app.py

import gradio as gr
from gradio_molecule2d import molecule2d
from rdkit import Chem
from rdkit.Chem.inchi import MolToInchi, InchiToInchiKey


def transform_molecule(smiles_input):
    """Convert drawn molecule SMILES to canonical SMILES and InChIKey."""
    if not smiles_input:
        return "", ""

    mol = Chem.MolFromSmiles(smiles_input)
    if mol is None:
        return "Invalid molecule", "Invalid molecule"

    canonical_smiles = Chem.MolToSmiles(mol)

    inchi = MolToInchi(mol)
    inchi_key = InchiToInchiKey(inchi) if inchi else "Could not generate InChIKey"

    return canonical_smiles, inchi_key


with gr.Blocks(title="Chemical Structure Transformer") as demo:
    gr.Markdown(
        """
        # 🧪 Chemical Structure Transformer
        Draw a chemical structure using the editor below, then click **Transform** to get the canonical SMILES and InChIKey.
        """
    )

    with gr.Row():
        with gr.Column():
            mol_input = molecule2d(label="Draw Chemical Structure")
            transform_btn = gr.Button("🔄 Transform", variant="primary", size="lg")

        with gr.Column():
            smiles_output = gr.Textbox(
                label="Canonical SMILES",
                placeholder="SMILES string will appear here...",
                interactive=False,
            )
            inchi_key_output = gr.Textbox(
                label="InChIKey",
                placeholder="InChIKey will appear here...",
                interactive=False,
            )

    transform_btn.click(
        fn=transform_molecule,
        inputs=[mol_input],
        outputs=[smiles_output, inchi_key_output],
    )

    gr.Examples(
        examples=[
            ["c1ccccc1"],           # Benzene
            ["CC(=O)Oc1ccccc1C(=O)O"],  # Aspirin
            ["CC12CCC3C(C1CCC2O)CCC4=CC(=O)CCC34C"],  # Testosterone
        ],
        inputs=[mol_input],
        label="Example Molecules (SMILES)",
    )


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