import asyncio
import io
import unittest

from fastapi import HTTPException, UploadFile
from fastapi.responses import JSONResponse

from dea_api import BodeParams, DesignParams, add_security_headers, calculate_bode, design_filter, filter_csv


class DeaApiTest(unittest.TestCase):
    def test_design_returns_normalized_coefficients_for_default_lowpass(self):
        body = design_filter(
            DesignParams(
                filter_type="Lowpass (低通)",
                fs=100000,
                lp_fc=1000,
                lp_order=1,
            )
        )

        self.assertGreater(len(body["b"]), 0)
        self.assertGreater(len(body["a"]), 0)
        self.assertAlmostEqual(body["a"][0], 1.0)

    def test_design_rejects_cutoff_at_or_above_nyquist(self):
        try:
            design_filter(
                DesignParams(
                    filter_type="Lowpass (低通)",
                    fs=1000,
                    lp_fc=500,
                    lp_order=1,
                )
            )
        except HTTPException as exc:
            self.assertEqual(exc.status_code, 400)
            self.assertIn("Nyquist", exc.detail)
        else:
            raise AssertionError("Expected Nyquist validation to fail")

    def test_design_supports_2p1z_filter(self):
        body = design_filter(
            DesignParams(
                filter_type="2P1Z (二極一零)",
                fs=100000,
                tp1z_fz=200,
                tp1z_fp1=10,
                tp1z_fp2=5000,
            )
        )

        self.assertEqual(len(body["b"]), 3)
        self.assertEqual(len(body["a"]), 3)
        self.assertAlmostEqual(body["a"][0], 1.0)


    def test_bode_rejects_zero_a0(self):
        try:
            calculate_bode(BodeParams(fs=1000, b=[1.0], a=[0.0, 1.0]))
        except HTTPException as exc:
            self.assertEqual(exc.status_code, 400)
            self.assertIn("a[0]", exc.detail)
        else:
            raise AssertionError("Expected a[0] validation to fail")


    def test_filter_downsamples_plot_response_for_large_csv(self):
        rows = ["value"] + [str(i) for i in range(6001)]
        upload = UploadFile(
            io.BytesIO(("\n".join(rows) + "\n").encode("utf-8")),
            filename="input.csv",
        )

        body = asyncio.run(filter_csv(file=upload, b="1", a="1", col_idx=0))

        self.assertEqual(body["total_points"], 6001)
        self.assertLessEqual(body["plot_points"], 5000)
        self.assertGreater(body["downsample_step"], 1)


    def test_filter_rejects_non_numeric_signal_column(self):
        upload = UploadFile(io.BytesIO(b"value\n1\nbad\n3\n"), filename="input.csv")

        try:
            asyncio.run(filter_csv(file=upload, b="1", a="1", col_idx=0))
        except HTTPException as exc:
            self.assertEqual(exc.status_code, 400)
            self.assertIn("非數值", exc.detail)
        else:
            raise AssertionError("Expected non-numeric column validation to fail")

    def test_security_headers_are_applied(self):
        response = add_security_headers(JSONResponse({"ok": True}))

        self.assertEqual(response.headers["X-Content-Type-Options"], "nosniff")
        self.assertEqual(response.headers["X-Frame-Options"], "DENY")
        self.assertIn("frame-ancestors 'none'", response.headers["Content-Security-Policy"])
        self.assertNotIn("unsafe-eval", response.headers["Content-Security-Policy"])