from __future__ import annotations
import re
import logging
from tavily import TavilyClient  # type:ignore
from youtube_transcript_api import YouTubeTranscriptApi #type:ignore
from config import TAVILY_API_KEY

logger = logging.getLogger(__name__)


# ── Web Search (Tavily) ───────────────────────────────────────
def run_web_search(
    query: str,
    api_key: str = "",
    *,
    search_depth: str = "advanced",
    topic: str = "general",
    max_results: int = 5,
    include_answer: bool = True,
) -> str:
    """
    Run a web search using the Tavily API.

    `api_key` is the user's own Tavily key (BYOK). Falls back to the shared
    server key if the user didn't provide one. If no key is available at all,
    web search is treated as disabled.

    Returns a formatted block: an optional LLM-ready answer followed by
    result cards (title, URL, relevance score, content snippet).
    """
    key = api_key or TAVILY_API_KEY
    if not key:
        return (
            "Web search is unavailable: no Tavily API key configured. "
            "Add a Tavily API key in Settings to enable web search."
        )

    try:
        client = TavilyClient(api_key=key)
        resp = client.search(
            query,
            search_depth=search_depth,
            topic=topic,
            max_results=max_results,
            include_answer=include_answer,
            include_raw_content=False,
            chunks_per_source=3,
        )
    except Exception as e:
        logger.warning("tavily search error: %s", e)
        return f"Web search is temporarily unavailable. (Error: {e})"

    results = resp.get("results", []) if isinstance(resp, dict) else []
    if not results and not (isinstance(resp, dict) and resp.get("answer")):
        return "No search results found."

    blocks = []
    answer = resp.get("answer") if isinstance(resp, dict) else None
    if answer:
        blocks.append(f"Answer: {answer}\n")

    for r in results:
        title = r.get("title", "No Title")
        url = r.get("url", "")
        score = r.get("score", "")
        content = r.get("content", "")
        score_str = f" (relevance: {score:.2f})" if isinstance(score, (int, float)) else ""
        blocks.append(f"Title: {title}{score_str}\nURL: {url}\nSnippet: {content}\n")

    return "\n".join(blocks)


def _extract_video_id(url_or_id: str) -> str | None:
    """Extract YouTube 11-character video ID from URL or bare ID."""
    patterns = [
        r"(?:v=|youtu\.be/|embed/|shorts/)([A-Za-z0-9_-]{11})",
        r"^([A-Za-z0-9_-]{11})$",
    ]
    for pat in patterns:
        m = re.search(pat, url_or_id.strip())
        if m:
            return m.group(1)
    return None


def fetch_yt_transcript(youtube_url: str) -> str:
    """
    Programmatic helper to fetch the transcript of a YouTube video URL or ID.
    """
    video_id = _extract_video_id(youtube_url)
    if not video_id:
        logger.info("yt: no video id in input: %s", youtube_url[:80])
        return "TRANSCRIPT_UNAVAILABLE: Could not extract a valid YouTube video ID from the message."

    try:
        langs = ["en", "hi", "en-IN", "en-US"]
        # youtube-transcript-api ≥ 1.0 replaced the static `get_transcript`
        # with an instance method `.fetch()`. Support both APIs.
        if hasattr(YouTubeTranscriptApi, "get_transcript"):
            fetched = YouTubeTranscriptApi.get_transcript(video_id, languages=langs)  # type:ignore[attr-defined]
            transcript = " ".join(seg["text"] for seg in fetched)
        else:
            fetched = YouTubeTranscriptApi().fetch(video_id, languages=langs)
            # FetchedTranscript yields snippet objects with a `.text` attribute
            # (older dict form `seg["text"]` is handled as a fallback).
            transcript = " ".join(
                getattr(seg, "text", None) or (seg.get("text", "") if isinstance(seg, dict) else "")
                for seg in fetched
            )
        if not transcript.strip():
            logger.info("yt: empty transcript for %s", video_id)
            return "TRANSCRIPT_UNAVAILABLE: Transcript is empty for this video."
        logger.info("yt transcript ok — %d chars for %s", len(transcript), video_id)
        return transcript
    except Exception as exc:
        logger.warning("yt transcript exception for %s: %s", video_id, exc)
        err = str(exc).lower()
        if "disabled" in err or "no transcript" in err or "no element" in err:
            return (
                "TRANSCRIPT_UNAVAILABLE: This video has no transcript available "
                "(subtitles are disabled or no captions exist for this video)."
            )
        if "too many requests" in err or "429" in err:
            return (
                "TRANSCRIPT_UNAVAILABLE: YouTube is rate-limiting transcript requests right now. "
                "Please try again in a few minutes."
            )
        return (
            f"TRANSCRIPT_UNAVAILABLE: Could not retrieve transcript. Reason: {exc}"
        )