func TestRemoveQuad(t *testing.T) {
	qs, w, _ := makeTestStore(simpleGraph)

	err := w.RemoveQuad(quad.Quad{
		Subject:   "E",
		Predicate: "follows",
		Object:    "F",
		Label:     "",
	})

	if err != nil {
		t.Error("Couldn't remove quad", err)
	}

	fixed := qs.FixedIterator()
	fixed.Add(qs.ValueOf("E"))

	fixed2 := qs.FixedIterator()
	fixed2.Add(qs.ValueOf("follows"))

	innerAnd := iterator.NewAnd(qs)
	innerAnd.AddSubIterator(iterator.NewLinksTo(qs, fixed, quad.Subject))
	innerAnd.AddSubIterator(iterator.NewLinksTo(qs, fixed2, quad.Predicate))

	hasa := iterator.NewHasA(qs, innerAnd, quad.Object)

	newIt, _ := hasa.Optimize()
	if graph.Next(newIt) {
		t.Error("E should not have any followers.")
	}
}

func buildSave(
	qs graph.QuadStore, via interface{},
	tag string, from graph.Iterator, reverse bool, optional bool,
) graph.Iterator {

	allNodes := qs.NodesAllIterator()
	allNodes.Tagger().Add(tag)

	start, goal := quad.Subject, quad.Object
	if reverse {
		start, goal = goal, start
	}
	viaIter := buildViaPath(qs, via).
		BuildIterator()

	dest := iterator.NewLinksTo(qs, allNodes, goal)
	trail := iterator.NewLinksTo(qs, viaIter, quad.Predicate)

	route := join(qs, trail, dest)
	save := graph.Iterator(iterator.NewHasA(qs, route, start))

	if optional {
		save = iterator.NewOptional(save)
	}
	return join(qs, from, save)
}

func TestIteratorsAndNextResultOrderA(t *testing.T) {
	clog.Infof("\n-----------\n")
	inst, opts, err := createInstance()
	defer inst.Close()

	if err != nil {
		t.Fatalf("failed to create instance: %v", err)
	}
	qs, _, _ := makeTestStore(simpleGraph, opts)
	if qs.Size() != 11 {
		t.Fatal("Incorrect number of quads")
	}

	fixed := qs.FixedIterator()
	fixed.Add(qs.ValueOf("C"))

	fixed2 := qs.FixedIterator()
	fixed2.Add(qs.ValueOf("follows"))

	all := qs.NodesAllIterator()

	innerAnd := iterator.NewAnd(qs)
	innerAnd.AddSubIterator(iterator.NewLinksTo(qs, fixed2, quad.Predicate))
	innerAnd.AddSubIterator(iterator.NewLinksTo(qs, all, quad.Object))

	hasa := iterator.NewHasA(qs, innerAnd, quad.Subject)
	outerAnd := iterator.NewAnd(qs)
	outerAnd.AddSubIterator(fixed)
	outerAnd.AddSubIterator(hasa)

	if !outerAnd.Next() {
		t.Error("Expected one matching subtree")
	}
	val := outerAnd.Result()
	if qs.NameOf(val) != "C" {
		t.Errorf("Matching subtree should be %s, got %s", "barak", qs.NameOf(val))
	}

	var (
		got    []string
		expect = []string{"B", "D"}
	)
	for {
		got = append(got, qs.NameOf(all.Result()))
		if !outerAnd.NextPath() {
			break
		}
	}
	sort.Strings(got)

	if !reflect.DeepEqual(got, expect) {
		t.Errorf("Unexpected result, got:%q expect:%q", got, expect)
	}

	if outerAnd.Next() {
		t.Error("More than one possible top level output?")
	}
}

func TestLinksToOptimization(t *testing.T) {
	qs, _, _ := makeTestStore(simpleGraph)

	fixed := qs.FixedIterator()
	fixed.Add(qs.ValueOf("cool"))

	lto := iterator.NewLinksTo(qs, fixed, quad.Object)
	lto.Tagger().Add("foo")

	newIt, changed := lto.Optimize()
	if !changed {
		t.Error("Iterator didn't change")
	}
	if newIt.Type() != Type() {
		t.Fatal("Didn't swap out to LLRB")
	}

	v := newIt.(*Iterator)
	vClone := v.Clone()
	origDesc := v.Describe()
	cloneDesc := vClone.Describe()
	origDesc.UID, cloneDesc.UID = 0, 0 // We are more strict now, so fake UID equality.
	if !reflect.DeepEqual(cloneDesc, origDesc) {
		t.Fatalf("Unexpected iterator description.\ngot: %#v\nexpect: %#v", cloneDesc, origDesc)
	}
	vt := vClone.Tagger()
	if len(vt.Tags()) < 1 || vt.Tags()[0] != "foo" {
		t.Fatal("Tag on LinksTo did not persist")
	}
}

func TestIteratorsAndNextResultOrderA(t testing.TB, gen DatabaseFunc) {
	qs, opts, closer := gen(t)
	defer closer()

	MakeWriter(t, qs, opts, MakeQuadSet()...)

	require.Equal(t, int64(11), qs.Size(), "Incorrect number of quads")

	fixed := qs.FixedIterator()
	fixed.Add(qs.ValueOf(quad.Raw("C")))

	fixed2 := qs.FixedIterator()
	fixed2.Add(qs.ValueOf(quad.Raw("follows")))

	all := qs.NodesAllIterator()

	innerAnd := iterator.NewAnd(qs)
	innerAnd.AddSubIterator(iterator.NewLinksTo(qs, fixed2, quad.Predicate))
	innerAnd.AddSubIterator(iterator.NewLinksTo(qs, all, quad.Object))

	hasa := iterator.NewHasA(qs, innerAnd, quad.Subject)
	outerAnd := iterator.NewAnd(qs)
	outerAnd.AddSubIterator(fixed)
	outerAnd.AddSubIterator(hasa)

	require.True(t, outerAnd.Next(), "Expected one matching subtree")

	val := outerAnd.Result()
	require.Equal(t, quad.Raw("C"), qs.NameOf(val))

	var (
		got    []string
		expect = []string{"B", "D"}
	)
	for {
		got = append(got, qs.NameOf(all.Result()).String())
		if !outerAnd.NextPath() {
			break
		}
	}
	sort.Strings(got)

	require.Equal(t, expect, got)

	require.True(t, !outerAnd.Next(), "More than one possible top level output?")
}

func buildHas(qs graph.QuadStore, via interface{}, in graph.Iterator, reverse bool, nodes []string) graph.Iterator {
	viaIter := buildViaPath(qs, via).
		BuildIterator()
	ends := func() graph.Iterator {
		if len(nodes) == 0 {
			return qs.NodesAllIterator()
		}

		fixed := qs.FixedIterator()
		for _, n := range nodes {
			fixed.Add(qs.ValueOf(n))
		}
		return fixed
	}()

	start, goal := quad.Subject, quad.Object
	if reverse {
		start, goal = goal, start
	}

	trail := iterator.NewLinksTo(qs, viaIter, quad.Predicate)
	dest := iterator.NewLinksTo(qs, ends, goal)

	// If we were given nodes, intersecting with them first will
	// be extremely cheap-- otherwise, it will be the most expensive
	// (requiring iteration over all nodes). We have enough info to
	// make this optimization now since intersections are commutative
	if len(nodes) == 0 { // Where dest involves an All iterator.
		route := join(qs, trail, dest)
		has := iterator.NewHasA(qs, route, start)
		return join(qs, in, has)
	}

	// This looks backwards. That's OK-- see the note above.
	route := join(qs, dest, trail)
	has := iterator.NewHasA(qs, route, start)
	return join(qs, has, in)
}

func inOutIterator(viaPath *Path, from graph.Iterator, inIterator bool, tags []string, ctx *context) graph.Iterator {
	start, goal := quad.Subject, quad.Object
	if inIterator {
		start, goal = goal, start
	}

	viaIter := viaPath.BuildIterator()
	for _, tag := range tags {
		viaIter.Tagger().Add(tag)
	}

	source := iterator.NewLinksTo(viaPath.qs, from, start)
	trail := iterator.NewLinksTo(viaPath.qs, viaIter, quad.Predicate)
	var label graph.Iterator
	if ctx != nil {
		if ctx.labelSet != nil {
			labeliter := ctx.labelSet.BuildIteratorOn(viaPath.qs)
			label = iterator.NewLinksTo(viaPath.qs, labeliter, quad.Label)
		}
	}
	route := join(viaPath.qs, source, trail, label)

	return iterator.NewHasA(viaPath.qs, route, goal)
}

func TestOptimize(t *testing.T) {
	tmpDir, _ := ioutil.TempDir(os.TempDir(), "cayley_test")
	t.Log(tmpDir)
	defer os.RemoveAll(tmpDir)
	err := createNewLevelDB(tmpDir, nil)
	if err != nil {
		t.Fatalf("Failed to create working directory")
	}
	qs, err := newQuadStore(tmpDir, nil)
	if qs == nil || err != nil {
		t.Error("Failed to create leveldb QuadStore.")
	}

	w, _ := writer.NewSingleReplication(qs, nil)
	w.AddQuadSet(makeQuadSet())

	// With an linksto-fixed pair
	fixed := qs.FixedIterator()
	fixed.Add(qs.ValueOf("F"))
	fixed.Tagger().Add("internal")
	lto := iterator.NewLinksTo(qs, fixed, quad.Object)

	oldIt := lto.Clone()
	newIt, ok := lto.Optimize()
	if !ok {
		t.Errorf("Failed to optimize iterator")
	}
	if newIt.Type() != Type() {
		t.Errorf("Optimized iterator type does not match original, got:%v expect:%v", newIt.Type(), Type())
	}

	newQuads := iteratedQuads(qs, newIt)
	oldQuads := iteratedQuads(qs, oldIt)
	if !reflect.DeepEqual(newQuads, oldQuads) {
		t.Errorf("Optimized iteration does not match original")
	}

	graph.Next(oldIt)
	oldResults := make(map[string]graph.Value)
	oldIt.TagResults(oldResults)
	graph.Next(newIt)
	newResults := make(map[string]graph.Value)
	newIt.TagResults(newResults)
	if !reflect.DeepEqual(newResults, oldResults) {
		t.Errorf("Discordant tag results, new:%v old:%v", newResults, oldResults)
	}
}

// predicatesMorphism iterates to the uniqified set of predicates from
// the given set of nodes in the path.
func predicatesMorphism(isIn bool) morphism {
	m := morphism{
		Name: "out_predicates",
		Reversal: func(ctx *context) (morphism, *context) {
			panic("not implemented: need a function from predicates to their associated edges")
		},
		Apply: func(qs graph.QuadStore, in graph.Iterator, ctx *context) (graph.Iterator, *context) {
			dir := quad.Subject
			if isIn {
				dir = quad.Object
			}
			lto := iterator.NewLinksTo(qs, in, dir)
			hasa := iterator.NewHasA(qs, lto, quad.Predicate)
			return iterator.NewUnique(hasa), ctx
		},
	}
	if isIn {
		m.Name = "in_predicates"
	}
	return m
}

func TestOptimize(t *testing.T) {
	qs, opts, closer := makeBolt(t)
	defer closer()

	graphtest.MakeWriter(t, qs, opts, graphtest.MakeQuadSet()...)

	// With an linksto-fixed pair
	fixed := qs.FixedIterator()
	fixed.Add(qs.ValueOf(quad.Raw("F")))
	fixed.Tagger().Add("internal")
	lto := iterator.NewLinksTo(qs, fixed, quad.Object)

	oldIt := lto.Clone()
	newIt, ok := lto.Optimize()
	if !ok {
		t.Errorf("Failed to optimize iterator")
	}
	if newIt.Type() != Type() {
		t.Errorf("Optimized iterator type does not match original, got:%v expect:%v", newIt.Type(), Type())
	}

	newQuads := graphtest.IteratedQuads(t, qs, newIt)
	oldQuads := graphtest.IteratedQuads(t, qs, oldIt)
	if !reflect.DeepEqual(newQuads, oldQuads) {
		t.Errorf("Optimized iteration does not match original")
	}

	oldIt.Next()
	oldResults := make(map[string]graph.Value)
	oldIt.TagResults(oldResults)
	newIt.Next()
	newResults := make(map[string]graph.Value)
	newIt.TagResults(newResults)
	if !reflect.DeepEqual(newResults, oldResults) {
		t.Errorf("Discordant tag results, new:%v old:%v", newResults, oldResults)
	}
}

func (q *Query) buildIteratorTreeMapInternal(query map[string]interface{}, path Path) (graph.Iterator, error) {
	it := iterator.NewAnd(q.ses.qs)
	it.AddSubIterator(q.ses.qs.NodesAllIterator())
	var err error
	err = nil
	outputStructure := make(map[string]interface{})
	for key, subquery := range query {
		optional := false
		outputStructure[key] = nil
		reverse := false
		pred := key
		if strings.HasPrefix(pred, "@") {
			i := strings.Index(pred, ":")
			if i != -1 {
				pred = pred[(i + 1):]
			}
		}
		if strings.HasPrefix(pred, "!") {
			reverse = true
			pred = strings.TrimPrefix(pred, "!")
		}

		// Other special constructs here
		var subit graph.Iterator
		if key == "id" {
			subit, optional, err = q.buildIteratorTreeInternal(subquery, path.Follow(key))
			if err != nil {
				return nil, err
			}
		} else {
			var builtIt graph.Iterator
			builtIt, optional, err = q.buildIteratorTreeInternal(subquery, path.Follow(key))
			if err != nil {
				return nil, err
			}
			subAnd := iterator.NewAnd(q.ses.qs)
			predFixed := q.ses.qs.FixedIterator()
			predFixed.Add(q.ses.qs.ValueOf(pred))
			subAnd.AddSubIterator(iterator.NewLinksTo(q.ses.qs, predFixed, quad.Predicate))
			if reverse {
				lto := iterator.NewLinksTo(q.ses.qs, builtIt, quad.Subject)
				subAnd.AddSubIterator(lto)
				hasa := iterator.NewHasA(q.ses.qs, subAnd, quad.Object)
				subit = hasa
			} else {
				lto := iterator.NewLinksTo(q.ses.qs, builtIt, quad.Object)
				subAnd.AddSubIterator(lto)
				hasa := iterator.NewHasA(q.ses.qs, subAnd, quad.Subject)
				subit = hasa
			}
		}
		if optional {
			it.AddSubIterator(iterator.NewOptional(subit))
		} else {
			it.AddSubIterator(subit)
		}
	}
	if err != nil {
		return nil, err
	}
	q.queryStructure[path] = outputStructure
	return it, nil
}

func buildIteratorTree(tree *peg.ExpressionTree, qs graph.QuadStore) graph.Iterator {
	switch tree.Name {
	case "Start":
		return buildIteratorTree(tree.Children[0], qs)
	case "NodeIdentifier":
		var out graph.Iterator
		nodeID := getIdentString(tree)
		if tree.Children[0].Name == "Variable" {
			allIt := qs.NodesAllIterator()
			allIt.Tagger().Add(nodeID)
			out = allIt
		} else {
			n := nodeID
			if tree.Children[0].Children[0].Name == "ColonIdentifier" {
				n = nodeID[1:]
			}
			fixed := qs.FixedIterator()
			fixed.Add(qs.ValueOf(n))
			out = fixed
		}
		return out
	case "PredIdentifier":
		i := 0
		if tree.Children[0].Name == "Reverse" {
			//Taken care of below
			i++
		}
		it := buildIteratorTree(tree.Children[i], qs)
		lto := iterator.NewLinksTo(qs, it, quad.Predicate)
		return lto
	case "RootConstraint":
		constraintCount := 0
		and := iterator.NewAnd(qs)
		for _, c := range tree.Children {
			switch c.Name {
			case "NodeIdentifier":
				fallthrough
			case "Constraint":
				it := buildIteratorTree(c, qs)
				and.AddSubIterator(it)
				constraintCount++
				continue
			default:
				continue
			}
		}
		return and
	case "Constraint":
		var hasa *iterator.HasA
		topLevelDir := quad.Subject
		subItDir := quad.Object
		subAnd := iterator.NewAnd(qs)
		isOptional := false
		for _, c := range tree.Children {
			switch c.Name {
			case "PredIdentifier":
				if c.Children[0].Name == "Reverse" {
					topLevelDir = quad.Object
					subItDir = quad.Subject
				}
				it := buildIteratorTree(c, qs)
				subAnd.AddSubIterator(it)
				continue
			case "PredicateKeyword":
				switch c.Children[0].Name {
				case "OptionalKeyword":
					isOptional = true
				}
			case "NodeIdentifier":
				fallthrough
			case "RootConstraint":
				it := buildIteratorTree(c, qs)
				l := iterator.NewLinksTo(qs, it, subItDir)
				subAnd.AddSubIterator(l)
				continue
			default:
				continue
			}
		}
		hasa = iterator.NewHasA(qs, subAnd, topLevelDir)
		if isOptional {
			optional := iterator.NewOptional(hasa)
			return optional
		}
		return hasa
	default:
		return &iterator.Null{}
	}
}