import gradio as gr
from transformers import AutoTokenizer, AutoModelForMaskedLM
import torch
import numpy as np
from tqdm.auto import tqdm
import os
import ir_datasets

# --- Model Loading (Keep as is) ---
tokenizer_splade = None
model_splade = None
tokenizer_splade_lexical = None
model_splade_lexical = None
tokenizer_splade_doc = None
model_splade_doc = 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()
    print("SPLADE-cocondenser-distil model loaded successfully!")
except Exception as e:
    print(f"Error loading SPLADE-cocondenser-distil 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()
    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).")

# Load SPLADE v3 Doc model
try:
    splade_doc_model_name = "naver/splade-v3-doc"
    tokenizer_splade_doc = AutoTokenizer.from_pretrained(splade_doc_model_name)
    model_splade_doc = AutoModelForMaskedLM.from_pretrained(splade_doc_model_name)
    model_splade_doc.eval()
    print(f"SPLADE-v3-Doc model '{splade_doc_model_name}' loaded successfully!")
except Exception as e:
    print(f"Error loading SPLADE-v3-Doc model: {e}")
    print(f"Please ensure '{splade_doc_model_name}' is accessible (check Hugging Face Hub for potential agreements).")


# --- Global Variables for Document Index ---
document_representations = {} # Stores {doc_id: sparse_vector}
document_texts = {}           # Stores {doc_id: doc_text}
initial_doc_model_for_indexing = "SPLADE-cocondenser-distil" # Fixed for initial demo index


# --- Load SciFact Corpus using ir_datasets ---
def load_scifact_corpus_ir_datasets():
    global document_texts
    print("Loading SciFact corpus using ir_datasets...")
    try:
        dataset = ir_datasets.load("scifact")
        for doc in tqdm(dataset.docs_iter(), desc="Loading SciFact documents"):
            document_texts[doc.doc_id] = doc.text.strip()
        print(f"Loaded {len(document_texts)} documents from SciFact corpus.")
    except Exception as e:
        print(f"Error loading SciFact corpus with ir_datasets: {e}")
        print("Please ensure 'ir_datasets' is installed and your internet connection is stable.")


# --- Helper function for lexical mask (Keep as is) ---
def create_lexical_bow_mask(input_ids, vocab_size, tokenizer):
    bow_mask = torch.zeros(vocab_size, device=input_ids.device)
    meaningful_token_ids = []
    for token_id in input_ids.squeeze().tolist():
        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
        ]:
            meaningful_token_ids.append(token_id)
            
    if meaningful_token_ids:
        bow_mask[list(set(meaningful_token_ids))] = 1
            
    return bow_mask.unsqueeze(0)


# --- Core Representation Functions (Return Formatted Strings - for Explorer Tab) ---
# These are your original functions, re-added.

def get_splade_cocondenser_representation(text):
    if tokenizer_splade is None or model_splade is None:
        return "SPLADE-cocondenser-distil 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-distil. 'logits' not found."

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

    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-distil Representation (Weighting and Expansion):\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):
    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."

    # Always apply lexical mask for this model's specific behavior
    vocab_size = tokenizer_splade_lexical.vocab_size
    bow_mask = create_lexical_bow_mask(
        inputs['input_ids'], vocab_size, tokenizer_splade_lexical
    ).squeeze()
    splade_vector = splade_vector * bow_mask

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

    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 (Weighting):\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


def get_splade_doc_representation(text):
    if tokenizer_splade_doc is None or model_splade_doc is None:
        return "SPLADE-v3-Doc model is not loaded. Please check the console for loading errors."

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

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

    if not hasattr(output, "logits"):
        return "SPLADE-v3-Doc model output structure not as expected. 'logits' not found."

    vocab_size = tokenizer_splade_doc.vocab_size
    binary_splade_vector = create_lexical_bow_mask(
        inputs['input_ids'], vocab_size, tokenizer_splade_doc
    ).squeeze()
    
    indices = torch.nonzero(binary_splade_vector).squeeze().cpu().tolist()
    if not isinstance(indices, list):
        indices = [indices] if indices else []
        
    values = [1.0] * len(indices) # All values are 1 for binary representation
    token_weights = dict(zip(indices, values))

    meaningful_tokens = {}
    for token_id, weight in token_weights.items():
        decoded_token = tokenizer_splade_doc.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[0]) # Sort alphabetically for clarity

    formatted_output = "SPLADE-v3-Doc Representation (Binary):\n"
    if not sorted_representation:
        formatted_output += "No significant terms found for this input.\n"
    else:
        for i, (term, _) in enumerate(sorted_representation):
            if i >= 50: # Limit display for very long lists
                formatted_output += f"...and {len(sorted_representation) - 50} more terms.\n"
                break
            formatted_output += f"- **{term}**\n"

    formatted_output += "\n--- Raw Binary Sparse Vector Info ---\n"
    formatted_output += f"Total activated terms: {len(indices)}\n"
    formatted_output += f"Sparsity: {1 - (len(indices) / tokenizer_splade_doc.vocab_size):.2%}\n"

    return formatted_output


# --- Unified Prediction Function for the Explorer Tab ---
def predict_representation_explorer(model_choice, text):
    if model_choice == "SPLADE-cocondenser-distil (weighting and expansion)":
        return get_splade_cocondenser_representation(text)
    elif model_choice == "SPLADE-v3-Lexical (weighting)":
        return get_splade_lexical_representation(text)
    elif model_choice == "SPLADE-v3-Doc (binary)":
        return get_splade_doc_representation(text)
    else:
        return "Please select a model."


# --- Internal Core Representation Functions (Return Raw Vectors - for Retrieval Tab) ---
# These are the ones ending with _internal, as previously defined.

def get_splade_cocondenser_representation_internal(text, tokenizer, model):
    if tokenizer is None or model is None: return None
    inputs = tokenizer(text, return_tensors="pt", padding=True, truncation=True)
    inputs = {k: v.to(model.device) for k, v in inputs.items()}
    with torch.no_grad(): output = model(**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()
        return splade_vector
    else:
        print("Model output structure not as expected for SPLADE-cocondenser-distil. 'logits' not found.")
        return None

def get_splade_lexical_representation_internal(text, tokenizer, model):
    if tokenizer is None or model is None: return None
    inputs = tokenizer(text, return_tensors="pt", padding=True, truncation=True)
    inputs = {k: v.to(model.device) for k, v in inputs.items()}
    with torch.no_grad(): output = model(**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()
        vocab_size = tokenizer.vocab_size
        bow_mask = create_lexical_bow_mask(inputs['input_ids'], vocab_size, tokenizer).squeeze()
        splade_vector = splade_vector * bow_mask
        return splade_vector
    else:
        print("Model output structure not as expected for SPLADE-v3-Lexical. 'logits' not found.")
        return None

def get_splade_doc_representation_internal(text, tokenizer, model):
    if tokenizer is None or model is None: return None
    inputs = tokenizer(text, return_tensors="pt", padding=True, truncation=True)
    inputs = {k: v.to(model.device) for k, v in inputs.items()}
    vocab_size = tokenizer.vocab_size
    binary_splade_vector = create_lexical_bow_mask(inputs['input_ids'], vocab_size, tokenizer).squeeze()
    return binary_splade_vector


# --- Document Indexing Function (for Retrieval Tab) ---
def index_documents(doc_model_choice):
    global document_representations
    if document_representations:
        print("Documents already indexed. Skipping re-indexing.")
        return True

    tokenizer_to_use = None
    model_to_use = None
    representation_func_to_use = None

    if doc_model_choice == "SPLADE-cocondenser-distil":
        if tokenizer_splade is None or model_splade is None:
            print("SPLADE-cocondenser-distil model not loaded for indexing.")
            return False
        tokenizer_to_use = tokenizer_splade
        model_to_use = model_splade
        representation_func_to_use = get_splade_cocondenser_representation_internal
    elif doc_model_choice == "SPLADE-v3-Lexical":
        if tokenizer_splade_lexical is None or model_splade_lexical is None:
            print("SPLADE-v3-Lexical model not loaded for indexing.")
            return False
        tokenizer_to_use = tokenizer_splade_lexical
        model_to_use = model_splade_lexical
        representation_func_to_use = get_splade_lexical_representation_internal
    elif doc_model_choice == "SPLADE-v3-Doc":
        if tokenizer_splade_doc is None or model_splade_doc is None:
            print("SPLADE-v3-Doc model not loaded for indexing.")
            return False
        tokenizer_to_use = tokenizer_splade_doc
        model_to_use = model_splade_doc
        representation_func_to_use = get_splade_doc_representation_internal
    else:
        print(f"Invalid model choice for document indexing: {doc_model_choice}")
        return False

    print(f"Indexing documents using {doc_model_choice}...")
    
    doc_items = list(document_texts.items())
    
    for doc_id, doc_text in tqdm(doc_items, desc="Indexing Documents"):
        sparse_vector = representation_func_to_use(doc_text, tokenizer_to_use, model_to_use)
        if sparse_vector is not None:
            document_representations[doc_id] = sparse_vector.cpu()
        else:
            print(f"Warning: Failed to get representation for doc_id {doc_id}")

    print(f"Finished indexing {len(document_representations)} documents.")
    return True

# --- Retrieval Function (for Retrieval Tab) ---
def retrieve_documents(query_text, query_model_choice, indexed_doc_model_name, top_k=5):
    if not document_representations:
        return "Document index is not loaded or empty. Please ensure documents are indexed.", []

    query_vector = None
    query_tokenizer = None
    query_model = None

    if query_model_choice == "SPLADE-cocondenser-distil (weighting and expansion)":
        query_tokenizer = tokenizer_splade
        query_model = model_splade
        query_vector = get_splade_cocondenser_representation_internal(query_text, query_tokenizer, query_model)
    elif query_model_choice == "SPLADE-v3-Lexical (weighting)":
        query_tokenizer = tokenizer_splade_lexical
        query_model = model_splade_lexical
        query_vector = get_splade_lexical_representation_internal(query_text, query_tokenizer, query_model)
    elif query_model_choice == "SPLADE-v3-Doc (binary)":
        query_tokenizer = tokenizer_splade_doc
        query_model = model_splade_doc
        query_vector = get_splade_doc_representation_internal(query_text, query_tokenizer, query_model)
    else:
        return "Invalid query model choice.", []

    if query_vector is None:
        return "Failed to get query representation. Check console for model loading errors.", []

    query_vector = query_vector.cpu()

    scores = {}
    for doc_id, doc_vec in document_representations.items():
        score = torch.dot(query_vector, doc_vec).item()
        scores[doc_id] = score

    sorted_scores = sorted(scores.items(), key=lambda item: item[1], reverse=True)
    top_results = sorted_scores[:top_k]

    formatted_output = f"Retrieval Results for Query: '{query_text}'\n"
    formatted_output += f"Using Query Model: **{query_model_choice}**\n"
    formatted_output += f"Documents Indexed with: **{indexed_doc_model_name}**\n\n"

    if not top_results:
        formatted_output += "No documents found or scored.\n"
    else:
        for i, (doc_id, score) in enumerate(top_results):
            doc_text = document_texts.get(doc_id, "Document text not available.")
            formatted_output += f"**{i+1}. Document ID: {doc_id}** (Score: {score:.4f})\n"
            formatted_output += f"> {doc_text[:300]}...\n\n"

    return formatted_output, top_results

# --- Unified Prediction Function for Gradio (for Retrieval Tab) ---
def predict_retrieval_gradio(query_text, query_model_choice, selected_doc_model_display_only):
    formatted_output, _ = retrieve_documents(query_text, query_model_choice, initial_doc_model_for_indexing, top_k=5)
    return formatted_output

# --- Initial Load and Indexing Calls ---
# This part runs once when the app starts.
load_scifact_corpus_ir_datasets() # Or load_cranfield_corpus_ir_datasets() if you switch back

if initial_doc_model_for_indexing == "SPLADE-cocondenser-distil" and model_splade is not None:
    index_documents(initial_doc_model_for_indexing)
elif initial_doc_model_for_indexing == "SPLADE-v3-Lexical" and model_splade_lexical is not None:
    index_documents(initial_doc_model_for_indexing)
elif initial_doc_model_for_indexing == "SPLADE-v3-Doc" and model_splade_doc is not None:
    index_documents(initial_doc_model_for_indexing)
else:
    print(f"Skipping document indexing: Model '{initial_doc_model_for_indexing}' failed to load or is not a valid choice for indexing.")


# --- Gradio Interface Setup with Tabs ---
with gr.Blocks(title="SPLADE Demos") as demo:
    gr.Markdown("# 🌌 SPLADE Demos: Sparse Representation Explorer & Document Retrieval")
    gr.Markdown("Explore different SPLADE models and their sparse representation types, or perform document retrieval on a test collection.")

    with gr.Tabs():
        with gr.TabItem("Sparse Representation Explorer"):
            gr.Markdown("### Explore Raw SPLADE Representations for Any Text")
            gr.Interface(
                fn=predict_representation_explorer,
                inputs=[
                    gr.Radio(
                        [
                            "SPLADE-cocondenser-distil (weighting and expansion)",
                            "SPLADE-v3-Lexical (weighting)",
                            "SPLADE-v3-Doc (binary)"
                        ],
                        label="Choose Representation Model",
                        value="SPLADE-cocondenser-distil (weighting and expansion)"
                    ),
                    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(),
                allow_flagging="never",
                # Don't show redundant title/description within the tab, as it's above
                # Setting live=True might be slow for complex models on every keystroke
                # live=True
            )

        with gr.TabItem("Document Retrieval Demo"):
            gr.Markdown("### Retrieve Documents from SciFact Collection")
            gr.Interface(
                fn=predict_retrieval_gradio,
                inputs=[
                    gr.Textbox(
                        lines=3,
                        label="Enter your query text here:",
                        placeholder="e.g., Does high-dose vitamin C cure cancer?"
                    ),
                    gr.Radio(
                        [
                            "SPLADE-cocondenser-distil (weighting and expansion)",
                            "SPLADE-v3-Lexical (weighting)",
                            "SPLADE-v3-Doc (binary)"
                        ],
                        label="Choose Query Representation Model",
                        value="SPLADE-cocondenser-distil (weighting and expansion)"
                    ),
                    gr.Radio(
                        [
                            "SPLADE-cocondenser-distil",
                            "SPLADE-v3-Lexical",
                            "SPLADE-v3-Doc"
                        ],
                        label=f"Document Index Model (Pre-indexed with: {initial_doc_model_for_indexing})",
                        value=initial_doc_model_for_indexing,
                        interactive=False # This radio is fixed for simplicity
                    )
                ],
                outputs=gr.Markdown(),
                allow_flagging="never",
                # live=True # retrieval is too heavy for live
            )

demo.launch()