// Copyright 2021 Google LLC
//
// 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 compliance

import (
	"fmt"
)

// SourceSharePrivacyConflict describes an individual conflict between a source-sharing
// condition and a source privacy condition
type SourceSharePrivacyConflict struct {
	SourceNode       *TargetNode
	ShareCondition   LicenseCondition
	PrivacyCondition LicenseCondition
}

// Error returns a string describing the conflict.
func (conflict SourceSharePrivacyConflict) Error() string {
	return fmt.Sprintf("%s %s and must share from %s condition\n", conflict.SourceNode.name,
		conflict.PrivacyCondition.Name(), conflict.ShareCondition.Name())
}

// IsEqualTo returns true when `conflict` and `other` describe the same conflict.
func (conflict SourceSharePrivacyConflict) IsEqualTo(other SourceSharePrivacyConflict) bool {
	return conflict.SourceNode.name == other.SourceNode.name &&
		conflict.ShareCondition == other.ShareCondition &&
		conflict.PrivacyCondition == other.PrivacyCondition
}

// ConflictingSharedPrivateSource lists all of the targets where conflicting conditions to
// share the source and to keep the source private apply to the target.
func ConflictingSharedPrivateSource(lg *LicenseGraph) []SourceSharePrivacyConflict {

	ResolveTopDownConditions(lg)
	// combined is the combination of source-sharing and source privacy.
	combined := WalkActionsForCondition(lg, ImpliesShared.Union(ImpliesPrivate))

	// size is the size of the result
	size := 0
	for actsOn, cs := range combined {
		if actsOn.pure && !actsOn.LicenseConditions().MatchesAnySet(ImpliesShared) {
			// no need to share code to build "a distribution medium"
			continue
		}
		size += cs.Intersection(ImpliesShared).Len() * cs.Intersection(ImpliesPrivate).Len()
	}
	if size == 0 {
		return nil
	}
	result := make([]SourceSharePrivacyConflict, 0, size)
	for actsOn, cs := range combined {
		if actsOn.pure { // no need to share code for "a distribution medium"
			continue
		}
		pconditions := cs.Intersection(ImpliesPrivate).AsList()
		ssconditions := cs.Intersection(ImpliesShared).AsList()

		// report all conflicting condition combinations
		for _, p := range pconditions {
			for _, ss := range ssconditions {
				result = append(result, SourceSharePrivacyConflict{actsOn, ss, p})
			}
		}
	}
	return result
}