app.py

import os
from PIL import Image
import sys

from omegaconf import OmegaConf
import requests
from typing import Tuple
from bs4 import BeautifulSoup

import streamlit as st
from streamlit_pills import pills

from dotenv import load_dotenv
load_dotenv(override=True)

from pydantic import Field, BaseModel
from vectara_agent.agent import Agent, AgentStatusType
from vectara_agent.tools import ToolsFactory
from vectara_agent.tools_catalog import summarize_text

initial_prompt = "How can I help you today?"

get_headers = {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:98.0) Gecko/20100101 Firefox/98.0",
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8",
    "Accept-Language": "en-US,en;q=0.5",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "keep-alive",
}


def create_tools(cfg):    
    
    class QueryHackerNews(BaseModel):
        query: str = Field(..., description="The user query.")

    tools_factory = ToolsFactory(vectara_api_key=cfg.api_key, 
                                 vectara_customer_id=cfg.customer_id, 
                                 vectara_corpus_id=cfg.corpus_id)
    ask_hackernews = tools_factory.create_rag_tool(
        tool_name = "ask_hackernews",
        tool_description = """
        Responds to query based on information and stories in hacker news from the last 6-9 months.
        """,
        tool_args_schema = QueryHackerNews,
        reranker = "multilingual_reranker_v1", rerank_k = 100, 
        n_sentences_before = 2, n_sentences_after = 2, lambda_val = 0.005,
        summary_num_results = 10,
        vectara_summarizer = 'vectara-summary-ext-24-05-med-omni',
        include_citations = True,
    )

    def get_top_stories(
            n_stories: int = Field(default=10, description="The number of top stories to return.")
    ) -> list[str]:
        """
        Get the top stories from hacker news.
        Returns a list of story IDS for the top stories right now. These are the top stories on hacker news.
        """
        db_url = 'https://hacker-news.firebaseio.com/v0/'
        top_stories = requests.get(f"{db_url}topstories.json").json()
        return top_stories[:n_stories]

    def get_show_stories(
            n_stories: int = Field(default=10, description="The number of top SHOW HN stories to return.")
    ) -> list[str]:
        """
        Get the top SHOW HN stories from hacker news.
        Returns a list of story IDS for the top SHOW HN stories right now. These are stories where users show their projects.
        """
        db_url = 'https://hacker-news.firebaseio.com/v0/'
        top_stories = requests.get(f"{db_url}showstories.json").json()
        return top_stories[:n_stories]

    def get_ask_stories(
            n_stories: int = Field(default=10, description="The number of top ASK HN stories to return.")
    ) -> list[str]:
        """
        Get the top ASK HN stories from hacker news.
        Returns a list of story IDS for the top ASK HN stories right now. These are stories where users ask questions to the community.
        """
        db_url = 'https://hacker-news.firebaseio.com/v0/'
        top_stories = requests.get(f"{db_url}askstories.json").json()
        return top_stories[:n_stories]

    def get_story_details(
            story_id: str = Field(..., description="The story ID.")
    ) -> Tuple[str, str]:
        """
        Get the title of a story from hacker news.
        Returns:
         - The title of the story (str)
         - The main URL of the story (str)
         - The external link pointed to in the story (str)
        """
        db_url = 'https://hacker-news.firebaseio.com/v0/'
        story = requests.get(f"{db_url}item/{story_id}.json").json()
        story_url = f'https://news.ycombinator.com/item?id={story_id}'
        return story['title'], story_url, story['url'], 

    def get_story_text(
            story_id: str = Field(..., description="The story ID.")
    ) -> str:
        """
        Get the text of the story from hacker news (original text + all comments)
        Returns the extracted text of the story as a string.
        """
        url = f'https://news.ycombinator.com/item?id={story_id}'
        html = requests.get(url, headers=get_headers).text
        soup = BeautifulSoup(html, 'html5lib')
        for element in soup.find_all(['script', 'style']):
            element.decompose()
        text = soup.get_text(" ", strip=True).replace('\n', ' ')
        return text

    def whats_new(
            n_stories: int = Field(default=10, description="The number of new stories to return.")
    ) -> list[str]:
        """
        Provides a succint summary of what is new in the hackernews community
        by summarizing the content and comments of top stories.
        Returns a string with the summary.
        """
        stories = get_top_stories(n_stories)
        texts = [get_story_text(story_id) for story_id in stories[:n_stories]]
        all_stories = '---------\n\n'.join(texts)
        return summarize_text(all_stories)

    return (
        tools_factory.get_tools(
                [
                    get_top_stories, 
                    get_show_stories,
                    get_ask_stories,
                    get_story_details,
                    get_story_text,
                    whats_new
                ]
            ) +
        tools_factory.standard_tools() + 
        tools_factory.guardrail_tools() +
        [ask_hackernews]
    )

def initialize_agent(_cfg):
    if 'agent' in st.session_state:
        return st.session_state.agent
    
    bot_instructions = """
    - You are a helpful assistant, with expertise in answering user questions about Hacker News stories and comments.
    - Never discuss politics, and always respond politely.
    - This is important: when you include links to Hacker News stories, use the actual title of the story as the link's displayed text.
      Don't use text like "Source" which doesn't tell the user what the link is about.
    - Don't include external links in your responses unless the user asks for them.
    - Give slight preference to newer stories when answering questions.
    """

    def update_func(status_type: AgentStatusType, msg: str):
        if status_type != AgentStatusType.AGENT_UPDATE:
            output = f"{status_type.value} - {msg}"
            st.session_state.log_messages.append(output)

    agent = Agent(
        tools=create_tools(_cfg),
        topic="hacker news",
        custom_instructions=bot_instructions,
        update_func=update_func
    )
    agent.report()
    return agent

def toggle_logs():
    st.session_state.show_logs = not st.session_state.show_logs

def show_example_questions():        
    if len(st.session_state.example_messages) > 0 and st.session_state.first_turn:
        selected_example = pills("Queries to Try:", st.session_state.example_messages, index=None)
        if selected_example:
            st.session_state.ex_prompt = selected_example
            st.session_state.first_turn = False
            return True
    return False

def launch_bot():
    def reset():
        st.session_state.messages = [{"role": "assistant", "content": initial_prompt, "avatar": "🦖"}]
        st.session_state.thinking_message = "Agent at work..."
        st.session_state.log_messages = []
        st.session_state.prompt = None
        st.session_state.first_turn = True
        st.session_state.show_logs = False

    st.set_page_config(page_title="Hacker News Bot", layout="wide")
    if 'cfg' not in st.session_state:
        cfg = OmegaConf.create({
            'customer_id': str(os.environ['VECTARA_CUSTOMER_ID']),
            'corpus_id': str(os.environ['VECTARA_CORPUS_ID']),
            'api_key': str(os.environ['VECTARA_API_KEY']),
            'examples': os.environ.get('QUERY_EXAMPLES', None)
        })
        st.session_state.cfg = cfg
        st.session_state.ex_prompt = None
        example_messages = [example.strip() for example in cfg.examples.split(",")] if cfg.examples else []
        st.session_state.example_messages = [em for em in example_messages if len(em)>0]
        reset()

    cfg = st.session_state.cfg
    if 'agent' not in st.session_state:
        st.session_state.agent = initialize_agent(cfg)

    # left side content
    with st.sidebar:
        image = Image.open('Vectara-logo.png')
        st.image(image, width=175)
        st.markdown("## Welcome to the hacker news assistant demo.\n\n\n")

        st.markdown("\n\n")
        bc1, _ = st.columns([1, 1])
        with bc1:
            if st.button('Start Over'):
                reset()

        st.markdown("---")
        st.markdown(
            "## How this works?\n"
            "This app was built with [Vectara](https://vectara.com).\n\n"
            "It demonstrates the use of Agentic RAG functionality with Vectara"
        )
        st.markdown("---")

    if "messages" not in st.session_state.keys():
        reset()
    
    # Display chat messages
    for message in st.session_state.messages:
        with st.chat_message(message["role"], avatar=message["avatar"]):
            st.write(message["content"])

    example_container = st.empty()
    with example_container:
        if show_example_questions():
            example_container.empty()
            st.rerun()

    # User-provided prompt
    if st.session_state.ex_prompt:
        prompt = st.session_state.ex_prompt
    else:
        prompt = st.chat_input()
    if prompt:
        st.session_state.messages.append({"role": "user", "content": prompt, "avatar": '🧑‍💻'})
        st.session_state.prompt = prompt  # Save the prompt in session state
        st.session_state.log_messages = []
        st.session_state.show_logs = False
        with st.chat_message("user", avatar='🧑‍💻'):
            print(f"Starting new question: {prompt}\n")
            st.write(prompt)
        st.session_state.ex_prompt = None
    
    # Generate a new response if last message is not from assistant
    if st.session_state.prompt:
        with st.chat_message("assistant", avatar='🤖'):
            with st.spinner(st.session_state.thinking_message):
                res = st.session_state.agent.chat(st.session_state.prompt)
                res = res.replace('$', '\\$')  # escape dollar sign for markdown
            message = {"role": "assistant", "content": res, "avatar": '🤖'}
            st.session_state.messages.append(message)
            st.markdown(res)
        st.session_state.ex_prompt = None
        st.session_state.prompt = None
        st.rerun()

    log_placeholder = st.empty()
    with log_placeholder.container():
        if st.session_state.show_logs:
            st.button("Hide Logs", on_click=toggle_logs)
            for msg in st.session_state.log_messages:
                st.text(msg)
        else:
            if len(st.session_state.log_messages) > 0:
                st.button("Show Logs", on_click=toggle_logs)


    sys.stdout.flush()

if __name__ == "__main__":
    launch_bot()