#include "range.hpp"

#include "catch.hpp"

#include <stdexcept>

TEST_CASE("range basic") {
	SECTION("one argument") {
		int i = 0;
		for (int x : range(5)) {
			REQUIRE(i < 5);
			REQUIRE(x == i++);
		}

		auto r = range(5);
		REQUIRE(*std::next(r.begin(), 4) == 4);
		REQUIRE(std::next(r.begin(), 5) == r.end());
	}

	SECTION("two arguments") {
		int i = 5;
		for (int x : range(5, 10)) {
			REQUIRE(i < 10);
			REQUIRE(x == i++);
		}
		auto r = range(5, 10);
		REQUIRE(*std::next(r.begin(), 4) == 9);
		REQUIRE(std::next(r.begin(), 5) == r.end());
	}

	SECTION("three arguments") {
		int i = 5;
		auto r = range(5, 100, 5);
		for (int x : r) {
			REQUIRE(i < 100);
			REQUIRE(x == i);
			i += 5;
		}
		REQUIRE(*std::next(r.begin(), 18) == 95);
		REQUIRE(std::next(r.begin(), 19) == r.end());
	}

	SECTION("with zero step") {
		REQUIRE_THROWS_AS(range(1, 2, 0), std::invalid_argument);
		REQUIRE_THROWS_AS(range(1.1, 2.2, 0.0), std::invalid_argument);
	}

	SECTION("with negative step") {
		int i = 10;
		auto r = range(10, 0, -1);
		for (int x : r) {
			REQUIRE(x == i);
			--i;
			REQUIRE(i >= 0);
		}
		REQUIRE(i == 0);
		REQUIRE(*std::next(r.begin(), 5) == 5);
		REQUIRE(*std::next(r.begin(), 9) == 1);
		REQUIRE(std::next(r.begin(), 10) == r.end());
	}

	SECTION("basic examples from the assignment") {
		int x = -1;
		for (int n : range(10)) {
			x++;
			REQUIRE(x == n);
		}
		REQUIRE(x == 9);

		x = -5;
		for (int n : range(0, 30, 5)) {
			x += 5;
			REQUIRE(x == n);
		}
		REQUIRE(x == 25);

		x = 1;
		for (int n : range(0, -10, -1)) {
			x--;
			REQUIRE(x == n);
		}
		REQUIRE(x == -9);

		x = 9;
		for (int n : range(4, -9, -5)) {
			x -= 5;
			REQUIRE(x == n);
		}
		REQUIRE(x == -6);

		x = -9;
		for (int n : range(-4, 9, 5)) {
			x += 5;
			REQUIRE(x == n);
		}
		REQUIRE(x == 6);
	}

	SECTION("operations") {
		auto ranger = range(1, 10, 5);
		auto it = ranger.begin();
		auto it2 = ranger.begin();

		REQUIRE(*it == 1);

		++it;

		REQUIRE(*it == 6);

		++it2;

		REQUIRE((it == it2));

		REQUIRE((*(++it) == 11));
		REQUIRE((*it++ == 11));
		REQUIRE((*(++it) != 10));

		REQUIRE((++it != it2));

		auto it3 = it;
		auto it4 = it++;
		REQUIRE(it3 == it4);
		REQUIRE(it != it4);

	}

	SECTION("floats") {
		auto ranger = range(1.1, 10.1, 5.2);
		double x = -4.1;
		for (double i : ranger) {
			x += 5.2;
			REQUIRE(x - i < 0.00001);
		}
		REQUIRE(x - 6.3 < 0.00001);
	}

	SECTION("with incorrect step") {
		int i = 10;
		auto opposite1 = range(10, 1, 1);
		for (int x : opposite1) {
			--i;
			--x;
		}
		REQUIRE(i == 10);

		auto opposite2 = range(0, 10, -1);
		for (int x : opposite2) {
			--i;
			--x;
		}
		REQUIRE(i == 10);

		auto opposite3 = range(1, 1, -1);
		for (int x : opposite3) {
			--i;
			--x;
		}
		REQUIRE(i == 10);
	}
}