app.py

import gradio as gr
from transformers import AutoTokenizer, AutoModelForMaskedLM, AutoModel
import torch

# --- Model Loading ---
tokenizer_splade = None
model_splade = None
tokenizer_splade_lexical = None
model_splade_lexical = None

# Load SPLADE v3 model (original)
try:
    tokenizer_splade = AutoTokenizer.from_pretrained("naver/splade-cocondenser-selfdistil")
    model_splade = AutoModelForMaskedLM.from_pretrained("naver/splade-cocondenser-selfdistil")
    model_splade.eval() # Set to evaluation mode for inference
    print("SPLADE v3 (cocondenser) model loaded successfully!")
except Exception as e:
    print(f"Error loading SPLADE (cocondenser) model: {e}")
    print("Please ensure you have accepted any user access agreements on the Hugging Face Hub page for 'naver/splade-cocondenser-selfdistil'.")

# Load SPLADE v3 Lexical model
try:
    splade_lexical_model_name = "naver/splade-v3-lexical"
    tokenizer_splade_lexical = AutoTokenizer.from_pretrained(splade_lexical_model_name)
    model_splade_lexical = AutoModelForMaskedLM.from_pretrained(splade_lexical_model_name)
    model_splade_lexical.eval() # Set to evaluation mode for inference
    print(f"SPLADE v3 Lexical model '{splade_lexical_model_name}' loaded successfully!")
except Exception as e:
    print(f"Error loading SPLADE v3 Lexical model: {e}")
    print(f"Please ensure '{splade_lexical_model_name}' is accessible (check Hugging Face Hub for potential agreements).")

# --- Helper function for lexical mask ---
def create_lexical_bow_mask(input_ids, vocab_size, tokenizer):
    """
    Creates a binary bag-of-words mask from input_ids,
    zeroing out special tokens and padding.
    """
    # Initialize a zero vector for the entire vocabulary
    bow_mask = torch.zeros(vocab_size, device=input_ids.device)

    # Get unique token IDs from the input, excluding special tokens
    # input_ids is typically [batch_size, seq_len], we assume batch_size=1
    meaningful_token_ids = []
    for token_id in input_ids.squeeze().tolist(): # Squeeze to remove batch dim and convert to list
        if token_id not in [
            tokenizer.pad_token_id,
            tokenizer.cls_token_id,
            tokenizer.sep_token_id,
            tokenizer.mask_token_id,
            tokenizer.unk_token_id # Also exclude unknown tokens
        ]:
            meaningful_token_ids.append(token_id)
    
    # Set 1 for tokens present in the original input
    if meaningful_token_ids:
        bow_mask[list(set(meaningful_token_ids))] = 1 # Use set to handle duplicates
            
    return bow_mask.unsqueeze(0) # Keep batch dimension for consistency


# --- Core Representation Functions ---

def get_splade_representation(text):
    if tokenizer_splade is None or model_splade is None:
        return "SPLADE (cocondenser) model is not loaded. Please check the console for loading errors."

    inputs = tokenizer_splade(text, return_tensors="pt", padding=True, truncation=True)
    inputs = {k: v.to(model_splade.device) for k, v in inputs.items()}

    with torch.no_grad():
        output = model_splade(**inputs)

    if hasattr(output, 'logits'):
        splade_vector = torch.max(
            torch.log(1 + torch.relu(output.logits)) * inputs['attention_mask'].unsqueeze(-1),
            dim=1
        )[0].squeeze()
    else:
        return "Model output structure not as expected for SPLADE (cocondenser). 'logits' not found."

    indices = torch.nonzero(splade_vector).squeeze().cpu().tolist()
    if not isinstance(indices, list):
        indices = [indices]

    values = splade_vector[indices].cpu().tolist()
    token_weights = dict(zip(indices, values))

    meaningful_tokens = {}
    for token_id, weight in token_weights.items():
        decoded_token = tokenizer_splade.decode([token_id])
        if decoded_token not in ["[CLS]", "[SEP]", "[PAD]", "[UNK]"] and len(decoded_token.strip()) > 0:
            meaningful_tokens[decoded_token] = weight

    sorted_representation = sorted(meaningful_tokens.items(), key=lambda item: item[1], reverse=True)

    formatted_output = "SPLADE (cocondenser) Representation (All Non-Zero Terms):\n"
    if not sorted_representation:
        formatted_output += "No significant terms found for this input.\n"
    else:
        for term, weight in sorted_representation:
            formatted_output += f"- **{term}**: {weight:.4f}\n"

    formatted_output += "\n--- Raw SPLADE Vector Info ---\n"
    formatted_output += f"Total non-zero terms in vector: {len(indices)}\n"
    formatted_output += f"Sparsity: {1 - (len(indices) / tokenizer_splade.vocab_size):.2%}\n"

    return formatted_output


def get_splade_lexical_representation(text, apply_lexical_mask: bool): # Added parameter
    if tokenizer_splade_lexical is None or model_splade_lexical is None:
        return "SPLADE v3 Lexical model is not loaded. Please check the console for loading errors."

    inputs = tokenizer_splade_lexical(text, return_tensors="pt", padding=True, truncation=True)
    inputs = {k: v.to(model_splade_lexical.device) for k, v in inputs.items()}

    with torch.no_grad():
        output = model_splade_lexical(**inputs)

    if hasattr(output, 'logits'):
        splade_vector = torch.max(
            torch.log(1 + torch.relu(output.logits)) * inputs['attention_mask'].unsqueeze(-1),
            dim=1
        )[0].squeeze()
    else:
        return "Model output structure not as expected for SPLADE v3 Lexical. 'logits' not found."

    # --- Apply Lexical Mask if requested ---
    if apply_lexical_mask:
        # Get the vocabulary size from the tokenizer
        vocab_size = tokenizer_splade_lexical.vocab_size
        
        # Create the Bag-of-Words mask
        bow_mask = create_lexical_bow_mask(
            inputs['input_ids'], vocab_size, tokenizer_splade_lexical
        ).squeeze() # Squeeze to match splade_vector's [vocab_size] shape
        
        # Multiply the SPLADE vector by the BoW mask to zero out expanded terms
        splade_vector = splade_vector * bow_mask
    # --- End Lexical Mask Logic ---

    indices = torch.nonzero(splade_vector).squeeze().cpu().tolist()
    if not isinstance(indices, list):
        indices = [indices]

    values = splade_vector[indices].cpu().tolist()
    token_weights = dict(zip(indices, values))

    meaningful_tokens = {}
    for token_id, weight in token_weights.items():
        decoded_token = tokenizer_splade_lexical.decode([token_id])
        if decoded_token not in ["[CLS]", "[SEP]", "[PAD]", "[UNK]"] and len(decoded_token.strip()) > 0:
            meaningful_tokens[decoded_token] = weight

    sorted_representation = sorted(meaningful_tokens.items(), key=lambda item: item[1], reverse=True)

    formatted_output = "SPLADE v3 Lexical Representation (All Non-Zero Terms):\n"
    if not sorted_representation:
        formatted_output += "No significant terms found for this input.\n"
    else:
        for term, weight in sorted_representation:
            formatted_output += f"- **{term}**: {weight:.4f}\n"

    formatted_output += "\n--- Raw SPLADE Vector Info ---\n"
    formatted_output += f"Total non-zero terms in vector: {len(indices)}\n"
    formatted_output += f"Sparsity: {1 - (len(indices) / tokenizer_splade_lexical.vocab_size):.2%}\n"

    return formatted_output


# --- Unified Prediction Function for Gradio ---
def predict_representation(model_choice, text):
    if model_choice == "SPLADE (cocondenser)":
        return get_splade_representation(text)
    elif model_choice == "SPLADE-v3-Lexical (with expansion)":
        # Call the lexical function without applying the mask
        return get_splade_lexical_representation(text, apply_lexical_mask=False)
    elif model_choice == "SPLADE-v3-Lexical (lexical-only)":
        # Call the lexical function applying the mask
        return get_splade_lexical_representation(text, apply_lexical_mask=True)
    else:
        return "Please select a model."

# --- Gradio Interface Setup ---
demo = gr.Interface(
    fn=predict_representation,
    inputs=[
        gr.Radio(
            [
                "SPLADE (cocondenser)",
                "SPLADE-v3-Lexical (with expansion)", # Option to see full neural output
                "SPLADE-v3-Lexical (lexical-only)"    # Option with lexical mask applied
            ],
            label="Choose Representation Model",
            value="SPLADE (cocondenser)" # Default selection
        ),
        gr.Textbox(
            lines=5,
            label="Enter your query or document text here:",
            placeholder="e.g., Why is Padua the nicest city in Italy?"
        )
    ],
    outputs=gr.Markdown(),
    title="🌌 Sparse Representation Generator",
    description="Enter any text to see its SPLADE sparse vector. Explore the difference between full neural expansion and lexical-only representations.",
    allow_flagging="never"
)

# Launch the Gradio app
demo.launch()