class_name Math

static func get_chunk_from_pos(coord) -> Vector2i:
    return Vector2i(
        floori(coord.x / (Planet.CHUNK_TILE_SIZE * Planet.TILE_SIZE)),
        floori(coord.y / (Planet.CHUNK_TILE_SIZE * Planet.TILE_SIZE))
    )

static func get_tile_from_pos(coord) -> Vector2i:
    return Vector2i(
        floori(coord.x / (Planet.TILE_SIZE)),
        floori(coord.y / (Planet.TILE_SIZE)),
    )

static func get_tiles_in_circle(center: Vector2, radius : float) -> Array[Vector2i]:
    var tiles : Array[Vector2i] = []

    for x in range(
        floori((center.x - radius/2.) / Planet.TILE_SIZE),
        ceili((center.x + radius/2.) / Planet.TILE_SIZE),
    ):
        for y in range(
            floori((center.y - radius/2.) / Planet.TILE_SIZE),
            ceili((center.y + radius/2.) / Planet.TILE_SIZE),
        ):
            if is_tile_on_circle(Vector2i(x,y), center, radius):
                tiles.append(Vector2i(x,y))
    return tiles
        
static func is_tile_on_circle(tile_coord : Vector2i, circle_center: Vector2, circle_radius : float) -> bool:
    var absolute_tile_pos : Vector2 = tile_coord * Planet.TILE_SIZE

    # Loop over tile corners to know if the area collide
    var corners : Array[Vector2] = []
    for x in [0,1]:
        for y in [0,1]:
            corners.append(
                absolute_tile_pos
                + Vector2.RIGHT * x * Planet.TILE_SIZE
                + Vector2.DOWN * y * Planet.TILE_SIZE
            )
    
    # Check if segment touch area
    for i in range(4):
        var a = corners[i%4]
        var b = corners[(i+1)%4]
        if segment_intersect_circle(a,b,circle_center,circle_radius):
            return true

    return false


# Stolen here https://stackoverflow.com/questions/1073336/circle-line-segment-collision-detection-algorithm
static func segment_intersect_circle(
    a : Vector2,
    b : Vector2,
    c : Vector2,
    radius: float
) -> bool:
    var a_circle = c - a
    var b_a = b - a

    var proj_point = proj(a_circle,b_a) + a

    return proj_point.distance_to(c) < radius

static func proj(a : Vector2,b : Vector2) -> Vector2:
    var k = a.dot(b) / b.dot(b)
    return Vector2(k * b.x, k * b.y)