"""
Nexus-Core Inference API
Fast and efficient chess engine
"""

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel, Field
import time
import logging
from typing import Optional

from engine import NexusCoreEngine

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

app = FastAPI(
    title="Nexus-Core Inference API",
    description="Fast chess engine (13M params)",
    version="2.0.0"
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

engine = None


class MoveRequest(BaseModel):
    fen: str
    depth: Optional[int] = Field(4, ge=1, le=6)
    time_limit: Optional[int] = Field(3000, ge=1000, le=10000)


class MoveResponse(BaseModel):
    best_move: str
    evaluation: float
    depth_searched: int
    nodes_evaluated: int
    time_taken: int


class HealthResponse(BaseModel):
    status: str
    model_loaded: bool
    version: str


@app.on_event("startup")
async def startup_event():
    global engine
    logger.info("🚀 Starting Nexus-Core API...")
    
    try:
        engine = NexusCoreEngine(
            model_path="/app/models/nexus_core.onnx",
            num_threads=2
        )
        logger.info("✅ Nexus-Core loaded")
    except Exception as e:
        logger.error(f"❌ Failed: {e}")
        raise


@app.get("/health", response_model=HealthResponse)
async def health_check():
    return {
        "status": "healthy" if engine else "unhealthy",
        "model_loaded": engine is not None,
        "version": "2.0.0"
    }


@app.post("/get-move", response_model=MoveResponse)
async def get_move(request: MoveRequest):
    if not engine:
        raise HTTPException(503, "Engine not loaded")
    
    if not engine.validate_fen(request.fen):
        raise HTTPException(400, "Invalid FEN")
    
    start = time.time()
    
    try:
        result = engine.get_best_move(
            request.fen,
            request.depth,
            request.time_limit
        )
        
        logger.info(
            f"Move: {result['best_move']} | "
            f"Eval: {result['evaluation']:+.2f} | "
            f"Depth: {result['depth_searched']} | "
            f"Time: {result['time_taken']}ms"
        )
        
        return MoveResponse(**result)
    
    except Exception as e:
        logger.error(f"Error: {e}")
        raise HTTPException(500, str(e))


@app.get("/")
async def root():
    return {
        "name": "Nexus-Core API",
        "version": "2.0.0",
        "model": "13M parameters",
        "speed": "Ultra-fast",
        "endpoints": {
            "POST /get-move": "Get best move",
            "GET /health": "Health check"
        }
    }


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860)