import numpy as np
import pandas as pd
from sklearn.feature_extraction.text import TfidfVectorizer
from rank_bm25 import BM25Okapi

# Read CSV file
data = pd.read_csv(r'books.csv', encoding='latin1')

class TFIDFDoc2Vec:
    def __init__(self):
        self.tfidf_vectorizer = TfidfVectorizer()
        self.doc_vectors = None

    def initialize_vectors(self, documents):
        tfidf_matrix = self.tfidf_vectorizer.fit_transform(documents)
        self.doc_vectors = tfidf_matrix.toarray()

    def find_similar_documents(self, query, threshold=0.5):
        query_vector = self.tfidf_vectorizer.transform([query]).toarray()
        similarities = np.dot(query_vector, self.doc_vectors.T)
        similar_indices = np.where(similarities >= threshold)[1]
        return similar_indices, similarities

def answer(query, threshold=0.5, top_n=10):
    # Find similar documents using TF-IDF
    similar_documents_indices, similarities = tfidf_doc2vec_model.find_similar_documents(query, threshold=threshold)

    # Check if no similar documents are found
    if len(similar_documents_indices) == 0:
        return "No books found for the query."

    # Rank similar documents using BM25
    scores = bm25_model.get_scores(query.split())  # Split the query into tokens
    bm25_ranked_indices = np.argsort(scores)[::-1]

    # Initialize a set to keep track of unique document indices
    unique_indices = set()

    # Combine results from TF-IDF and BM25, keeping unique indices
    combined_indices = []
    for index in similar_documents_indices:
        if index not in unique_indices:
            combined_indices.append(index)
            unique_indices.add(index)
    for index in bm25_ranked_indices:
        if index not in unique_indices:
            combined_indices.append(index)
            unique_indices.add(index)

    # Retrieve document details
    ranked_documents = []
    for index in combined_indices[:top_n]:  # Adjust to the desired number of results
        document_details = {
            "Book": data['Book Title'].iloc[index],
            "Author": data['Author'].iloc[index],
            "Edition": data['Edition'].iloc[index],
            "Copyright Year": data['Copyright Year'].iloc[index],
            "File Name": data['File_name'].iloc[index]
        }
        ranked_documents.append(document_details)

    return ranked_documents

# Initialize TF-IDF model
tfidf_doc2vec_model = TFIDFDoc2Vec()
documents = data['Book Title'].astype(str)
tfidf_doc2vec_model.initialize_vectors(documents)

# Initialize BM25 model
bm25_model = BM25Okapi([doc.split() for doc in documents])

# Example usage
#query = "mathematics"
#result = answer(query)
#print(result)