// Copyright 2014 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 "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.Equals(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, TransformInterleavedPlain),
			c, t)
	})
	allData(func(c Coord) {
		checkTransformer(
			"P2I(I2P(interleaved))",
			CoordToInterleaved,
			compose(TransformInterleavedPlain, TransformPlainToInterleaved),
			c, t)
	})
}