/*
 * Copyright 2019-present Open Networking Foundation

 * 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 db

import (
	"context"
	"github.com/opencord/voltha-lib-go/v2/pkg/log"
	"github.com/opencord/voltha-lib-go/v2/pkg/mocks"
	"github.com/stretchr/testify/assert"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"os"
	"testing"
	"time"
)

func init() {
	log.AddPackage(log.JSON, log.PanicLevel, nil)
}

const (
	embedEtcdServerHost = "localhost"
	embedEtcdServerPort = 2379
	dummyEtcdServerPort = 12379
	defaultTimeout      = 1
	defaultPathPrefix   = "Prefix"
)

func TestMain(m *testing.M) {
	etcdServer := mocks.StartEtcdServer(nil)

	res := m.Run()

	etcdServer.Stop()
	os.Exit(res)
}

func provisionBackendWithEmbeddedEtcdServer(t *testing.T) *Backend {
	backend := NewBackend("etcd", embedEtcdServerHost, embedEtcdServerPort, defaultTimeout, defaultPathPrefix)
	assert.NotNil(t, backend)
	assert.NotNil(t, backend.Client)
	return backend
}

func provisionBackendWithDummyEtcdServer(t *testing.T) *Backend {
	backend := NewBackend("etcd", embedEtcdServerHost, dummyEtcdServerPort, defaultTimeout, defaultPathPrefix)
	assert.NotNil(t, backend)
	assert.NotNil(t, backend.Client)
	return backend
}

// Create instance using Etcd Kvstore
func TestNewBackend_EtcdKvStore(t *testing.T) {
	backend := NewBackend("etcd", embedEtcdServerHost, embedEtcdServerPort, defaultTimeout, defaultPathPrefix)

	// Verify all attributes of backend have got set correctly
	assert.NotNil(t, backend)
	assert.NotNil(t, backend.Client)
	assert.Equal(t, backend.StoreType, "etcd")
	assert.Equal(t, backend.Host, embedEtcdServerHost)
	assert.Equal(t, backend.Port, embedEtcdServerPort)
	assert.Equal(t, backend.Timeout, defaultTimeout)
	assert.Equal(t, backend.PathPrefix, defaultPathPrefix)
	assert.Equal(t, backend.alive, false) // backend is not alive at start
	assert.Nil(t, backend.liveness)       // no liveness channel is created at start
	assert.Equal(t, backend.LivenessChannelInterval, DefaultLivenessChannelInterval)
}

// Create instance using Consul Kvstore
func TestNewBackend_ConsulKvStore(t *testing.T) {
	backend := NewBackend("consul", embedEtcdServerHost, embedEtcdServerPort, defaultTimeout, defaultPathPrefix)

	// Verify kvstore type attribute of backend has got set correctly
	assert.NotNil(t, backend)
	assert.NotNil(t, backend.Client)
	assert.Equal(t, backend.StoreType, "consul")
}

// Create instance using Invalid Kvstore; instance creation should fail
func TestNewBackend_InvalidKvstore(t *testing.T) {
	backend := NewBackend("unknown", embedEtcdServerHost, embedEtcdServerPort, defaultTimeout, defaultPathPrefix)

	assert.NotNil(t, backend)
	assert.Nil(t, backend.Client)
}

func TestMakePath(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	path := backend.makePath("Suffix")
	assert.Equal(t, defaultPathPrefix+"/Suffix", path)
}

// Liveness Check against Embedded Etcd Server should return alive state
func TestPerformLivenessCheck_EmbeddedEtcdServer(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	alive := backend.PerformLivenessCheck(defaultTimeout)
	assert.True(t, alive)
}

// Liveness Check against Dummy Etcd Server should return not-alive state
func TestPerformLivenessCheck_DummyEtcdServer(t *testing.T) {
	backend := provisionBackendWithDummyEtcdServer(t)
	alive := backend.PerformLivenessCheck(defaultTimeout)
	assert.False(t, alive)
}

// Enabling Liveness Channel before First Liveness Check
func TestEnableLivenessChannel_EmbeddedEtcdServer_BeforeLivenessCheck(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)

	alive := backend.EnableLivenessChannel()
	assert.NotNil(t, alive)
	assert.Equal(t, 1, len(alive))
	assert.Equal(t, false, <-alive)
	assert.NotNil(t, backend.liveness)
}

// Enabling Liveness Channel after First Liveness Check
func TestEnableLivenessChannel_EmbeddedEtcdServer_AfterLivenessCheck(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	backend.PerformLivenessCheck(defaultTimeout)

	alive := backend.EnableLivenessChannel()
	assert.NotNil(t, alive)
	assert.Equal(t, 1, len(alive))
	assert.Equal(t, true, <-alive)
	assert.NotNil(t, backend.liveness)
}

// Update Liveness with alive status change
func TestUpdateLiveness_AliveStatusChange(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	// Enable Liveness Channel and verify initial state is not-alive
	aliveState := backend.EnableLivenessChannel()
	assert.NotNil(t, aliveState)
	assert.Equal(t, 1, len(backend.liveness))
	assert.Equal(t, false, <-backend.liveness)
	lastUpdateTime := backend.lastLivenessTime

	// Update with changed alive state. Verify alive state push & liveness time update
	backend.updateLiveness(true)
	assert.Equal(t, 1, len(backend.liveness))
	assert.Equal(t, true, <-backend.liveness)
	assert.NotEqual(t, lastUpdateTime, backend.lastLivenessTime)
}

// Update Liveness with same alive status reporting
func TestUpdateLiveness_AliveStatusUnchanged(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	// Enable Liveness Channel and verify initial state is not-alive
	aliveState := backend.EnableLivenessChannel()
	assert.NotNil(t, aliveState)
	assert.Equal(t, false, <-backend.liveness)
	lastUpdateTime := backend.lastLivenessTime

	// Update with same alive state. Verify no further alive state push
	backend.updateLiveness(false)
	assert.Equal(t, 0, len(backend.liveness))
	assert.Equal(t, lastUpdateTime, backend.lastLivenessTime)

	// Now set lastUpdateTime 10 min back and push again
	tenMinDuration, _ := time.ParseDuration("10m")
	backend.lastLivenessTime = time.Now().Add(-tenMinDuration)
	lastUpdateTime = backend.lastLivenessTime

	backend.updateLiveness(false)
	assert.Equal(t, 1, len(backend.liveness))
	assert.Equal(t, false, <-backend.liveness)
	assert.NotEqual(t, lastUpdateTime, backend.lastLivenessTime)
}

func TestIsErrorIndicatingAliveKvstore(t *testing.T) {
	tests := []struct {
		name string
		arg  error
		want bool
	}{
		{"No Error", nil, true},
		{"Request Canceled", context.Canceled, true},
		{"Request Timeout", context.DeadlineExceeded, false},
		{"Etcd Error - InvalidArgument", status.New(codes.InvalidArgument, "").Err(), true},
		{"Etcd Error - DeadlineExceeded", status.New(codes.DeadlineExceeded, "").Err(), false},
		{"Etcd Error - Unavailable", status.New(codes.Unavailable, "").Err(), false},
		{"Etcd Error - DataLoss", status.New(codes.DataLoss, "").Err(), false},
		{"Etcd Error - NotFound", status.New(codes.NotFound, "").Err(), true},
		{"Etcd Error - PermissionDenied ", status.New(codes.PermissionDenied, "").Err(), true},
		{"Etcd Error - FailedPrecondition  ", status.New(codes.FailedPrecondition, "").Err(), true},
	}

	backend := provisionBackendWithEmbeddedEtcdServer(t)

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if backend.isErrorIndicatingAliveKvstore(tt.arg) != tt.want {
				t.Errorf("isErrorIndicatingAliveKvstore failed for %s: expected %t but got %t", tt.name, tt.want, !tt.want)
			}
		})
	}
}

func TestPut_EmbeddedEtcdServer(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	err := backend.Put("key1", []uint8("value1"))
	assert.Nil(t, err)

	// Assert alive state has become true
	assert.True(t, backend.alive)

	// Assert that kvstore has this value stored
	kvpair, err := backend.Get("key1")
	assert.NotNil(t, kvpair)
	assert.Equal(t, defaultPathPrefix+"/key1", kvpair.Key)
	assert.Equal(t, []uint8("value1"), kvpair.Value)

	// Assert that Put overrides the Value
	err = backend.Put("key1", []uint8("value11"))
	assert.Nil(t, err)
	kvpair, err = backend.Get("key1")
	assert.NotNil(t, kvpair)
	assert.Equal(t, defaultPathPrefix+"/key1", kvpair.Key)
	assert.Equal(t, []uint8("value11"), kvpair.Value)
}

// Put operation should fail against Dummy Non-existent Etcd Server
func TestPut_DummyEtcdServer(t *testing.T) {
	backend := provisionBackendWithDummyEtcdServer(t)
	err := backend.Put("key1", []uint8("value1"))
	assert.NotNil(t, err)

	// Assert alive state is still false
	assert.False(t, backend.alive)
}

// Test Get for existing and non-existing key
func TestGet_EmbeddedEtcdServer(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	err := backend.Put("key2", []uint8("value2"))

	// Assert alive state has become true
	assert.True(t, backend.alive)

	// Assert that kvstore has this key stored
	kvpair, err := backend.Get("key2")
	assert.NotNil(t, kvpair)
	assert.Nil(t, err)
	assert.Equal(t, defaultPathPrefix+"/key2", kvpair.Key)
	assert.Equal(t, []uint8("value2"), kvpair.Value)

	// Assert that Get works fine for absent key3
	kvpair, err = backend.Get("key3")
	assert.Nil(t, kvpair)
	assert.Nil(t, err) // no error as lookup is successful
}

// Get operation should fail against Dummy Non-existent Etcd Server
func TestGet_DummyEtcdServer(t *testing.T) {
	backend := provisionBackendWithDummyEtcdServer(t)
	kvpair, err := backend.Get("key2")
	assert.NotNil(t, err)
	assert.Nil(t, kvpair)

	// Assert alive state is still false
	assert.False(t, backend.alive)
}

// Test Delete for existing and non-existing key
func TestDelete_EmbeddedEtcdServer(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	err := backend.Put("key3", []uint8("value3"))

	// Assert alive state has become true
	assert.True(t, backend.alive)

	// Assert that kvstore has this key stored
	kvpair, err := backend.Get("key3")
	assert.NotNil(t, kvpair)

	// Delete and Assert that key has been removed
	err = backend.Delete("key3")
	assert.Nil(t, err)
	kvpair, err = backend.Get("key3")
	assert.Nil(t, kvpair)

	// Assert that Delete silently ignores absent key3
	err = backend.Delete("key3")
	assert.Nil(t, err)
}

// Delete operation should fail against Dummy Non-existent Etcd Server
func TestDelete_DummyEtcdServer(t *testing.T) {
	backend := provisionBackendWithDummyEtcdServer(t)
	err := backend.Delete("key3")
	assert.NotNil(t, err)

	// Assert alive state is still false
	assert.False(t, backend.alive)
}

// Test List for series of values under a key path
func TestList_EmbeddedEtcdServer(t *testing.T) {
	key41 := "key4/subkey1"
	key42 := "key4/subkey2"

	backend := provisionBackendWithEmbeddedEtcdServer(t)
	backend.Put(key41, []uint8("value4-1"))
	backend.Put(key42, []uint8("value4-2"))

	// Assert alive state has become true
	assert.True(t, backend.alive)

	// Assert that Get does not retrieve these Subkeys
	kvpair, err := backend.Get("key4")
	assert.Nil(t, kvpair)
	assert.Nil(t, err)

	// Assert that List operation retrieves these Child Keys
	kvmap, err := backend.List("key4")
	assert.NotNil(t, kvmap)
	assert.Nil(t, err)
	assert.Equal(t, 2, len(kvmap))
	fullkey41 := defaultPathPrefix + "/" + key41
	fullkey42 := defaultPathPrefix + "/" + key42
	assert.Equal(t, fullkey41, kvmap[fullkey41].Key)
	assert.Equal(t, []uint8("value4-1"), kvmap[fullkey41].Value)
	assert.Equal(t, fullkey42, kvmap[fullkey42].Key)
	assert.Equal(t, []uint8("value4-2"), kvmap[fullkey42].Value)
}

// List operation should fail against Dummy Non-existent Etcd Server
func TestList_DummyEtcdServer(t *testing.T) {
	backend := provisionBackendWithDummyEtcdServer(t)
	kvmap, err := backend.List("key4")
	assert.Nil(t, kvmap)
	assert.NotNil(t, err)

	// Assert alive state is still false
	assert.False(t, backend.alive)
}

// Test Create and Delete Watch for Embedded Etcd Server
func TestCreateWatch_EmbeddedEtcdServer(t *testing.T) {
	backend := provisionBackendWithEmbeddedEtcdServer(t)
	eventChan := backend.CreateWatch("key5")
	assert.NotNil(t, eventChan)
	assert.Equal(t, 0, len(eventChan))

	// Assert this method does not change alive state
	assert.False(t, backend.alive)

	// Put a value for watched key and event should appear
	err := backend.Put("key5", []uint8("value5"))
	assert.Nil(t, err)
	time.Sleep(time.Millisecond * 100)
	assert.Equal(t, 1, len(eventChan))

	backend.DeleteWatch("key5", eventChan)
}