//! Error handling and edge case tests
//!
//! This module tests error conditions, edge cases, and recovery scenarios
//! for all dictionary operations.

#[cfg(test)]
mod tests {
    use super::*;
    use crate::traits::*;
    use crate::util::test_utils::*;
    use std::io;

    /// Test dictionary operation errors
    mod dict_error_tests {
        use super::*;

        #[test]
        fn test_file_not_found_error() {
            let loader = DictLoader::new();
            let non_existent_path = std::path::Path::new("nonexistent.mdict");

            let result = loader.load(non_existent_path);
            assert!(result.is_err());

            if let Err(error) = result {
                assert!(matches!(error, DictError::FileNotFound(_)));
            }
        }

        #[test]
        fn test_invalid_format_error() {
            let temp_dir = temp_dir().unwrap();
            let invalid_file = temp_dir.path().join("invalid.mdict");

            // Create an invalid dictionary file
            std::fs::write(&invalid_file, "This is not a valid dictionary").unwrap();

            let loader = DictLoader::new();
            let result = loader.load(&invalid_file);

            // Should either fail to load or detect invalid format
            if result.is_err() {
                if let Err(error) = result {
                    assert!(matches!(error, DictError::InvalidFormat(_)));
                }
            }
        }

        #[test]
        fn test_unsupported_operation_error() {
            // Test unsupported operations
            let error = DictError::UnsupportedOperation("test operation".to_string());
            assert!(matches!(error, DictError::UnsupportedOperation(_)));

            let error_str = error.to_string();
            assert!(error_str.contains("test operation"));
            assert!(error_str.contains("Unsupported operation"));
        }

        #[test]
        fn test_io_error_handling() {
            let error = DictError::IoError("I/O test error".to_string());
            assert!(matches!(error, DictError::IoError(_)));

            let error_str = error.to_string();
            assert!(error_str.contains("I/O test error"));
            assert!(error_str.contains("I/O error"));
        }

        #[test]
        fn test_index_error_handling() {
            let error = DictError::IndexError("Index test error".to_string());
            assert!(matches!(error, DictError::IndexError(_)));

            let error_str = error.to_string();
            assert!(error_str.contains("Index test error"));
            assert!(error_str.contains("Index error"));
        }

        #[test]
        fn test_decompression_error_handling() {
            let error = DictError::DecompressionError("Decompression test error".to_string());
            assert!(matches!(error, DictError::DecompressionError(_)));

            let error_str = error.to_string();
            assert!(error_str.contains("Decompression test error"));
            assert!(error_str.contains("Decompression error"));
        }

        #[test]
        fn test_internal_error_handling() {
            let error = DictError::Internal("Internal test error".to_string());
            assert!(matches!(error, DictError::Internal(_)));

            let error_str = error.to_string();
            assert!(error_str.contains("Internal test error"));
            assert!(error_str.contains("Internal error"));
        }
    }

    /// Test file I/O error scenarios
    mod io_error_tests {
        use super::*;
        use std::fs;

        #[test]
        fn test_permission_denied_error() {
            // This test simulates permission errors
            // In a real test, you might create a file with restricted permissions

            // Test that the library handles permission issues gracefully
            let temp_dir = temp_dir().unwrap();
            let restricted_file = temp_dir.path().join("restricted.txt");

            // Create a file first
            std::fs::write(&restricted_file, "test content").unwrap();

            // Check that readable utility works
            assert!(crate::dict::utils::is_readable(&restricted_file));
        }

        #[test]
        fn test_disk_full_simulation() {
            // Simulate disk full scenarios
            // In practice, this would be difficult to test reliably

            let temp_dir = temp_dir().unwrap();
            let test_file = temp_dir.path().join("test_file");

            // Test basic file operations
            let result = std::fs::write(&test_file, "test content");
            assert!(result.is_ok());

            // Clean up
            let _ = std::fs::remove_file(&test_file);
        }

        #[test]
        fn test_concurrent_file_access_errors() {
            // Test concurrent access scenarios
            let temp_dir = temp_dir().unwrap();
            let test_file = temp_dir.path().join("concurrent_test.txt");

            // Create initial file
            std::fs::write(&test_file, "initial content").unwrap();

            // Test that file exists and is readable
            assert!(test_file.exists());
            assert!(crate::dict::utils::is_readable(&test_file));

            // Clean up
            let _ = std::fs::remove_file(&test_file);
        }
    }

    /// Test format-specific error conditions
    mod format_error_tests {
        use super::*;

        #[test]
        fn test_mdict_format_errors() {
            let temp_dir = temp_dir().unwrap();
            let mdict_file = temp_dir.path().join("test.mdict");

            // Test various invalid MDict files
            let invalid_contents = vec![
                "",  // Empty file
                "InvalidHeader",  // Wrong magic header
                "MDictInvalidVersion",  // Wrong version
                "MDictVersion 1.0.0\x00\x00\x00\x00",  // Incomplete header
            ];

            for content in invalid_contents {
                std::fs::write(&mdict_file, content).unwrap();

                let loader = DictLoader::new();
                let result = loader.load(&mdict_file);

                // Should fail gracefully
                if result.is_err() {
                    if let Err(error) = result {
                        assert!(matches!(error, DictError::InvalidFormat(_) |
                                        DictError::IoError(_) |
                                        DictError::UnsupportedOperation(_)));
                    }
                }
            }
        }

        #[test]
        fn test_stardict_format_errors() {
            let temp_dir = temp_dir().unwrap();
            let dict_file = temp_dir.path().join("test.dict");

            let invalid_contents = vec![
                "",  // Empty file
                "InvalidMagic",  // Wrong magic
                "StarDict's dictInvalidVersion\x00",  // Invalid version
            ];

            for content in invalid_contents {
                std::fs::write(&dict_file, content).unwrap();

                let loader = DictLoader::new();
                let result = loader.load(&dict_file);

                // Should handle gracefully
                if result.is_err() {
                    if let Err(error) = result {
                        assert!(matches!(error, DictError::InvalidFormat(_) |
                                        DictError::IoError(_)));
                    }
                }
            }
        }

        #[test]
        fn test_zim_format_errors() {
            let temp_dir = temp_dir().unwrap();
            let zim_file = temp_dir.path().join("test.zim");

            let invalid_contents = vec![
                "",  // Empty file
                "ZIM\x00",  // Wrong version
                "ZIM\x01Invalid",  // Invalid header
            ];

            for content in invalid_contents {
                std::fs::write(&zim_file, content).unwrap();

                let loader = DictLoader::new();
                let result = loader.load(&zim_file);

                // Should handle gracefully
                if result.is_err() {
                    if let Err(error) = result {
                        assert!(matches!(error, DictError::InvalidFormat(_) |
                                        DictError::IoError(_)));
                    }
                }
            }
        }
    }

    /// Test edge case scenarios
    mod edge_case_tests {
        use super::*;

        #[test]
        fn test_empty_dictionary_handling() {
            let temp_dir = temp_dir().unwrap();
            let empty_dict = temp_dir.path().join("empty.mdict");

            // Create an empty dictionary
            std::fs::write(&empty_dict, "").unwrap();

            let loader = DictLoader::new();

            // Format detection might succeed but loading should fail gracefully
            let format_result = loader.detect_format(&empty_dict);
            // Empty files should be handled gracefully

            let load_result = loader.load(&empty_dict);
            if load_result.is_err() {
                if let Err(error) = load_result {
                    assert!(matches!(error, DictError::InvalidFormat(_) |
                                    DictError::IoError(_)));
                }
            }
        }

        #[test]
        fn test_extremely_long_keys() {
            let temp_dir = temp_dir().unwrap();
            let long_key_dict = temp_dir.path().join("long_key.mdict");

            // Test with very long keys (within reasonable limits)
            let long_key = "a".repeat(4096); // 4KB key
            let content = "This is content for a very long key";

            std::fs::write(&long_key_dict, format!("{}\n{}", long_key, content)).unwrap();

            // Should handle long keys gracefully
            assert!(long_key_dict.exists());
        }

        #[test]
        fn test_very_large_entries() {
            let temp_dir = temp_dir().unwrap();
            let large_entry_dict = temp_dir.path().join("large_entry.mdict");

            // Create entry with large content
            let large_content = "x".repeat(1024 * 1024); // 1MB content
            let entry = format!("large_key\n{}", large_content);

            std::fs::write(&large_entry_dict, entry).unwrap();

            assert!(large_entry_dict.exists());
            assert!(large_entry_dict.metadata().unwrap().len() > 1024 * 1024);
        }

        #[test]
        fn test_invalid_utf8_content() {
            let temp_dir = temp_dir().unwrap();
            let invalid_utf8_dict = temp_dir.path().join("invalid_utf8.mdict");

            // Create content with invalid UTF-8 sequences
            let invalid_content = vec![0xFF, 0xFE, 0x00, 0x01];
            std::fs::write(&invalid_utf8_dict, &invalid_content).unwrap();

            // Should handle invalid UTF-8 gracefully
            assert!(invalid_utf8_dict.exists());

            let loader = DictLoader::new();
            let result = loader.load(&invalid_utf8_dict);

            // Should either handle gracefully or fail with appropriate error
            if result.is_err() {
                if let Err(error) = result {
                    assert!(matches!(error, DictError::InvalidFormat(_) |
                                    DictError::IoError(_)));
                }
            }
        }

        #[test]
        fn test_maximum_file_size_handling() {
            // Test with very large files
            let temp_dir = temp_dir().unwrap();
            let large_file = temp_dir.path().join("large_file.mdict");

            // Create a file approaching system limits
            let large_content = "data".repeat(1024 * 1024 * 10); // ~40MB
            let write_result = std::fs::write(&large_file, large_content);

            // Should either succeed or fail gracefully
            if write_result.is_err() {
                if let Err(error) = write_result {
                    assert!(matches!(error, io::ErrorKind::DiskFull |
                                    io::ErrorKind::FileTooLarge |
                                    io::ErrorKind::PermissionDenied));
                }
            } else {
                assert!(large_file.exists());
                let size = large_file.metadata().unwrap().len();
                assert!(size > 10 * 1024 * 1024);
            }
        }
    }

    /// Test recovery and retry mechanisms
    mod recovery_tests {
        use super::*;

        #[test]
        fn test_format_detection_retry() {
            let temp_dir = temp_dir().unwrap();
            let ambiguous_file = temp_dir.path().join("ambiguous");

            // Create file without extension - format detection should try multiple methods
            std::fs::write(&ambiguous_file, "MDict version").unwrap();

            let loader = DictLoader::new();

            // Test that format detection attempts different methods
            // Note: actual format detection might need content-based analysis
            let result = loader.detect_format(&ambiguous_file);

            // Should either succeed or fail with appropriate error
            if result.is_err() {
                if let Err(error) = result {
                    assert!(matches!(error, DictError::UnsupportedOperation(_)));
                }
            }
        }

        #[test]
        fn test_partial_file_recovery() {
            let temp_dir = temp_dir().unwrap();
            let partial_file = temp_dir.path().join("partial.mdict");

            // Create a partially written file
            let partial_content = "MDict version 1.0.0";
            std::fs::write(&partial_file, partial_content).unwrap();

            let loader = DictLoader::new();
            let result = loader.load(&partial_file);

            // Should fail gracefully for incomplete files
            if result.is_err() {
                if let Err(error) = result {
                    assert!(matches!(error, DictError::InvalidFormat(_) |
                                    DictError::IoError(_)));
                }
            }
        }

        #[test]
        fn test_concurrent_access_recovery() {
            let temp_dir = temp_dir().unwrap();
            let shared_file = temp_dir.path().join("shared.mdict");

            // Create a file that might be accessed concurrently
            let content = "MDict version 1.0.0\n1\n0\n0\n0\n";
            std::fs::write(&shared_file, content).unwrap();

            // Test that basic operations work
            assert!(shared_file.exists());
            assert!(crate::dict::utils::is_readable(&shared_file));

            // Test format detection still works
            let loader = DictLoader::new();
            let format = loader.detect_format(&shared_file);

            if let Ok(format_type) = format {
                assert_eq!(format_type, "mdict");
            }
        }
    }

    /// Test memory and resource limits
    mod resource_limit_tests {
        use super::*;

        #[test]
        fn test_memory_limit_handling() {
            // Test handling of memory constraints
            let temp_dir = temp_dir().unwrap();

            // Create multiple files to test memory usage
            for i in 0..10 {
                let file_path = temp_dir.path().join(format!("memory_test_{}.mdict", i));
                let content = format!("MDict version 1.0.0\n{}", i);
                std::fs::write(&file_path, content).unwrap();
            }

            // Test directory scanning
            let loader = DictLoader::new();
            let dict_files = loader.scan_directory(&temp_dir).unwrap();

            assert_eq!(dict_files.len(), 10);
        }

        #[test]
        fn test_cache_limit_handling() {
            // Test cache behavior with limited size
            let limited_config = DictConfig {
                cache_size: 5, // Very small cache
                batch_size: 10,
                ..Default::default()
            };

            let loader = DictLoader::with_config(limited_config);
            assert_eq!(loader.default_config().cache_size, 5);
        }

        #[test]
        fn test_concurrent_resource_usage() {
            let temp_dir = temp_dir().unwrap();

            // Create multiple dictionary files for concurrent testing
            for i in 0..5 {
                let file_path = temp_dir.path().join(format!("concurrent_{}.mdict", i));
                let content = format!("MDict version 1.0.0\n{}", i);
                std::fs::write(&file_path, content).unwrap();
            }

            // Test multiple file operations
            let loader = DictLoader::new();

            for i in 0..5 {
                let file_path = temp_dir.path().join(format!("concurrent_{}.mdict", i));
                assert!(loader.is_dictionary_file(&file_path));
            }
        }
    }
}