// Copyright 2016 Google Inc. All rights reserved.
//
// 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 s2

import (
	"testing"

	"github.com/golang/geo/r3"
	"github.com/golang/geo/s1"
)

func TestShapeIndexBasics(t *testing.T) {
	index := NewShapeIndex()
	s := &edgeVectorShape{}

	if index.Len() != 0 {
		t.Errorf("initial index should be empty after creation")
	}
	index.Add(s)

	if index.Len() == 0 {
		t.Errorf("index should not be empty after adding shape")
	}

	index.Reset()
	if index.Len() != 0 {
		t.Errorf("index should be empty after reset, got %v %+v", index.Len(), index)
	}
}

func TestShapeEdgeComparisons(t *testing.T) {
	tests := []struct {
		a, b Edge
		want int
	}{
		{
			// a.V0 < b.V0
			a:    Edge{PointFromCoords(-1, 0, 0), PointFromCoords(0, 0, 0)},
			b:    Edge{PointFromCoords(0, 0, 0), PointFromCoords(0, 0, 0)},
			want: -1,
		},
		{
			// a.V0 = b.V0
			a:    Edge{PointFromCoords(0, 2, 0), PointFromCoords(0, 0, 5)},
			b:    Edge{PointFromCoords(0, 2, 0), PointFromCoords(0, 0, 5)},
			want: 0,
		},
		{
			// a.V0 > b.V0
			a:    Edge{PointFromCoords(1, 0, 0), PointFromCoords(-6, 7, 8)},
			b:    Edge{PointFromCoords(0, 0, 0), PointFromCoords(1, 3, 5)},
			want: 1,
		},
		{
			// a.V0 = b.V0 && a.V1 < b.V1
			a:    Edge{PointFromCoords(5, -2, -0.4), PointFromCoords(-1, 0, 0)},
			b:    Edge{PointFromCoords(5, -2, -0.4), PointFromCoords(0, -1, -1)},
			want: -1,
		},
		{
			// a.V0 = b.V0 && a.V1 = b.V1
			a:    Edge{PointFromCoords(9, 8, 7), PointFromCoords(12, 3, -4)},
			b:    Edge{PointFromCoords(9, 8, 7), PointFromCoords(12, 3, -4)},
			want: 0,
		},
		{
			// a.V0 = b.V0 && a.V1 > b.V1
			a:    Edge{PointFromCoords(-11, 7.2, -4.6), PointFromCoords(0, 1, 0)},
			b:    Edge{PointFromCoords(-11, 7.2, -4.6), PointFromCoords(0, 0, 0.9)},
			want: 1,
		},
	}

	for _, test := range tests {
		if got := test.a.Cmp(test.b); got != test.want {
			t.Errorf("%v.Cmp(%v) = %v, want %v", test.a, test.b, got, test.want)
		}
	}
}

func TestShapeIndexCellBasics(t *testing.T) {
	s := &ShapeIndexCell{}

	if len(s.shapes) != 0 {
		t.Errorf("len(s.shapes) = %v, want %d", len(s.shapes), 0)
	}

	// create some clipped shapes to add.
	c1 := &clippedShape{}
	s.add(c1)

	c2 := newClippedShape(7, 1)
	s.add(c2)

	c3 := &clippedShape{}
	s.add(c3)

	// look up the element at a given index
	if got := s.shapes[1]; got != c2 {
		t.Errorf("%v.shapes[%d] = %v, want %v", s, 1, got, c2)
	}

	// look for the clipped shape that is part of the given shape.
	if got := s.findByShapeID(7); got != c2 {
		t.Errorf("%v.findByShapeID(%v) = %v, want %v", s, 7, got, c2)
	}
}

// validateEdge determines whether or not the edge defined by points A and B should be
// present in that CellID and verify that this matches hasEdge.
func validateEdge(t *testing.T, a, b Point, ci CellID, hasEdge bool) {
	// Expand or shrink the padding slightly to account for errors in the
	// function we use to test for intersection (IntersectsRect).
	padding := cellPadding
	sign := 1.0
	if !hasEdge {
		sign = -1
	}
	padding += sign * intersectsRectErrorUVDist
	bound := ci.boundUV().ExpandedByMargin(padding)
	aUV, bUV, ok := ClipToPaddedFace(a, b, ci.Face(), padding)

	if got := ok && edgeIntersectsRect(aUV, bUV, bound); got != hasEdge {
		t.Errorf("edgeIntersectsRect(%v, %v, %v) = %v && clip = %v, want %v", aUV, bUV, bound, edgeIntersectsRect(aUV, bUV, bound), ok, hasEdge)
	}
}

// validateInterior tests if the given Shape contains the center of the given CellID,
// and that this matches the expected value of indexContainsCenter.
func validateInterior(t *testing.T, shape Shape, ci CellID, indexContainsCenter bool) {
	if shape == nil {
		if indexContainsCenter {
			t.Errorf("%v was nil or does not have an interior, but should have", shape)
		}
		return
	}
	if got := containsBruteForce(shape, ci.Point()); got != indexContainsCenter {
		t.Errorf("validating interior of shape containsCenter = %v, want %v", got, indexContainsCenter)
	}
}

// quadraticValidate verifies that that every cell of the index contains the correct
// edges, and that no cells are missing from the index.  The running time of this
// function is quadratic in the number of edges.
func quadraticValidate(t *testing.T, index *ShapeIndex) {
	// Iterate through a sequence of nonoverlapping cell ids that cover the
	// sphere and include as a subset all the cell ids used in the index.  For
	// each cell id, verify that the expected set of edges is present.
	// "minCellID" is the first CellID that has not been validated yet.
	minCellID := CellIDFromFace(0).ChildBeginAtLevel(MaxLevel)
	for it := index.Iterator(); ; it.Next() {
		// Generate a list of CellIDs ("skipped cells") that cover the gap
		// between the last cell we validated and the next cell in the index.
		var skipped CellUnion
		if !it.Done() {
			cellID := it.CellID()
			if cellID < minCellID {
				t.Errorf("cell ID below min, got %v, want %v", cellID, minCellID)
			}
			skipped = CellUnionFromRange(minCellID, cellID.RangeMin())
			minCellID = cellID.RangeMax().Next()
		} else {
			// Validate the empty cells beyond the last cell in the index.
			skipped = CellUnionFromRange(minCellID,
				CellIDFromFace(5).ChildEndAtLevel(MaxLevel))
		}

		// Iterate through all the shapes, simultaneously validating the current
		// index cell and all the skipped cells.
		shortEdges := 0 // number of edges counted toward subdivision
		for id, shape := range index.shapes {
			for j := 0; j < len(skipped); j++ {
				validateInterior(t, shape, skipped[j], false)
			}

			// First check that containsCenter() is set correctly.
			var clipped *clippedShape
			if !it.Done() {
				clipped = it.IndexCell().findByShapeID(id)
				containsCenter := clipped != nil && clipped.containsCenter
				validateInterior(t, shape, it.CellID(), containsCenter)
			}
			// If this shape has been removed, it should not be present at all.
			if shape == nil {
				if clipped != nil {
					t.Errorf("clipped should be nil when shape is nil")
				}
				continue
			}

			// Otherwise check that the appropriate edges are present.
			for e := 0; e < shape.NumEdges(); e++ {
				edge := shape.Edge(e)
				for j := 0; j < len(skipped); j++ {
					validateEdge(t, edge.V0, edge.V1, skipped[j], false)
				}
				if !it.Done() {
					hasEdge := clipped != nil && clipped.containsEdge(e)
					validateEdge(t, edge.V0, edge.V1, it.CellID(), hasEdge)
					if hasEdge && it.CellID().Level() < maxLevelForEdge(edge) {
						shortEdges++
					}
				}
			}
		}

		if shortEdges > index.maxEdgesPerCell {
			t.Errorf("too many edges")
		}

		if it.Done() {
			break
		}
	}
}

// copyIterator copies the internal state of the given iterator to a new iterator.
func copyIterator(i *ShapeIndexIterator) *ShapeIndexIterator {
	s := &ShapeIndexIterator{
		index:    i.index,
		position: i.position,
		id:       i.id,
		cell:     i.cell,
	}
	return s
}

func testIteratorMethods(t *testing.T, index *ShapeIndex) {
	it := index.Iterator()
	if it.Prev() {
		t.Fatalf("new iterator should not be able to go backwards")
	}

	it.End()
	if !it.Done() {
		t.Errorf("iterator positioned at end should report as done")
	}

	var ids []CellID
	// minCellID is the first CellID in a complete traversal.
	minCellID := CellIDFromFace(0).ChildBeginAtLevel(MaxLevel)

	for it.Begin(); !it.Done(); it.Next() {
		// Get the next cell in the iterator.
		ci := it.CellID()
		skipped := CellUnionFromRange(minCellID, ci.RangeMin())

		it2 := NewShapeIndexIterator(index, IteratorEnd)
		for i := 0; i < len(skipped); i++ {
			if it2.LocatePoint(skipped[i].Point()) {
				t.Errorf("iterator should not have been able to find the cell %v which was not in the index", skipped[i].Point())
			}

			if got := it2.LocateCellID(skipped[i]); got != Disjoint {
				t.Errorf("CellID location should be Disjoint for non-existent entry, got %v", got)
			}
			it2.Begin()
			it2.seek(skipped[i])
			if ci != it2.CellID() {
				t.Errorf("seeking the current cell in the skipped list should match the current cellid. got %v, want %v", it2.CellID(), ci)
			}
		}

		if len(ids) != 0 {
			prevCell := ids[len(ids)-1]
			// C++ overloads operator= to clone the iterator. We can't
			// just assign directly since it2 will than change it when
			// it should not.
			it2 = copyIterator(it)
			if !it2.Prev() {
				t.Errorf("should have been able to go back because there are cells")
			}
			if prevCell != it2.CellID() {
				t.Errorf("ShapeIndexIterator should be positioned at the beginning and not equal to last entry")
			}

			it2.Next()
			if ci != it2.CellID() {
				t.Errorf("advancing back one spot should give us the current cell")
			}

			it2.seek(prevCell)
			if prevCell != it2.CellID() {
				t.Errorf("seek from beginning for the first previous cell %v should not give us the current cell %v", prevCell, it.CellID())
			}
		}

		it2.Begin()
		if ci.Point() != it.Center() {
			t.Errorf("point at center of current position should equal center of the crrent CellID. got %v, want %v", it.Center(), ci.Point())
		}

		if !it2.LocatePoint(it.Center()) {
			t.Errorf("it.LocatePoint(it.Center()) should have been able to locate the point it is currently at")
		}

		if ci != it2.CellID() {
			t.Errorf("CellID of the Point we just located should be equal. got %v, want %v", it2.CellID(), ci)
		}

		it2.Begin()
		if got := it2.LocateCellID(ci); got != Indexed {
			t.Errorf("it.LocateCellID(%v) = %v, want %v", ci, got, Indexed)
		}

		if ci != it2.CellID() {
			t.Errorf("CellID of the CellID we just located should match. got %v, want %v", it2.CellID(), ci)
		}

		if !ci.isFace() {
			it2.Begin()
			if got := it2.LocateCellID(ci.immediateParent()); Subdivided != got {
				t.Errorf("it2.LocateCellID(%v) = %v, want %v", ci.immediateParent(), got, Subdivided)
			}

			if it2.CellID() > ci {
				t.Errorf("CellID of the immediate parent should be above the current cell, got %v, want %v", it2.CellID(), ci)
			}

			if it2.CellID() < ci.immediateParent().RangeMin() {
				t.Errorf("CellID of the current position should fall below the RangeMin of the parent. got %v, want %v", it2.CellID(), ci.immediateParent().RangeMin())
			}
		}

		if !ci.IsLeaf() {
			for i := 0; i < 4; i++ {
				it2.Begin()
				if got, want := it2.LocateCellID(ci.Children()[i]), Indexed; got != want {
					t.Errorf("it2.LocateCellID(%v.Children[%d]) = %v, want %v", ci, i, got, want)
				}

				if ci != it2.CellID() {
					t.Errorf("it2.CellID() = %v, want %v", it2.CellID(), ci)
				}
			}
		}
		// Add this cellID to the set of cells to examine.
		ids = append(ids, ci)
		// Move the minimal CellID to the next CellID past our current position.
		minCellID = ci.RangeMax().Next()
	}
}

func TestShapeIndexNoEdges(t *testing.T) {
	index := NewShapeIndex()
	iter := index.Iterator()

	if !iter.Done() {
		t.Errorf("iterator for empty index should start at Done but did not")
	}
	testIteratorMethods(t, index)
}

func TestShapeIndexOneEdge(t *testing.T) {
	index := NewShapeIndex()
	e := edgeVectorShapeFromPoints(PointFromCoords(1, 0, 0), PointFromCoords(0, 1, 0))
	if got := index.Add(e); got != 0 {
		t.Errorf("the first element added to the index should have id 0, got %v", got)
	}
	quadraticValidate(t, index)
	testIteratorMethods(t, index)
}

func TestShapeIndexManyIdenticalEdges(t *testing.T) {
	const numEdges = 100
	a := PointFromCoords(0.99, 0.99, 1)
	b := PointFromCoords(-0.99, -0.99, 1)

	index := NewShapeIndex()
	for i := int32(0); i < numEdges; i++ {
		if got := index.Add(edgeVectorShapeFromPoints(a, b)); got != i {
			t.Errorf("element %d id = %v, want %v", i, got, i)
		}
	}
	quadraticValidate(t, index)
	testIteratorMethods(t, index)

	// Since all edges span the diagonal of a face, no subdivision should
	// have occurred (with the default index options).
	for it := index.Iterator(); !it.Done(); it.Next() {
		if it.CellID().Level() != 0 {
			t.Errorf("it.CellID.Level() = %v, want nonzero", it.CellID().Level())
		}
	}
}

func TestShapeIndexDegenerateEdge(t *testing.T) {
	// This test verifies that degenerate edges are supported.  The following
	// point is a cube face vertex, and so it should be indexed in 3 cells.
	a := PointFromCoords(1, 1, 1)
	shape := edgeVectorShapeFromPoints(a, a)
	index := NewShapeIndex()
	index.Add(shape)
	quadraticValidate(t, index)
	// Check that exactly 3 index cells contain the degenerate edge.
	count := 0
	for it := index.Iterator(); !it.Done(); it.Next() {
		if !it.CellID().IsLeaf() {
			t.Errorf("the cell for this shape should be a leaf cell.")
		}
		if got := len(it.IndexCell().shapes); got != 1 {
			t.Errorf("there should only be one shape stored in the index cell, got %d", got)
		}
		if got := len(it.IndexCell().shapes[0].edges); got != 1 {
			t.Errorf("point should only have one edge, got %d", got)
		}
		count++
	}
	if count != 3 {
		t.Errorf("expected 3 index cells, got %d", count)
	}

}

func TestShapeIndexManyTinyEdges(t *testing.T) {
	// This test adds many edges to a single leaf cell, to check that
	// subdivision stops when no further subdivision is possible.

	// Construct two points in the same leaf cell.
	a := cellIDFromPoint(PointFromCoords(1, 0, 0)).Point()
	b := Point{a.Add(r3.Vector{0, 1e-12, 0}).Normalize()}
	shape := &edgeVectorShape{}
	for i := 0; i < 100; i++ {
		shape.Add(a, b)
	}

	index := NewShapeIndex()
	index.Add(shape)
	quadraticValidate(t, index)

	// Check that there is exactly one index cell and that it is a leaf cell.
	it := index.Iterator()
	if it.Done() {
		t.Errorf("ShapeIndexIterator should not be positioned at the end for %v", index)
		return
	}
	if !(it.CellID().IsLeaf()) {
		t.Errorf("there should be only one leaf cell in the index but it.CellID().IsLeaf() returned false")
	}
	it.Next()
	if !(it.Done()) {
		t.Errorf("ShapeIndexIterator should be positioned at the end now since there should have been only one element")
	}
}

func TestShapeIndexShrinkToFitOptimization(t *testing.T) {
	// This used to trigger a bug in the ShrinkToFit optimization. The loop
	// below contains almost all of face 0 except for a small region in the
	// 0/00000 subcell. That subcell is the only one that contains any edges.
	// This caused the index to be built only in that subcell. However, all the
	// other cells on that face should also have index entries, in order to
	// indicate that they are contained by the loop.
	loop := RegularLoop(PointFromCoords(1, 0.5, 0.5), s1.Degree*89, 100)
	index := NewShapeIndex()
	index.Add(loop)
	quadraticValidate(t, index)
}

func TestShapeIndexMixedGeometry(t *testing.T) {
	// This test used to trigger a bug where the presence of a shape with an
	// interior could cause shapes that don't have an interior to suddenly
	// acquire one. This would cause extra ShapeIndex cells to be created
	// that are outside the bounds of the given geometry.
	index := NewShapeIndex()
	index.Add(makePolyline("0:0, 2:1, 0:2, 2:3, 0:4, 2:5, 0:6"))
	index.Add(makePolyline("1:0, 3:1, 1:2, 3:3, 1:4, 3:5, 1:6"))
	index.Add(makePolyline("2:0, 4:1, 2:2, 4:3, 2:4, 4:5, 2:6"))

	loop := LoopFromCell(CellFromCellID(CellIDFromFace(0).ChildBeginAtLevel(MaxLevel)))
	index.Add(loop)
	it := index.Iterator()
	// No geometry intersects face 1, so there should be no index cells there.
	c := CellIDFromFace(1)
	if got, want := it.LocateCellID(c), Disjoint; got != want {
		t.Errorf("%v.LocateCellID(%v) = %v, want %v\n%v", it, c, got, want, index)
	}
}

func TestShapeIndexLoopSpanningThreeFaces(t *testing.T) {
	const numEdges = 100
	// Construct two loops consisting of numEdges vertices each, centered
	// around the cube vertex at the start of the Hilbert curve.
	polygon := concentricLoopsPolygon(PointFromCoords(1, -1, -1), 2, numEdges)
	index := NewShapeIndex()

	for _, l := range polygon.loops {
		index.Add(l)
	}

	quadraticValidate(t, index)
	testIteratorMethods(t, index)
}

func TestShapeIndexNumEdgesUpTo(t *testing.T) {
	index := makeShapeIndex("0:0 | 0:1 | 0:2 | 0:3 | 0:4 # 1:0, 1:1 | 1:2, 1:3 | 1:4, 1:5, 1:6 #")

	if got, want := len(index.shapes), 4; got != want {
		t.Errorf("len(index.shapes) = %v, want %v", got, want)
	}

	numEdgesTests := []struct {
		shapeID int32
		want    int
	}{
		{shapeID: 0, want: 5},
		{shapeID: 1, want: 1},
		{shapeID: 2, want: 1},
		{shapeID: 3, want: 2},
	}

	for _, test := range numEdgesTests {
		if got := index.Shape(test.shapeID).NumEdges(); got != test.want {
			t.Errorf("index.Shape(%d).NumEdges() = %d, want %d", test.shapeID, got, test.want)
		}
	}

	if got, want := index.NumEdges(), 9; got != want {
		t.Errorf("index.NumEdges() = %d, want %d", got, want)
	}

	countTests := []struct {
		limit int
		want  int
	}{
		{limit: 1, want: 5},
		{limit: 5, want: 5},
		{limit: 6, want: 6},
		{limit: 8, want: 9},
	}
	for _, test := range countTests {
		if got := index.NumEdgesUpTo(test.limit); got != test.want {
			t.Errorf("index.NumEdgesUpTo(%d) = %d, want %d", test.limit, got, test.want)
		}
	}
}

// TODO(roberts): Differences from C++:
// TestShapeIndexSimpleUpdates(t *testing.T) {}
// TestShapeIndexRandomUpdates(t *testing.T) {}
// TestShapeIndexHasCrossing(t *testing.T) {}

func BenchmarkShapeIndexIteratorLocatePoint(b *testing.B) {
	index := NewShapeIndex()
	for i := 0; i < 100; i++ {
		var points []Point
		for j := 0; j < 100; j++ {
			points = append(points, randomPoint())
		}
		polyline := Polyline(points)
		index.Add(&polyline)
	}

	it := index.Iterator()
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		it.LocatePoint(randomPoint())
	}
}