"""Offline PostgreSQL DDL checks for the articles/cards migration; no database access."""
import io
import os
import unittest
from pathlib import Path
from unittest.mock import patch

os.environ['DATABASE_URL'] = 'sqlite:///:memory:'
from alembic import command
from alembic.config import Config
from alembic.script import ScriptDirectory


class ArticlesMigrationTests(unittest.TestCase):
    def test_models_register_fresh_and_offline_upgrade_downgrade(self):
        import subprocess
        import sys
        result = subprocess.run([sys.executable, '-c',
            "import app.models; from app.database import Base; "
            "assert {'articles','question_article_links','flashcard_question_links','flashcard_article_links'} <= set(Base.metadata.tables)"],
            capture_output=True, text=True, env={**os.environ, 'DATABASE_URL': 'sqlite:///:memory:'})
        self.assertEqual(result.returncode, 0, result.stderr)
        output = io.StringIO()
        config = Config(output_buffer=output)
        config.set_main_option('script_location', str(Path(__file__).resolve().parents[1] / 'alembic'))
        scripts = ScriptDirectory.from_config(config)
        self.assertEqual(len(scripts.get_heads()), 1)
        self.assertEqual(scripts.get_revision('e8d4f1a27c93').down_revision, 'd94a26b8f302')
        with patch.dict(os.environ, {'DATABASE_URL': 'postgresql://unused@127.0.0.1/offline_only'}):
            command.upgrade(config, 'd94a26b8f302:e8d4f1a27c93', sql=True)
            sql = output.getvalue()
            for table in ('articles', 'question_article_links', 'flashcard_question_links', 'flashcard_article_links'):
                self.assertIn(f'CREATE TABLE IF NOT EXISTS {table}', sql)
            self.assertIn('UNIQUE (question_id, article_id, section_id)', sql)
            self.assertIn('ON DELETE CASCADE', sql)
            output.seek(0)
            output.truncate()
            command.downgrade(config, 'e8d4f1a27c93:d94a26b8f302', sql=True)
            for table in ('flashcard_article_links', 'flashcard_question_links', 'question_article_links', 'articles'):
                self.assertIn(f'DROP TABLE IF EXISTS {table}', output.getvalue())


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