package resourcepolicies

import (
	"bytes"
	"fmt"
	"strings"

	"github.com/pkg/errors"
	"gopkg.in/yaml.v3"
	corev1api "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/resource"
)

type volPolicy struct {
	action     Action
	conditions []volumeCondition
}

type volumeCondition interface {
	match(v *structuredVolume) bool
	validate() error
}

// capacity consist of the lower and upper boundary
type capacity struct {
	lower resource.Quantity
	upper resource.Quantity
}

type structuredVolume struct {
	capacity     resource.Quantity
	storageClass string
	nfs          *nFSVolumeSource
	csi          *csiVolumeSource
}

func (s *structuredVolume) parsePV(pv *corev1api.PersistentVolume) {
	s.capacity = *pv.Spec.Capacity.Storage()
	s.storageClass = pv.Spec.StorageClassName
	nfs := pv.Spec.NFS
	if nfs != nil {
		s.nfs = &nFSVolumeSource{Server: nfs.Server, Path: nfs.Path}
	}

	csi := pv.Spec.CSI
	if csi != nil {
		s.csi = &csiVolumeSource{Driver: csi.Driver}
	}
}

func (s *structuredVolume) parsePodVolume(vol *corev1api.Volume) {
	nfs := vol.NFS
	if nfs != nil {
		s.nfs = &nFSVolumeSource{Server: nfs.Server, Path: nfs.Path}
	}

	csi := vol.CSI
	if csi != nil {
		s.csi = &csiVolumeSource{Driver: csi.Driver}
	}
}

type capacityCondition struct {
	capacity capacity
}

func (c *capacityCondition) match(v *structuredVolume) bool {
	return c.capacity.isInRange(v.capacity)
}

type storageClassCondition struct {
	storageClass []string
}

func (s *storageClassCondition) match(v *structuredVolume) bool {
	if len(s.storageClass) == 0 {
		return true
	}

	if v.storageClass == "" {
		return false
	}

	for _, sc := range s.storageClass {
		if v.storageClass == sc {
			return true
		}
	}

	return false
}

type nfsCondition struct {
	nfs *nFSVolumeSource
}

func (c *nfsCondition) match(v *structuredVolume) bool {
	if c.nfs == nil {
		return true
	}
	if v.nfs == nil {
		return false
	}

	if c.nfs.Path == "" {
		if c.nfs.Server == "" { // match nfs: {}
			return v.nfs != nil
		}
		if c.nfs.Server != v.nfs.Server {
			return false
		}
		return true
	}
	if c.nfs.Path != v.nfs.Path {
		return false
	}
	if c.nfs.Server == "" {
		return true
	}
	if c.nfs.Server != v.nfs.Server {
		return false
	}
	return true
}

type csiCondition struct {
	csi *csiVolumeSource
}

func (c *csiCondition) match(v *structuredVolume) bool {
	if c.csi == nil {
		return true
	}

	if c.csi.Driver == "" { // match csi: {}
		return v.csi != nil
	}

	if v.csi == nil {
		return false
	}

	return c.csi.Driver == v.csi.Driver
}

// parseCapacity parse string into capacity format
func parseCapacity(cap string) (*capacity, error) {
	if cap == "" {
		cap = ","
	}
	capacities := strings.Split(cap, ",")
	var quantities []resource.Quantity
	if len(capacities) != 2 {
		return nil, fmt.Errorf("wrong format of Capacity %v", cap)
	}

	for _, v := range capacities {
		if strings.TrimSpace(v) == "" {
			// case similar "10Gi,"
			// if empty, the quantity will assigned with 0
			quantities = append(quantities, *resource.NewQuantity(int64(0), resource.DecimalSI))
		} else {
			quantity, err := resource.ParseQuantity(strings.TrimSpace(v))
			if err != nil {
				return nil, fmt.Errorf("wrong format of Capacity %v with err %v", v, err)
			}
			quantities = append(quantities, quantity)
		}
	}

	return &capacity{lower: quantities[0], upper: quantities[1]}, nil
}

// isInRange returns true if the quantity y is in range of capacity, or it returns false
func (c *capacity) isInRange(y resource.Quantity) bool {
	if c.lower.IsZero() && c.upper.Cmp(y) >= 0 {
		// [0, a] y
		return true
	}
	if c.upper.IsZero() && c.lower.Cmp(y) <= 0 {
		// [b, 0] y
		return true
	}
	if !c.lower.IsZero() && !c.upper.IsZero() {
		// [a, b] y
		return c.lower.Cmp(y) <= 0 && c.upper.Cmp(y) >= 0
	}
	return false
}

// unmarshalVolConditions parse map[string]interface{} into volumeConditions format
// and validate key fields of the map.
func unmarshalVolConditions(con map[string]interface{}) (*volumeConditions, error) {
	volConditons := &volumeConditions{}
	buffer := new(bytes.Buffer)
	err := yaml.NewEncoder(buffer).Encode(con)
	if err != nil {
		return nil, errors.Wrap(err, "failed to encode volume conditions")
	}

	if err := decodeStruct(buffer, volConditons); err != nil {
		return nil, errors.Wrap(err, "failed to decode volume conditions")
	}
	return volConditons, nil
}