import logging
import os
from fastapi import FastAPI, HTTPException
from pydantic import BaseModel

from google.adk.sessions import InMemorySessionService
from google.adk.runners import Runner
from google.genai import types

from agent import root_agent
import callback

logger = logging.getLogger(__name__)

# =========================
# FASTAPI APP
# =========================
app = FastAPI(
    title="Leave Policy Assistant",
    description="AI agent to answer leave policy questions",
    version="1.0.0"
)

# =========================
# ADK SESSION SETUP
# =========================
APP_NAME = "leave_policy_app"
session_service = InMemorySessionService()

runner = Runner(
    agent=root_agent,
    app_name=APP_NAME,
    session_service=session_service,
)

# Optional: persist ADK callback events to Snowflake (set ENABLE_AUDIT_SINK=1 in .env)
if os.getenv("ENABLE_AUDIT_SINK", "").strip().lower() in ("1", "true", "yes"):
    try:
        from audit_db import SnowflakeAuditSink, ensure_table
        callback.set_audit_sink(SnowflakeAuditSink())
        ensure_table()
    except Exception as e:
        import logging
        logging.getLogger(__name__).warning("Audit sink not enabled: %s", e)

# =========================
# REQUEST / RESPONSE MODELS
# =========================
class ChatRequest(BaseModel):
    user_id: str
    message: str


class ChatResponse(BaseModel):
    response: str


# =========================
# CHAT ENDPOINT
# =========================
def _text_from_content(content) -> str | None:
    """Extract response text from event content (check all parts)."""
    if content is None:
        return None
    try:
        parts = getattr(content, "parts", None)
        if not parts:
            return None
        for part in parts:
            text = getattr(part, "text", None)
            if text is not None and str(text).strip():
                return str(text).strip()
    except (AttributeError, TypeError, IndexError):
        pass
    return None


@app.post("/chat", response_model=ChatResponse)
async def chat(req: ChatRequest):
    try:
        session_id = f"{req.user_id}_session"

        session = await session_service.get_session(
            app_name=APP_NAME,
            user_id=req.user_id,
            session_id=session_id,
        )
        if not session:
            await session_service.create_session(
                app_name=APP_NAME,
                user_id=req.user_id,
                session_id=session_id,
            )

        user_content = types.Content(
            role="user",
            parts=[types.Part(text=req.message)],
        )

        final_response = None

        try:
            async for event in runner.run_async(
                user_id=req.user_id,
                session_id=session_id,
                new_message=user_content,
            ):
                try:
                    if getattr(event, "is_final_response", lambda: False)() and getattr(event, "content", None):
                        text = _text_from_content(event.content)
                        if text:
                            final_response = text
                            break
                    if getattr(event, "content", None):
                        text = _text_from_content(event.content)
                        if text:
                            final_response = text
                except (AttributeError, TypeError, KeyError) as e:
                    logger.debug("Skipping event parse error: %s", e)
                    continue
        except ValueError as e:
            logger.warning("Runner run_async ValueError: %s", e)
            raise HTTPException(status_code=400, detail=str(e))

        if not final_response:
            logger.warning("Chat: no response text from agent for user_id=%s", req.user_id)
            raise HTTPException(
                status_code=503,
                detail="Agent did not return a response. Please try again or check server logs.",
            )

        return ChatResponse(response=final_response)

    except HTTPException:
        raise
    except Exception as e:
        logger.exception("Chat failed: %s", e)
        raise HTTPException(
            status_code=500,
            detail="An error occurred while processing your request. Check server logs for details.",
        )


# =========================
# HEALTH CHECK
# =========================
@app.get("/health")
def health():
    return {"status": "ok"}