"""
This is a book recommendation system.
"""

import pickle
import streamlit as st
import pandas as pd
import numpy as np
from sklearn.preprocessing import LabelEncoder
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.metrics.pairwise import cosine_similarity
from tensorflow.keras.models import load_model

# Load datasets
books = pd.read_csv("./dataset/books.csv")
ratings = pd.read_csv("./dataset/ratings.csv")

# Preprocess data
user_encoder = LabelEncoder()
book_encoder = LabelEncoder()


ratings["user_id"] = user_encoder.fit_transform(ratings["user_id"])
ratings["book_id"] = book_encoder.fit_transform(ratings["book_id"])

# Load TF-IDF models
with open("tfidf_model_authors.pkl", "rb") as f:
    tfidf_model_authors = pickle.load(f)

with open("tfidf_model_titles.pkl", "rb") as f:
    tfidf_model_titles = pickle.load(f)

# Define TF-IDF vectorizer
tfidf_vectorizer = TfidfVectorizer(stop_words="english")

# Fit and transform the book descriptions
tfidf_matrix = tfidf_vectorizer.fit_transform(books["original_title"].fillna(""))

# Load collaborative filtering model
model_cf = load_model("recommendation_model.keras")


# Content-Based Recommendation
def content_based_recommendation(
    query, books, tfidf_model_authors, tfidf_model_titles, num_recommendations=10
):
    """
    Recommend books based on content similarity.
    Args:
        query (str): The name of the book or author.
        books (DataFrame): DataFrame containing book information.
        tfidf_model_authors: Pre-trained TF-IDF model for authors.
        tfidf_model_titles: Pre-trained TF-IDF model for titles.
        num_recommendations (int): The number of books to recommend.
    Returns:
        DataFrame: A DataFrame containing recommended books with details.
    """
    # Check if the query corresponds to an author or a book
    if query in books["authors"].values:
        book_name = books.loc[books["authors"] == query, "original_title"].values[0]
    elif query in books["original_title"].values:
        book_name = query
    else:
        print("Query not found in authors or titles.")
        return None

    book_author = books.loc[books["original_title"] == book_name, "authors"].values[0]
    book_title = books.loc[books["title"] == book_name, "title"].values[0]

    # Transform book author, title, and description into TF-IDF vectors
    book_author_tfidf = tfidf_model_authors.transform([book_author])
    book_title_tfidf = tfidf_model_titles.transform([book_title])

    # Compute cosine similarity for authors and titles separately
    similarity_scores_authors = cosine_similarity(
        book_author_tfidf, tfidf_model_authors.transform(books["authors"])
    )
    similarity_scores_titles = cosine_similarity(
        book_title_tfidf, tfidf_model_titles.transform(books["title"])
    )

    # Combine similarity scores for authors and titles
    similarity_scores_combined = (
        similarity_scores_authors + similarity_scores_titles
    ) / 2

    # Get indices of recommended books
    recommended_indices = np.argsort(similarity_scores_combined.flatten())[
        -num_recommendations:
    ][::-1]

    # Get recommended books
    recommended_books = books.iloc[recommended_indices]

    return recommended_books


# Collaborative Recommendation
def collaborative_recommendation(user_id, model_cf, ratings, num_recommendations=10):
    """
    Recommend books based on collaborative filtering.
    Args:
        user_id (int): The user ID.
        model_cf: The trained collaborative filtering model.
        ratings (DataFrame): DataFrame containing user ratings.
        num_recommendations (int): The number of books to recommend.
    Returns:
        DataFrame: A DataFrame containing recommended books with details.
    """
    # Check if the user ID exists in the ratings dataset
    if user_id not in ratings["user_id"].unique():
        print("User ID not found in ratings dataset.")
        return None

    # Get unrated books for the user
    unrated_books = ratings[
        ~ratings["book_id"].isin(ratings[ratings["user_id"] == user_id]["book_id"])
    ]["book_id"].unique()

    # Check if there are unrated books
    if len(unrated_books) == 0:
        print("No unrated books found for the user.")
        return None

    # Predict ratings for unrated books
    predictions = model_cf.predict(
        [np.full_like(unrated_books, user_id), unrated_books]
    ).flatten()

    # Get top indices based on predictions
    top_indices = np.argsort(predictions)[-num_recommendations:][::-1]

    # Get recommended books
    recommended_books = books.iloc[top_indices][["original_title", "authors"]]
    return recommended_books


# History-Based Recommendation
def history_based_recommendation(user_id, ratings, num_recommendations=10):
    """
    Recommend books based on user's historical ratings.
    Args:
        user_id (int): The user ID.
        ratings (DataFrame): DataFrame containing user ratings.
        num_recommendations (int): The number of books to recommend.
    Returns:
        DataFrame: A DataFrame containing recommended books with details.
    """
    user_ratings = ratings[ratings["user_id"] == user_id]
    top_books = user_ratings.sort_values(by="rating", ascending=False).head(
        num_recommendations
    )["book_id"]
    recommended_books = books[books["book_id"].isin(top_books)]
    return recommended_books


# Hybrid Recommendation
def hybrid_recommendation(
    user_id,
    query,
    model_cf,
    books,
    ratings,
    tfidf_model_authors,
    tfidf_model_titles,
    num_recommendations=10,
):
    """
    Recommend books using hybrid recommendation approach.
    Args:
        user_id (int): The user ID.
        query (str): The name of the book or author.
        model_cf: The collaborative filtering model.
        books (DataFrame): DataFrame containing book information.
        ratings (DataFrame): DataFrame containing user ratings.
        tfidf_model_authors: Pre-trained TF-IDF model for authors.
        tfidf_model_titles: Pre-trained TF-IDF model for titles.
        num_recommendations (int): The number of books to recommend.
    Returns:
        DataFrame: A DataFrame containing recommended books with details.
    """
    content_based_rec = content_based_recommendation(
        query,
        books,
        tfidf_model_authors,
        tfidf_model_titles,
        num_recommendations=num_recommendations,
    )
    collaborative_rec = collaborative_recommendation(
        user_id, model_cf, ratings, num_recommendations=num_recommendations
    )
    history_based_rec = history_based_recommendation(
        user_id, ratings, num_recommendations=num_recommendations
    )

    # Combine recommendations from different approaches
    hybrid_rec = pd.concat(
        [content_based_rec, collaborative_rec, history_based_rec]
    ).drop_duplicates(subset="book_id", keep="first")
    return hybrid_rec


# Top Recommendations (most popular books)
def top_recommendations(books, num_recommendations=10):
    """
    Recommend top books based on popularity (highest ratings count).
    Args:
        books (DataFrame): DataFrame containing book information.
        num_recommendations (int): The number of books to recommend.
    Returns:
        DataFrame: A DataFrame containing recommended books with details.
    """
    top_books = books.sort_values(by="ratings_count", ascending=False).head(
        num_recommendations
    )
    return top_books


# Test the recommendation functions
query = input("Enter book name or author: ")
USER_ID = 0  # Example user ID for collaborative and history-based recommendations

print("Content-Based Recommendation:")
print(
    content_based_recommendation(query, books, tfidf_model_authors, tfidf_model_titles)
)

print("\nCollaborative Recommendation:")
print(collaborative_recommendation(USER_ID, model_cf, ratings))

print("\nHistory-Based Recommendation:")
print(history_based_recommendation(USER_ID, ratings))

print("\nHybrid Recommendation:")
print(
    hybrid_recommendation(
        user_id,
        query,
        model_cf,
        books,
        ratings,
        tfidf_model_authors,
        tfidf_model_titles,
    )
)

print("\nTop Recommendations:")
print(top_recommendations(books))

# Streamlit App
st.title("Book Recommendation System")

# Sidebar for user input
user_input = st.text_input("Enter book name or author:", "")

# Get recommendations on button click
if st.button("Get Recommendations"):
    st.write("Content-Based Recommendation:")
    content_based_rec = content_based_recommendation(
        user_input, books, tfidf_model_authors, tfidf_model_titles
    )
    st.write(content_based_rec)

    st.write("Collaborative Recommendation:")
    collaborative_rec = collaborative_recommendation(0, model_cf, ratings)
    st.write(collaborative_rec)

    st.write("Hybrid Recommendation:")
    hybrid_rec = hybrid_recommendation(
        0, user_input, model_cf, books, ratings, tfidf_model_authors, tfidf_model_titles
    )
    st.write(hybrid_rec)