from __future__ import annotations

import sys
import subprocess
from pathlib import Path
from typing import List
import re

import streamlit as st
from sentence_transformers import SentenceTransformer

from search_engine import SemanticSearchEngine


# ================= CONFIG =================
DATASET_PATH = Path("data/stackoverflow_sample_3000.json")


# ================= DATASET SETUP =================
def ensure_dataset():
    if not DATASET_PATH.exists():
        with st.spinner("Preparing dataset (first run only)..."):
            script = Path(__file__).parent / "prepare_stackoverflow_sample.py"
            result = subprocess.run(
                [sys.executable, str(script)],
                capture_output=True,
                text=True
            )
            if result.returncode != 0:
                st.error(f"Dataset preparation failed:\n\n{result.stderr}")
                st.stop()


# ================= ENGINE =================
@st.cache_resource(show_spinner=False)
def load_engine() -> SemanticSearchEngine:
    return SemanticSearchEngine(DATASET_PATH)


# ================= EMBEDDING =================
@st.cache_resource(show_spinner=False)
def load_embedder() -> SentenceTransformer:
    return SentenceTransformer("all-MiniLM-L6-v2")


def get_query_embedding(query: str) -> List[float]:
    model = load_embedder()
    return model.encode(query).tolist()


# ================= HTML → MARKDOWN RENDER =================
def render_answer(answer: str):
    """
    Converts StackOverflow-style HTML into clean Streamlit output
    """

    # Split text and code blocks
    parts = re.split(r"<pre><code>|</code></pre>", answer)

    for i, part in enumerate(parts):
        if i % 2 == 0:
            # Normal text → remove simple HTML tags
            clean_text = re.sub(r"<.*?>", "", part)
            if clean_text.strip():
                st.markdown(clean_text)
        else:
            # Code block
            code = part.strip()
            st.code(code, language="python")  # default language


# ================= CHAT STATE =================
def init_chat():
    if "messages" not in st.session_state:
        st.session_state.messages = []


# ================= MAIN APP =================
def main():
    st.set_page_config(
        page_title="CodeSeek AI",
        page_icon="🔎",
        layout="wide"
    )

    init_chat()
    ensure_dataset()

    # ================= SIDEBAR =================
    with st.sidebar:
        st.title("⚙️ Settings")
        top_k = st.slider("Number of results", 1, 10, 5)

        st.markdown("---")

        if st.button("🗑️ Clear Chat"):
            st.session_state.messages = []
            st.rerun()

    # ================= HEADER =================
    st.title("🔎 CodeSeek AI")
    st.caption("Semantic Programming Search (Chat Style)")

    # ================= DISPLAY CHAT =================
    for msg in st.session_state.messages:
        with st.chat_message(msg["role"]):
            if msg["role"] == "assistant":
                render_answer(msg["content"])
            else:
                st.markdown(msg["content"])

    # ================= INPUT =================
    user_input = st.chat_input("Ask a programming question...")

    if user_input:
        # Store user message
        st.session_state.messages.append({
            "role": "user",
            "content": user_input
        })

        with st.chat_message("user"):
            st.markdown(user_input)

        # Generate response
        try:
            with st.chat_message("assistant"):
                with st.spinner("🔎 Searching..."):
                    engine = load_engine()
                    query_embedding = get_query_embedding(user_input.strip())
                    results = engine.search(query_embedding, top_k=top_k)

                # Save raw response for rendering
                full_response = ""

                for i, item in enumerate(results, start=1):
                    st.markdown(f"### 🔹 Result {i}")
                    st.markdown(f"**{item['question']}**")

                    render_answer(item["answer"])

                    st.caption(f"Score: {item['score']:.4f}")
                    st.divider()

                    # Save for history (raw)
                    full_response += f"{item['question']}\n{item['answer']}\n"

        except Exception as e:
            full_response = f"Error: {e}"
            with st.chat_message("assistant"):
                st.error(full_response)

        # Store assistant message
        st.session_state.messages.append({
            "role": "assistant",
            "content": full_response
        })


# ================= RUN =================
if __name__ == "__main__":
    main()