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/*  test_list.h                                                          */
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#ifndef TEST_LIST_H
#define TEST_LIST_H

#include "core/templates/list.h"

#include "tests/test_macros.h"

namespace TestList {

static void populate_integers(List<int> &p_list, List<int>::Element *r_elements[], int num_elements) {
	p_list.clear();
	for (int i = 0; i < num_elements; ++i) {
		List<int>::Element *n = p_list.push_back(i);
		r_elements[i] = n;
	}
}

TEST_CASE("[List] Push/pop back") {
	List<String> list;

	List<String>::Element *n;
	n = list.push_back("A");
	CHECK(n->get() == "A");
	n = list.push_back("B");
	CHECK(n->get() == "B");
	n = list.push_back("C");
	CHECK(n->get() == "C");

	CHECK(list.size() == 3);
	CHECK(!list.is_empty());

	String v;
	v = list.back()->get();
	list.pop_back();
	CHECK(v == "C");
	v = list.back()->get();
	list.pop_back();
	CHECK(v == "B");
	v = list.back()->get();
	list.pop_back();
	CHECK(v == "A");

	CHECK(list.size() == 0);
	CHECK(list.is_empty());

	CHECK(list.back() == nullptr);
	CHECK(list.front() == nullptr);
}

TEST_CASE("[List] Push/pop front") {
	List<String> list;

	List<String>::Element *n;
	n = list.push_front("A");
	CHECK(n->get() == "A");
	n = list.push_front("B");
	CHECK(n->get() == "B");
	n = list.push_front("C");
	CHECK(n->get() == "C");

	CHECK(list.size() == 3);
	CHECK(!list.is_empty());

	String v;
	v = list.front()->get();
	list.pop_front();
	CHECK(v == "C");
	v = list.front()->get();
	list.pop_front();
	CHECK(v == "B");
	v = list.front()->get();
	list.pop_front();
	CHECK(v == "A");

	CHECK(list.size() == 0);
	CHECK(list.is_empty());

	CHECK(list.back() == nullptr);
	CHECK(list.front() == nullptr);
}

TEST_CASE("[List] Set and get") {
	List<String> list;
	list.push_back("A");

	List<String>::Element *n = list.front();
	CHECK(n->get() == "A");

	n->set("X");
	CHECK(n->get() == "X");
}

TEST_CASE("[List] Insert before") {
	List<String> list;
	List<String>::Element *a = list.push_back("A");
	List<String>::Element *b = list.push_back("B");
	List<String>::Element *c = list.push_back("C");

	list.insert_before(b, "I");

	CHECK(a->next()->get() == "I");
	CHECK(c->prev()->prev()->get() == "I");
	CHECK(list.front()->next()->get() == "I");
	CHECK(list.back()->prev()->prev()->get() == "I");
}

TEST_CASE("[List] Insert after") {
	List<String> list;
	List<String>::Element *a = list.push_back("A");
	List<String>::Element *b = list.push_back("B");
	List<String>::Element *c = list.push_back("C");

	list.insert_after(b, "I");

	CHECK(a->next()->next()->get() == "I");
	CHECK(c->prev()->get() == "I");
	CHECK(list.front()->next()->next()->get() == "I");
	CHECK(list.back()->prev()->get() == "I");
}

TEST_CASE("[List] Insert before null") {
	List<String> list;
	List<String>::Element *a = list.push_back("A");
	List<String>::Element *b = list.push_back("B");
	List<String>::Element *c = list.push_back("C");

	list.insert_before(nullptr, "I");

	CHECK(a->next()->get() == "B");
	CHECK(b->get() == "B");
	CHECK(c->prev()->prev()->get() == "A");
	CHECK(list.front()->next()->get() == "B");
	CHECK(list.back()->prev()->prev()->get() == "B");
	CHECK(list.back()->get() == "I");
}

TEST_CASE("[List] Insert after null") {
	List<String> list;
	List<String>::Element *a = list.push_back("A");
	List<String>::Element *b = list.push_back("B");
	List<String>::Element *c = list.push_back("C");

	list.insert_after(nullptr, "I");

	CHECK(a->next()->get() == "B");
	CHECK(b->get() == "B");
	CHECK(c->prev()->prev()->get() == "A");
	CHECK(list.front()->next()->get() == "B");
	CHECK(list.back()->prev()->prev()->get() == "B");
	CHECK(list.back()->get() == "I");
}

TEST_CASE("[List] Find") {
	List<int> list;
	List<int>::Element *n[10];
	// Indices match values.
	populate_integers(list, n, 10);

	for (int i = 0; i < 10; ++i) {
		CHECK(n[i]->get() == list.find(i)->get());
	}
}

TEST_CASE("[List] Erase (by value)") {
	List<int> list;
	List<int>::Element *n[4];
	// Indices match values.
	populate_integers(list, n, 4);

	CHECK(list.front()->next()->next()->get() == 2);
	bool erased = list.erase(2); // 0, 1, 3.
	CHECK(erased);
	CHECK(list.size() == 3);

	// The pointer n[2] points to the freed memory which is not reset to zero,
	// so the below assertion may pass, but this relies on undefined behavior.
	// CHECK(n[2]->get() == 2);

	CHECK(list.front()->get() == 0);
	CHECK(list.front()->next()->next()->get() == 3);
	CHECK(list.back()->get() == 3);
	CHECK(list.back()->prev()->get() == 1);

	CHECK(n[1]->next()->get() == 3);
	CHECK(n[3]->prev()->get() == 1);

	erased = list.erase(9000); // Doesn't exist.
	CHECK(!erased);
}

TEST_CASE("[List] Erase (by element)") {
	List<int> list;
	List<int>::Element *n[4];
	// Indices match values.
	populate_integers(list, n, 4);

	bool erased = list.erase(n[2]);
	CHECK(erased);
	CHECK(list.size() == 3);
	CHECK(n[1]->next()->get() == 3);
	CHECK(n[3]->prev()->get() == 1);
}

TEST_CASE("[List] Element erase") {
	List<int> list;
	List<int>::Element *n[4];
	// Indices match values.
	populate_integers(list, n, 4);

	n[2]->erase();

	CHECK(list.size() == 3);
	CHECK(n[1]->next()->get() == 3);
	CHECK(n[3]->prev()->get() == 1);
}

TEST_CASE("[List] Clear") {
	List<int> list;
	List<int>::Element *n[100];
	populate_integers(list, n, 100);

	list.clear();

	CHECK(list.size() == 0);
	CHECK(list.is_empty());
}

TEST_CASE("[List] Invert") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.reverse();

	CHECK(list.front()->get() == 3);
	CHECK(list.front()->next()->get() == 2);
	CHECK(list.back()->prev()->get() == 1);
	CHECK(list.back()->get() == 0);
}

TEST_CASE("[List] Move to front") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.move_to_front(n[3]);

	CHECK(list.front()->get() == 3);
	CHECK(list.back()->get() == 2);
}

TEST_CASE("[List] Move to back") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.move_to_back(n[0]);

	CHECK(list.back()->get() == 0);
	CHECK(list.front()->get() == 1);
}

TEST_CASE("[List] Move before") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.move_before(n[3], n[1]);

	CHECK(list.front()->next()->get() == n[3]->get());
}

TEST_CASE("[List] Sort") {
	List<String> list;
	list.push_back("D");
	list.push_back("B");
	list.push_back("A");
	list.push_back("C");

	list.sort();

	CHECK(list.front()->get() == "A");
	CHECK(list.front()->next()->get() == "B");
	CHECK(list.back()->prev()->get() == "C");
	CHECK(list.back()->get() == "D");
}

TEST_CASE("[List] Swap adjacent front and back") {
	List<int> list;
	List<int>::Element *n[2];
	populate_integers(list, n, 2);

	list.swap(list.front(), list.back());

	CHECK(list.front()->prev() == nullptr);
	CHECK(list.front() != list.front()->next());

	CHECK(list.front() == n[1]);
	CHECK(list.back() == n[0]);

	CHECK(list.back()->next() == nullptr);
	CHECK(list.back() != list.back()->prev());
}

TEST_CASE("[List] Swap first adjacent pair") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.swap(n[0], n[1]);

	CHECK(list.front()->prev() == nullptr);
	CHECK(list.front() != list.front()->next());

	CHECK(list.front() == n[1]);
	CHECK(list.front()->next() == n[0]);
	CHECK(list.back()->prev() == n[2]);
	CHECK(list.back() == n[3]);

	CHECK(list.back()->next() == nullptr);
	CHECK(list.back() != list.back()->prev());
}

TEST_CASE("[List] Swap middle adjacent pair") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.swap(n[1], n[2]);

	CHECK(list.front()->prev() == nullptr);

	CHECK(list.front() == n[0]);
	CHECK(list.front()->next() == n[2]);
	CHECK(list.back()->prev() == n[1]);
	CHECK(list.back() == n[3]);

	CHECK(list.back()->next() == nullptr);
}

TEST_CASE("[List] Swap last adjacent pair") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.swap(n[2], n[3]);

	CHECK(list.front()->prev() == nullptr);

	CHECK(list.front() == n[0]);
	CHECK(list.front()->next() == n[1]);
	CHECK(list.back()->prev() == n[3]);
	CHECK(list.back() == n[2]);

	CHECK(list.back()->next() == nullptr);
}

TEST_CASE("[List] Swap first cross pair") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.swap(n[0], n[2]);

	CHECK(list.front()->prev() == nullptr);

	CHECK(list.front() == n[2]);
	CHECK(list.front()->next() == n[1]);
	CHECK(list.back()->prev() == n[0]);
	CHECK(list.back() == n[3]);

	CHECK(list.back()->next() == nullptr);
}

TEST_CASE("[List] Swap last cross pair") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.swap(n[1], n[3]);

	CHECK(list.front()->prev() == nullptr);

	CHECK(list.front() == n[0]);
	CHECK(list.front()->next() == n[3]);
	CHECK(list.back()->prev() == n[2]);
	CHECK(list.back() == n[1]);

	CHECK(list.back()->next() == nullptr);
}

TEST_CASE("[List] Swap edges") {
	List<int> list;
	List<int>::Element *n[4];
	populate_integers(list, n, 4);

	list.swap(n[1], n[3]);

	CHECK(list.front()->prev() == nullptr);

	CHECK(list.front() == n[0]);
	CHECK(list.front()->next() == n[3]);
	CHECK(list.back()->prev() == n[2]);
	CHECK(list.back() == n[1]);

	CHECK(list.back()->next() == nullptr);
}

TEST_CASE("[List] Swap middle (values check)") {
	List<String> list;
	List<String>::Element *n_str1 = list.push_back("Still");
	List<String>::Element *n_str2 = list.push_back("waiting");
	List<String>::Element *n_str3 = list.push_back("for");
	List<String>::Element *n_str4 = list.push_back("Godot.");

	CHECK(n_str1->get() == "Still");
	CHECK(n_str4->get() == "Godot.");

	CHECK(list.front()->get() == "Still");
	CHECK(list.front()->next()->get() == "waiting");
	CHECK(list.back()->prev()->get() == "for");
	CHECK(list.back()->get() == "Godot.");

	list.swap(n_str2, n_str3);

	CHECK(list.front()->next()->get() == "for");
	CHECK(list.back()->prev()->get() == "waiting");
}

TEST_CASE("[List] Swap front and back (values check)") {
	List<Variant> list;
	Variant str = "Godot";
	List<Variant>::Element *n_str = list.push_back(str);
	Variant color = Color(0, 0, 1);
	List<Variant>::Element *n_color = list.push_back(color);

	CHECK(list.front()->get() == "Godot");
	CHECK(list.back()->get() == Color(0, 0, 1));

	list.swap(n_str, n_color);

	CHECK(list.front()->get() == Color(0, 0, 1));
	CHECK(list.back()->get() == "Godot");
}

TEST_CASE("[List] Swap adjacent back and front (reverse order of elements)") {
	List<int> list;
	List<int>::Element *n[2];
	populate_integers(list, n, 2);

	list.swap(n[1], n[0]);

	List<int>::Element *it = list.front();
	while (it) {
		List<int>::Element *prev_it = it;
		it = it->next();
		if (it == prev_it) {
			FAIL_CHECK("Infinite loop detected.");
			break;
		}
	}
}

static void swap_random(List<int> &p_list, List<int>::Element *r_elements[], size_t p_size, size_t p_iterations) {
	Math::seed(0);

	for (size_t test_i = 0; test_i < p_iterations; ++test_i) {
		// A and B elements have corresponding indices as values.
		const int a_idx = static_cast<int>(Math::rand() % p_size);
		const int b_idx = static_cast<int>(Math::rand() % p_size);
		List<int>::Element *a = p_list.find(a_idx); // via find.
		List<int>::Element *b = r_elements[b_idx]; // via pointer.

		int va = a->get();
		int vb = b->get();

		p_list.swap(a, b);

		CHECK(va == a->get());
		CHECK(vb == b->get());

		size_t element_count = 0;

		// Fully traversable after swap?
		List<int>::Element *it = p_list.front();
		while (it) {
			element_count += 1;
			List<int>::Element *prev_it = it;
			it = it->next();
			if (it == prev_it) {
				FAIL_CHECK("Infinite loop detected.");
				break;
			}
		}
		// We should not lose anything in the process.
		if (element_count != p_size) {
			FAIL_CHECK("Element count mismatch.");
			break;
		}
	}
}

TEST_CASE("[Stress][List] Swap random 100 elements, 500 iterations.") {
	List<int> list;
	List<int>::Element *n[100];
	populate_integers(list, n, 100);
	swap_random(list, n, 100, 500);
}

TEST_CASE("[Stress][List] Swap random 10 elements, 1000 iterations.") {
	List<int> list;
	List<int>::Element *n[10];
	populate_integers(list, n, 10);
	swap_random(list, n, 10, 1000);
}
} // namespace TestList

#endif // TEST_LIST_H