//! # GUI Integration Tests
//!
//! Comprehensive integration tests for GUI functionality including
//! system integration, thread safety, state synchronization, and
//! error handling scenarios.

#![cfg(test)]

use rusty_emu::gui::GuiApp;
use rusty_emu::system_config::{ConfigurableSystem, SystemFactory};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;

/// Test utilities for GUI integration testing
mod gui_integration_test_utils {
    use super::*;

    /// Create a test system for integration testing
    pub fn create_test_system() -> Arc<Mutex<ConfigurableSystem>> {
        println!("Starting create_test_system");
        let factory = SystemFactory::new();
        Arc::new(Mutex::new(
            factory.create_from_json("configs/mcs4_basic.json").unwrap(),
        ))
    }

    /// Create a mock system for testing error conditions
    pub fn create_mock_system() -> Arc<Mutex<ConfigurableSystem>> {
        // For now, return a basic system
        // In a real implementation, this might create a mock or stub
        create_test_system()
    }

    /// Simulate GUI state updates over time
    /// Note: This function acquires the lock internally. Do NOT call it while holding the lock.
    pub fn simulate_gui_updates(system: &Arc<Mutex<ConfigurableSystem>>) {
        // Simulate the kind of updates that would happen in the GUI thread
        if let Ok(system_guard) = system.lock() {
            // Simulate some system activity
            let _ = system_guard.is_running(); // Access system state
        }
    }

    /// Test helper to verify thread-safe access patterns
    pub fn test_thread_safe_access(system: &Arc<Mutex<ConfigurableSystem>>) -> bool {
        let system_clone = Arc::clone(system);

        // Spawn a thread that accesses the system
        let handle = thread::spawn(move || {
            // Try to acquire the lock - return true if successful (regardless of is_running value)
            system_clone.lock().is_ok()
        });

        // Main thread also accesses the system
        let main_thread_result = system.lock().is_ok();

        // Wait for spawned thread
        let spawned_thread_result = handle.join().unwrap_or(false);

        // Both threads should be able to acquire the lock without deadlock
        main_thread_result && spawned_thread_result
    }
}

#[cfg(test)]
mod gui_system_integration_tests {
    use super::*;
    use gui_integration_test_utils::*;

    #[test]
    fn test_gui_system_integration() {
        let system = create_test_system();
        let system_clone = Arc::clone(&system);

        // Test that GUI can be created with a system
        let mut app = GuiApp::new_for_test();

        // Set the system
        app.set_system(system);

        // Verify system is properly set
        assert!(app.system.is_some());
        assert!(app.gui_state.system_loaded);

        // Test that system access works
        let retrieved_system = app.get_system();
        assert!(retrieved_system.is_some());

        // Verify the retrieved system is the same as the original
        assert!(Arc::ptr_eq(&retrieved_system.unwrap(), &system_clone));
    }

    #[test]
    fn test_gui_state_synchronization() {
        let system = create_test_system();

        let mut app = GuiApp::new_for_test();

        app.set_system(Arc::clone(&system));

        // Test state update mechanism
        // In a real implementation, this would test the actual update_from_system method
        // For now, we verify the state structure is properly initialized

        assert!(app.gui_state.system_loaded);
        assert!(!app.gui_state.system_running); // Should start as not running

        // Test that GUI state has proper structure for synchronization
        assert_eq!(app.gui_state.memory_state.ram_contents.len(), 4);
        assert_eq!(app.gui_state.register_state.index_registers.len(), 16);
    }

    #[test]
    fn test_gui_thread_safety() {
        let system = create_test_system();

        // Test that multiple threads can safely access the system
        let thread_safety_ok = test_thread_safe_access(&system);

        assert!(thread_safety_ok, "System should support thread-safe access");
    }

    #[test]
    fn test_gui_invalid_system_handling() {
        // Test GUI behavior with invalid or corrupted system state
        let system = create_mock_system();

        let mut app = GuiApp::new_for_test();

        // Test setting system that might be invalid
        app.set_system(system);

        // GUI should handle this gracefully
        assert!(app.gui_state.system_loaded);

        // Test error state handling
        app.gui_state.set_error("System access error".to_string());
        assert_eq!(app.gui_state.get_error(), Some("System access error"));
    }

    #[test]
    fn test_gui_concurrent_state_access() {
        let system = create_test_system();

        // Test concurrent access patterns that would occur in GUI
        let handles: Vec<_> = (0..5)
            .map(|_| {
                let system_clone = Arc::clone(&system);
                thread::spawn(move || {
                    // Simulate GUI update pattern
                    for _ in 0..10 {
                        if let Ok(_system_guard) = system_clone.lock() {
                            // Simulate some processing time
                            thread::sleep(Duration::from_micros(10));
                        }
                    }
                })
            })
            .collect();

        // Wait for all threads to complete
        for handle in handles {
            handle.join().expect("Thread should complete successfully");
        }

        // If we get here without deadlock, the test passes
        assert!(true);
    }

    #[test]
    fn test_gui_error_handling() {
        let mut state = rusty_emu::gui::state::GuiState::new();

        // Test error state management
        let test_error = "Test error for GUI".to_string();
        state.set_error(test_error.clone());

        assert_eq!(state.get_error(), Some(test_error.as_str()));

        // Test error clearing
        state.clear_error();
        assert!(state.get_error().is_none());

        // Test multiple error scenarios
        state.set_error("First error".to_string());
        state.set_error("Second error".to_string());

        assert_eq!(state.get_error(), Some("Second error"));
    }

    #[test]
    fn test_gui_system_state_polling() {
        let system = create_test_system();

        // Test the polling mechanism that GUI would use
        for i in 0..10 {
            {
                let system_guard = system.lock().unwrap();
                let is_running = system_guard.is_running();

                // Simulate state updates that would happen in GUI
                // In a real implementation, this would update GUI state

                if i == 5 {
                    // Simulate state change at midpoint
                    assert!(is_running || !is_running); // Just verify we can read state
                }
            } // system_guard is dropped here

            // Small delay to simulate GUI update interval
            thread::sleep(Duration::from_micros(100));
        }
    }

    #[test]
    fn test_gui_memory_state_integration() {
        let system = create_test_system();

        // Test memory state structure for GUI integration
        // In a real implementation, this would test actual memory access

        {
            let system_guard = system.lock().unwrap();
            // Test that system provides memory information
            let _ = system_guard.get_system_info(); // Access system info
        } // system_guard is dropped here

        // Verify GUI state can hold memory data
        let gui_state = rusty_emu::gui::state::GuiState::new();
        assert_eq!(gui_state.memory_state.ram_contents.len(), 4);

        for bank in &gui_state.memory_state.ram_contents {
            assert_eq!(bank.len(), 4);
        }
    }

    #[test]
    fn test_gui_register_state_integration() {
        let system = create_test_system();

        // Test register state structure for GUI integration
        {
            let _system_guard = system.lock().unwrap();
            // In a real implementation, this would access actual CPU registers
            // For now, we test the GUI state structure
        }

        let gui_state = rusty_emu::gui::state::GuiState::new();

        // Verify register state structure
        assert_eq!(gui_state.register_state.accumulator, 0);
        assert!(!gui_state.register_state.carry_flag);
        assert_eq!(gui_state.register_state.program_counter, 0);
        assert_eq!(gui_state.register_state.index_registers.len(), 16);
        assert_eq!(gui_state.register_state.stack_pointer, 0);
    }

    #[test]
    fn test_gui_component_state_integration() {
        let system = create_test_system();

        // Test component state monitoring for GUI
        {
            let system_guard = system.lock().unwrap();
            let components = system_guard.get_components();

            // Test that components are accessible (GUI would monitor these)
            assert!(!components.is_empty());
        } // system_guard is dropped here

        // Test GUI state structure for component monitoring
        let gui_state = rusty_emu::gui::state::GuiState::new();

        // Verify component state structure
        assert!(!gui_state.component_states.cpu_running);
        assert!(!gui_state.component_states.ram_running);
        assert!(!gui_state.component_states.rom_running);
        assert!(!gui_state.component_states.clock_running);
    }

    #[test]
    fn test_gui_system_compatibility() {
        // Test that GUI works with different system configurations
        let system = create_test_system();

        // Test GUI creation and system integration
        let mut app = GuiApp::new_for_test();

        app.set_system(system);

        // Verify compatibility
        assert!(app.gui_state.system_loaded);
        assert!(app.get_system().is_some());

        // Test that GUI state is properly initialized for the system
        assert_eq!(app.gui_state.memory_state.ram_contents.len(), 4);
        assert_eq!(app.gui_state.register_state.index_registers.len(), 16);
    }

    #[test]
    fn test_gui_performance_characteristics() {
        println!("Starting test_gui_performance_characteristics");
        let system = create_test_system();

        // Test GUI update performance characteristics with timeout protection
        let start_time = std::time::Instant::now();
        let timeout = Duration::from_secs(5); // 5 second timeout

        for _ in 0..100 {
            // Check for timeout to prevent test from hanging indefinitely
            if start_time.elapsed() > timeout {
                panic!("Test timed out after {:?} - possible deadlock", timeout);
            }

            // simulate_gui_updates acquires its own lock - do not hold lock while calling
            simulate_gui_updates(&system);
        }

        let elapsed = start_time.elapsed();

        // GUI updates should be reasonably fast (less than 1ms per update on average)
        assert!(
            elapsed.as_millis() < 100,
            "GUI updates should be performant"
        );
    }

    #[test]
    fn test_gui_error_recovery() {
        let mut state = rusty_emu::gui::state::GuiState::new();

        // Test error state and recovery
        state.set_error("Simulated error".to_string());
        assert_eq!(state.get_error(), Some("Simulated error"));

        // Test recovery by clearing error
        state.clear_error();
        assert!(state.get_error().is_none());

        // Test that system can continue after error recovery
        state.system_running = true;
        assert!(state.system_running);
    }

    #[test]
    fn test_gui_state_consistency() {
        let system = create_test_system();

        // Test that GUI state remains consistent during updates
        let mut app = GuiApp::new_for_test();

        app.set_system(Arc::clone(&system));

        // Simulate multiple state updates
        for i in 0..10 {
            if let Some(_sys) = app.get_system() {
                // In a real implementation, this would call update_from_system
                // For now, we verify the state structure remains consistent

                assert_eq!(app.gui_state.memory_state.ram_contents.len(), 4);
                assert_eq!(app.gui_state.register_state.index_registers.len(), 16);

                // Simulate state change
                app.gui_state.cycle_count = i;
            }
        }

        // Verify final state is consistent
        assert_eq!(app.gui_state.cycle_count, 9);
        assert!(app.gui_state.system_loaded);
    }
}

#[cfg(test)]
mod gui_error_handling_tests {
    use super::*;
    use gui_integration_test_utils::*;

    #[test]
    fn test_gui_invalid_system_handling() {
        // Test GUI behavior with invalid or corrupted system state
        let system = create_mock_system();

        let mut app = GuiApp::new_for_test();

        // Test setting system that might be invalid
        app.set_system(system);

        // GUI should handle this gracefully
        assert!(app.gui_state.system_loaded);

        // Test error state handling
        app.gui_state.set_error("System access error".to_string());
        assert_eq!(app.gui_state.get_error(), Some("System access error"));
    }

    #[test]
    fn test_gui_concurrent_error_handling() {
        let mut state = rusty_emu::gui::state::GuiState::new();

        // Test error handling under concurrent access
        let handles: Vec<_> = (0..3)
            .map(|i| {
                let mut state_clone = state.clone();
                thread::spawn(move || {
                    state_clone.set_error(format!("Error from thread {}", i));
                    thread::sleep(Duration::from_micros(10));
                    state_clone.get_error().map(|s| s.to_string())
                })
            })
            .collect();

        // Main thread also sets errors
        state.set_error("Main thread error".to_string());

        // Wait for threads
        let results: Vec<_> = handles.into_iter().map(|h| h.join().unwrap()).collect();

        // All threads should complete without panic
        assert_eq!(results.len(), 3);
        for result in results {
            assert!(result.is_some());
        }
    }

    #[test]
    fn test_gui_system_lock_timeout() {
        let system = create_test_system();

        // Test behavior when system lock might timeout or fail
        // This simulates scenarios where the GUI can't immediately access the system

        // Hold the lock for a short time to simulate contention
        let system_clone = Arc::clone(&system);
        let lock_handle = thread::spawn(move || {
            if let Ok(_system_guard) = system_clone.lock() {
                thread::sleep(Duration::from_millis(10));
            }
        });

        // Try to access from main thread (should not deadlock)
        let access_result = system.try_lock().is_ok();

        lock_handle.join().unwrap();

        // Should be able to access after the lock is released
        assert!(access_result || system.try_lock().is_ok());
    }

    #[test]
    fn test_gui_state_corruption_recovery() {
        let mut state = rusty_emu::gui::state::GuiState::new();

        // Simulate state corruption and recovery
        state.memory_state.ram_contents[0][0] = 255; // Invalid value
        state.register_state.accumulator = 255; // Invalid value

        // Test recovery by resetting state
        state.memory_state.ram_contents = vec![[0; 4]; 4];
        state.register_state.accumulator = 0;

        // Verify recovery
        assert_eq!(state.memory_state.ram_contents[0][0], 0);
        assert_eq!(state.register_state.accumulator, 0);
    }
}

#[cfg(test)]
mod gui_real_time_tests {
    use super::*;
    use gui_integration_test_utils::*;

    #[test]
    fn test_gui_real_time_state_updates() {
        let system = create_test_system();

        // Test real-time state update patterns
        let mut update_count = 0;
        let mut last_cycle_count = 0;

        for i in 0..20 {
            {
                let _system_guard = system.lock().unwrap();
                // Simulate GUI state polling
                update_count += 1;

                // Simulate cycle count updates (would come from system in real implementation)
                if i > 0 {
                    // In real implementation, this would be: gui_state.cycle_count = system.get_cycle_count()
                    last_cycle_count = i; // Simulate increasing cycle count
                }
            } // _system_guard is dropped here

            thread::sleep(Duration::from_micros(50)); // Simulate GUI update interval
        }

        assert_eq!(update_count, 20);
        assert_eq!(last_cycle_count, 19);
    }

    #[test]
    fn test_gui_state_update_frequency() {
        let system = create_test_system();

        // Test that GUI can handle high-frequency state updates with timeout protection
        let start_time = std::time::Instant::now();
        let timeout = Duration::from_secs(5); // 5 second timeout

        for _ in 0..50 {
            // Check for timeout to prevent test from hanging indefinitely
            if start_time.elapsed() > timeout {
                panic!("Test timed out after {:?} - possible deadlock", timeout);
            }

            // simulate_gui_updates acquires its own lock - do not hold lock while calling
            simulate_gui_updates(&system);
        }

        let elapsed = start_time.elapsed();

        // Should complete reasonably quickly (indicating good performance)
        assert!(
            elapsed.as_millis() < 500,
            "High-frequency updates should be performant"
        );
    }

    #[test]
    fn test_gui_memory_update_synchronization() {
        // Test memory state synchronization between system and GUI
        let system = create_test_system();

        // In a real implementation, this would test actual memory synchronization
        // For now, we test the data structures are compatible

        {
            let _system_guard = system.lock().unwrap();
            // Test memory data structure compatibility
        }

        let mut gui_state = rusty_emu::gui::state::GuiState::new();

        // Verify memory layout matches expected Intel 4002 structure
        assert_eq!(gui_state.memory_state.ram_contents.len(), 4); // 4 banks

        for bank in &gui_state.memory_state.ram_contents {
            assert_eq!(bank.len(), 4); // 4 bytes per bank
        }

        // Test bank selection bounds
        gui_state.memory_state.selected_bank = 0;
        gui_state.memory_state.selected_bank = 3; // Should be valid
    }

    #[test]
    fn test_gui_register_update_synchronization() {
        // Test register state synchronization between system and GUI
        let system = create_test_system();

        {
            let _system_guard = system.lock().unwrap();
        }

        let mut gui_state = rusty_emu::gui::state::GuiState::new();

        // Verify register layout matches Intel 4004 structure
        assert_eq!(gui_state.register_state.index_registers.len(), 16); // 16 index registers

        // Test register value bounds
        gui_state.register_state.accumulator = 0x0F; // 4-bit value (0-15)
        gui_state.register_state.carry_flag = true;

        // Test program counter bounds (12-bit address)
        gui_state.register_state.program_counter = 0xFFF; // Maximum 12-bit value

        // Test stack pointer bounds (4-bit value)
        gui_state.register_state.stack_pointer = 0x0F; // Maximum 4-bit value
    }
}