/*
Copyright 2016 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 unversioned

import (
	"fmt"

	"k8s.io/kubernetes/pkg/labels"
	"k8s.io/kubernetes/pkg/util/sets"
)

// LabelSelectorAsSelector converts the LabelSelector api type into a struct that implements
// labels.Selector
// Note: This function should be kept in sync with the selector methods in pkg/labels/selector.go
func LabelSelectorAsSelector(ps *LabelSelector) (labels.Selector, error) {
	if ps == nil {
		return labels.Nothing(), nil
	}
	if len(ps.MatchLabels)+len(ps.MatchExpressions) == 0 {
		return labels.Everything(), nil
	}
	selector := labels.NewSelector()
	for k, v := range ps.MatchLabels {
		r, err := labels.NewRequirement(k, labels.EqualsOperator, sets.NewString(v))
		if err != nil {
			return nil, err
		}
		selector = selector.Add(*r)
	}
	for _, expr := range ps.MatchExpressions {
		var op labels.Operator
		switch expr.Operator {
		case LabelSelectorOpIn:
			op = labels.InOperator
		case LabelSelectorOpNotIn:
			op = labels.NotInOperator
		case LabelSelectorOpExists:
			op = labels.ExistsOperator
		case LabelSelectorOpDoesNotExist:
			op = labels.DoesNotExistOperator
		default:
			return nil, fmt.Errorf("%q is not a valid pod selector operator", expr.Operator)
		}
		r, err := labels.NewRequirement(expr.Key, op, sets.NewString(expr.Values...))
		if err != nil {
			return nil, err
		}
		selector = selector.Add(*r)
	}
	return selector, nil
}

// ParseToLabelSelector parses a string representing a selector into a LabelSelector object.
// Note: This function should be kept in sync with the parser in pkg/labels/selector.go
func ParseToLabelSelector(selector string) (*LabelSelector, error) {
	reqs, err := labels.ParseToRequirements(selector)
	if err != nil {
		return nil, fmt.Errorf("couldn't parse the selector string \"%s\": %v", selector, err)
	}

	labelSelector := &LabelSelector{
		MatchLabels:      map[string]string{},
		MatchExpressions: []LabelSelectorRequirement{},
	}
	for _, req := range reqs {
		var op LabelSelectorOperator
		switch req.Operator() {
		case labels.EqualsOperator, labels.DoubleEqualsOperator:
			vals := req.Values()
			if vals.Len() != 1 {
				return nil, fmt.Errorf("equals operator must have exactly one value")
			}
			val, ok := vals.PopAny()
			if !ok {
				return nil, fmt.Errorf("equals operator has exactly one value but it cannot be retrieved")
			}
			labelSelector.MatchLabels[req.Key()] = val
			continue
		case labels.InOperator:
			op = LabelSelectorOpIn
		case labels.NotInOperator:
			op = LabelSelectorOpNotIn
		case labels.ExistsOperator:
			op = LabelSelectorOpExists
		case labels.DoesNotExistOperator:
			op = LabelSelectorOpDoesNotExist
		case labels.GreaterThanOperator, labels.LessThanOperator:
			// Adding a separate case for these operators to indicate that this is deliberate
			return nil, fmt.Errorf("%q isn't supported in label selectors", req.Operator())
		default:
			return nil, fmt.Errorf("%q is not a valid label selector operator", req.Operator())
		}
		labelSelector.MatchExpressions = append(labelSelector.MatchExpressions, LabelSelectorRequirement{
			Key:      req.Key(),
			Operator: op,
			Values:   req.Values().List(),
		})
	}
	return labelSelector, nil
}

// SetAsLabelSelector converts the labels.Set object into a LabelSelector api object.
func SetAsLabelSelector(ls labels.Set) *LabelSelector {
	if ls == nil {
		return nil
	}

	selector := &LabelSelector{
		MatchLabels: make(map[string]string),
	}
	for label, value := range ls {
		selector.MatchLabels[label] = value
	}

	return selector
}

// FormatLabelSelector convert labelSelector into plain string
func FormatLabelSelector(labelSelector *LabelSelector) string {
	selector, err := LabelSelectorAsSelector(labelSelector)
	if err != nil {
		return "<error>"
	}

	l := selector.String()
	if len(l) == 0 {
		l = "<none>"
	}
	return l
}

func ExtractGroupVersions(l *APIGroupList) []string {
	var groupVersions []string
	for _, g := range l.Groups {
		for _, gv := range g.Versions {
			groupVersions = append(groupVersions, gv.GroupVersion)
		}
	}
	return groupVersions
}
