from __future__ import annotations

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.requests import Request
from fastapi.responses import JSONResponse

from nexus_claude_api.config import Settings
from nexus_claude_api.errors import NexusClaudeError, anthropic_error_response
from nexus_claude_api.nexus_client import NexusClient
from nexus_claude_api.routes.health import router as health_router
from nexus_claude_api.routes.messages import router as messages_router
from nexus_claude_api.routes.models import router as models_router


def create_app(
    settings: Settings | None = None,
    nexus_client: NexusClient | None = None,
) -> FastAPI:
    resolved_settings = settings or Settings.from_values(require_api_key=False)
    app = FastAPI(title="nexus-claude-api", version="0.1.0")
    app.state.settings = resolved_settings
    app.state.nexus_client = nexus_client or NexusClient(resolved_settings)

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

    app.include_router(health_router)
    app.include_router(models_router)
    app.include_router(messages_router)

    @app.exception_handler(NexusClaudeError)
    async def handle_nexus_error(_: Request, exc: NexusClaudeError) -> JSONResponse:
        return anthropic_error_response(
            exc.message,
            status_code=exc.status_code,
            error_type=exc.error_type,
        )

    return app