#[cfg(test)]
mod tests {
    use crate::ocr::OcrService;
    use std::fs;
    use std::path::Path;
    use tempfile::NamedTempFile;
    
    // Mock database for testing
    mod mock_db {
        use anyhow::Result;
        use uuid::Uuid;
        use std::sync::{Arc, Mutex};
        use std::collections::HashMap;
        
        #[derive(Clone)]
        pub struct MockDatabase {
            ocr_updates: Arc<Mutex<HashMap<Uuid, String>>>,
        }
        
        impl MockDatabase {
            pub fn new() -> Self {
                Self {
                    ocr_updates: Arc::new(Mutex::new(HashMap::new())),
                }
            }
            
            pub async fn update_document_ocr(&self, id: Uuid, ocr_text: &str) -> Result<()> {
                let mut updates = self.ocr_updates.lock().unwrap();
                updates.insert(id, ocr_text.to_string());
                Ok(())
            }
            
            pub fn get_ocr_text(&self, id: &Uuid) -> Option<String> {
                let updates = self.ocr_updates.lock().unwrap();
                updates.get(id).cloned()
            }
            
            pub fn get_all_ocr_updates(&self) -> HashMap<Uuid, String> {
                let updates = self.ocr_updates.lock().unwrap();
                updates.clone()
            }
        }
    }
    
    use mock_db::MockDatabase;

    #[test]
    fn test_is_image_file() {
        let ocr_service = OcrService::new();
        
        assert!(ocr_service.is_image_file("image.png"));
        assert!(ocr_service.is_image_file("photo.jpg"));
        assert!(ocr_service.is_image_file("picture.JPEG"));
        assert!(ocr_service.is_image_file("scan.tiff"));
        assert!(ocr_service.is_image_file("bitmap.bmp"));
        assert!(ocr_service.is_image_file("animation.gif"));
        
        assert!(!ocr_service.is_image_file("document.pdf"));
        assert!(!ocr_service.is_image_file("text.txt"));
        assert!(!ocr_service.is_image_file("archive.zip"));
        assert!(!ocr_service.is_image_file("noextension"));
    }

    #[tokio::test]
    async fn test_extract_text_from_plain_text() {
        let ocr_service = OcrService::new();
        
        let temp_file = NamedTempFile::new().unwrap();
        let test_content = "This is a test text file.\nWith multiple lines.";
        fs::write(temp_file.path(), test_content).unwrap();
        
        let result = ocr_service
            .extract_text(temp_file.path().to_str().unwrap(), "text/plain")
            .await;
        
        assert!(result.is_ok());
        let extracted_text = result.unwrap();
        assert_eq!(extracted_text, test_content);
    }

    #[tokio::test]
    async fn test_extract_text_unsupported_type() {
        let ocr_service = OcrService::new();
        
        let temp_file = NamedTempFile::new().unwrap();
        fs::write(temp_file.path(), "some content").unwrap();
        
        let result = ocr_service
            .extract_text(temp_file.path().to_str().unwrap(), "application/zip")
            .await;
        
        assert!(result.is_err());
        assert!(result.unwrap_err().to_string().contains("Unsupported MIME type"));
    }

    #[tokio::test]
    async fn test_extract_text_from_nonexistent_file() {
        let ocr_service = OcrService::new();
        
        let result = ocr_service
            .extract_text("/path/to/nonexistent/file.txt", "text/plain")
            .await;
        
        assert!(result.is_err());
    }

    #[tokio::test]
    #[ignore = "Requires tesseract runtime - run with: cargo test --release -- --ignored"]
    async fn test_extract_text_with_real_image() {
        let ocr_service = OcrService::new();
        
        // Create a simple test image with text if it doesn't exist
        let test_image_path = "test_data/hello_ocr.png";
        
        // Skip test if test data doesn't exist
        if !Path::new(test_image_path).exists() {
            eprintln!("Skipping test_extract_text_with_real_image: test data not found");
            return;
        }
        
        let result = ocr_service
            .extract_text(test_image_path, "image/png")
            .await;
        
        match result {
            Ok(text) => {
                println!("OCR extracted text: '{}'", text);
                // OCR might not be perfect, so we check if it contains expected words
                assert!(text.to_lowercase().contains("hello") || text.to_lowercase().contains("ocr"));
            }
            Err(e) => {
                eprintln!("OCR test failed: {}", e);
                // Don't fail the test if OCR is not available
            }
        }
    }

    #[tokio::test]
    async fn test_extract_text_from_pdf_with_content() {
        let ocr_service = OcrService::new();
        
        // Create a minimal valid PDF
        let temp_file = NamedTempFile::with_suffix(".pdf").unwrap();
        
        // This is a minimal PDF that says "Hello"
        let pdf_content = b"%PDF-1.4
1 0 obj
<< /Type /Catalog /Pages 2 0 R >>
endobj
2 0 obj
<< /Type /Pages /Kids [3 0 R] /Count 1 >>
endobj
3 0 obj
<< /Type /Page /Parent 2 0 R /Resources << /Font << /F1 4 0 R >> >> /MediaBox [0 0 612 792] /Contents 5 0 R >>
endobj
4 0 obj
<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>
endobj
5 0 obj
<< /Length 44 >>
stream
BT
/F1 12 Tf
100 700 Td
(Hello) Tj
ET
endstream
endobj
xref
0 6
0000000000 65535 f
0000000009 00000 n
0000000058 00000 n
0000000115 00000 n
0000000262 00000 n
0000000341 00000 n
trailer
<< /Size 6 /Root 1 0 R >>
startxref
435
%%EOF";
        
        fs::write(temp_file.path(), pdf_content).unwrap();
        
        let result = ocr_service
            .extract_text_from_pdf(temp_file.path().to_str().unwrap())
            .await;
        
        // The pdf-extract library might not work with our minimal PDF
        // so we just check that it attempts to process it
        match result {
            Ok(text) => {
                println!("PDF extracted text: '{}'", text);
            }
            Err(e) => {
                println!("PDF extraction error (expected): {}", e);
            }
        }
    }

    #[tokio::test]
    async fn test_extract_text_with_image_extension_fallback() {
        let ocr_service = OcrService::new();
        
        let temp_file = NamedTempFile::with_suffix(".png").unwrap();
        fs::write(temp_file.path(), "fake image data").unwrap();
        
        let result = ocr_service
            .extract_text(temp_file.path().to_str().unwrap(), "unknown/type")
            .await;
        
        // This should try to process as image due to extension, but fail due to invalid data
        assert!(result.is_err());
    }
    
    #[tokio::test]
    async fn test_ocr_with_mock_database_integration() {
        let ocr_service = OcrService::new();
        let mock_db = MockDatabase::new();
        let doc_id = uuid::Uuid::new_v4();
        
        // Create a simple text file to simulate OCR processing
        let temp_file = NamedTempFile::with_suffix(".txt").unwrap();
        let test_content = "This is test OCR content for mock database integration.";
        fs::write(temp_file.path(), test_content).unwrap();
        
        // Extract text using OCR service
        let result = ocr_service
            .extract_text(temp_file.path().to_str().unwrap(), "text/plain")
            .await;
        
        assert!(result.is_ok());
        let extracted_text = result.unwrap();
        
        // Mock database update
        let update_result = mock_db.update_document_ocr(doc_id, &extracted_text).await;
        assert!(update_result.is_ok());
        
        // Verify the text was stored in mock database
        let stored_text = mock_db.get_ocr_text(&doc_id);
        assert!(stored_text.is_some());
        assert_eq!(stored_text.unwrap(), test_content);
    }
    
    #[tokio::test]
    async fn test_ocr_error_handling_with_mock_db() {
        let ocr_service = OcrService::new();
        let mock_db = MockDatabase::new();
        let doc_id = uuid::Uuid::new_v4();
        
        // Test with non-existent file
        let result = ocr_service
            .extract_text("/nonexistent/path/file.txt", "text/plain")
            .await;
        
        assert!(result.is_err());
        
        // Verify no update was made to mock database for failed OCR
        let stored_text = mock_db.get_ocr_text(&doc_id);
        assert!(stored_text.is_none());
    }
    
    #[tokio::test]
    async fn test_batch_ocr_processing_with_mock_db() {
        let ocr_service = OcrService::new();
        let mock_db = MockDatabase::new();
        
        let mut doc_ids = Vec::new();
        let mut temp_files = Vec::new();
        
        // Create multiple test files
        for i in 0..3 {
            let temp_file = NamedTempFile::with_suffix(".txt").unwrap();
            let content = format!("Test document {} content for batch processing.", i + 1);
            fs::write(temp_file.path(), &content).unwrap();
            
            let doc_id = uuid::Uuid::new_v4();
            doc_ids.push(doc_id);
            temp_files.push((temp_file, content));
        }
        
        // Process all files
        for (i, (temp_file, _expected_content)) in temp_files.iter().enumerate() {
            let result = ocr_service
                .extract_text(temp_file.path().to_str().unwrap(), "text/plain")
                .await;
            
            assert!(result.is_ok());
            let extracted_text = result.unwrap();
            
            let update_result = mock_db.update_document_ocr(doc_ids[i], &extracted_text).await;
            assert!(update_result.is_ok());
        }
        
        // Verify all documents were processed
        let all_updates = mock_db.get_all_ocr_updates();
        assert_eq!(all_updates.len(), 3);
        
        for (i, doc_id) in doc_ids.iter().enumerate() {
            let stored_text = all_updates.get(doc_id);
            assert!(stored_text.is_some());
            assert!(stored_text.unwrap().contains(&format!("Test document {}", i + 1)));
        }
    }
    
    #[tokio::test]
    async fn test_ocr_language_support() {
        let ocr_service = OcrService::new();
        
        let temp_file = NamedTempFile::with_suffix(".txt").unwrap();
        let test_content = "Hello world test content";
        fs::write(temp_file.path(), test_content).unwrap();
        
        // Test different language codes
        let languages = vec!["eng", "spa", "fra", "deu"];
        
        for lang in languages {
            let result = ocr_service
                .extract_text_with_lang(temp_file.path().to_str().unwrap(), "text/plain", lang)
                .await;
            
            // Should succeed for text files regardless of language setting
            assert!(result.is_ok());
            let extracted = result.unwrap();
            assert_eq!(extracted, test_content);
        }
    }
    
    #[tokio::test]
    async fn test_ocr_mime_type_detection() {
        let ocr_service = OcrService::new();
        
        // Test various mime types
        let test_cases = vec![
            ("test.txt", "text/plain"),
            ("document.pdf", "application/pdf"),
            ("image.png", "image/png"),
            ("photo.jpg", "image/jpeg"),
            ("scan.tiff", "image/tiff"),
        ];
        
        for (filename, mime_type) in test_cases {
            let temp_file = NamedTempFile::with_suffix(&Path::new(filename).extension().unwrap().to_str().unwrap()).unwrap();
            
            if mime_type == "text/plain" {
                fs::write(temp_file.path(), "test content").unwrap();
                
                let result = ocr_service
                    .extract_text(temp_file.path().to_str().unwrap(), mime_type)
                    .await;
                
                assert!(result.is_ok(), "Failed for mime type: {}", mime_type);
            } else {
                // For non-text files, we expect either success or specific errors
                let result = ocr_service
                    .extract_text(temp_file.path().to_str().unwrap(), mime_type)
                    .await;
                
                // These will likely fail with our test setup, but should not panic
                if result.is_err() {
                    println!("Expected failure for {}: {}", mime_type, result.unwrap_err());
                }
            }
        }
    }
    
    #[test]
    fn test_mock_database_functionality() {
        let mock_db = MockDatabase::new();
        let doc_id1 = uuid::Uuid::new_v4();
        let doc_id2 = uuid::Uuid::new_v4();
        
        // Test empty state
        assert!(mock_db.get_ocr_text(&doc_id1).is_none());
        
        // Test single update
        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async {
            let result = mock_db.update_document_ocr(doc_id1, "Test OCR text").await;
            assert!(result.is_ok());
        });
        
        assert_eq!(mock_db.get_ocr_text(&doc_id1).unwrap(), "Test OCR text");
        
        // Test multiple updates
        rt.block_on(async {
            let result = mock_db.update_document_ocr(doc_id2, "Another OCR text").await;
            assert!(result.is_ok());
        });
        
        let all_updates = mock_db.get_all_ocr_updates();
        assert_eq!(all_updates.len(), 2);
        assert!(all_updates.contains_key(&doc_id1));
        assert!(all_updates.contains_key(&doc_id2));
    }

    /// Test that malformed PDFs don't crash the OCR system
    #[tokio::test]
    async fn test_malformed_pdf_panic_handling() {
        let ocr_service = OcrService::new();
        
        // Create a malformed PDF in memory that will cause pdf-extract to panic
        let malformed_pdf_content = b"%PDF-1.4
1 0 obj
<< /Type /Catalog /Pages 2 0 R >>
endobj
2 0 obj
<< /Type /Pages /Kids [3 0 R] /Count 1 >>
endobj
3 0 obj
<< /Type /Page /Parent 2 0 R /Resources << /Font << /F1 4 0 R >> >> /MediaBox [0 0 612 792] /Contents 5 0 R >>
endobj
4 0 obj
<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>
endobj
5 0 obj
<< /Length 999 >>
stream
BT
/F1 12 Tf
100 700 Td
(This is a malformed PDF with invalid content stream) Tj
ET
INVALID_CONTENT_STREAM_DATA_THAT_CAUSES_PANIC
endstream
endobj
xref
0 6
0000000000 65535 f
0000000009 00000 n
0000000058 00000 n
0000000115 00000 n
0000000262 00000 n
0000000341 00000 n
trailer
<< /Size 6 /Root 1 0 R >>
startxref
999
%%EOF";

        // Write to temporary file
        let temp_file = NamedTempFile::with_suffix(".pdf").unwrap();
        std::fs::write(temp_file.path(), malformed_pdf_content).unwrap();
        
        let result = ocr_service.extract_text_from_pdf(temp_file.path().to_str().unwrap()).await;
        // With the enhanced OCR service, this should either succeed or fail gracefully
        match result {
            Ok(text) => {
                println!("Successfully extracted text from malformed PDF: '{}'", text);
                // The robust extraction might find some text even in malformed PDFs
                assert!(!text.is_empty() || text.contains("Test"));
            }
            Err(e) => {
                println!("Error extracting from malformed PDF: {}", e);
                // Should contain descriptive error message if it fails
                let error_msg = e.to_string();
                assert!(
                    error_msg.contains("ocrmypdf") || 
                    error_msg.contains("extraction") ||
                    error_msg.contains("InputFileError") ||
                    error_msg.contains("Failed to extract") ||
                    error_msg.contains("All PDF extraction strategies failed")
                );
            }
        }
    }

    #[tokio::test]
    async fn test_corrupted_pdf_structure_handling() {
        let ocr_service = OcrService::new();
        
        // Create a corrupted PDF structure that will cause pdf-extract to fail
        let corrupted_pdf_content = b"%PDF-1.4
1 0 obj
<< /Type /Catalog /Pages 2 0 R >>
endobj
2 0 obj
<< /Type /Pages /Kids [3 0 R] /Count 1 >>
endobj
3 0 obj
<< /Type /Page /Parent 2 0 R /Resources << /Font << /F1 4 0 R >> >> /MediaBox [0 0 612 792] /Contents 5 0 R >>
endobj
4 0 obj
<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>
endobj
5 0 obj
<< /Length 44 >>
stream
BT
/F1 12 Tf
100 700 Td
(Corrupted PDF) Tj
ET
endstream
endobj
xref
0 6
0000000000 65535 f
0000000009 00000 n
0000000058 00000 n
0000000115 00000 n
0000000262 00000 n
0000000341 00000 n
trailer
<< /Size 6 /Root 1 0 R /InvalidKey >>
startxref
999999
%%EOF";

        let temp_file = NamedTempFile::with_suffix(".pdf").unwrap();
        std::fs::write(temp_file.path(), corrupted_pdf_content).unwrap();
        
        let result = ocr_service.extract_text_from_pdf(temp_file.path().to_str().unwrap()).await;
        // The enhanced OCR service might extract text even from corrupted PDFs
        match result {
            Ok(text) => {
                println!("Successfully extracted text from corrupted PDF: '{}'", text);
                // The robust extraction might find "Corrupted PDF" text
                assert!(text.contains("Corrupted PDF") || !text.is_empty());
            },
            Err(e) => {
                let error_msg = e.to_string();
                println!("Corrupted PDF error: {}", error_msg);
                // Should contain descriptive error message
                assert!(
                    error_msg.contains("panic") || 
                    error_msg.contains("corrupted") ||
                    error_msg.contains("extract") ||
                    error_msg.contains("PDF") ||
                    error_msg.contains("Failed to extract") ||
                    error_msg.contains("All PDF extraction strategies failed")
                );
            }
        }
    }

    #[tokio::test]
    async fn test_invalid_font_encoding_handling() {
        let ocr_service = OcrService::new();
        
        // Test with invalid font encoding
        let invalid_font = "tests/test_pdfs/invalid_font_encoding.pdf";
        if Path::new(invalid_font).exists() {
            let result = ocr_service.extract_text_from_pdf(invalid_font).await;
            // With the enhanced OCR service, this might succeed or fail gracefully
            match result {
                Ok(text) => {
                    println!("Successfully extracted text from invalid font PDF: '{}'", text);
                    // Even with invalid fonts, OCR service might extract something
                },
                Err(e) => {
                    let error_msg = e.to_string();
                    println!("Failed to extract from invalid font PDF: {}", error_msg);
                    // Should contain descriptive error message
                    assert!(
                        error_msg.contains("panic") || 
                        error_msg.contains("font") ||
                        error_msg.contains("encoding") ||
                        error_msg.contains("extract") ||
                        error_msg.contains("All PDF extraction strategies failed")
                    );
                }
            }
        }
    }

    #[tokio::test]
    async fn test_fake_pdf_handling() {
        let ocr_service = OcrService::new();
        
        // Create a fake PDF file (not actually a PDF) that will definitely cause an error
        let fake_pdf_content = b"This is not a PDF file at all, just plain text with a PDF extension.
It should cause pdf-extract to fail when trying to parse it.
This tests the error handling for files that aren't actually PDFs.";

        let temp_file = NamedTempFile::with_suffix(".pdf").unwrap();
        std::fs::write(temp_file.path(), fake_pdf_content).unwrap();
        
        let result = ocr_service.extract_text_from_pdf(temp_file.path().to_str().unwrap()).await;
        // The enhanced OCR might extract the text content even from a fake PDF
        match result {
            Ok(text) => {
                println!("Extracted text from fake PDF: '{}'", text);
                // Should contain the actual text content
                assert!(text.contains("This is not a PDF") || text.contains("plain text"));
            },
            Err(e) => {
                let error_msg = e.to_string();
                println!("Fake PDF error: {}", error_msg);
                // Should contain descriptive error message about parsing failure
                assert!(
                    error_msg.contains("extract") ||
                    error_msg.contains("parse") ||
                    error_msg.contains("PDF") ||
                    error_msg.contains("format") ||
                    error_msg.contains("Failed to extract") ||
                    error_msg.contains("All PDF extraction strategies failed")
                );
            }
        }
    }

    #[tokio::test]
    async fn test_problematic_encoding_pdf_handling() {
        let ocr_service = OcrService::new();
        
        // Test with the existing problematic encoding PDF
        let problematic_encoding = "tests/test_pdfs/problematic_encoding.pdf";
        if Path::new(problematic_encoding).exists() {
            let result = ocr_service.extract_text_from_pdf(problematic_encoding).await;
            // With ocrmypdf, this may succeed gracefully or return descriptive error
            match result {
                Ok(text) => {
                    println!("Successfully extracted text from problematic encoding PDF: '{}'", text);
                    // OCRmyPDF's robustness allows it to handle some problematic encoding PDFs
                }
                Err(e) => {
                    println!("Error extracting from problematic encoding PDF: {}", e);
                    let error_msg = e.to_string();
                    assert!(
                        error_msg.contains("ocrmypdf") || 
                        error_msg.contains("extraction") ||
                        error_msg.contains("strategies") ||
                        error_msg.contains("Failed to extract")
                    );
                }
            }
        }
    }

    /// Test that the enhanced OCR service also handles panics correctly
    #[tokio::test]
    async fn test_enhanced_ocr_panic_handling() {
        use crate::ocr::enhanced::EnhancedOcrService;
        use crate::services::file_service::FileService;
        use crate::models::Settings;
        
        let ocr_service = EnhancedOcrService::new("tests".to_string());
        let settings = Settings::default();
        
        // Test all malformed PDFs with enhanced OCR
        let test_files = vec![
            "tests/test_pdfs/malformed_content_stream.pdf",
            "tests/test_pdfs/corrupted_structure.pdf", 
            "tests/test_pdfs/invalid_font_encoding.pdf",
            "tests/test_pdfs/fake_pdf.pdf",
            "tests/test_pdfs/problematic_encoding.pdf",
        ];
        
        for test_file in test_files {
            if Path::new(test_file).exists() {
                let result = ocr_service.extract_text_with_context(
                    test_file,
                    "application/pdf",
                    &Path::new(test_file).file_name().unwrap().to_str().unwrap(),
                    1024, // file_size
                    &settings
                ).await;
                
                // The enhanced OCR service might succeed or fail gracefully
                match result {
                    Ok(ocr_result) => {
                        println!("Enhanced OCR successfully extracted from {}: '{}'", test_file, ocr_result.text);
                        // Even problematic PDFs might yield some text with the robust extraction
                    },
                    Err(e) => {
                        let error_msg = e.to_string();
                        println!("Enhanced OCR failed for {}: {}", test_file, error_msg);
                        // Should contain descriptive error message
                        assert!(
                            error_msg.contains("panic") || 
                            error_msg.contains("extract") ||
                            error_msg.contains("PDF") ||
                            error_msg.contains("corrupted") ||
                            error_msg.contains("encoding") ||
                            error_msg.contains("font") ||
                            error_msg.contains("All PDF extraction strategies failed"),
                            "Error message should be descriptive for {}: {}", test_file, error_msg
                        );
                    }
                }
            }
        }
    }

    /// Test that panic handling works correctly in concurrent scenarios
    #[tokio::test]
    async fn test_concurrent_pdf_panic_handling() {
        use std::sync::Arc;
        use futures::future::join_all;
        
        let ocr_service = Arc::new(OcrService::new());
        let mut handles = Vec::new();
        
        // Test concurrent processing of malformed PDFs
        let test_files = vec![
            "tests/test_pdfs/malformed_content_stream.pdf",
            "tests/test_pdfs/corrupted_structure.pdf",
            "tests/test_pdfs/invalid_font_encoding.pdf",
            "tests/test_pdfs/fake_pdf.pdf",
        ];
        
        for test_file in test_files {
            if Path::new(test_file).exists() {
                let ocr_service_clone = Arc::clone(&ocr_service);
                let test_file_owned = test_file.to_string();
                
                let handle = tokio::spawn(async move {
                    let result = ocr_service_clone.extract_text_from_pdf(&test_file_owned).await;
                    // The enhanced OCR might succeed or fail gracefully
                    match result {
                        Ok(text) => {
                            println!("Concurrent test: Successfully extracted from {}: '{}'", test_file_owned, text);
                            // Even problematic PDFs might yield some text
                        },
                        Err(e) => {
                            let error_msg = e.to_string();
                            println!("Concurrent test: Failed for {}: {}", test_file_owned, error_msg);
                            // Should contain descriptive error message
                            assert!(
                                error_msg.contains("panic") || 
                                error_msg.contains("extract") ||
                                error_msg.contains("PDF") ||
                                error_msg.contains("corrupted") ||
                                error_msg.contains("encoding") ||
                                error_msg.contains("All PDF extraction strategies failed") ||
                                error_msg.contains("No such file or directory"),
                                "Error message should be descriptive for {}: {}", test_file_owned, error_msg
                            );
                        }
                    }
                });
                
                handles.push(handle);
            }
        }
        
        // Wait for all concurrent tasks to complete
        let results = join_all(handles).await;
        
        // Verify all tasks completed without panicking
        for result in results {
            assert!(result.is_ok(), "Task should complete without panicking");
        }
    }
}