(),
		}
	)

	var (
		last       = time.Now()
		current    = time.Now()
		lastCurMtx = &sync.Mutex{}
		alertsCh   = make(chan types.AlertSlice)
	)

	ntfy := func(ctx context.Context, alerts ...*types.Alert) bool {
		// Validate that the context is properly populated.
		if _, ok := notify.Now(ctx); !ok {
			t.Errorf("now missing")
		}
		if _, ok := notify.GroupKey(ctx); !ok {
			t.Errorf("group key missing")
		}
		if lbls, ok := notify.GroupLabels(ctx); !ok || !reflect.DeepEqual(lbls, lset) {
			t.Errorf("wrong group labels: %q", lbls)
		}
		if rcv, ok := notify.ReceiverName(ctx); !ok || rcv != opts.Receiver {
			t.Errorf("wrong receiver: %q", rcv)
		}
		if ri, ok := notify.RepeatInterval(ctx); !ok || ri != opts.RepeatInterval {
			t.Errorf("wrong repeat interval: %q", ri)
		}

		lastCurMtx.Lock()
		last = current
		current = time.Now()
		lastCurMtx.Unlock()

		alertsCh <- types.AlertSlice(alerts)

		return true
	}

	// Test regular situation where we wait for group_wait to send out alerts.
	ag := newAggrGroup(context.Background(), lset, route, nil, log.NewNopLogger())
	go ag.run(ntfy)

	ag.insert(a1)

	select {
	case <-time.After(2 * opts.GroupWait):
		t.Fatalf("expected initial batch after group_wait")

	case batch := <-alertsCh:
		if s := time.Since(last); s < opts.GroupWait {
			t.Fatalf("received batch too early after %v", s)
		}
		exp := types.AlertSlice{a1}
		sort.Sort(batch)

		if !reflect.DeepEqual(batch, exp) {
			t.Fatalf("expected alerts %v but got %v", exp, batch)
		}
	}

	for i := 0; i < 3; i++ {
		// New alert should come in after group interval.
		ag.insert(a3)

		select {
		case <-time.After(2 * opts.GroupInterval):
			t.Fatalf("expected new batch after group interval but received none")

		case batch := <-alertsCh:
			if s := time.Since(last); s < opts.GroupInterval {
				t.Fatalf("received batch too early after %v", s)
			}
			exp := types.AlertSlice{a1, a3}
			sort.Sort(batch)

			if !reflect.DeepEqual(batch, exp) {
				t.Fatalf("expected alerts %v but got %v", exp, batch)
			}
		}
	}

	ag.stop()

	// Add an alert that started more than group_interval in the past. We expect
	// immediate flushing.
	// Finally, set all alerts to be resolved. After successful notify the aggregation group
	// should empty itself.
	ag = newAggrGroup(context.Background(), lset, route, nil, log.NewNopLogger())
	go ag.run(ntfy)

	ag.insert(a1)
	ag.insert(a2)

	// a2 lies way in the past so the initial group_wait should be skipped.
	select {
	case <-time.After(opts.GroupWait / 2):
		t.Fatalf("expected immediate alert but received none")

	case batch := <-alertsCh:
		exp := types.AlertSlice{a1, a2}
		sort.Sort(batch)

		if !reflect.DeepEqual(batch, exp) {
			t.Fatalf("expected alerts %v but got %v", exp, batch)
		}
	}

	for i := 0; i < 3; i++ {
		// New alert should come in after group interval.
		ag.insert(a3)

		select {
		case <-time.After(2 * opts.GroupInterval):
			t.Fatalf("expected new batch after group interval but received none")

		case batch := <-alertsCh:
			lastCurMtx.Lock()
			s := time.Since(last)
			lastCurMtx.Unlock()
			if s < opts.GroupInterval {
				t.Fatalf("received batch too early after %v", s)
			}
			exp := types.AlertSlice{a1, a2, a3}
			sort.Sort(batch)

			if !reflect.DeepEqual(batch, exp) {
				t.Fatalf("expected alerts %v but got %v", exp, batch)
			}
		}
	}

	// Resolve all alerts, they should be removed after the next batch was sent.
	a1r, a2r, a3r := *a1, *a2, *a3
	resolved := types.AlertSlice{&a1r, &a2r, &a3r}
	for _, a := range resolved {
		a.EndsAt = time.Now()
		ag.insert(a)
	}

	select {
	case <-time.After(2 * opts.GroupInterval):
		t.Fatalf("expected new batch after group interval but received none")

	case batch := <-alertsCh:
		if s := time.Since(last); s < opts.GroupInterval {
			t.Fatalf("received batch too early after %v", s)
		}
		sort.Sort(batch)

		if !reflect.DeepEqual(batch, resolved) {
			t.Fatalf("expected alerts %v but got %v", resolved, batch)
		}

		if !ag.empty() {
			t.Fatalf("Expected aggregation group to be empty after resolving alerts: %v", ag)
		}
	}

	ag.stop()
}