// 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 storage

import (
	"context"
	"errors"

	"github.com/prometheus/common/model"
	"github.com/prometheus/prometheus/pkg/labels"
	"github.com/prometheus/prometheus/storage"
	"github.com/prometheus/prometheus/util/teststorage"
	"github.com/prometheus/prometheus/util/testutil"

	"testing"
)

func TestSelectSorted(t *testing.T) {
	inputLabel := labels.FromStrings(model.MetricNameLabel, "a")
	outputLabel := labels.FromStrings(model.MetricNameLabel, "a")

	inputTotalSize := 0

	priStorage := teststorage.New(t)
	defer priStorage.Close()
	app1 := priStorage.Appender()
	app1.Add(inputLabel, 0, 0)
	inputTotalSize++
	app1.Add(inputLabel, 1000, 1)
	inputTotalSize++
	app1.Add(inputLabel, 2000, 2)
	inputTotalSize++
	err := app1.Commit()
	testutil.Ok(t, err)

	remoteStorage1 := teststorage.New(t)
	defer remoteStorage1.Close()
	app2 := remoteStorage1.Appender()
	app2.Add(inputLabel, 3000, 3)
	inputTotalSize++
	app2.Add(inputLabel, 4000, 4)
	inputTotalSize++
	app2.Add(inputLabel, 5000, 5)
	inputTotalSize++
	err = app2.Commit()
	testutil.Ok(t, err)

	remoteStorage2 := teststorage.New(t)
	defer remoteStorage2.Close()

	app3 := remoteStorage2.Appender()
	app3.Add(inputLabel, 6000, 6)
	inputTotalSize++
	app3.Add(inputLabel, 7000, 7)
	inputTotalSize++
	app3.Add(inputLabel, 8000, 8)
	inputTotalSize++

	err = app3.Commit()
	testutil.Ok(t, err)

	fanoutStorage := storage.NewFanout(nil, priStorage, remoteStorage1, remoteStorage2)

	querier, err := fanoutStorage.Querier(context.Background(), 0, 8000)
	testutil.Ok(t, err)
	defer querier.Close()

	matcher, err := labels.NewMatcher(labels.MatchEqual, model.MetricNameLabel, "a")
	testutil.Ok(t, err)

	seriesSet, _, err := querier.Select(true, nil, matcher)
	testutil.Ok(t, err)

	result := make(map[int64]float64)
	var labelsResult labels.Labels
	for seriesSet.Next() {
		series := seriesSet.At()
		seriesLabels := series.Labels()
		labelsResult = seriesLabels
		iterator := series.Iterator()
		for iterator.Next() {
			timestamp, value := iterator.At()
			result[timestamp] = value
		}
	}

	testutil.Equals(t, labelsResult, outputLabel)
	testutil.Equals(t, inputTotalSize, len(result))
}

func TestFanoutErrors(t *testing.T) {
	workingStorage := teststorage.New(t)
	defer workingStorage.Close()

	cases := []struct {
		primary   storage.Storage
		secondary storage.Storage
		warnings  storage.Warnings
		err       error
	}{
		{
			primary:   workingStorage,
			secondary: errStorage{},
			warnings:  storage.Warnings{errSelect},
			err:       nil,
		},
		{
			primary:   errStorage{},
			secondary: workingStorage,
			warnings:  nil,
			err:       errSelect,
		},
	}

	for _, tc := range cases {
		fanoutStorage := storage.NewFanout(nil, tc.primary, tc.secondary)

		querier, err := fanoutStorage.Querier(context.Background(), 0, 8000)
		testutil.Ok(t, err)
		defer querier.Close()

		matcher := labels.MustNewMatcher(labels.MatchEqual, "a", "b")
		ss, warnings, err := querier.Select(true, nil, matcher)
		testutil.Equals(t, tc.err, err)
		testutil.Equals(t, tc.warnings, warnings)

		// Only test series iteration if there are no errors.
		if err != nil {
			continue
		}

		for ss.Next() {
			ss.At()
		}
		testutil.Ok(t, ss.Err())
	}
}

var errSelect = errors.New("select error")

type errStorage struct{}

func (errStorage) Querier(_ context.Context, _, _ int64) (storage.Querier, error) {
	return errQuerier{}, nil
}

func (errStorage) Appender() storage.Appender {
	return nil
}

func (errStorage) StartTime() (int64, error) {
	return 0, nil
}

func (errStorage) Close() error {
	return nil
}

type errQuerier struct{}

func (errQuerier) Select(bool, *storage.SelectHints, ...*labels.Matcher) (storage.SeriesSet, storage.Warnings, error) {
	return nil, nil, errSelect
}

func (errQuerier) LabelValues(name string) ([]string, storage.Warnings, error) {
	return nil, nil, errors.New("label values error")
}

func (errQuerier) LabelNames() ([]string, storage.Warnings, error) {
	return nil, nil, errors.New("label names error")
}

func (errQuerier) Close() error {
	return nil
}