package cloudwatch

import (
	"encoding/json"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awsutil"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/cloudwatch"
	"github.com/grafana/grafana/pkg/middleware"
	"github.com/grafana/grafana/pkg/util"
)

var metricsMap map[string][]string
var dimensionsMap map[string][]string

type CustomMetricsCache struct {
	Expire time.Time
	Cache  []string
}

var customMetricsMetricsMap map[string]map[string]map[string]*CustomMetricsCache
var customMetricsDimensionsMap map[string]map[string]map[string]*CustomMetricsCache

func init() {
	metricsMap = map[string][]string{
		"AWS/AutoScaling": {"GroupMinSize", "GroupMaxSize", "GroupDesiredCapacity", "GroupInServiceInstances", "GroupPendingInstances", "GroupStandbyInstances", "GroupTerminatingInstances", "GroupTotalInstances"},
		"AWS/Billing":     {"EstimatedCharges"},
		"AWS/CloudFront":  {"Requests", "BytesDownloaded", "BytesUploaded", "TotalErrorRate", "4xxErrorRate", "5xxErrorRate"},
		"AWS/CloudSearch": {"SuccessfulRequests", "SearchableDocuments", "IndexUtilization", "Partitions"},
		"AWS/DynamoDB":    {"ConditionalCheckFailedRequests", "ConsumedReadCapacityUnits", "ConsumedWriteCapacityUnits", "OnlineIndexConsumedWriteCapacity", "OnlineIndexPercentageProgress", "OnlineIndexThrottleEvents", "ProvisionedReadCapacityUnits", "ProvisionedWriteCapacityUnits", "ReadThrottleEvents", "ReturnedItemCount", "SuccessfulRequestLatency", "SystemErrors", "ThrottledRequests", "UserErrors", "WriteThrottleEvents"},
		"AWS/ECS":         {"CPUUtilization", "MemoryUtilization"},
		"AWS/ElastiCache": {
			"CPUUtilization", "FreeableMemory", "NetworkBytesIn", "NetworkBytesOut", "SwapUsage",
			"BytesUsedForCacheItems", "BytesReadIntoMemcached", "BytesWrittenOutFromMemcached", "CasBadval", "CasHits", "CasMisses", "CmdFlush", "CmdGet", "CmdSet", "CurrConnections", "CurrItems", "DecrHits", "DecrMisses", "DeleteHits", "DeleteMisses", "Evictions", "GetHits", "GetMisses", "IncrHits", "IncrMisses", "Reclaimed",
			"BytesUsedForHash", "CmdConfigGet", "CmdConfigSet", "CmdTouch", "CurrConfig", "EvictedUnfetched", "ExpiredUnfetched", "SlabsMoved", "TouchHits", "TouchMisses",
			"NewConnections", "NewItems", "UnusedMemory",
			"BytesUsedForCache", "CacheHits", "CacheMisses", "CurrConnections", "Evictions", "HyperLogLogBasedCmds", "NewConnections", "Reclaimed", "ReplicationBytes", "ReplicationLag", "SaveInProgress",
			"CurrItems", "GetTypeCmds", "HashBasedCmds", "KeyBasedCmds", "ListBasedCmds", "SetBasedCmds", "SetTypeCmds", "SortedSetBasedCmds", "StringBasedCmds",
		},
		"AWS/EBS": {"VolumeReadBytes", "VolumeWriteBytes", "VolumeReadOps", "VolumeWriteOps", "VolumeTotalReadTime", "VolumeTotalWriteTime", "VolumeIdleTime", "VolumeQueueLength", "VolumeThroughputPercentage", "VolumeConsumedReadWriteOps"},
		"AWS/EC2": {"CPUCreditUsage", "CPUCreditBalance", "CPUUtilization", "DiskReadOps", "DiskWriteOps", "DiskReadBytes", "DiskWriteBytes", "NetworkIn", "NetworkOut", "StatusCheckFailed", "StatusCheckFailed_Instance", "StatusCheckFailed_System"},
		"AWS/ELB": {"HealthyHostCount", "UnHealthyHostCount", "RequestCount", "Latency", "HTTPCode_ELB_4XX", "HTTPCode_ELB_5XX", "HTTPCode_Backend_2XX", "HTTPCode_Backend_3XX", "HTTPCode_Backend_4XX", "HTTPCode_Backend_5XX", "BackendConnectionErrors", "SurgeQueueLength", "SpilloverCount"},
		"AWS/ElasticMapReduce": {"IsIdle", "JobsRunning", "JobsFailed",
			"MapTasksRunning", "MapTasksRemaining", "MapSlotsOpen", "RemainingMapTasksPerSlot", "ReduceTasksRunning", "ReduceTasksRemaining", "ReduceSlotsOpen",
			"CoreNodesRunning", "CoreNodesPending", "LiveDataNodes", "TaskNodesRunning", "TaskNodesPending", "LiveTaskTrackers",
			"S3BytesWritten", "S3BytesRead", "HDFSUtilization", "HDFSBytesRead", "HDFSBytesWritten", "MissingBlocks", "TotalLoad",
			"BackupFailed", "MostRecentBackupDuration", "TimeSinceLastSuccessfulBackup",
			"IsIdle", "ContainerAllocated", "ContainerReserved", "ContainerPending", "AppsCompleted", "AppsFailed", "AppsKilled", "AppsPending", "AppsRunning", "AppsSubmitted",
			"CoreNodesRunning", "CoreNodesPending", "LiveDataNodes", "MRTotalNodes", "MRActiveNodes", "MRLostNodes", "MRUnhealthyNodes", "MRDecommissionedNodes", "MRRebootedNodes",
			"S3BytesWritten", "S3BytesRead", "HDFSUtilization", "HDFSBytesRead", "HDFSBytesWritten", "MissingBlocks", "CorruptBlocks", "TotalLoad", "MemoryTotalMB", "MemoryReservedMB", "MemoryAvailableMB", "MemoryAllocatedMB", "PendingDeletionBlocks", "UnderReplicatedBlocks", "DfsPendingReplicationBlocks", "CapacityRemainingGB",
			"HbaseBackupFailed", "MostRecentBackupDuration", "TimeSinceLastSuccessfulBackup"},
		"AWS/ES":       {"ClusterStatus.green", "ClusterStatus.yellow", "ClusterStatus.red", "Nodes", "SearchableDocuments", "DeletedDocuments", "CPUUtilization", "FreeStorageSpace", "JVMMemoryPressure", "AutomatedSnapshotFailure", "MasterCPUUtilization", "MasterFreeStorageSpace", "MasterJVMMemoryPressure", "ReadLatency", "WriteLatency", "ReadThroughput", "WriteThroughput", "DiskQueueLength", "ReadIOPS", "WriteIOPS"},
		"AWS/Events":   {"Invocations", "FailedInvocations", "TriggeredRules", "MatchedEvents", "ThrottledRules"},
		"AWS/Kinesis":  {"PutRecord.Bytes", "PutRecord.Latency", "PutRecord.Success", "PutRecords.Bytes", "PutRecords.Latency", "PutRecords.Records", "PutRecords.Success", "IncomingBytes", "IncomingRecords", "GetRecords.Bytes", "GetRecords.IteratorAgeMilliseconds", "GetRecords.Latency", "GetRecords.Success"},
		"AWS/Lambda":   {"Invocations", "Errors", "Duration", "Throttles"},
		"AWS/Logs":     {"IncomingBytes", "IncomingLogEvents", "ForwardedBytes", "ForwardedLogEvents", "DeliveryErrors", "DeliveryThrottling"},
		"AWS/ML":       {"PredictCount", "PredictFailureCount"},
		"AWS/OpsWorks": {"cpu_idle", "cpu_nice", "cpu_system", "cpu_user", "cpu_waitio", "load_1", "load_5", "load_15", "memory_buffers", "memory_cached", "memory_free", "memory_swap", "memory_total", "memory_used", "procs"},
		"AWS/Redshift": {"CPUUtilization", "DatabaseConnections", "HealthStatus", "MaintenanceMode", "NetworkReceiveThroughput", "NetworkTransmitThroughput", "PercentageDiskSpaceUsed", "ReadIOPS", "ReadLatency", "ReadThroughput", "WriteIOPS", "WriteLatency", "WriteThroughput"},
		"AWS/RDS":      {"BinLogDiskUsage", "CPUUtilization", "CPUCreditUsage", "CPUCreditBalance", "DatabaseConnections", "DiskQueueDepth", "FreeableMemory", "FreeStorageSpace", "ReplicaLag", "SwapUsage", "ReadIOPS", "WriteIOPS", "ReadLatency", "WriteLatency", "ReadThroughput", "WriteThroughput", "NetworkReceiveThroughput", "NetworkTransmitThroughput"},
		"AWS/Route53":  {"HealthCheckStatus", "HealthCheckPercentageHealthy", "ConnectionTime", "SSLHandshakeTime", "TimeToFirstByte"},
		"AWS/SNS":      {"NumberOfMessagesPublished", "PublishSize", "NumberOfNotificationsDelivered", "NumberOfNotificationsFailed"},
		"AWS/SQS":      {"NumberOfMessagesSent", "SentMessageSize", "NumberOfMessagesReceived", "NumberOfEmptyReceives", "NumberOfMessagesDeleted", "ApproximateNumberOfMessagesDelayed", "ApproximateNumberOfMessagesVisible", "ApproximateNumberOfMessagesNotVisible"},
		"AWS/S3":       {"BucketSizeBytes", "NumberOfObjects"},
		"AWS/SWF": {"DecisionTaskScheduleToStartTime", "DecisionTaskStartToCloseTime", "DecisionTasksCompleted", "StartedDecisionTasksTimedOutOnClose", "WorkflowStartToCloseTime", "WorkflowsCanceled", "WorkflowsCompleted", "WorkflowsContinuedAsNew", "WorkflowsFailed", "WorkflowsTerminated", "WorkflowsTimedOut",
			"ActivityTaskScheduleToCloseTime", "ActivityTaskScheduleToStartTime", "ActivityTaskStartToCloseTime", "ActivityTasksCanceled", "ActivityTasksCompleted", "ActivityTasksFailed", "ScheduledActivityTasksTimedOutOnClose", "ScheduledActivityTasksTimedOutOnStart", "StartedActivityTasksTimedOutOnClose", "StartedActivityTasksTimedOutOnHeartbeat"},
		"AWS/StorageGateway": {"CacheHitPercent", "CachePercentUsed", "CachePercentDirty", "CloudBytesDownloaded", "CloudDownloadLatency", "CloudBytesUploaded", "UploadBufferFree", "UploadBufferPercentUsed", "UploadBufferUsed", "QueuedWrites", "ReadBytes", "ReadTime", "TotalCacheSize", "WriteBytes", "WriteTime", "TimeSinceLastRecoveryPoint", "WorkingStorageFree", "WorkingStoragePercentUsed", "WorkingStorageUsed",
			"CacheHitPercent", "CachePercentUsed", "CachePercentDirty", "ReadBytes", "ReadTime", "WriteBytes", "WriteTime", "QueuedWrites"},
		"AWS/WAF":        {"AllowedRequests", "BlockedRequests", "CountedRequests"},
		"AWS/WorkSpaces": {"Available", "Unhealthy", "ConnectionAttempt", "ConnectionSuccess", "ConnectionFailure", "SessionLaunchTime", "InSessionLatency", "SessionDisconnect"},
	}
	dimensionsMap = map[string][]string{
		"AWS/AutoScaling":      {"AutoScalingGroupName"},
		"AWS/Billing":          {"ServiceName", "LinkedAccount", "Currency"},
		"AWS/CloudFront":       {"DistributionId", "Region"},
		"AWS/CloudSearch":      {},
		"AWS/DynamoDB":         {"TableName", "GlobalSecondaryIndexName", "Operation"},
		"AWS/ECS":              {"ClusterName", "ServiceName"},
		"AWS/ElastiCache":      {"CacheClusterId", "CacheNodeId"},
		"AWS/EBS":              {"VolumeId"},
		"AWS/EC2":              {"AutoScalingGroupName", "ImageId", "InstanceId", "InstanceType"},
		"AWS/ELB":              {"LoadBalancerName", "AvailabilityZone"},
		"AWS/ElasticMapReduce": {"ClusterId", "JobFlowId", "JobId"},
		"AWS/ES":               {},
		"AWS/Events":           {"RuleName"},
		"AWS/Kinesis":          {"StreamName"},
		"AWS/Lambda":           {"FunctionName"},
		"AWS/Logs":             {"LogGroupName", "DestinationType", "FilterName"},
		"AWS/ML":               {"MLModelId", "RequestMode"},
		"AWS/OpsWorks":         {"StackId", "LayerId", "InstanceId"},
		"AWS/Redshift":         {"NodeID", "ClusterIdentifier"},
		"AWS/RDS":              {"DBInstanceIdentifier", "DatabaseClass", "EngineName"},
		"AWS/Route53":          {"HealthCheckId"},
		"AWS/SNS":              {"Application", "Platform", "TopicName"},
		"AWS/SQS":              {"QueueName"},
		"AWS/S3":               {"BucketName", "StorageType"},
		"AWS/SWF":              {"Domain", "WorkflowTypeName", "WorkflowTypeVersion", "ActivityTypeName", "ActivityTypeVersion"},
		"AWS/StorageGateway":   {"GatewayId", "GatewayName", "VolumeId"},
		"AWS/WAF":              {"Rule", "WebACL"},
		"AWS/WorkSpaces":       {"DirectoryId", "WorkspaceId"},
	}

	customMetricsMetricsMap = make(map[string]map[string]map[string]*CustomMetricsCache)
	customMetricsDimensionsMap = make(map[string]map[string]map[string]*CustomMetricsCache)
}

// Whenever this list is updated, frontend list should also be updated.
// Please update the region list in public/app/plugins/datasource/cloudwatch/partials/config.html
func handleGetRegions(req *cwRequest, c *middleware.Context) {
	regions := []string{
		"ap-northeast-1", "ap-northeast-2", "ap-southeast-1", "ap-southeast-2", "cn-north-1",
		"eu-central-1", "eu-west-1", "sa-east-1", "us-east-1", "us-west-1", "us-west-2",
	}

	result := []interface{}{}
	for _, region := range regions {
		result = append(result, util.DynMap{"text": region, "value": region})
	}

	c.JSON(200, result)
}

func handleGetNamespaces(req *cwRequest, c *middleware.Context) {
	keys := []string{}
	for key := range metricsMap {
		keys = append(keys, key)
	}

	customNamespaces := req.DataSource.JsonData.Get("customMetricsNamespaces").MustString()
	if customNamespaces != "" {
		for _, key := range strings.Split(customNamespaces, ",") {
			keys = append(keys, key)
		}
	}

	sort.Sort(sort.StringSlice(keys))

	result := []interface{}{}
	for _, key := range keys {
		result = append(result, util.DynMap{"text": key, "value": key})
	}

	c.JSON(200, result)
}

func handleGetMetrics(req *cwRequest, c *middleware.Context) {
	reqParam := &struct {
		Parameters struct {
			Namespace string `json:"namespace"`
		} `json:"parameters"`
	}{}

	json.Unmarshal(req.Body, reqParam)

	var namespaceMetrics []string
	if !isCustomMetrics(reqParam.Parameters.Namespace) {
		var exists bool
		if namespaceMetrics, exists = metricsMap[reqParam.Parameters.Namespace]; !exists {
			c.JsonApiErr(404, "Unable to find namespace "+reqParam.Parameters.Namespace, nil)
			return
		}
	} else {
		var err error
		if namespaceMetrics, err = getMetricsForCustomMetrics(req.Region, reqParam.Parameters.Namespace, req.DataSource.Database, getAllMetrics); err != nil {
			c.JsonApiErr(500, "Unable to call AWS API", err)
			return
		}
	}
	sort.Sort(sort.StringSlice(namespaceMetrics))

	result := []interface{}{}
	for _, name := range namespaceMetrics {
		result = append(result, util.DynMap{"text": name, "value": name})
	}

	c.JSON(200, result)
}

func handleGetDimensions(req *cwRequest, c *middleware.Context) {
	reqParam := &struct {
		Parameters struct {
			Namespace string `json:"namespace"`
		} `json:"parameters"`
	}{}

	json.Unmarshal(req.Body, reqParam)

	var dimensionValues []string
	if !isCustomMetrics(reqParam.Parameters.Namespace) {
		var exists bool
		if dimensionValues, exists = dimensionsMap[reqParam.Parameters.Namespace]; !exists {
			c.JsonApiErr(404, "Unable to find dimension "+reqParam.Parameters.Namespace, nil)
			return
		}
	} else {
		var err error
		if dimensionValues, err = getDimensionsForCustomMetrics(req.Region, reqParam.Parameters.Namespace, req.DataSource.Database, getAllMetrics); err != nil {
			c.JsonApiErr(500, "Unable to call AWS API", err)
			return
		}
	}
	sort.Sort(sort.StringSlice(dimensionValues))

	result := []interface{}{}
	for _, name := range dimensionValues {
		result = append(result, util.DynMap{"text": name, "value": name})
	}

	c.JSON(200, result)
}

func getAllMetrics(region string, namespace string, database string) (cloudwatch.ListMetricsOutput, error) {
	cfg := &aws.Config{
		Region:      aws.String(region),
		Credentials: getCredentials(database),
	}

	svc := cloudwatch.New(session.New(cfg), cfg)

	params := &cloudwatch.ListMetricsInput{
		Namespace: aws.String(namespace),
	}

	var resp cloudwatch.ListMetricsOutput
	err := svc.ListMetricsPages(params,
		func(page *cloudwatch.ListMetricsOutput, lastPage bool) bool {
			metrics, _ := awsutil.ValuesAtPath(page, "Metrics")
			for _, metric := range metrics {
				resp.Metrics = append(resp.Metrics, metric.(*cloudwatch.Metric))
			}
			return !lastPage
		})
	if err != nil {
		return resp, err
	}

	return resp, nil
}

var metricsCacheLock sync.Mutex

func getMetricsForCustomMetrics(region string, namespace string, database string, getAllMetrics func(string, string, string) (cloudwatch.ListMetricsOutput, error)) ([]string, error) {
	result, err := getAllMetrics(region, namespace, database)
	if err != nil {
		return []string{}, err
	}

	metricsCacheLock.Lock()
	defer metricsCacheLock.Unlock()

	if _, ok := customMetricsMetricsMap[database]; !ok {
		customMetricsMetricsMap[database] = make(map[string]map[string]*CustomMetricsCache)
	}
	if _, ok := customMetricsMetricsMap[database][region]; !ok {
		customMetricsMetricsMap[database][region] = make(map[string]*CustomMetricsCache)
	}
	if _, ok := customMetricsMetricsMap[database][region][namespace]; !ok {
		customMetricsMetricsMap[database][region][namespace] = &CustomMetricsCache{}
		customMetricsMetricsMap[database][region][namespace].Cache = make([]string, 0)
	}

	if customMetricsMetricsMap[database][region][namespace].Expire.After(time.Now()) {
		return customMetricsMetricsMap[database][region][namespace].Cache, nil
	}
	customMetricsMetricsMap[database][region][namespace].Cache = make([]string, 0)
	customMetricsMetricsMap[database][region][namespace].Expire = time.Now().Add(5 * time.Minute)

	for _, metric := range result.Metrics {
		if isDuplicate(customMetricsMetricsMap[database][region][namespace].Cache, *metric.MetricName) {
			continue
		}
		customMetricsMetricsMap[database][region][namespace].Cache = append(customMetricsMetricsMap[database][region][namespace].Cache, *metric.MetricName)
	}

	return customMetricsMetricsMap[database][region][namespace].Cache, nil
}

var dimensionsCacheLock sync.Mutex

func getDimensionsForCustomMetrics(region string, namespace string, database string, getAllMetrics func(string, string, string) (cloudwatch.ListMetricsOutput, error)) ([]string, error) {
	result, err := getAllMetrics(region, namespace, database)
	if err != nil {
		return []string{}, err
	}

	dimensionsCacheLock.Lock()
	defer dimensionsCacheLock.Unlock()

	if _, ok := customMetricsDimensionsMap[database]; !ok {
		customMetricsDimensionsMap[database] = make(map[string]map[string]*CustomMetricsCache)
	}
	if _, ok := customMetricsDimensionsMap[database][region]; !ok {
		customMetricsDimensionsMap[database][region] = make(map[string]*CustomMetricsCache)
	}
	if _, ok := customMetricsDimensionsMap[database][region][namespace]; !ok {
		customMetricsDimensionsMap[database][region][namespace] = &CustomMetricsCache{}
		customMetricsDimensionsMap[database][region][namespace].Cache = make([]string, 0)
	}

	if customMetricsDimensionsMap[database][region][namespace].Expire.After(time.Now()) {
		return customMetricsDimensionsMap[database][region][namespace].Cache, nil
	}
	customMetricsDimensionsMap[database][region][namespace].Cache = make([]string, 0)
	customMetricsDimensionsMap[database][region][namespace].Expire = time.Now().Add(5 * time.Minute)

	for _, metric := range result.Metrics {
		for _, dimension := range metric.Dimensions {
			if isDuplicate(customMetricsDimensionsMap[database][region][namespace].Cache, *dimension.Name) {
				continue
			}
			customMetricsDimensionsMap[database][region][namespace].Cache = append(customMetricsDimensionsMap[database][region][namespace].Cache, *dimension.Name)
		}
	}

	return customMetricsDimensionsMap[database][region][namespace].Cache, nil
}

func isDuplicate(nameList []string, target string) bool {
	for _, name := range nameList {
		if name == target {
			return true
		}
	}
	return false
}

func isCustomMetrics(namespace string) bool {
	return strings.Index(namespace, "AWS/") != 0
}