#include <flecs.h>
#include <iostream>

struct Position {
    double x, y;
};

struct Velocity {
    double x, y;
};

int main() {
    flecs::world ecs;

    // Create a system for Position, Velocity. Systems are like queries (see
    // queries) with a function that can be ran or scheduled (see pipeline).
    flecs::system s = ecs.system<Position, const Velocity>()
        .each([](flecs::entity e, Position& p, const Velocity& v) {
            p.x += v.x;
            p.y += v.y;
            std::cerr << e.name() << ": {" << p.x << ", " << p.y << "}\n";
        });

    // Create a few test entities for a Position, Velocity query
    ecs.entity("e1")
        .set<Position>({10, 20})
        .set<Velocity>({1, 2});

    ecs.entity("e2")
        .set<Position>({10, 20})
        .set<Velocity>({3, 4});

    // This entity will not match as it does not have Position, Velocity
    ecs.entity("e3")
        .set<Position>({10, 20});

    // Run the system
    s.run();
}