"""Socket endpoints and conservative curve footprints for placement and preview."""

from .flow import socket_links


def socket_position(socket, positions, sizes):
    node = socket.node
    x, y = positions[node]
    if node.bl_idname == "NodeReroute":
        return x + 8, y - 8
    return x + (sizes[node].width if socket.is_output else 0), y - sizes[node].sockets[socket]


def link_endpoints(link, positions, sizes):
    start = socket_position(link.from_socket, positions, sizes)
    x, y = socket_position(link.to_socket, positions, sizes)
    if link.to_socket.is_multi_input:
        siblings = socket_links(link.to_socket)
        y -= (siblings.index(link) - (len(siblings) - 1) / 2) * 8
    return start, (x, y)


def curve_footprint(start, end):
    """Reserve eight convex hulls covering a horizontal-tangent Bezier curve."""
    x1, y1 = start
    x2, y2 = end
    bend = max(40, abs(x2 - x1) * 0.42)
    curves = [(start, (x1 + bend, y1), (x2 - bend, y2), end)]
    for _ in range(3):
        divided = []
        for points in curves:
            rows = [points]
            for _ in range(3):
                rows.append([((a[0] + b[0]) / 2, (a[1] + b[1]) / 2)
                             for a, b in zip(rows[-1], rows[-1][1:])])
            divided.extend((tuple(row[0] for row in rows), tuple(row[-1] for row in reversed(rows))))
        curves = divided
    return [(min(x for x, _ in curve), max(x for x, _ in curve),
             max(y for _, y in curve), min(y for _, y in curve)) for curve in curves]