import graphviz
import json
from tempfile import NamedTemporaryFile
import os
from graph_generator_utils import add_nodes_and_edges

def generate_radial_diagram(json_input: str, base_color: str) -> str: # base_color is now correctly used
    """
    Generates a radial (center-expanded) diagram from JSON input.

    Args:
        json_input (str): A JSON string describing the radial diagram structure.
                          It must follow the Expected JSON Format Example below.
        base_color (str): The hexadecimal color string (e.g., '#19191a') for the base
                          color of the nodes, from which a gradient will be generated.

    Returns:
        str: The filepath to the generated PNG image file.

    Expected JSON Format Example:
    {
      "central_node": "Making Coffee",
      "nodes": [
        {
          "id": "coffee_components",
          "label": "Coffee Components",
          "relationship": "Involves",
          "subnodes": [
            {
              "id": "equipment",
              "label": "Equipment Needed",
              "relationship": "Requires",
              "subnodes": [
                {"id": "coffee_maker", "label": "Coffee Maker", "relationship": "e.g."},
                {"id": "mug", "label": "Mug", "relationship": "For"}
              ]
            }
          ]
        },
        {
          "id": "coffee_process_enjoyment",
          "label": "Process & Enjoyment",
          "relationship": "Leads to",
          "subnodes": [
            {
              "id": "preparation_steps",
              "label": "Preparation Steps",
              "relationship": "Involves",
              "subnodes": [
                {"id": "grind_beans", "label": "Grind Beans", "relationship": "Step 1 (if whole)"},
                {"id": "heat_water", "label": "Heat Water", "relationship": "Step 2"}
              ]
            }
          ]
        }
      ]
    }
    """
    try:
        if not json_input.strip():
            return "Error: Empty input"
            
        data = json.loads(json_input)
        
        if 'central_node' not in data or 'nodes' not in data:
            raise ValueError("Missing required fields: central_node or nodes")

        dot = graphviz.Digraph(
            name='RadialDiagram',
            format='png',
            engine='neato', # Use 'neato' or 'fdp' for radial/force-directed layout
            graph_attr={
                'overlap': 'false', # Prevent node overlap
                'splines': 'true',  # Smooth splines for edges
                'bgcolor': 'white', # White background
                'pad': '0.5',       # Padding around the graph
                'layout': 'neato'   # Explicitly set layout engine for consistency
            },
            node_attr={
                'fixedsize': 'false' # Allow nodes to resize based on content
            }
        )
        
        # This line was REMOVED to ensure the passed base_color is used: base_color = '#19191a' 

        # Central node styling (rounded box, dark color)
        dot.node(
            'central',
            data['central_node'],
            shape='box',            # Rectangular shape
            style='filled,rounded', # Filled and rounded corners
            fillcolor=base_color,   # Darkest color
            fontcolor='white',      # White text for dark background
            fontsize='16'           # Larger font for central node
        )
        
        # Add child nodes and edges recursively starting from depth 1
        # The add_nodes_and_edges function will handle styling consistent with other graphs
        add_nodes_and_edges(dot, 'central', data.get('nodes', []), current_depth=1, base_color=base_color)

        # Save to temporary file
        with NamedTemporaryFile(delete=False, suffix='.png') as tmp:
            dot.render(tmp.name, format='png', cleanup=True)
            return tmp.name + '.png'

    except json.JSONDecodeError:
        return "Error: Invalid JSON format"
    except Exception as e:
        return f"Error: {str(e)}"