// Structs, arrays of structs, and a linked list on the heap.
import "math.h"

struct Point {
    float x
    float y
}

struct Shape {
    str name
    []Point corners
    int color = 0xFF8800
}

struct Node {
    int value
    ptr[Node] next
}

fn perimeter(Shape s) -> float {
    total := 0.0
    for i in 0..s.corners.len {
        a := s.corners[i]
        b := s.corners[(i + 1) % s.corners.len]
        dx := b.x - a.x
        dy := b.y - a.y
        total += sqrt(dx * dx + dy * dy)
    }
    return total
}

fn main() {
    square := Shape(name: "square", corners: [Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1)])
    print(square.name, square.corners.len, "corners, perimeter", perimeter(square))
    print(square)

    // a linked list: new(...) puts a value on the heap, free(...) gives it back
    ptr[Node] head = null
    for i in 0..3 {
        head = new(Node(value: i, next: head))
    }
    n := head
    while n != null {
        print("node", n.value)
        next := n.next
        free(n)
        n = next
    }
}