from __future__ import annotations

import unittest
from datetime import UTC, datetime

from govoplan_core.core.files import (
    CAPABILITY_FILES_TABULAR_CONTENT,
    ManagedTabularFile,
    ManagedTabularFileContent,
    ManagedTabularFileProvider,
    managed_tabular_file_provider,
)


class _Provider:
    def list_tabular_files(self, session, principal, *, query="", limit=100):
        del session, principal, query, limit
        return ()

    def get_tabular_file(
        self,
        session,
        principal,
        *,
        file_asset_id,
        file_version_id=None,
    ):
        del session, principal, file_asset_id, file_version_id
        return None

    def read_tabular_file(
        self,
        session,
        principal,
        *,
        file_asset_id,
        file_version_id,
        max_bytes,
    ):
        del session, principal, file_asset_id, file_version_id, max_bytes
        file = ManagedTabularFile(
            file_asset_id="asset-1",
            file_version_id="version-1",
            filename="source.csv",
            display_path="Imports/source.csv",
            content_type="text/csv",
            size_bytes=8,
            sha256="a" * 64,
            updated_at=datetime(2026, 8, 21, tzinfo=UTC),
        )
        return ManagedTabularFileContent(file=file, payload=b"id\n1\n")


class _Registry:
    def __init__(self, provider):
        self.provider = provider

    def has_capability(self, name):
        return name == CAPABILITY_FILES_TABULAR_CONTENT

    def require_capability(self, name):
        if not self.has_capability(name):
            raise KeyError(name)
        return self.provider


class ManagedTabularFileContractTests(unittest.TestCase):
    def test_runtime_protocol_and_registry_resolution(self) -> None:
        provider = _Provider()

        self.assertIsInstance(provider, ManagedTabularFileProvider)
        self.assertIs(provider, managed_tabular_file_provider(_Registry(provider)))
        self.assertIsNone(managed_tabular_file_provider(None))

    def test_exact_version_content_retains_safe_metadata(self) -> None:
        result = _Provider().read_tabular_file(
            object(),
            object(),
            file_asset_id="asset-1",
            file_version_id="version-1",
            max_bytes=100,
        )

        self.assertEqual("version-1", result.file.file_version_id)
        self.assertEqual("a" * 64, result.file.sha256)
        self.assertEqual(b"id\n1\n", result.payload)


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