From 8550265d75f23b8dacafe8e670e289c5b70c9620 Mon Sep 17 00:00:00 2001
From: Ettore Di Giacinto <edigiacinto@suse.com>
Date: Mon, 11 Nov 2019 14:58:12 +0100
Subject: [PATCH] Add assertion hashing

---
 pkg/solver/decoder.go      | 31 +++++++++++++++++
 pkg/solver/decoder_test.go | 68 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)

diff --git a/pkg/solver/decoder.go b/pkg/solver/decoder.go
index 060d069d..ce17ba12 100644
--- a/pkg/solver/decoder.go
+++ b/pkg/solver/decoder.go
@@ -16,6 +16,7 @@
 package solver
 
 import (
+	"crypto/sha256"
 	"fmt"
 
 	pkg "github.com/mudler/luet/pkg/package"
@@ -102,3 +103,33 @@ func (assertions PackagesAssertions) Order() PackagesAssertions {
 
 	return orderedAssertions
 }
+
+func (assertions PackagesAssertions) Explain() string {
+	var fingerprint string
+	for _, assertion := range assertions.Order() { // Always order them
+		fingerprint += assertion.ToString() + "\n"
+	}
+	return fingerprint
+}
+
+func (assertions PackagesAssertions) AssertionHash() string {
+	var fingerprint string
+	for _, assertion := range assertions.Order() { // Always order them
+		if assertion.Value && assertion.Package.Flagged() { // Tke into account only dependencies installed (get fingerprint of subgraph)
+			fingerprint += assertion.ToString() + "\n"
+		}
+	}
+	hash := sha256.Sum256([]byte(fingerprint))
+	return fmt.Sprintf("%x", hash)
+}
+
+func (assertions PackagesAssertions) Drop(p pkg.Package) PackagesAssertions {
+	ass := PackagesAssertions{}
+
+	for _, a := range assertions {
+		if a.Package.GetFingerPrint() != p.GetFingerPrint() {
+			ass = append(ass, a)
+		}
+	}
+	return ass
+}
diff --git a/pkg/solver/decoder_test.go b/pkg/solver/decoder_test.go
index b63761cd..0e0ecbea 100644
--- a/pkg/solver/decoder_test.go
+++ b/pkg/solver/decoder_test.go
@@ -129,4 +129,72 @@ var _ = Describe("Decoder", func() {
 			})
 		}
 	})
+
+	Context("Assertion hashing", func() {
+		It("Hashes them, and could be used for comparison", func() {
+			C := pkg.NewPackage("C", "", []*pkg.DefaultPackage{}, []*pkg.DefaultPackage{})
+			E := pkg.NewPackage("E", "", []*pkg.DefaultPackage{}, []*pkg.DefaultPackage{})
+			F := pkg.NewPackage("F", "", []*pkg.DefaultPackage{}, []*pkg.DefaultPackage{})
+			G := pkg.NewPackage("G", "", []*pkg.DefaultPackage{}, []*pkg.DefaultPackage{})
+			H := pkg.NewPackage("H", "", []*pkg.DefaultPackage{G}, []*pkg.DefaultPackage{})
+			D := pkg.NewPackage("D", "", []*pkg.DefaultPackage{H}, []*pkg.DefaultPackage{})
+			B := pkg.NewPackage("B", "", []*pkg.DefaultPackage{D}, []*pkg.DefaultPackage{})
+			A := pkg.NewPackage("A", "", []*pkg.DefaultPackage{B}, []*pkg.DefaultPackage{})
+
+			s := NewSolver([]pkg.Package{C}, []pkg.Package{A, B, C, D, E, F, G})
+
+			solution, err := s.Install([]pkg.Package{A})
+			Expect(solution).To(ContainElement(PackageAssert{Package: A.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: B.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: D.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: C.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: H.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: G.IsFlagged(true), Value: true}))
+
+			Expect(len(solution)).To(Equal(6))
+			Expect(err).ToNot(HaveOccurred())
+			solution = solution.Order()
+			Expect(len(solution)).To(Equal(6))
+			Expect(solution[0].Package.GetName()).To(Equal("G"))
+			Expect(solution[1].Package.GetName()).To(Equal("H"))
+			Expect(solution[2].Package.GetName()).To(Equal("D"))
+			Expect(solution[3].Package.GetName()).To(Equal("B"))
+
+			hash := solution.AssertionHash()
+
+			solution, err = s.Install([]pkg.Package{B})
+			Expect(solution).To(ContainElement(PackageAssert{Package: B.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: D.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: C.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: H.IsFlagged(true), Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: G.IsFlagged(true), Value: true}))
+
+			Expect(len(solution)).To(Equal(6))
+			Expect(err).ToNot(HaveOccurred())
+			solution = solution.Order()
+			hash2 := solution.AssertionHash()
+
+			Expect(len(solution)).To(Equal(6))
+			Expect(solution[0].Package.GetName()).To(Equal("G"))
+			Expect(solution[1].Package.GetName()).To(Equal("H"))
+			Expect(solution[2].Package.GetName()).To(Equal("D"))
+			Expect(solution[3].Package.GetName()).To(Equal("B"))
+
+			Expect(hash).ToNot(Equal(""))
+			Expect(hash2).ToNot(Equal(""))
+			Expect(hash != hash2).To(BeTrue())
+
+			X := pkg.NewPackage("X", "", []*pkg.DefaultPackage{}, []*pkg.DefaultPackage{})
+			Y := pkg.NewPackage("Y", "", []*pkg.DefaultPackage{X}, []*pkg.DefaultPackage{})
+			Z := pkg.NewPackage("Z", "", []*pkg.DefaultPackage{X}, []*pkg.DefaultPackage{})
+			s = NewSolver([]pkg.Package{}, []pkg.Package{X, Y, Z})
+			solution, err = s.Install([]pkg.Package{Y})
+			Expect(err).ToNot(HaveOccurred())
+
+			solution2, err := s.Install([]pkg.Package{Z})
+			Expect(err).ToNot(HaveOccurred())
+			Expect(solution.Drop(Y).AssertionHash() == solution2.Drop(Z).AssertionHash()).To(BeTrue())
+		})
+
+	})
 })