/*
Copyright 2020 Achilleas Tzenetopoulos

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.
*/

/*
Extension of the scheduler developed during my diploma thesis
Make it pluggable with Kubernetes logic in scheduler extension

Date started: 30/1/2020
Using the scheduling framework and plugins logic

*/

package noderesources

import (
	"context"
	"database/sql"
	"fmt"
	"os"

	_ "github.com/go-sql-driver/mysql"
	"gopkg.in/yaml.v2"
	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/klog"
	framework "k8s.io/kubernetes/pkg/scheduler/framework/v1alpha1"
	"k8s.io/kubernetes/pkg/scheduler/nodeinfo"
)

type Config struct {
	Server struct {
		Port string `yaml:"port"`
		Host string `yaml:"host"`
	} `yaml:"server"`
	Database struct {
		Type     string `yaml: "type"`
		Name     string `yaml:"name"`
		Username string `yaml:"username"`
		Password string `yaml:"password"`
	} `yaml:"database"`
}

// Custom allocation is a score plugin that favors nodes with a custom scoring function taking into account custom resources.
type CustomAllocated struct {
	handle framework.FrameworkHandle
	resourceAllocationScorer
	//customResourceAllocationScorer
}

type nodeMetrics struct {
	L3cacheMisses int64
	memoryReads   int64
	memoryWrites  int64
	averageIPC    float32
}

type System struct {
	ID         int    `json:"id"`
	Uuid       string `json:"uuid"`
	numSockets int    `json:"num_sockets"`
	numCores   int    `json:"num_cores`
}

type wrongValueError struct{}

var _ = framework.ScorePlugin(&CustomAllocated{})

//Map nodes to uuid
//var nodes = make(map[string]string)

var nodes = map[string]string{
	"kube-01": "c4766d29-4dc1-11ea-9d98-0242ac110002",
	"kube-02": "2",
	"kube-03": "2",
	"kube-04": "2",
}

// CustomAllocatedName is the name of the plugin used in the plugin registry and configurations.
const CustomAllocatedName = "NodeResourcesCustomAllocated"

// Name returns name of the plugin. It is used in logs, etc.
func (ca *CustomAllocated) Name() string {
	return CustomAllocatedName
}

func readFile(cfg *Config) {
	f, err := os.Open("/etc/kubernetes/scheduler-monitoringDB.yaml")
	if err != nil {
		panic(err.Error())
	}
	defer f.Close()

	decoder := yaml.NewDecoder(f)
	err = decoder.Decode(&cfg)
	if err != nil {
		panic(err.Error())
	}
}

func getCustomMetrics(name string) *nodeMetrics {

	var cfg Config
	readFile(&cfg)
	//Open the database connection
	DBstring := cfg.Database.Username + ":" + cfg.Database.Password + "@tcp(" + cfg.Server.Host + ":" + cfg.Server.Port + ")/" + cfg.Database.Name
	db, err := sql.Open(cfg.Database.Type, DBstring)
	if err != nil {
		panic(err.Error())
	}

	defer db.Close()

	curr_uuid, ok := nodes[name]

	nd := nodeMetrics{}

	if ok {

		results, err := db.Query("SELECT id, num_sockets, num_cores FROM systems WHERE uuid = ?", curr_uuid)

		if err != nil {
			panic(err.Error()) // proper error handling instead of panic in your app
		}
		sys := System{}
		sys.Uuid = curr_uuid

		for results.Next() {
			// for each row, scan the result into our tag composite object
			err = results.Scan(&sys.ID, &sys.numSockets, &sys.numCores)
			if err != nil {
				panic(err.Error()) // proper error handling instead of panic in your app
			}
			// and then print out the tag's Name attribute
			klog.Infof("This is the system with name: %s, id: %d and  number of cores: %d", name, sys.ID, sys.numCores)
		}
	}
	//nd := nodeMetrics{}
	if name == "kube-01" {
		nd.L3cacheMisses = 1
		nd.memoryReads = 1
		nd.memoryWrites = 1
		nd.averageIPC = 2.0

	} else {
		//some sample values for testing purposes
		nd.L3cacheMisses = 200
		nd.memoryReads = 50
		nd.memoryWrites = 60
		nd.averageIPC = 1.2
	}

	//query metrics for this node provided in the input

	if nd.L3cacheMisses < 0 || nd.memoryReads < 0 || nd.memoryWrites < 0 || nd.averageIPC < 0 {
		//err := errors.New("Failed to get the values")
		return nil
	}

	return &nd
}

func (ca *CustomAllocated) scoringFunction(pod *v1.Pod, node *nodeMetrics, nodeInfo *nodeinfo.NodeInfo) int64 {
	//rawScore := float32(node.memoryReads+node.memoryWrites) / node.averageIPC

	intScore := int64(float32(node.memoryReads+node.memoryWrites) / node.averageIPC)

	//Sample implementation in order to check functionality

	klog.Infof("Score: %d", intScore)
	return intScore
}

// Score invoked at the score extension point.
func (ca *CustomAllocated) Score(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string) (int64, *framework.Status) {
	nodeInfo, err := ca.handle.SnapshotSharedLister().NodeInfos().Get(nodeName)
	if err != nil {
		return 0, framework.NewStatus(framework.Error, fmt.Sprintf("getting node %q from Snapshot: %v", nodeName, err))
	}

	//Search into the monitored metrics for the specified node
	nodeMetrics := getCustomMetrics(nodeName)

	// ca.score favors nodes with 'better' monitored resources score.
	// It calculates the percentage of micro-architecture metrics like L3 cache misses and/or IPC and memory bandwidth, and
	// prioritizes based on the lowest score provided by a custom scoring function.
	//
	// Details:
	// TODO
	klog.Infof("Node: %s", nodeName)
	return ca.scoringFunction(pod, nodeMetrics, nodeInfo), nil
	//return ca.score(pod, nodeInfo)
}

// ScoreExtensions of the Score plugin.
func (ca *CustomAllocated) ScoreExtensions() framework.ScoreExtensions {
	return nil
}

// NewCustomAllocated initializes a new plugin and returns it.
func NewCustomAllocated(_ *runtime.Unknown, h framework.FrameworkHandle) (framework.Plugin, error) {
	return &CustomAllocated{
		handle: h,
		resourceAllocationScorer: resourceAllocationScorer{
			CustomAllocatedName,
			customResourceScorer,
			defaultRequestedRatioResources,
		},
	}, nil
}

func customResourceScorer(requested, allocable resourceToValueMap, includeVolumes bool, requestedVolumes int, allocatableVolumes int) int64 {

	//There I should call a function which will get my custom metrics

	var nodeScore, weightSum int64
	for resource, weight := range defaultRequestedRatioResources {
		resourceScore := customRequestedScore(requested[resource], allocable[resource])
		nodeScore += resourceScore * weight
		weightSum += weight
	}
	return nodeScore / weightSum
}

// The unused capacity is calculated on a scale of 0-10
// 0 being the lowest priority and 10 being the highest.
// The more unused resources the higher the score is.
func customRequestedScore(requested, capacity int64) int64 {
	if capacity == 0 {
		return 0
	}
	if requested > capacity {
		return 0
	}

	return ((capacity - requested) * int64(framework.MaxNodeScore)) / capacity
}