package fog

import "testing"

// blk 造一个块，cells 是块内的 (列, 行) 坐标。
func blk(gx, gy int, cells ...[2]int) Block {
	bm := make([]byte, bitmapSize)
	for _, c := range cells {
		bm[c[1]*8+c[0]/8] |= 0x80 >> (c[0] % 8)
	}
	return Block{GX: gx, GY: gy, Bitmap: bm}
}

func TestDiffEmptyBase(t *testing.T) {
	d := DiffBlocks(nil, []Block{blk(10, 20, [2]int{0, 0}, [2]int{1, 0})})
	if d.CurBlocks != 0 || d.CurCells != 0 {
		t.Fatalf("空库不该有现有数据: %+v", d)
	}
	if d.GainBlocks != 1 || d.GainCells != 2 || d.IncCells != 2 {
		t.Fatalf("空库叠加应为全部新增: %+v", d)
	}
	if d.LostBlocks != 0 || d.LostCells != 0 || !d.Changed() {
		t.Fatalf("空库不该有丢失: %+v", d)
	}
}

func TestDiffIdentical(t *testing.T) {
	cur := []Block{blk(10, 20, [2]int{0, 0}, [2]int{1, 0}), blk(11, 20, [2]int{5, 5})}
	d := DiffBlocks(cur, cur)
	if d.GainCells != 0 || d.Changed() {
		t.Fatalf("同一份快照再叠一次不该有任何新增: %+v", d)
	}
	if d.LostBlocks != 0 || d.LostCells != 0 {
		t.Fatalf("同一份快照不该有可丢的部分: %+v", d)
	}
	if d.OverlapBlocks != 2 || d.SameBlocks != 2 {
		t.Fatalf("两个块都应算作「重叠且无变化」: %+v", d)
	}
}

func TestDiffOverlapGain(t *testing.T) {
	d := DiffBlocks(
		[]Block{blk(10, 20, [2]int{0, 0})},
		[]Block{blk(10, 20, [2]int{0, 0}, [2]int{3, 4})})
	if d.GainBlocks != 0 || d.GainCells != 1 {
		t.Fatalf("重叠块应只补亮多出的那一格: %+v", d)
	}
	if d.OverlapBlocks != 1 || d.SameBlocks != 0 {
		t.Fatalf("重叠但补亮了，不该记为无变化: %+v", d)
	}
	if d.LostBlocks != 0 {
		t.Fatalf("同一个块不该被判为会丢失: %+v", d)
	}
}

func TestDiffDisjoint(t *testing.T) {
	d := DiffBlocks(
		[]Block{blk(10, 20, [2]int{0, 0})},
		[]Block{blk(30, 40, [2]int{1, 1})})
	if d.GainBlocks != 1 || d.GainCells != 1 {
		t.Fatalf("另一块应是新增: %+v", d)
	}
	if d.LostBlocks != 1 || d.LostCells != 1 {
		t.Fatalf("库里那块在快照里没有，整体替换会丢掉: %+v", d)
	}
}

// 面积按块中心纬度做 cos 修正，越靠近两极越小；总量关系也要自洽。
func TestDiffAreas(t *testing.T) {
	equator := DiffBlocks(nil, []Block{blk(100, WorldCells/BlockCells/2, [2]int{1, 1})})
	high := DiffBlocks(nil, []Block{blk(100, 20000, [2]int{1, 1})})
	if high.GainAreaKm2() <= 0 {
		t.Fatalf("高纬单格面积应为正: %v", high.GainAreaKm2())
	}
	if !(equator.GainAreaKm2() > high.GainAreaKm2()) {
		t.Fatalf("赤道单格应大于高纬: %v vs %v", equator.GainAreaKm2(), high.GainAreaKm2())
	}

	m := DiffBlocks(
		[]Block{blk(10, 20, [2]int{0, 0})},
		[]Block{blk(10, 20, [2]int{0, 0}, [2]int{9, 9})})
	if diff := m.MergeAreaKm2() - (m.CurAreaKm2() + m.GainAreaKm2()); diff > 1e-12 || diff < -1e-12 {
		t.Fatalf("叠加后总量应等于现有加新增: %v", diff)
	}
	if m.CoverAreaKm2() != m.IncAreaKm2() {
		t.Fatalf("整体替换后总量应等于快照本身: %v vs %v", m.CoverAreaKm2(), m.IncAreaKm2())
	}
}