// Geometry: Point and Rect records with computed properties. Demonstrates
// small value-records, deriving fields from nested records, and float
// tolerance in assertions.

cell Geometry {
    face {
        signal dist(a: Map, b: Map) -> Float
        signal area(r: Map) -> Int
        signal center(r: Map) -> Map
        signal contains_pt(r: Map, p: Map) -> Bool
        signal unit_square() -> Map
    }

    on dist(a: Map, b: Map) {
        let dx = a.x - b.x
        let dy = a.y - b.y
        return sqrt(dx * dx + dy * dy)
    }

    on area(r: Map) {
        return (r.hi.x - r.lo.x) * (r.hi.y - r.lo.y)
    }

    on center(r: Map) {
        return Point { x: (r.lo.x + r.hi.x) / 2, y: (r.lo.y + r.hi.y) / 2 }
    }

    on contains_pt(r: Map, p: Map) {
        return p.x >= r.lo.x && p.x <= r.hi.x && p.y >= r.lo.y && p.y <= r.hi.y
    }

    on unit_square() {
        return Rect { lo: Point { x: 0, y: 0 }, hi: Point { x: 1, y: 1 } }
    }
}

cell test GeometryTest {
    rules {
        assert abs(dist(Point { x: 0, y: 0 }, Point { x: 3, y: 4 }) - 5.0) < 0.0001
        assert area(Rect { lo: Point { x: 0, y: 0 }, hi: Point { x: 4, y: 3 } }) == 12
        assert center(unit_square()).x == 0.5
        assert contains_pt(unit_square(), Point { x: 0.5, y: 0.5 }) == true
        assert contains_pt(unit_square(), Point { x: 2, y: 0 }) == false
    }
}