app/arbitrage_analyzer.py

"""
The Discrepancy Analyzer Engine.

Uses Gemini to provide risk assessment for on-chain vs. off-chain
price discrepancies.
"""
import os
import logging
from typing import Optional, Dict
import json
import httpx

logger = logging.getLogger(__name__)

class ArbitrageAnalyzer:
    API_URL = "https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-pro-latest:generateContent"

    def __init__(self, client: httpx.AsyncClient, api_key: Optional[str] = None):
        self.client = client
        self.api_key = api_key or os.getenv("GEMINI_API_KEY")
        if not self.api_key: raise ValueError("GEMINI_API_KEY not set.")
        self.params = {"key": self.api_key}
        self.headers = {"Content-Type": "application/json"}

    def _build_prompt(self, opportunity: Dict) -> dict:
        return {
            "contents": [{
                "parts": [{
                    "text": f"""
                    You are a DeFi analyst. A significant price discrepancy for Bitcoin (BTC) has been detected between a decentralized on-chain oracle and a centralized off-chain aggregator.
                    Provide a concise "Alpha Briefing" as a single, minified JSON object with NO markdown formatting.

                    The JSON object must have these exact keys: "risk", "strategy", "rationale".

                    - "risk": Assess the execution risk. MUST be one of "LOW", "MEDIUM", "HIGH". Consider oracle latency, network congestion (gas fees), and DEX slippage.
                    - "strategy": A very brief, one-sentence action plan. For example: "Consider buying BTC on a DEX like Uniswap and selling on a CEX." or "Monitor situation, high risk of slippage."
                    - "rationale": A short explanation for the risk assessment.

                    DISCREPANCY DETAILS:
                    - On-Chain Price (Pyth): ${opportunity['on_chain_price']:,.2f}
                    - Off-Chain Agg. Price (CeFi): ${opportunity['off_chain_price']:,.2f}
                    - Discrepancy: {opportunity['spread_pct']:.3f}%
                    """
                }]
            }]
        }

    async def get_alpha_briefing(self, opportunity: Dict) -> Optional[Dict]:
        prompt = self._build_prompt(opportunity)
        try:
            response = await self.client.post(self.API_URL, json=prompt, params=self.params, headers=self.headers, timeout=20)
            response.raise_for_status()
            content = response.json()["candidates"][0]["content"]["parts"][0]["text"]
            if content.startswith("```"):
                content = content.strip("```json\n")
            return json.loads(content)
        except Exception as e:
            logger.error(f"❌ Gemini Alpha Briefing Error: {e}")
            return None