/*
Package testing provides utility functions for testing Module and MetricSet
implementations.

MetricSet Example

This is an example showing how to use this package to test a MetricSet. By
using these methods you ensure the MetricSet is instantiated in the same way
that Metricbeat does it and with the same validations.

	package mymetricset_test

	import (
		mbtest "github.com/elastic/beats/metricbeat/mb/testing"
	)

	func TestFetch(t *testing.T) {
		f := mbtest.NewEventFetcher(t, getConfig())
		event, err := f.Fetch()
		if err != nil {
			t.Fatal(err)
		}

		t.Logf("%s/%s event: %+v", f.Module().Name(), f.Name(), event)

		// Test event attributes...
	}

	func getConfig() map[string]interface{} {
		return map[string]interface{}{
			"module":     "mymodule",
			"metricsets": []string{"status"},
			"hosts":      []string{mymodule.GetHostFromEnv()},
		}
	}
*/
package testing

import (
	"testing"

	"github.com/elastic/beats/libbeat/common"
	"github.com/elastic/beats/metricbeat/mb"

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

type TestModule struct {
	ModName   string
	ModConfig mb.ModuleConfig
	RawConfig *common.Config
}

func (m *TestModule) Name() string                      { return m.ModName }
func (m *TestModule) Config() mb.ModuleConfig           { return m.ModConfig }
func (m *TestModule) UnpackConfig(to interface{}) error { return m.RawConfig.Unpack(to) }

func NewTestModule(t testing.TB, config interface{}) *TestModule {
	c, err := common.NewConfigFrom(config)
	if err != nil {
		t.Fatal(err)
	}

	return &TestModule{RawConfig: c}
}

// newMetricSet instantiates a new MetricSet using the given configuration.
// The ModuleFactory and MetricSetFactory are obtained from the global
// Registry.
func newMetricSet(t testing.TB, config interface{}) mb.MetricSet {
	c, err := common.NewConfigFrom(config)
	if err != nil {
		t.Fatal(err)
	}
	m, err := mb.NewModules([]*common.Config{c}, mb.Registry)
	if err != nil {
		t.Fatal(err)
	}
	if !assert.Len(t, m, 1) {
		t.FailNow()
	}

	var metricSet mb.MetricSet
	for _, v := range m {
		if !assert.Len(t, v, 1) {
			t.FailNow()
		}

		metricSet = v[0]
		break
	}

	if !assert.NotNil(t, metricSet) {
		t.FailNow()
	}
	return metricSet
}

// NewEventFetcher instantiates a new EventFetcher using the given
// configuration. The ModuleFactory and MetricSetFactory are obtained from the
// global Registry.
func NewEventFetcher(t testing.TB, config interface{}) mb.EventFetcher {
	metricSet := newMetricSet(t, config)

	fetcher, ok := metricSet.(mb.EventFetcher)
	if !ok {
		t.Fatal("MetricSet does not implement EventFetcher")
	}

	return fetcher
}

// NewEventsFetcher instantiates a new EventsFetcher using the given
// configuration. The ModuleFactory and MetricSetFactory are obtained from the
// global Registry.
func NewEventsFetcher(t testing.TB, config interface{}) mb.EventsFetcher {
	metricSet := newMetricSet(t, config)

	fetcher, ok := metricSet.(mb.EventsFetcher)
	if !ok {
		t.Fatal("MetricSet does not implement EventsFetcher")
	}

	return fetcher
}