"""
Simplified tests for sentiment fields migration that don't require database connection.
Tests the migration script structure and logic.
"""

import pytest
import ast
from pathlib import Path


class TestSentimentFieldsMigrationScript:
    """Test the sentiment fields migration script structure and content."""

    @pytest.fixture
    def migration_file_path(self):
        """Path to the migration file."""
        return Path(__file__).parent.parent.parent.parent / "alembic" / "versions" / "20250116_1200_0001_add_sentiment_fields.py"

    @pytest.fixture
    def migration_content(self, migration_file_path):
        """Read migration file content."""
        return migration_file_path.read_text()

    def test_migration_file_exists(self, migration_file_path):
        """Test that the migration file exists."""
        assert migration_file_path.exists(), "Migration file should exist"

    def test_migration_has_required_functions(self, migration_content):
        """Test that migration has upgrade and downgrade functions."""
        # Parse the Python code
        tree = ast.parse(migration_content)
        
        function_names = [node.name for node in ast.walk(tree) if isinstance(node, ast.FunctionDef)]
        
        assert "upgrade" in function_names, "Migration should have upgrade() function"
        assert "downgrade" in function_names, "Migration should have downgrade() function"

    def test_migration_has_required_metadata(self, migration_content):
        """Test that migration has required revision metadata."""
        # Check for required revision identifiers
        assert "revision = " in migration_content, "Should have revision identifier"
        assert "down_revision = " in migration_content, "Should have down_revision identifier"
        assert "upgrade() -> None:" in migration_content, "upgrade function should be typed"
        assert "downgrade() -> None:" in migration_content, "downgrade function should be typed"

    def test_upgrade_adds_sentiment_confidence_column(self, migration_content):
        """Test that upgrade adds sentiment_confidence column."""
        assert "op.add_column('news_articles', sa.Column('sentiment_confidence', sa.Float(), nullable=True))" in migration_content, \
            "Should add sentiment_confidence FLOAT column"

    def test_upgrade_adds_sentiment_label_column(self, migration_content):
        """Test that upgrade adds sentiment_label column."""
        assert "op.add_column('news_articles', sa.Column('sentiment_label', sa.String(20), nullable=True))" in migration_content, \
            "Should add sentiment_label VARCHAR(20) column"

    def test_upgrade_creates_index(self, migration_content):
        """Test that upgrade creates index on sentiment_label."""
        assert "op.create_index('idx_news_sentiment_label', 'news_articles', ['sentiment_label'])" in migration_content, \
            "Should create index on sentiment_label"

    def test_downgrade_removes_index_first(self, migration_content):
        """Test that downgrade removes index before columns (correct order)."""
        lines = migration_content.split('\n')
        
        # Find downgrade function
        downgrade_start = None
        for i, line in enumerate(lines):
            if "def downgrade()" in line:
                downgrade_start = i
                break
        
        assert downgrade_start is not None, "Should find downgrade function"
        
        # Check that drop_index comes before drop_column
        drop_index_line = None
        drop_column_line = None
        
        for i in range(downgrade_start, len(lines)):
            line = lines[i].strip()
            if "op.drop_index" in line:
                drop_index_line = i
            elif "op.drop_column" in line and "sentiment" in line:
                if drop_column_line is None:  # Only capture first sentiment column drop
                    drop_column_line = i
        
        assert drop_index_line is not None, "Should drop index"
        assert drop_column_line is not None, "Should drop columns"
        assert drop_index_line < drop_column_line, "Should drop index before columns"

    def test_downgrade_removes_sentiment_columns(self, migration_content):
        """Test that downgrade removes both sentiment columns."""
        assert "op.drop_column('news_articles', 'sentiment_label')" in migration_content, \
            "Should drop sentiment_label column"
        assert "op.drop_column('news_articles', 'sentiment_confidence')" in migration_content, \
            "Should drop sentiment_confidence column"

    def test_migration_follows_naming_convention(self, migration_file_path):
        """Test that migration follows naming convention."""
        filename = migration_file_path.name
        
        # Should follow pattern: YYYYMMDD_HHMM_XXXX_descriptive_name.py
        assert filename.startswith("20250116_"), "Should start with date"
        assert "_add_sentiment_fields.py" in filename, "Should have descriptive name"

    def test_migration_has_proper_imports(self, migration_content):
        """Test that migration has proper imports."""
        assert "from alembic import op" in migration_content, "Should import op from alembic"
        assert "import sqlalchemy as sa" in migration_content, "Should import sqlalchemy"

    def test_revision_format(self, migration_content):
        """Test that revision follows expected format."""
        lines = migration_content.split('\n')
        
        # Find revision line
        revision_line = None
        for line in lines:
            if line.strip().startswith("revision = "):
                revision_line = line.strip()
                break
        
        assert revision_line is not None, "Should have revision line"
        assert revision_line.startswith("revision = '20250116_1200_0001_add_sentiment_fields'"), \
            "Revision should match filename"


class TestMigrationLogic:
    """Test migration logic expectations."""

    def test_sentiment_confidence_column_spec(self):
        """Test sentiment_confidence column specification."""
        # Should be FLOAT, nullable (for existing data)
        # This represents confidence score from 0.0 to 1.0
        pass  # Column spec tested in migration content test above

    def test_sentiment_label_column_spec(self):
        """Test sentiment_label column specification."""
        # Should be VARCHAR(20), nullable
        # This stores "positive", "negative", "neutral"
        pass  # Column spec tested in migration content test above

    def test_index_specification(self):
        """Test index specification for sentiment filtering."""
        # Index on sentiment_label for efficient WHERE clauses
        # Name: idx_news_sentiment_label
        pass  # Index spec tested in migration content test above

    def test_backward_compatibility(self):
        """Test that migration maintains backward compatibility."""
        # New columns are nullable, so existing code continues to work
        # Index doesn't affect existing queries
        pass  # Tested by nullable=True in column specs


if __name__ == "__main__":
    # Run tests directly
    pytest.main([__file__, "-v"])