import os
import threading
import hashlib
import logging
import time
from datetime import datetime
from flask import Flask, render_template, request, jsonify
from rss_processor import fetch_rss_feeds, process_and_store_articles, download_from_hf_hub, upload_to_hf_hub, LOCAL_DB_DIR
from langchain.vectorstores import Chroma
from langchain.embeddings import HuggingFaceEmbeddings

app = Flask(__name__)
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

loading_complete = True
last_update_time = time.time()
last_data_hash = None

def get_embedding_model():
    if not hasattr(get_embedding_model, "model"):
        get_embedding_model.model = HuggingFaceEmbeddings(model_name="sentence-transformers/all-MiniLM-L6-v2")
    return get_embedding_model.model

def get_vector_db():
    if not os.path.exists(LOCAL_DB_DIR):
        return None
    try:
        if not hasattr(get_vector_db, "db_instance"):
            get_vector_db.db_instance = Chroma(
                persist_directory=LOCAL_DB_DIR,
                embedding_function=get_embedding_model(),
                collection_name="news_articles"
            )
        return get_vector_db.db_instance
    except Exception as e:
        logger.error(f"Failed to load vector DB: {e}")
        if hasattr(get_vector_db, "db_instance"):
            delattr(get_vector_db, "db_instance")
        return None

def load_feeds_in_background():
    global loading_complete, last_update_time
    if not loading_complete:
        return
    loading_complete = False
    try:
        logger.info("Starting background RSS feed fetch")
        articles = fetch_rss_feeds()
        logger.info(f"Fetched {len(articles)} articles")
        process_and_store_articles(articles)
        last_update_time = time.time()
        logger.info("Background feed processing complete")
        upload_to_hf_hub()
    except Exception as e:
        logger.error(f"Error in background feed loading: {e}")
    finally:
        loading_complete = True

def get_all_docs_from_db():
    vector_db = get_vector_db()
    if not vector_db or vector_db._collection.count() == 0:
        return {'documents': [], 'metadatas': []}
    return vector_db.get(include=['documents', 'metadatas'])

def format_articles_from_db_results(docs):
    enriched_articles = []
    seen_keys = set()

    items = []
    if isinstance(docs, dict) and 'metadatas' in docs:
        items = zip(docs.get('documents', []), docs.get('metadatas', []))
    elif isinstance(docs, list):
        items = [(doc.page_content, doc.metadata) for doc, score in docs]

    for doc_content, meta in items:
        if not meta: continue
        title = meta.get("title", "No Title")
        link = meta.get("link", "")
        published = meta.get("published", "Unknown Date").strip()
        key = f"{title}|{link}|{published}"

        if key not in seen_keys:
            seen_keys.add(key)
            try:
                published_iso = datetime.strptime(published, "%Y-%m-%d %H:%M:%S").isoformat()
            except (ValueError, TypeError):
                published_iso = "1970-01-01T00:00:00"
            
            enriched_articles.append({
                "title": title,
                "link": link,
                "description": meta.get("original_description", "No Description"),
                "category": meta.get("category", "Uncategorized"),
                "published": published_iso,
                "image": meta.get("image", "svg"),
            })
    
    enriched_articles.sort(key=lambda x: x["published"], reverse=True)
    return enriched_articles

def compute_data_hash(categorized_articles):
    if not categorized_articles: return ""
    data_str = ""
    for cat, articles in sorted(categorized_articles.items()):
        for article in sorted(articles, key=lambda x: x["published"]):
            data_str += f"{cat}|{article['title']}|{article['link']}|{article['published']}|"
    return hashlib.sha256(data_str.encode('utf-8')).hexdigest()

@app.route('/')
def index():
    global loading_complete, last_update_time, last_data_hash

    if not os.path.exists(LOCAL_DB_DIR):
        logger.info(f"No Chroma DB found at '{LOCAL_DB_DIR}', downloading from Hugging Face Hub...")
        download_from_hf_hub()

    threading.Thread(target=load_feeds_in_background, daemon=True).start()

    try:
        all_docs = get_all_docs_from_db()
        if not all_docs['metadatas']:
            return render_template("index.html", categorized_articles={}, has_articles=False, loading=True)

        enriched_articles = format_articles_from_db_results(all_docs)
        
        categorized_articles = {}
        for article in enriched_articles:
            cat = article["category"]
            categorized_articles.setdefault(cat, []).append(article)
        
        categorized_articles = dict(sorted(categorized_articles.items()))
        for cat in categorized_articles:
            categorized_articles[cat] = categorized_articles[cat][:10]

        last_data_hash = compute_data_hash(categorized_articles)
        
        return render_template("index.html", categorized_articles=categorized_articles, has_articles=True, loading=not loading_complete)
    except Exception as e:
        logger.error(f"Error retrieving articles at startup: {e}", exc_info=True)
        return render_template("index.html", categorized_articles={}, has_articles=False, loading=True)

@app.route('/search', methods=['POST'])
def search():
    query = request.form.get('search')
    if not query:
        return jsonify({"categorized_articles": {}, "has_articles": False, "loading": False})

    vector_db = get_vector_db()
    if not vector_db:
        return jsonify({"categorized_articles": {}, "has_articles": False, "loading": False})
    
    try:
        results = vector_db.similarity_search_with_relevance_scores(query, k=50, score_threshold=0.5)
        enriched_articles = format_articles_from_db_results(results)

        categorized_articles = {}
        for article in enriched_articles:
            cat = article["category"]
            categorized_articles.setdefault(cat, []).append(article)

        return jsonify({
            "categorized_articles": categorized_articles,
            "has_articles": bool(enriched_articles),
            "loading": False
        })
    except Exception as e:
        logger.error(f"Semantic search error: {e}", exc_info=True)
        return jsonify({"categorized_articles": {}, "has_articles": False, "loading": False}), 500

@app.route('/get_all_articles/<category>')
def get_all_articles(category):
    try:
        all_docs = get_all_docs_from_db()
        enriched_articles = format_articles_from_db_results(all_docs)
        category_articles = [article for article in enriched_articles if article["category"] == category]
        return jsonify({"articles": category_articles, "category": category})
    except Exception as e:
        logger.error(f"Error fetching all articles for category {category}: {e}")
        return jsonify({"articles": [], "category": category}), 500

@app.route('/check_loading')
def check_loading():
    return jsonify({"status": "complete" if loading_complete else "loading", "last_update": last_update_time})

@app.route('/get_updates')
def get_updates():
    global last_update_time, last_data_hash
    try:
        all_docs = get_all_docs_from_db()
        if not all_docs['metadatas']:
            return jsonify({"articles": {}, "last_update": last_update_time, "has_updates": False})
        
        enriched_articles = format_articles_from_db_results(all_docs)
        categorized_articles = {}
        for article in enriched_articles:
            cat = article["category"]
            categorized_articles.setdefault(cat, []).append(article)
        
        for cat in categorized_articles:
            categorized_articles[cat] = categorized_articles[cat][:10]

        current_data_hash = compute_data_hash(categorized_articles)
        has_updates = last_data_hash != current_data_hash
        
        if has_updates:
            last_data_hash = current_data_hash
            return jsonify({"articles": categorized_articles, "last_update": last_update_time, "has_updates": True})
        else:
            return jsonify({"articles": {}, "last_update": last_update_time, "has_updates": False})
    except Exception as e:
        logger.error(f"Error fetching updates: {e}")
        return jsonify({"articles": {}, "last_update": last_update_time, "has_updates": False}), 500

@app.route('/card')
def card_load():
    return render_template("card.html")

@app.route('/api/v1/search', methods=['GET'])
def api_search():
    query = request.args.get('q')
    limit = request.args.get('limit', default=20, type=int)

    if not query:
        return jsonify({"error": "Query parameter 'q' is required."}), 400

    vector_db = get_vector_db()
    if not vector_db:
        return jsonify({"error": "Database not available."}), 503

    try:
        results = vector_db.similarity_search_with_relevance_scores(query, k=limit)
        formatted_articles = format_articles_from_db_results(results)
        return jsonify(formatted_articles)
    except Exception as e:
        logger.error(f"API Search error: {e}", exc_info=True)
        return jsonify({"error": "An internal error occurred during search."}), 500

@app.route('/api/v1/articles/category/<string:category_name>', methods=['GET'])
def api_get_articles_by_category(category_name):
    limit = request.args.get('limit', default=20, type=int)
    offset = request.args.get('offset', default=0, type=int)

    vector_db = get_vector_db()
    if not vector_db:
        return jsonify({"error": "Database not available."}), 503

    try:
        results = vector_db.get(where={"category": category_name}, include=['documents', 'metadatas'])
        formatted_articles = format_articles_from_db_results(results)
        paginated_results = formatted_articles[offset : offset + limit]
        
        return jsonify({
            "category": category_name,
            "total_articles": len(formatted_articles),
            "articles": paginated_results
        })
    except Exception as e:
        logger.error(f"API Category fetch error: {e}", exc_info=True)
        return jsonify({"error": "An internal error occurred."}), 500

@app.route('/api/v1/categories', methods=['GET'])
def api_get_categories():
    vector_db = get_vector_db()
    if not vector_db:
        return jsonify({"error": "Database not available."}), 503
        
    try:
        all_metadata = vector_db.get(include=['metadatas'])['metadatas']
        if not all_metadata:
            return jsonify([])
            
        unique_categories = sorted(list({meta['category'] for meta in all_metadata if 'category' in meta}))
        return jsonify(unique_categories)
    except Exception as e:
        logger.error(f"API Categories fetch error: {e}", exc_info=True)
        return jsonify({"error": "An internal error occurred."}), 500

@app.route('/api/v1/status', methods=['GET'])
def api_get_status():
    return jsonify({
        "status": "complete" if loading_complete else "loading",
        "last_update_time": last_update_time
    })

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=7860)