class_name Math

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

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

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

    var margin = ceili(radius * 0.5)

    for x in range(
        floori((center.x - radius/2.) / Region.TILE_SIZE) - margin,
        ceili((center.x + radius/2.) / Region.TILE_SIZE) + margin,
    ):
        for y in range(
            floori((center.y - radius/2.) / Region.TILE_SIZE) - margin,
            ceili((center.y + radius/2.) / Region.TILE_SIZE) + margin,
        ):
            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 * Region.TILE_SIZE

    var tile_center = absolute_tile_pos + Vector2.ONE * Region.TILE_SIZE / 2
    var tile_radius = roundf(Region.TILE_SIZE/2.)

    return pow(tile_center.x - circle_center.x, 2) + pow(tile_center.y - circle_center.y, 2) <= pow(tile_radius + circle_radius, 2)

    # 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 * Region.TILE_SIZE
    #             + Vector2.DOWN * y * Region.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)