from functools import lru_cache
from pathlib import Path

from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles
from sklearn.datasets import make_blobs, make_s_curve, make_swiss_roll

app = FastAPI()
HERE = Path(__file__).parent


@lru_cache(maxsize=1)
def _datasets():
    s, sl = make_s_curve(n_samples=5000, noise=0.03, random_state=0)
    sr, srl = make_swiss_roll(n_samples=5000, noise=0.15, random_state=0)
    b, bl = make_blobs(
        n_samples=5000, n_features=3, centers=5, cluster_std=1.0, random_state=0
    )
    return {
        "s_curve": {
            "name": "S-Curve",
            "path": "sklearn.datasets.make_s_curve",
            "description": (
                "A 2-D manifold warped into R³. Continuous label encodes position "
                "along the curve — a good test of whether a reducer unrolls the "
                "sheet without tearing."
            ),
            "kind": "continuous",
            "points": s.tolist(),
            "labels": sl.tolist(),
        },
        "swiss_roll": {
            "name": "Swiss Roll",
            "path": "sklearn.datasets.make_swiss_roll",
            "description": (
                "A rolled-up plane. The canonical hard case for linear methods: "
                "PCA collapses the spiral, non-linear methods should recover the "
                "unroll."
            ),
            "kind": "continuous",
            "points": sr.tolist(),
            "labels": srl.tolist(),
        },
        "blobs": {
            "name": "Gaussian Blobs",
            "path": "sklearn.datasets.make_blobs",
            "description": (
                "Five isotropic Gaussian clusters in R³. Discrete class labels. "
                "Tests whether a reducer preserves cluster separation when "
                "projected to 2-D."
            ),
            "kind": "categorical",
            "points": b.tolist(),
            "labels": bl.tolist(),
        },
    }


@app.get("/data.json")
def data():
    return _datasets()


app.mount("/", StaticFiles(directory=str(HERE), html=True), name="static")