package ds

import "testing"

func TestBSTInsertInOrder(t *testing.T) {
	tree := NewBST[int]()
	vals := []int{5, 3, 8, 1, 4, 7, 9}
	for _, v := range vals {
		tree.Insert(v)
	}
	got := tree.InOrder()
	want := []int{1, 3, 4, 5, 7, 8, 9}
	if len(got) != len(want) {
		t.Fatalf("InOrder 长度 = %d, want %d", len(got), len(want))
	}
	for i := range want {
		if got[i] != want[i] {
			t.Fatalf("InOrder[%d] = %d, want %d", i, got[i], want[i])
		}
	}
}

func TestBSTSearch(t *testing.T) {
	tree := NewBST[int]()
	for _, v := range []int{5, 3, 8, 1} {
		tree.Insert(v)
	}
	if !tree.Search(3) {
		t.Fatal("Search(3) 应为 true")
	}
	if tree.Search(99) {
		t.Fatal("Search(99) 应为 false")
	}
	if tree.Search(0) {
		t.Fatal("Search(0) 应为 false")
	}
}

func TestBSTTraversals(t *testing.T) {
	tree := NewBST[int]()
	// 构造:
	//        4
	//       / \
	//      2   6
	//     / \ / \
	//    1  3 5  7
	for _, v := range []int{4, 2, 6, 1, 3, 5, 7} {
		tree.Insert(v)
	}
	pre := tree.PreOrder()
	wantPre := []int{4, 2, 1, 3, 6, 5, 7}
	for i := range wantPre {
		if pre[i] != wantPre[i] {
			t.Fatalf("PreOrder[%d] = %d, want %d", i, pre[i], wantPre[i])
		}
	}
	post := tree.PostOrder()
	wantPost := []int{1, 3, 2, 5, 7, 6, 4}
	for i := range wantPost {
		if post[i] != wantPost[i] {
			t.Fatalf("PostOrder[%d] = %d, want %d", i, post[i], wantPost[i])
		}
	}
	lvl := tree.LevelOrder()
	wantLvl := []int{4, 2, 6, 1, 3, 5, 7}
	for i := range wantLvl {
		if lvl[i] != wantLvl[i] {
			t.Fatalf("LevelOrder[%d] = %d, want %d", i, lvl[i], wantLvl[i])
		}
	}
	dfs := tree.DFS()
	// DFS 迭代版是前序,应与 PreOrder 相同
	for i := range wantPre {
		if dfs[i] != wantPre[i] {
			t.Fatalf("DFS[%d] = %d, want %d", i, dfs[i], wantPre[i])
		}
	}
}

func TestBSTHeightAndEmpty(t *testing.T) {
	tree := NewBST[int]()
	if tree.Height() != 0 {
		t.Fatal("空树高度应为 0")
	}
	tree.Insert(1)
	if tree.Height() != 1 {
		t.Fatal("单节点高度应为 1")
	}
	tree.Insert(2)
	tree.Insert(3)
	// 退化为链表,高度 3
	if tree.Height() != 3 {
		t.Fatalf("Height = %d, want 3 (退化链表)", tree.Height())
	}
}