import gradio as gr
import requests
from datetime import datetime, timezone

API_URL = "https://huggingface.co/api/daily_papers"

class PaperManager:
    def __init__(self, papers_per_page=10):
        self.papers_per_page = papers_per_page
        self.cache = []
        self.last_fetch_date = None
        self.total_pages = 1

    def fetch_papers(self):
        """
        Fetch papers from the API if not already fetched today.
        Returns:
            tuple: (success: bool, data: list, error_message: str)
        """
        today = datetime.now(timezone.utc).date()
        if self.last_fetch_date == today and self.cache:
            print("Using cached papers.")
            return True, self.cache, ""
        else:
            try:
                # Attempt to fetch all papers at once. Adjust 'limit' as per API's capability.
                response = requests.get(f"{API_URL}?page=1&limit=1000")
                response.raise_for_status()
                data = response.json()
                self.cache = sorted(data, key=lambda x: x.get('paper', {}).get('upvotes', 0), reverse=True)
                self.last_fetch_date = today
                self.total_pages = (len(self.cache) + self.papers_per_page - 1) // self.papers_per_page
                print(f"Fetched {len(self.cache)} papers. Total pages: {self.total_pages}")
                return True, self.cache, ""
            except requests.RequestException as e:
                print(f"Error fetching papers: {e}")
                return False, [], str(e)

    def format_paper(self, paper):
        """
        Format a single paper's information into HTML.
        """
        title = paper.get('title', 'No title')
        paper_id = paper.get('paper', {}).get('id', '')
        url = f"https://huggingface.co/papers/{paper_id}" if paper_id else "#"
        authors = ', '.join([author.get('name', 'Unknown') for author in paper.get('paper', {}).get('authors', [])])
        upvotes = paper.get('paper', {}).get('upvotes', 0)
        comments = paper.get('numComments', 0)
        published_at = paper.get('publishedAt', datetime.now(timezone.utc).isoformat())
        try:
            published_time = datetime.fromisoformat(published_at.replace('Z', '+00:00'))
            time_ago = (datetime.now(timezone.utc) - published_time).days
        except ValueError:
            time_ago = "Unknown"

        return f"""<div style='border-bottom: 1px solid #eee; padding: 10px 0;'>
<a href='{url}' target='_blank' style='color: #000; text-decoration: none; font-weight: bold;'>{title}</a>
<div style='font-size: 0.8em; color: #666; margin-top: 5px;'>
{upvotes} upvotes | by {authors} | {time_ago} days ago | {comments} comments
</div>
</div>"""

    def render_papers(self, papers, page=1):
        """
        Render HTML for a list of papers based on the current page.
        """
        if not papers:
            return "<div>No papers available for this page.</div>"
        start = (page - 1) * self.papers_per_page
        end = start + self.papers_per_page
        page_papers = papers[start:end]
        return "".join([self.format_paper(paper) for paper in page_papers])

    def search_papers(self, query):
        """
        Filter papers based on the search query.
        """
        if not query:
            return self.cache
        return [paper for paper in self.cache if query.lower() in paper.get('title', '').lower()]

css = """
html, body {
    height: 100%;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #f0f0f0;
}
.container {
    font-family: Arial, sans-serif;
    max-width: 800px;
    width: 100%;
    background-color: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
.paper-list { 
    max-height: 400px; 
    overflow-y: auto;
    border: 1px solid #eee;
    border-radius: 5px;
    padding: 10px;
    margin-bottom: 10px;
}
.search-row {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}
.title {
    text-align: center;
    color: #333;
}
.footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 10px;
}
.error-message {
    color: red;
    margin-bottom: 10px;
    text-align: center;
}
"""

# Instantiate the PaperManager
paper_manager = PaperManager()

def initialize():
    """
    Initialize the app by fetching papers and setting initial states.
    """
    success, papers, error_message = paper_manager.fetch_papers()
    if success:
        page = 1
        total_pages = paper_manager.total_pages
        page_papers = paper_manager.render_papers(papers, page)
        page_info_text = f"Page {page} of {total_pages}"
        return page_papers, page, total_pages, papers, page_info_text, ""
    else:
        error_html = f"<div class='error-message'>Error fetching papers: {error_message}</div>"
        return error_html, 1, 1, [], "Page 1 of 1", error_message

def refresh_papers(current_page, query):
    """
    Refresh the papers. Fetch new data if a new day has started.
    """
    success, papers, error_message = paper_manager.fetch_papers()
    if success:
        # Reset to first page on refresh
        new_page = 1
        if query:
            filtered = paper_manager.search_papers(query)
            total_pages = (len(filtered) + paper_manager.papers_per_page - 1) // paper_manager.papers_per_page if filtered else 1
            page_papers = paper_manager.render_papers(filtered, new_page)
            page_info_text = f"Page {new_page} of {total_pages}"
            return page_papers, new_page, total_pages, filtered, page_info_text, ""
        else:
            papers = paper_manager.cache
            total_pages = paper_manager.total_pages
            page_papers = paper_manager.render_papers(papers, new_page)
            page_info_text = f"Page {new_page} of {total_pages}"
            return page_papers, new_page, total_pages, papers, page_info_text, ""
    else:
        error_html = f"<div cla