/*
Copyright 2014 The Kubernetes 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 resource

import (
	"fmt"
	"math"
	"strconv"
	"strings"

	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/resource"
)

// PodRequestsAndLimits returns a dictionary of all defined resources summed up for all
// containers of the pod. Pod overhead is added to the
// total container resource requests and to the total container limits which have a
// non-zero quantity.
func PodRequestsAndLimits(pod *v1.Pod) (reqs, limits v1.ResourceList) {
	return PodRequestsAndLimitsReuse(pod, nil, nil)
}

// PodRequestsAndLimitsWithoutOverhead will create a dictionary of all defined resources summed up for all
// containers of the pod.
func PodRequestsAndLimitsWithoutOverhead(pod *v1.Pod) (reqs, limits v1.ResourceList) {
	reqs = make(v1.ResourceList, 4)
	limits = make(v1.ResourceList, 4)
	podRequestsAndLimitsWithoutOverhead(pod, reqs, limits)

	return reqs, limits
}

func podRequestsAndLimitsWithoutOverhead(pod *v1.Pod, reqs, limits v1.ResourceList) {
	for _, container := range pod.Spec.Containers {
		addResourceList(reqs, container.Resources.Requests)
		addResourceList(limits, container.Resources.Limits)
	}
	// init containers define the minimum of any resource
	for _, container := range pod.Spec.InitContainers {
		maxResourceList(reqs, container.Resources.Requests)
		maxResourceList(limits, container.Resources.Limits)
	}
}

// PodRequestsAndLimitsReuse returns a dictionary of all defined resources summed up for all
// containers of the pod. Pod overhead is added to the
// total container resource requests and to the total container limits which have a
// non-zero quantity. The caller may avoid allocations of resource lists by passing
// a requests and limits list to the function, which will be cleared before use.
func PodRequestsAndLimitsReuse(pod *v1.Pod, reuseReqs, reuseLimits v1.ResourceList) (reqs, limits v1.ResourceList) {
	// attempt to reuse the maps if passed, or allocate otherwise
	reqs, limits = reuseOrClearResourceList(reuseReqs), reuseOrClearResourceList(reuseLimits)

	podRequestsAndLimitsWithoutOverhead(pod, reqs, limits)

	// Add overhead for running a pod
	// to the sum of requests and to non-zero limits:
	if pod.Spec.Overhead != nil {
		addResourceList(reqs, pod.Spec.Overhead)

		for name, quantity := range pod.Spec.Overhead {
			if value, ok := limits[name]; ok && !value.IsZero() {
				value.Add(quantity)
				limits[name] = value
			}
		}
	}

	return
}

// reuseOrClearResourceList is a helper for avoiding excessive allocations of
// resource lists within the inner loop of resource calculations.
func reuseOrClearResourceList(reuse v1.ResourceList) v1.ResourceList {
	if reuse == nil {
		return make(v1.ResourceList, 4)
	}
	for k := range reuse {
		delete(reuse, k)
	}
	return reuse
}

// addResourceList adds the resources in newList to list.
func addResourceList(list, newList v1.ResourceList) {
	for name, quantity := range newList {
		if value, ok := list[name]; !ok {
			list[name] = quantity.DeepCopy()
		} else {
			value.Add(quantity)
			list[name] = value
		}
	}
}

// maxResourceList sets list to the greater of list/newList for every resource in newList
func maxResourceList(list, newList v1.ResourceList) {
	for name, quantity := range newList {
		if value, ok := list[name]; !ok || quantity.Cmp(value) > 0 {
			list[name] = quantity.DeepCopy()
		}
	}
}

// GetResourceRequestQuantity finds and returns the request quantity for a specific resource.
func GetResourceRequestQuantity(pod *v1.Pod, resourceName v1.ResourceName) resource.Quantity {
	requestQuantity := resource.Quantity{}

	switch resourceName {
	case v1.ResourceCPU:
		requestQuantity = resource.Quantity{Format: resource.DecimalSI}
	case v1.ResourceMemory, v1.ResourceStorage, v1.ResourceEphemeralStorage:
		requestQuantity = resource.Quantity{Format: resource.BinarySI}
	default:
		requestQuantity = resource.Quantity{Format: resource.DecimalSI}
	}

	for _, container := range pod.Spec.Containers {
		if rQuantity, ok := container.Resources.Requests[resourceName]; ok {
			requestQuantity.Add(rQuantity)
		}
	}

	for _, container := range pod.Spec.InitContainers {
		if rQuantity, ok := container.Resources.Requests[resourceName]; ok {
			if requestQuantity.Cmp(rQuantity) < 0 {
				requestQuantity = rQuantity.DeepCopy()
			}
		}
	}

	// Add overhead for running a pod
	// to the total requests if the resource total is non-zero
	if pod.Spec.Overhead != nil {
		if podOverhead, ok := pod.Spec.Overhead[resourceName]; ok && !requestQuantity.IsZero() {
			requestQuantity.Add(podOverhead)
		}
	}

	return requestQuantity
}

// GetResourceRequest finds and returns the request value for a specific resource.
func GetResourceRequest(pod *v1.Pod, resource v1.ResourceName) int64 {
	if resource == v1.ResourcePods {
		return 1
	}

	requestQuantity := GetResourceRequestQuantity(pod, resource)

	if resource == v1.ResourceCPU {
		return requestQuantity.MilliValue()
	}

	return requestQuantity.Value()
}

// ExtractResourceValueByContainerName extracts the value of a resource
// by providing container name
func ExtractResourceValueByContainerName(fs *v1.ResourceFieldSelector, pod *v1.Pod, containerName string) (string, error) {
	container, err := findContainerInPod(pod, containerName)
	if err != nil {
		return "", err
	}
	return ExtractContainerResourceValue(fs, container)
}

// ExtractResourceValueByContainerNameAndNodeAllocatable extracts the value of a resource
// by providing container name and node allocatable
func ExtractResourceValueByContainerNameAndNodeAllocatable(fs *v1.ResourceFieldSelector, pod *v1.Pod, containerName string, nodeAllocatable v1.ResourceList) (string, error) {
	realContainer, err := findContainerInPod(pod, containerName)
	if err != nil {
		return "", err
	}

	container := realContainer.DeepCopy()

	MergeContainerResourceLimits(container, nodeAllocatable)

	return ExtractContainerResourceValue(fs, container)
}

// ExtractContainerResourceValue extracts the value of a resource
// in an already known container
func ExtractContainerResourceValue(fs *v1.ResourceFieldSelector, container *v1.Container) (string, error) {
	divisor := resource.Quantity{}
	if divisor.Cmp(fs.Divisor) == 0 {
		divisor = resource.MustParse("1")
	} else {
		divisor = fs.Divisor
	}

	switch fs.Resource {
	case "limits.cpu":
		return convertResourceCPUToString(container.Resources.Limits.Cpu(), divisor)
	case "limits.memory":
		return convertResourceMemoryToString(container.Resources.Limits.Memory(), divisor)
	case "limits.ephemeral-storage":
		return convertResourceEphemeralStorageToString(container.Resources.Limits.StorageEphemeral(), divisor)
	case "requests.cpu":
		return convertResourceCPUToString(container.Resources.Requests.Cpu(), divisor)
	case "requests.memory":
		return convertResourceMemoryToString(container.Resources.Requests.Memory(), divisor)
	case "requests.ephemeral-storage":
		return convertResourceEphemeralStorageToString(container.Resources.Requests.StorageEphemeral(), divisor)
	}
	// handle extended standard resources with dynamic names
	// example: requests.hugepages-<pageSize> or limits.hugepages-<pageSize>
	if strings.HasPrefix(fs.Resource, "requests.") {
		resourceName := v1.ResourceName(strings.TrimPrefix(fs.Resource, "requests."))
		if IsHugePageResourceName(resourceName) {
			return convertResourceHugePagesToString(container.Resources.Requests.Name(resourceName, resource.BinarySI), divisor)
		}
	}
	if strings.HasPrefix(fs.Resource, "limits.") {
		resourceName := v1.ResourceName(strings.TrimPrefix(fs.Resource, "limits."))
		if IsHugePageResourceName(resourceName) {
			return convertResourceHugePagesToString(container.Resources.Limits.Name(resourceName, resource.BinarySI), divisor)
		}
	}
	return "", fmt.Errorf("unsupported container resource : %v", fs.Resource)
}

// convertResourceCPUToString converts cpu value to the format of divisor and returns
// ceiling of the value.
func convertResourceCPUToString(cpu *resource.Quantity, divisor resource.Quantity) (string, error) {
	c := int64(math.Ceil(float64(cpu.MilliValue()) / float64(divisor.MilliValue())))
	return strconv.FormatInt(c, 10), nil
}

// convertResourceMemoryToString converts memory value to the format of divisor and returns
// ceiling of the value.
func convertResourceMemoryToString(memory *resource.Quantity, divisor resource.Quantity) (string, error) {
	m := int64(math.Ceil(float64(memory.Value()) / float64(divisor.Value())))
	return strconv.FormatInt(m, 10), nil
}

// convertResourceHugePagesToString converts hugepages value to the format of divisor and returns
// ceiling of the value.
func convertResourceHugePagesToString(hugePages *resource.Quantity, divisor resource.Quantity) (string, error) {
	m := int64(math.Ceil(float64(hugePages.Value()) / float64(divisor.Value())))
	return strconv.FormatInt(m, 10), nil
}

// convertResourceEphemeralStorageToString converts ephemeral storage value to the format of divisor and returns
// ceiling of the value.
func convertResourceEphemeralStorageToString(ephemeralStorage *resource.Quantity, divisor resource.Quantity) (string, error) {
	m := int64(math.Ceil(float64(ephemeralStorage.Value()) / float64(divisor.Value())))
	return strconv.FormatInt(m, 10), nil
}

// findContainerInPod finds a container by its name in the provided pod
func findContainerInPod(pod *v1.Pod, containerName string) (*v1.Container, error) {
	for _, container := range pod.Spec.Containers {
		if container.Name == containerName {
			return &container, nil
		}
	}
	for _, container := range pod.Spec.InitContainers {
		if container.Name == containerName {
			return &container, nil
		}
	}
	return nil, fmt.Errorf("container %s not found", containerName)
}

// MergeContainerResourceLimits checks if a limit is applied for
// the container, and if not, it sets the limit to the passed resource list.
func MergeContainerResourceLimits(container *v1.Container,
	allocatable v1.ResourceList) {
	if container.Resources.Limits == nil {
		container.Resources.Limits = make(v1.ResourceList)
	}
	// NOTE: we exclude hugepages-* resources because hugepages are never overcommitted.
	// This means that the container always has a limit specified.
	for _, resource := range []v1.ResourceName{v1.ResourceCPU, v1.ResourceMemory, v1.ResourceEphemeralStorage} {
		if quantity, exists := container.Resources.Limits[resource]; !exists || quantity.IsZero() {
			if cap, exists := allocatable[resource]; exists {
				container.Resources.Limits[resource] = cap.DeepCopy()
			}
		}
	}
}

// IsHugePageResourceName returns true if the resource name has the huge page
// resource prefix.
func IsHugePageResourceName(name v1.ResourceName) bool {
	return strings.HasPrefix(string(name), v1.ResourceHugePagesPrefix)
}
