// Copyright 2014, 2015 by Sascha L. Teichmann
// Use of this source code is governed by the MIT license
// that can be found in the LICENSE file.

package common

import (
	"math/rand"
	"testing"
)

var data = []int16{
	-2045, -1850, -1811, -1629, -1104,
	-967, -725, -646, -329, -212,
	-150, -1, 0, 1, 88, 524, 527, 549,
	1783, 1817, 1826, 2028, 2032}

func allData(f func(Coord)) {
	for _, z := range data {
		for _, y := range data {
			for _, x := range data {
				f(Coord{X: x, Y: y, Z: z})
			}
		}
	}
}

func checkEncodeDecode(
	desc string,
	join KeyJoiner,
	encode KeyEncoder, decode KeyDecoder,
	c Coord, t *testing.T) {

	k1 := join(c)
	var err error
	var b []byte
	if b, err = encode(k1); err != nil {
		t.Errorf("%s: Failed to encode %s %s\n", desc, c, err)
		return
	}
	var k2 int64
	if k2, err = decode(b); err != nil {
		t.Errorf("%s: Failed to decode %s %s\n", desc, c, err)
		return
	}

	if k1 != k2 {
		t.Errorf("%s: Expected %d got %d for %s\n", desc, k1, k2, c)
	}
}

func TestEncodeDecode(t *testing.T) {
	allData(func(c Coord) {
		checkEncodeDecode(
			"Big endian - interleaved",
			CoordToInterleaved,
			EncodeToBigEndian, DecodeFromBigEndian,
			c, t)
	})
	allData(func(c Coord) {
		checkEncodeDecode(
			"String - interleaved",
			CoordToInterleaved,
			EncodeStringToBytes, DecodeStringFromBytes,
			c, t)
	})
	allData(func(c Coord) {
		checkEncodeDecode(
			"Big endian - plain",
			CoordToPlain,
			EncodeToBigEndian, DecodeFromBigEndian,
			c, t)
	})
	allData(func(c Coord) {
		checkEncodeDecode(
			"String - plain",
			CoordToPlain,
			EncodeStringToBytes, DecodeStringFromBytes,
			c, t)
	})
}

func checkJoinSplit(
	desc string,
	join KeyJoiner, split KeySplitter,
	c Coord, t *testing.T) {

	k := join(c)
	s := split(k)
	if s != c {
		t.Errorf("%s: Expected %s got %s %b\n", desc, c, s, k)
	}
}

func TestJoinSplit(t *testing.T) {
	allData(func(c Coord) {
		checkJoinSplit(
			"P2C(C2P(xyz))",
			CoordToPlain, PlainToCoord,
			c, t)
	})
	allData(func(c Coord) {
		checkJoinSplit(
			"I2C(C2I(xyz))",
			CoordToInterleaved, InterleavedToCoord,
			c, t)
	})
}

func checkTransformer(
	desc string, joiner KeyJoiner,
	transform KeyTransformer,
	c Coord, t *testing.T) {

	k1 := joiner(c)
	k2 := transform(k1)
	if k2 != k1 {
		t.Errorf("%s: Expected %v got %v for %s\n", desc, k1, k2, c)
	}
}

func compose(transforms ...KeyTransformer) KeyTransformer {
	return func(x int64) int64 {
		for _, transform := range transforms {
			x = transform(x)
		}
		return x
	}
}

func TestTransforms(t *testing.T) {
	// Mainly to check the test itself.
	allData(func(c Coord) {
		checkTransformer(
			"plain",
			CoordToPlain,
			compose(),
			c, t)
	})
	allData(func(c Coord) {
		checkTransformer(
			"I2P(P2I(plain))",
			CoordToPlain,
			compose(TransformPlainToInterleaved, TransformInterleavedToPlain),
			c, t)
	})
	allData(func(c Coord) {
		checkTransformer(
			"P2I(I2P(interleaved))",
			CoordToInterleaved,
			compose(TransformInterleavedToPlain, TransformPlainToInterleaved),
			c, t)
	})
}

func TestCoordInterleaving(t *testing.T) {
	allData(func(c Coord) {
		d := InterleavedToCoord(CoordToInterleaved(c))
		if c != d {
			t.Errorf("Expected %v got %v\n", c, d)
		}
	})
}

func outsiders(zmin, zmax int64, fn func(int64)) {

	c1 := InterleavedToCoord(zmin)
	c2 := InterleavedToCoord(zmax)
	cub := Cuboid{P1: c1, P2: c2}
	var c Coord
	for c.X = c1.X; c.X <= c2.X; c.X++ {
		for c.Y = c1.Y; c.Y <= c2.Y; c.Y++ {
			for c.Z = c1.Z; c.Z <= c2.Z; c.Z++ {
				zn := CoordToInterleaved(c) + 1
				if zn > zmin && zn < zmax && !cub.Contains(InterleavedToCoord(zn)) {
					fn(zn)
				}
			}
		}
	}
}

func TestBigMin(t *testing.T) {
	const tries = 20
	for i := 0; i < tries; i++ {
		x1 := rand.Intn(4000) - 2000
		y1 := rand.Intn(4000) - 2000
		z1 := rand.Intn(4000) - 2000
		w := rand.Intn(18) + 1
		h := rand.Intn(18) + 1
		d := rand.Intn(18) + 1
		x2 := x1 + w
		y2 := y1 + h
		z2 := z1 + d

		c1 := Coord{X: int16(x1), Y: int16(y1), Z: int16(z1)}
		c2 := Coord{X: int16(x2), Y: int16(y2), Z: int16(z2)}

		zmin := CoordToInterleaved(c1)
		zmax := CoordToInterleaved(c2)

		if zmin > zmax {
			t.Errorf("zmin > zmax: %d > %d\n", zmin, zmax)
		}

		errors, success := 0, 0
		outsiders(zmin, zmax, func(zcode int64) {
			nbm := NaiveBigMin(zmin, zmax, zcode)
			cbm := BigMin(zmin, zmax, zcode)
			//fmt.Printf("nbm: %b\n", nbm)
			//fmt.Printf("cbm: %b\n", cbm)
			if nbm != cbm {
				errors++
			} else {
				success++
			}
		})
		if errors > 0 {
			cub := Cuboid{P1: c1, P2: c2}
			t.Errorf("BigMin: %s (%d %d) %d errors out of %d (%f)\n",
				cub,
				zmin, zmax,
				errors, errors+success,
				float64(errors)/float64(errors+success))
		}
	}
}