import os
import requests
import pdfplumber
import trafilatura
from bs4 import BeautifulSoup
from urllib.parse import urljoin, urlparse
from sentence_transformers import SentenceTransformer
import faiss
import numpy as np
import pickle
import argparse

# from ollama_initial import start_ollama_model
from llama_query import ask_llm_with_context
from smart_chunk import smart_chunk_text  # for semantic-aware chunking

# === Config ===
INDEX_FILE = "legal_index.faiss"
DOCS_FILE = "legal_chunks.pkl"
PDF_CACHE_FILE = "processed_pdfs.pkl"
URL_CACHE_FILE = "processed_urls.pkl"

EMBEDDING_MODEL = "intfloat/e5-base-v2"
ALLOWED_DOMAINS = ["gov", "org", "ca"]
PDF_FOLDER = "pdf"
URL_FILE = "urls.txt"

# === CLI args ===
parser = argparse.ArgumentParser()
parser.add_argument("--update", action="store_true", help="Update only new PDFs/URLs (uses cache)")
parser.add_argument("--updateall", action="store_true", help="Force complete reindexing of all documents (ignores cache)")
args = parser.parse_args()

# === Embedding setup ===
model = SentenceTransformer(EMBEDDING_MODEL)
vector_index = faiss.IndexFlatL2(model.get_sentence_embedding_dimension())
documents = []

# === Cache handling ===
def load_cache(file):
    if os.path.exists(file):
        with open(file, "rb") as f:
            return pickle.load(f)
    return set()

def save_cache(data, file):
    with open(file, "wb") as f:
        pickle.dump(data, f)

# === Index persistence ===
def save_index():
    faiss.write_index(vector_index, INDEX_FILE)
    with open(DOCS_FILE, "wb") as f:
        pickle.dump(documents, f)
    print("✅ Vector index and chunks saved.")

def load_index():
    global vector_index, documents
    if os.path.exists(INDEX_FILE) and os.path.exists(DOCS_FILE):
        print("📂 Found existing FAISS index and document chunks...")
        vector_index = faiss.read_index(INDEX_FILE)
        with open(DOCS_FILE, "rb") as f:
            documents = pickle.load(f)
        print(f"✅ Loaded {vector_index.ntotal} vectors and {len(documents)} text chunks.")
        return True
    else:
        print("❌ FAISS or document file not found.")
    return False


# === Chunk + embed ===
def store_text_chunks(text):
    chunks = smart_chunk_text(text, max_tokens=128)
    chunks = [chunk.strip() for chunk in chunks if chunk.strip()]

    if not chunks:
        return

    vectors = model.encode(chunks, batch_size=16, show_progress_bar=True)
    vector_index.add(np.array(vectors))
    documents.extend(chunks)


# === Text extraction ===
def get_text_from_pdf_file(filepath):
    try:
        with pdfplumber.open(filepath) as pdf:
            return "\n".join(page.extract_text() or '' for page in pdf.pages)
    except Exception as e:
        print(f"[!] Failed to read PDF: {filepath} — {e}")
        return ""

def get_text_from_pdf_url(url):
    try:
        response = requests.get(url)
        filename = "temp.pdf"
        with open(filename, "wb") as f:
            f.write(response.content)
        text = get_text_from_pdf_file(filename)
        os.remove(filename)
        return text
    except Exception as e:
        print(f"[!] Failed to fetch PDF from URL: {url} — {e}")
        return ""

def get_text_from_html(url):
    try:
        html = requests.get(url).text
        return trafilatura.extract(html, include_comments=False, include_tables=False) or ""
    except Exception as e:
        print(f"[!] Failed HTML: {url} — {e}")
        return ""

def is_valid_link(link, base_url):
    full_url = urljoin(base_url, link)
    parsed = urlparse(full_url)
    return parsed.scheme.startswith("http") and any(tld in parsed.netloc for tld in ALLOWED_DOMAINS)

# === Processing ===
def process_pdf_folder(folder_path=PDF_FOLDER, processed_files=None):
    if processed_files is None:
        processed_files = set()
    for filename in os.listdir(folder_path):
        if filename.lower().endswith(".pdf") and filename not in processed_files:
            full_path = os.path.join(folder_path, filename)
            print(f"📄 Reading new PDF: {full_path}")
            text = get_text_from_pdf_file(full_path)
            store_text_chunks(text)
            processed_files.add(filename)
        else:
            print(f"✅ Skipping already processed PDF: {filename}")

def crawl_url(url, depth=1, processed_urls=None):
    if processed_urls is None:
        processed_urls = set()
    if url in processed_urls:
        print(f"✅ Skipping already crawled URL: {url}")
        return

    print(f"🔗 Crawling: {url}")
    visited = set()
    to_visit = [url]

    while to_visit and depth > 0:
        current = to_visit.pop()
        visited.add(current)

        if current.endswith(".pdf"):
            text = get_text_from_pdf_url(current)
        else:
            text = get_text_from_html(current)

        store_text_chunks(text)
        processed_urls.add(current)

        try:
            page = requests.get(current).text
            soup = BeautifulSoup(page, "html.parser")
            for a in soup.find_all("a", href=True):
                href = a["href"]
                full_url = urljoin(current, href)
                if full_url not in visited and is_valid_link(href, current):
                    to_visit.append(full_url)
        except Exception:
            continue

        depth -= 1

# === Retrieval ===
def load_urls(file_path=URL_FILE):
    with open(file_path, "r", encoding="utf-8") as f:
        return [line.strip() for line in f if line.strip()]

def query_index(question, top_k=5):
    if not documents:
        return "No documents found in the index."
    query = f"query: {question}"
    q_vector = model.encode(query)
    D, I = vector_index.search(np.array([q_vector]), top_k)
    return "\n---\n".join([documents[i] for i in I[0]])

# === Main Execution ===
if __name__ == "__main__":
    print("🚀 Starting BC Land Survey Legal Assistant")

    # Default behavior: load existing index
    update_mode = "none"  # can be "none", "update", or "updateall"
    if args.updateall:
        update_mode = "updateall"
    elif args.update:
        update_mode = "update"

    # Load caches for local PDF and URL tracking
    processed_pdfs = load_cache(PDF_CACHE_FILE)
    processed_urls = load_cache(URL_CACHE_FILE)

    if update_mode == "updateall":
        print("🔁 Rebuilding index from scratch...")
        processed_pdfs = set()
        processed_urls = set()

    index_loaded = load_index()

    if update_mode == "updateall" or not index_loaded or update_mode == "update":
        if not index_loaded:
            print("⚠️ Index not found — will rebuild from source.")
        print("🔄 Indexing content...")

        process_pdf_folder(processed_files=processed_pdfs)
        for url in load_urls():
            crawl_url(url, depth=1, processed_urls=processed_urls)

        save_index()
        save_cache(processed_pdfs, PDF_CACHE_FILE)
        save_cache(processed_urls, URL_CACHE_FILE)
    else:
        print(f"✅ Loaded FAISS index with {vector_index.ntotal} vectors.")
        print(f"✅ Loaded {len(documents)} legal chunks.")

    print("\n❓ Ready to query your legal database (type 'exit' to quit)")
    while True:
        question = input("\n🔎 Your question: ")
        if question.strip().lower() in ["exit", "quit", "q"]:
            print("👋 Exiting. See you next time!")
            break
        context = query_index(question)
        answer = ask_llm_with_context(question, context)
        print("\n🧠 LLaMA 3 Answer:")
        print(answer)


def initialize_index(update_mode="none"):
    global documents, vector_index

    processed_pdfs = load_cache(PDF_CACHE_FILE)
    processed_urls = load_cache(URL_CACHE_FILE)

    if update_mode == "updateall":
        processed_pdfs = set()
        processed_urls = set()

    index_loaded = load_index()

    if update_mode == "updateall" or not index_loaded or update_mode == "update":
        process_pdf_folder(processed_files=processed_pdfs)
        for url in load_urls():
            crawl_url(url, depth=1, processed_urls=processed_urls)
        save_index()
        save_cache(processed_pdfs, PDF_CACHE_FILE)
        save_cache(processed_urls, URL_CACHE_FILE)
    else:
        print(f"✅ FAISS index with {vector_index.ntotal} vectors loaded.")
        print(f"✅ Loaded {len(documents)} legal document chunks.")


# This version includes all 3 enhancements:
# - Smart chunking via smart_chunk.py
# - High-quality embedding model (E5)
# - Structured prompt with legal assistant context and disclaimer