/*
Copyright 2017 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 env

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

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apimachinery/pkg/util/validation"
	"k8s.io/client-go/kubernetes"
)

// ResourceStore defines a new resource store data structure.
type ResourceStore struct {
	SecretStore    map[string]*corev1.Secret
	ConfigMapStore map[string]*corev1.ConfigMap
}

// NewResourceStore returns a pointer to a new resource store data structure.
func NewResourceStore() *ResourceStore {
	return &ResourceStore{
		SecretStore:    make(map[string]*corev1.Secret),
		ConfigMapStore: make(map[string]*corev1.ConfigMap),
	}
}

// getSecretRefValue returns the value of a secret in the supplied namespace
func getSecretRefValue(client kubernetes.Interface, namespace string, store *ResourceStore, secretSelector *corev1.SecretKeySelector) (string, error) {
	secret, ok := store.SecretStore[secretSelector.Name]
	if !ok {
		var err error
		secret, err = client.CoreV1().Secrets(namespace).Get(context.TODO(), secretSelector.Name, metav1.GetOptions{})
		if err != nil {
			return "", err
		}
		store.SecretStore[secretSelector.Name] = secret
	}
	if data, ok := secret.Data[secretSelector.Key]; ok {
		return string(data), nil
	}
	return "", fmt.Errorf("key %s not found in secret %s", secretSelector.Key, secretSelector.Name)

}

// getConfigMapRefValue returns the value of a configmap in the supplied namespace
func getConfigMapRefValue(client kubernetes.Interface, namespace string, store *ResourceStore, configMapSelector *corev1.ConfigMapKeySelector) (string, error) {
	configMap, ok := store.ConfigMapStore[configMapSelector.Name]
	if !ok {
		var err error
		configMap, err = client.CoreV1().ConfigMaps(namespace).Get(context.TODO(), configMapSelector.Name, metav1.GetOptions{})
		if err != nil {
			return "", err
		}
		store.ConfigMapStore[configMapSelector.Name] = configMap
	}
	if data, ok := configMap.Data[configMapSelector.Key]; ok {
		return string(data), nil
	}
	return "", fmt.Errorf("key %s not found in config map %s", configMapSelector.Key, configMapSelector.Name)
}

// getFieldRef returns the value of the supplied path in the given object
func getFieldRef(obj runtime.Object, from *corev1.EnvVarSource) (string, error) {
	return extractFieldPathAsString(obj, from.FieldRef.FieldPath)
}

// extractFieldPathAsString extracts the field from the given object
// and returns it as a string.  The object must be a pointer to an
// API type.
func extractFieldPathAsString(obj interface{}, fieldPath string) (string, error) {
	accessor, err := meta.Accessor(obj)
	if err != nil {
		return "", nil
	}

	if path, subscript, ok := splitMaybeSubscriptedPath(fieldPath); ok {
		switch path {
		case "metadata.annotations":
			if errs := validation.IsQualifiedName(strings.ToLower(subscript)); len(errs) != 0 {
				return "", fmt.Errorf("invalid key subscript in %s: %s", fieldPath, strings.Join(errs, ";"))
			}
			return accessor.GetAnnotations()[subscript], nil
		case "metadata.labels":
			if errs := validation.IsQualifiedName(subscript); len(errs) != 0 {
				return "", fmt.Errorf("invalid key subscript in %s: %s", fieldPath, strings.Join(errs, ";"))
			}
			return accessor.GetLabels()[subscript], nil
		default:
			return "", fmt.Errorf("fieldPath %q does not support subscript", fieldPath)
		}
	}

	switch fieldPath {
	case "metadata.annotations":
		return formatMap(accessor.GetAnnotations()), nil
	case "metadata.labels":
		return formatMap(accessor.GetLabels()), nil
	case "metadata.name":
		return accessor.GetName(), nil
	case "metadata.namespace":
		return accessor.GetNamespace(), nil
	case "metadata.uid":
		return string(accessor.GetUID()), nil
	}

	return "", fmt.Errorf("unsupported fieldPath: %v", fieldPath)
}

// splitMaybeSubscriptedPath checks whether the specified fieldPath is
// subscripted, and
//  - if yes, this function splits the fieldPath into path and subscript, and
//    returns (path, subscript, true).
//  - if no, this function returns (fieldPath, "", false).
//
// Example inputs and outputs:
//  - "metadata.annotations['myKey']" --> ("metadata.annotations", "myKey", true)
//  - "metadata.annotations['a[b]c']" --> ("metadata.annotations", "a[b]c", true)
//  - "metadata.labels['']"           --> ("metadata.labels", "", true)
//  - "metadata.labels"               --> ("metadata.labels", "", false)
func splitMaybeSubscriptedPath(fieldPath string) (string, string, bool) {
	if !strings.HasSuffix(fieldPath, "']") {
		return fieldPath, "", false
	}
	s := strings.TrimSuffix(fieldPath, "']")
	parts := strings.SplitN(s, "['", 2)
	if len(parts) < 2 {
		return fieldPath, "", false
	}
	if len(parts[0]) == 0 {
		return fieldPath, "", false
	}
	return parts[0], parts[1], true
}

// formatMap formats map[string]string to a string.
func formatMap(m map[string]string) (fmtStr string) {
	// output with keys in sorted order to provide stable output
	keys := sets.NewString()
	for key := range m {
		keys.Insert(key)
	}
	for _, key := range keys.List() {
		fmtStr += fmt.Sprintf("%v=%q\n", key, m[key])
	}
	fmtStr = strings.TrimSuffix(fmtStr, "\n")

	return
}

// getResourceFieldRef returns the value of a resource in the given container
func getResourceFieldRef(from *corev1.EnvVarSource, container *corev1.Container) (string, error) {
	return extractContainerResourceValue(from.ResourceFieldRef, container)
}

// ExtractContainerResourceValue extracts the value of a resource
// in an already known container
func extractContainerResourceValue(fs *corev1.ResourceFieldSelector, container *corev1.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 := corev1.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 := corev1.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
}

// GetEnvVarRefValue returns the value referenced by the supplied EnvVarSource given the other supplied information.
func GetEnvVarRefValue(kc kubernetes.Interface, ns string, store *ResourceStore, from *corev1.EnvVarSource, obj runtime.Object, c *corev1.Container) (string, error) {
	if from.SecretKeyRef != nil {
		return getSecretRefValue(kc, ns, store, from.SecretKeyRef)
	}

	if from.ConfigMapKeyRef != nil {
		return getConfigMapRefValue(kc, ns, store, from.ConfigMapKeyRef)
	}

	if from.FieldRef != nil {
		return getFieldRef(obj, from)
	}

	if from.ResourceFieldRef != nil {
		return getResourceFieldRef(from, c)
	}

	return "", fmt.Errorf("invalid valueFrom")
}

// GetEnvVarRefString returns a text description of whichever field is set within the supplied EnvVarSource argument.
func GetEnvVarRefString(from *corev1.EnvVarSource) string {
	if from.ConfigMapKeyRef != nil {
		return fmt.Sprintf("configmap %s, key %s", from.ConfigMapKeyRef.Name, from.ConfigMapKeyRef.Key)
	}

	if from.SecretKeyRef != nil {
		return fmt.Sprintf("secret %s, key %s", from.SecretKeyRef.Name, from.SecretKeyRef.Key)
	}

	if from.FieldRef != nil {
		return fmt.Sprintf("field path %s", from.FieldRef.FieldPath)
	}

	if from.ResourceFieldRef != nil {
		containerPrefix := ""
		if from.ResourceFieldRef.ContainerName != "" {
			containerPrefix = fmt.Sprintf("%s/", from.ResourceFieldRef.ContainerName)
		}
		return fmt.Sprintf("resource field %s%s", containerPrefix, from.ResourceFieldRef.Resource)
	}

	return "invalid valueFrom"
}

// IsHugePageResourceName returns true if the resource name has the huge page
// resource prefix.
func IsHugePageResourceName(name corev1.ResourceName) bool {
	return strings.HasPrefix(string(name), corev1.ResourceHugePagesPrefix)
}
