from __future__ import annotations

import csv
import io
import unittest

from fastapi import HTTPException

from app.main import (
    SimulationResultCsvPayload,
    SimulationResultVariablePayload,
    export_simulation_results_csv,
)


def result_variable(
    key: str,
    component_id: str,
    name: str,
    label: str,
    unit: str,
) -> SimulationResultVariablePayload:
    return SimulationResultVariablePayload(
        key=key,
        componentId=component_id,
        componentType="tank",
        scope="component",
        name=name,
        label=label,
        quantity="pressure",
        unit=unit,
    )


class ResultCsvExportTests(unittest.TestCase):
    def valid_payload(self) -> SimulationResultCsvPayload:
        return SimulationResultCsvPayload(
            projectName="储气系统",
            variables=[
                result_variable(
                    "cylinder_1.p",
                    "cylinder_1",
                    "p",
                    "压力",
                    "Pa",
                ),
                result_variable("tank_1.p", "tank_1", "p", "压力", "Pa"),
            ],
            series={
                "time": [0.0, 0.1],
                "cylinder_1.p": [35000000.0, 34900000.0],
                "tank_1.p": [100000.0, 101000.0],
            },
        )

    def test_csv_export_preserves_result_keys_and_rows(self) -> None:
        response = export_simulation_results_csv(self.valid_payload())

        text = response.body.decode("utf-8-sig")
        rows = list(csv.reader(io.StringIO(text)))
        self.assertEqual(
            rows[0],
            ["time", "cylinder_1.p", "tank_1.p"],
        )
        self.assertEqual(rows[1], ["0.0", "35000000.0", "100000.0"])
        self.assertEqual(rows[2], ["0.1", "34900000.0", "101000.0"])
        self.assertIn(
            "filename*=UTF-8''",
            response.headers["content-disposition"],
        )

    def test_csv_export_rejects_inconsistent_column_lengths(self) -> None:
        payload = self.valid_payload()
        payload.series["tank_1.p"] = [100000.0]

        with self.assertRaises(HTTPException) as caught:
            export_simulation_results_csv(payload)

        self.assertEqual(caught.exception.status_code, 422)
        self.assertIn("inconsistent length", str(caught.exception.detail))

    def test_csv_export_requires_metadata_for_every_result_column(self) -> None:
        payload = self.valid_payload()
        payload.series["orphan.value"] = [1.0, 2.0]

        with self.assertRaises(HTTPException) as caught:
            export_simulation_results_csv(payload)

        self.assertEqual(caught.exception.status_code, 422)
        self.assertIn("unmapped orphan.value", str(caught.exception.detail))


if __name__ == "__main__":
    unittest.main()