app.py

import os
import subprocess

def install(package):
    subprocess.check_call(["pip", "install", package])

# Install dependencies
install("numpy")
install("networkx")
install("matplotlib")
install("gradio")

# Now import the installed libraries
import math
import itertools
import numpy as np
import networkx as nx
import matplotlib.pyplot as plt
import gradio as gr

# --- Topological Index Functions ---

def wiener_index(graph):
    sp = dict(nx.all_pairs_shortest_path_length(graph))
    total = 0
    for u in sp:
        for v in sp[u]:
            if u < v:
                total += sp[u][v]
    return total

def compute_indices(graph, index_type):
    if index_type == "Wiener Index":
        return wiener_index(graph)
    elif index_type == "Randić Index":
        return sum(1 / math.sqrt(graph.degree(u) * graph.degree(v)) for u, v in graph.edges())
    elif index_type == "Balaban Index":
        n = graph.number_of_nodes()
        m = graph.number_of_edges()
        if m == 0 or n <= 1:
            return 0
        return (m / (n - 1)) * sum(1 / math.sqrt(graph.degree(u) * graph.degree(v)) for u, v in graph.edges())
    elif index_type == "Zagreb Index M1":
        return sum(d**2 for _, d in graph.degree())
    elif index_type == "Zagreb Index M2":
        return sum(graph.degree(u) * graph.degree(v) for u, v in graph.edges())
    elif index_type == "Harary Index":
        return sum(1 / nx.shortest_path_length(graph, u, v) for u, v in itertools.combinations(graph.nodes(), 2))
    elif index_type == "Schultz Index":
        return sum((graph.degree(u) + graph.degree(v)) * nx.shortest_path_length(graph, u, v) for u, v in graph.edges())
    elif index_type == "Gutman Index":
        return sum(graph.degree(u) * graph.degree(v) * nx.shortest_path_length(graph, u, v) for u, v in graph.edges())
    elif index_type == "Estrada Index":
        A = nx.adjacency_matrix(graph).todense()
        eigenvalues = np.linalg.eigvals(A)
        return sum(math.exp(ev) for ev in eigenvalues)
    elif index_type == "Hosoya Index":
        return graph.number_of_edges()
    else:
        return "Invalid Index Type"

# --- Graph Drawing Function ---

def draw_graph(graph, index_type, index_value):
    plt.figure(figsize=(6, 6))
    
    # Fixed layout for more consistent shapes
    pos = nx.spring_layout(graph, seed=42)

    # Draw only edges (no nodes, no labels)
    nx.draw_networkx_edges(graph, pos, edge_color="gray", width=2)

    plt.title(f"{index_type}: {round(index_value, 3)}", fontsize=14)
    plt.axis('off')

    filename = "graph.png"
    plt.savefig(filename, bbox_inches='tight')
    plt.close()
    return filename

# --- Main Logic ---

def process_graph(node_count, edge_count, index_type, custom_edges):
    G = nx.Graph()
    
    if not custom_edges.strip():
        G = nx.gnm_random_graph(int(node_count), int(edge_count))
    else:
        try:
            edges = [tuple(map(int, e.strip().split("-"))) for e in custom_edges.split(",")]
            all_nodes = set()
            for u, v in edges:
                all_nodes.update([u, v])
            n = max(all_nodes) + 1
            G.add_nodes_from(range(n))
            G.add_edges_from(edges)
        except Exception as e:
            return f"Error in custom edges input: {e}", None

    index_value = compute_indices(G, index_type)
    graph_img = draw_graph(G, index_type, index_value)
    return index_value, graph_img

# --- Gradio App ---

with gr.Blocks() as demo:
    gr.Markdown("# 🧠 Topological Index Calculator with Graph Visualization")
    
    with gr.Row():
        node_count = gr.Number(label="Number of Nodes", value=5, minimum=1)
        edge_count = gr.Number(label="Number of Edges", value=5, minimum=0)

    index_type = gr.Dropdown(
        choices=["Wiener Index", "Randić Index", "Balaban Index", "Zagreb Index M1", "Zagreb Index M2", 
                 "Harary Index", "Schultz Index", "Gutman Index", "Estrada Index", "Hosoya Index"],
        label="Select Topological Index"
    )

    custom_edges = gr.Textbox(
        label="Custom Edges (e.g., 0-1,1-2,2-3)", 
        placeholder="Leave blank for random graph"
    )

    calc_button = gr.Button("Calculate & Visualize")
    result_box = gr.Textbox(label="Computed Index Value", interactive=False)
    graph_output = gr.Image(label="Graph Visualization", interactive=False)

    calc_button.click(
        fn=process_graph,
        inputs=[node_count, edge_count, index_type, custom_edges],
        outputs=[result_box, graph_output]
    )

# --- Run the App ---

if __name__ == "__main__":
    demo.launch()