"""
Simple unit tests for error handling in reports system.

Tests error handling logic without requiring database setup.
"""

import unittest
from unittest.mock import Mock, MagicMock
from datetime import date
from decimal import Decimal

from reports.filter_service import ReportFilterService, FilterParams
from reports.calculation_service import LoanCalculationService
from reports.export_service import ReportExportService


class FilterServiceErrorHandlingTests(unittest.TestCase):
    """Test error handling in ReportFilterService"""
    
    def test_invalid_date_format_returns_none(self):
        """Test that invalid date formats are handled gracefully"""
        request = Mock()
        request.GET = {'start_date': 'invalid-date', 'end_date': '2024-13-45'}
        request.POST = {}
        
        params = ReportFilterService.parse_filter_params(request)
        
        # Should return None for invalid dates, not raise exception
        self.assertIsNone(params.start_date)
        self.assertIsNone(params.end_date)
    
    def test_missing_date_parameters(self):
        """Test handling of missing date parameters"""
        request = Mock()
        request.GET = {}
        request.POST = {}
        
        params = ReportFilterService.parse_filter_params(request)
        
        # Should have None values, not raise exception
        self.assertIsNone(params.start_date)
        self.assertIsNone(params.end_date)
    
    def test_empty_string_dates(self):
        """Test handling of empty string date values"""
        request = Mock()
        request.GET = {'start_date': '', 'end_date': ''}
        request.POST = {}
        
        params = ReportFilterService.parse_filter_params(request)
        
        # Empty strings should result in None
        self.assertIsNone(params.start_date)
        self.assertIsNone(params.end_date)
    
    def test_date_range_auto_swap(self):
        """Test that start date after end date is automatically swapped"""
        request = Mock()
        request.GET = {'start_date': '2024-12-31', 'end_date': '2024-01-01'}
        request.POST = {}
        
        params = ReportFilterService.parse_filter_params(request)
        
        # Dates should be swapped
        self.assertEqual(params.start_date, date(2024, 1, 1))
        self.assertEqual(params.end_date, date(2024, 12, 31))
    
    def test_validate_filter_params_valid(self):
        """Test validation of valid filter parameters"""
        params = FilterParams(
            start_date=date(2024, 1, 1),
            end_date=date(2024, 12, 31),
            gender='M',
            period='monthly'
        )
        
        is_valid, error = ReportFilterService.validate_filter_params(params)
        
        self.assertTrue(is_valid)
        self.assertEqual(error, "")
    
    def test_validate_filter_params_invalid_gender(self):
        """Test validation of invalid gender"""
        params = FilterParams(gender='INVALID')
        
        is_valid, error = ReportFilterService.validate_filter_params(params)
        
        self.assertFalse(is_valid)
        self.assertIn('gender', error.lower())


class CalculationServiceErrorHandlingTests(unittest.TestCase):
    """Test error handling in LoanCalculationService"""
    
    def test_calculate_amount_paid_with_none_loan(self):
        """Test amount paid calculation with None loan"""
        result = LoanCalculationService.calculate_amount_paid(None)
        
        self.assertEqual(result, Decimal('0.00'))
    
    def test_calculate_outstanding_with_none_loan(self):
        """Test outstanding amount calculation with None loan"""
        result = LoanCalculationService.calculate_outstanding_amount(None)
        
        self.assertEqual(result, Decimal('0.00'))
    
    def test_calculate_daily_payment_with_none_loan(self):
        """Test daily payment calculation with None loan"""
        result = LoanCalculationService.calculate_daily_payment_required(None)
        
        self.assertEqual(result, Decimal('0.00'))
    
    def test_calculate_days_overdue_with_none_loan(self):
        """Test days overdue calculation with None loan"""
        result = LoanCalculationService.calculate_days_overdue(None)
        
        self.assertEqual(result, 0)
    
    def test_format_currency_with_none(self):
        """Test currency formatting with None value"""
        result = LoanCalculationService.format_currency(None)
        
        self.assertEqual(result, "0.00")
    
    def test_format_currency_with_invalid_string(self):
        """Test currency formatting with invalid string"""
        result = LoanCalculationService.format_currency("not-a-number")
        
        # Should handle gracefully, returning "0.00"
        self.assertEqual(result, "0.00")
    
    def test_format_currency_with_valid_decimal(self):
        """Test currency formatting with valid decimal"""
        result = LoanCalculationService.format_currency(Decimal('1234.567'))
        
        # Should format with exactly 2 decimal places
        self.assertEqual(result, "1234.57")
    
    def test_calculate_total_with_none_values(self):
        """Test total calculation with None values"""
        result = LoanCalculationService.calculate_total_loan_amount(None, None, None)
        
        self.assertEqual(result, Decimal('0.00'))
    
    def test_calculate_total_with_negative_values(self):
        """Test total calculation with negative values"""
        result = LoanCalculationService.calculate_total_loan_amount(
            Decimal('-100'),
            Decimal('-50'),
            Decimal('-10')
        )
        
        # Should calculate correctly even with negative values
        self.assertEqual(result, Decimal('-160'))
    
    def test_calculate_total_with_invalid_strings(self):
        """Test total calculation with invalid string values"""
        result = LoanCalculationService.calculate_total_loan_amount(
            "invalid",
            "also-invalid",
            "not-a-number"
        )
        
        # Should handle gracefully, returning 0
        self.assertEqual(result, Decimal('0.00'))


class ExportServiceErrorHandlingTests(unittest.TestCase):
    """Test error handling in ReportExportService"""
    
    def setUp(self):
        self.export_service = ReportExportService()
    
    def test_export_pdf_with_empty_dataset(self):
        """Test PDF export with empty dataset"""
        report_data = {'loans': []}
        filters = {}
        
        response = self.export_service.export_to_pdf(
            report_data, 'loans_due', filters
        )
        
        # Should return valid response, not error
        self.assertEqual(response.status_code, 200)
        self.assertEqual(response['Content-Type'], 'application/pdf')
    
    def test_export_excel_with_empty_dataset(self):
        """Test Excel export with empty dataset"""
        report_data = {'loans': []}
        filters = {}
        
        response = self.export_service.export_to_excel(
            report_data, 'loans_due', filters
        )
        
        # Should return valid response, not error
        self.assertEqual(response.status_code, 200)
        self.assertIn('spreadsheet', response['Content-Type'])
    
    def test_format_currency_with_special_characters(self):
        """Test currency formatting with special characters"""
        result = self.export_service.format_currency("$1,000.00")
        
        # Should handle gracefully
        self.assertIsInstance(result, str)
        self.assertIn("KES", result)
    
    def test_format_date_with_none(self):
        """Test date formatting with None value"""
        result = self.export_service.format_date(None)
        
        self.assertEqual(result, "N/A")
    
    def test_format_date_with_invalid_string(self):
        """Test date formatting with invalid string"""
        result = self.export_service.format_date("not-a-date")
        
        # Should return the string as-is
        self.assertEqual(result, "not-a-date")
    
    def test_export_with_missing_loans_key(self):
        """Test export when 'loans' key is missing"""
        report_data = {}  # Missing 'loans' key
        filters = {}
        
        response = self.export_service.export_to_pdf(
            report_data, 'loans_due', filters
        )
        
        # Should handle gracefully
        self.assertEqual(response.status_code, 200)


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