import logging

logger = logging.getLogger(__name__)


# Define SVG code generation function with member_id parameter
def generate_chart(members, member_id=None):
    if not member_id:
        member_id = members[0]["id"]
    # Define some constants for layout
    node_radius = 30
    node_spacing = 80
    node_y = 100
    parent_y_offset = 50
    child_y_offset = 150

    # Find the specified member and its descendants
    member = None
    descendants = set()
    for m in members:
        if m["id"] == member_id:
            member = m
            descendants.add(member_id)
            break

    # calculate only if links are founded
    if member:
        stack = member["children"].copy()
        while stack:
            child_id = stack.pop()
            descendants.add(child_id)
            for m in members:
                if m["id"] == child_id:
                    stack.extend(m["children"])
                    break

        # Define the x position for each member
        x_positions = {}
        x_positions[member_id] = 0
        for i, m in enumerate(members):
            if m["id"] in descendants:
                x_positions[m["id"]] = (i * node_spacing) + node_radius

        # Start building the SVG code
        svg_width = (len(descendants) * node_spacing) + (2 * node_radius)
        svg_height = 200
        svg_code = f'<svg width="{svg_width}" height="{svg_height}">'

        # Generate nodes and names for each descendant
        for m in members:
            if m["id"] in descendants:
                node_x = x_positions[m["id"]]
                node_code = f'<circle cx="{node_x}" cy="{node_y}" r="{node_radius}" stroke="black" stroke-width="2" fill="white"/>'
                name_code = f'<text x="{node_x}" y="{node_y}" font-size="16" text-anchor="middle">{m["name"]}</text>'
                svg_code += node_code + name_code

                # Generate links to parent nodes
                for parent_id in m["parents"]:
                    if parent_id in descendants:
                        parent_x = x_positions[parent_id]
                        link_code = f'<line x1="{node_x}" y1="{node_y - parent_y_offset}" x2="{parent_x}" y2="{node_y}" stroke="black" stroke-width="2"/>'
                        svg_code += link_code

                # Generate links to child nodes
                for child_id in m["children"]:
                    if child_id in descendants:
                        child_x = x_positions[child_id]
                        link_code = f'<line x1="{node_x}" y1="{node_y + child_y_offset}" x2="{child_x}" y2="{node_y}" stroke="black" stroke-width="2"/>'
                        svg_code += link_code

        # Finish the SVG code
        svg_code += "</svg>"

        return svg_code.encode("utf-8")

    else:
        logger.error(f"no connections in graph for {member_id}")
        logger.debug(members)
        return ""