package vm_test

import (
	"testing"
)

func TestFunction(t *testing.T) {
	// function with no "return" statement returns "invalid" value.
	expect(t, `f1 = func() {}; out = f1();`, undefined())
	expect(t, `f1 = func() {}; f2 = func() { return f1(); }; f1(); out = f2();`, undefined())
	expect(t, `f = func(x) { x; }; out = f(5);`, undefined())

	expect(t, `f = func(x) { return x; }; out = f(5);`, 5)
	expect(t, `f = func(x) { return x * 2; }; out = f(5);`, 10)
	expect(t, `f = func(x, y) { return x + y; }; out = f(5, 5);`, 10)
	expect(t, `f = func(x, y) { return x + y; }; out = f(5 + 5, f(5, 5));`, 20)
	expect(t, `out = func(x) { return x; }(5)`, 5)
	expect(t, `x = 10; f = func(x) { return x; }; f(5); out = x;`, 10)

	expect(t, `
f2 = func(a) {
	f1 = func(a) {
		return a * 2;
	};

	return f1(a) * 3;
};

out = f2(10);
`, 60)

	// closures
	expect(t, `
	newAdder = func(x) {
		return func(y) { return x + y };
	};
	
	add2 = newAdder(2);
	out = add2(5);
	`, 7)

	// function as a argument
	expect(t, `
add = func(a, b) { return a + b };
sub = func(a, b) { return a - b };
applyFunc = func(a, b, f) { return f(a, b) };

out = applyFunc(applyFunc(2, 2, add), 3, sub);
`, 1)

	expect(t, `f1 = func() { return 5 + 10; }; out = f1();`, 15)
	expect(t, `f1 = func() { return 1 }; f2 = func() { return 2 }; out = f1() + f2()`, 3)
	expect(t, `f1 = func() { return 1 }; f2 = func() { return f1() + 2 }; f3 = func() { return f2() + 3 }; out = f3()`, 6)
	expect(t, `f1 = func() { return 99; 100 }; out = f1();`, 99)
	expect(t, `f1 = func() { return 99; return 100 }; out = f1();`, 99)
	expect(t, `f1 = func() { return 33; }; f2 = func() { return f1 }; out = f2()();`, 33)
	expect(t, `one = func() { one = 1; return one }; out = one()`, 1)
	expect(t, `three = func() { one = 1; two = 2; return one + two }; out = three()`, 3)
	expect(t, `three = func() { one = 1; two = 2; return one + two }; seven = func() { three = 3; four = 4; return three + four }; out = three() + seven()`, 10)
	expect(t, `foo1 = func() { foo = 50; return foo}; foo2 = func() { foo = 100; return foo }; out = foo1() + foo2()`, 150)
	expect(t, `
g = 50;
minusOne = func() {
	n = 1;
	return g - n;
};
minusTwo = func() {
	n = 2;
	return g - n;
};
out = minusOne() + minusTwo()
`, 97)
	expect(t, `
f1 = func() {
	f2 = func() { return 1; }
	return f2
};
out = f1()()
`, 1)

	expect(t, `
f1 = func(a) { return a; };
out = f1(4)`, 4)
	expect(t, `
f1 = func(a, b) { return a + b; };
out = f1(1, 2)`, 3)

	expect(t, `
sum = func(a, b) {
	c = a + b;
	return c;
};
out = sum(1, 2);`, 3)

	expect(t, `
sum = func(a, b) {
	c = a + b;
	return c;
};
out = sum(1, 2) + sum(3, 4);`, 10)

	expect(t, `
sum = func(a, b) {
	c = a + b
	return c
};
outer = func() {
	return sum(1, 2) + sum(3, 4)
};
out = outer();`, 10)

	expect(t, `
g = 10;

sum = func(a, b) {
	c = a + b;
	return c + g;
}

outer = func() {
	return sum(1, 2) + sum(3, 4) + g;
}

out = outer() + g
`, 50)

	expectError(t, `func() { return 1; }(1)`)
	expectError(t, `func(a) { return a; }()`)
	expectError(t, `func(a, b) { return a + b; }(1)`)

	expect(t, `
	f1 = func(a) {
		return func() { return a; };
	};
	f2 = f1(99);
	out = f2()
	`, 99)

	expect(t, `
	f1 = func(a, b) {
		return func(c) { return a + b + c };
	};
	
	f2 = f1(1, 2);
	out = f2(8);
	`, 11)
	expect(t, `
	f1 = func(a, b) {
		c = a + b;
		return func(d) { return c + d };
	};
	f2 = f1(1, 2);
	out = f2(8);
	`, 11)
	expect(t, `
	f1 = func(a, b) {
		c = a + b;
		return func(d) {
			e = d + c;
			return func(f) { return e + f };
		}
	};
	f2 = f1(1, 2);
	f3 = f2(3);
	out = f3(8);
	`, 14)
	expect(t, `
	a = 1;
	f1 = func(b) {
		return func(c) {
			return func(d) { return a + b + c + d }
		};
	};
	f2 = f1(2);
	f3 = f2(3);
	out = f3(8);
	`, 14)
	expect(t, `
	f1 = func(a, b) {
		one = func() { return a; };
		two = func() { return b; };
		return func() { return one() + two(); }
	};
	f2 = f1(9, 90);
	out = f2();
	`, 99)

	// fibonacci
	expect(t, `
	fib = func(x) {
		if(x == 0) {
			return 0;
		} else {
			if(x == 1) {
				return 1;
			} else {
				return fib(x-1) + fib(x-2);
			}
		}
	};
	out = fib(15);
	`, 610)
}