from __future__ import annotations

from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
from sqlalchemy import text

from app import __version__
from app.agents.runtime import get_agent_runtime
from app.api.v1.router import api_router
from app.core.config import settings
from app.core.errors import install_exception_handlers
from app.core.logging import setup_logging
from app.core.middleware import RequestContextMiddleware
from app.db.init_db import init_db
from app.db.session import SessionLocal


PROJECT_ROOT = Path(__file__).resolve().parents[1]
FRONTEND_DIR = PROJECT_ROOT / "frontend"


class FrontendStaticFiles(StaticFiles):
    async def get_response(self, path: str, scope):
        response = await super().get_response(path, scope)
        response.headers["Cache-Control"] = "no-store, no-cache, must-revalidate, max-age=0"
        response.headers["Pragma"] = "no-cache"
        response.headers["Expires"] = "0"
        return response


@asynccontextmanager
async def lifespan(_: FastAPI):
    setup_logging()
    init_db()
    if settings.seed_demo_data:
        from app.db.seed import seed_demo_data

        with SessionLocal() as db:
            seed_demo_data(db)
    yield


app = FastAPI(
    title=settings.app_name,
    version=__version__,
    description=(
        "基于 FastAPI 与 DeepAgent 的矿山通防业务智能管控平台后端。"
        "普通业务数据通过 REST API 管理，诊断、评价和知识问答通过 DeepAgent 工作流增强。"
    ),
    lifespan=lifespan,
    docs_url="/docs",
    redoc_url="/redoc",
    openapi_url="/openapi.json",
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.cors_origin_list,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)
app.add_middleware(RequestContextMiddleware)
install_exception_handlers(app)
app.include_router(api_router, prefix=settings.api_v1_prefix)

if FRONTEND_DIR.is_dir():
    app.mount(
        "/app",
        FrontendStaticFiles(directory=FRONTEND_DIR, html=True),
        name="frontend",
    )


@app.get("/", tags=["系统"], summary="服务入口")
def root() -> dict:
    return {
        "name": settings.app_name,
        "version": __version__,
        "docs": "/docs",
        "api": settings.api_v1_prefix,
        "app": "/app/",
    }


@app.get("/health", tags=["系统"], summary="服务健康检查")
def health() -> dict:
    database_status = "ok"
    database_error = ""
    try:
        with SessionLocal() as db:
            db.execute(text("SELECT 1"))
    except Exception as exc:  # pragma: no cover - depends on external DB
        database_status = "error"
        database_error = f"{type(exc).__name__}: {exc}"
    return {
        "status": "ok" if database_status == "ok" else "down",
        "version": __version__,
        "environment": settings.app_env,
        "database": {
            "dialect": settings.database_dialect,
            "status": database_status,
            "error": database_error,
        },
        "agent": get_agent_runtime().describe(),
    }


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(
        "app.main:app",
        host=settings.host,
        port=settings.port,
        reload=settings.debug,
    )