rusty_emu/src/components/memory/intel_4002.rs

use parking_lot::Mutex;
use std::any::Any;
use std::collections::HashMap;
use std::sync::Arc;
use std::thread;
use std::time::{Duration, Instant};

use crate::component::{BaseComponent, Component, RunnableComponent};
use crate::components::common::intel_400x::{
    process_event_direct, Intel400xAddressHandling, Intel400xClockHandling,
    Intel400xComponentBehavior, Intel400xComponentType, Intel400xControlPins, Intel400xDataBus,
    Intel400xEvent, Intel400xResetHandling, Intel400xStateMachine, Intel400xTimingState,
    Intel400xUnifiedState, TimingState,
};
use crate::pin::{Pin, PinValue};

/// Intel 4002 - 320-byte RAM with I/O ports
/// Part of the MCS-4 family, designed to work with Intel 4004 CPU
/// Features 320 bytes of RAM, 4 I/O ports, and status character generation
///
/// Hardware Deviations:
/// - I/O port writes are immediate (real hardware may have different timing)
/// - Status character generation timing simplified for testing
/// - RAM access timing may not exactly match real hardware
/// Pending operation type for the next memory cycle
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum PendingOperation {
    None,       // No operation pending
    Read,       // Read from RAM
    Write,      // Write to RAM
    OutputPort, // Write to output port
}

pub struct Intel4002 {
    pub base: BaseComponent,
    memory: [u8; 320],     // 320-byte RAM storage (4 registers * 80 characters)
    io_ports: [u8; 4],     // 4 I/O ports (4 bits each)
    status_character: u8,  // 7-bit status character output
    last_address: u16,     // Last accessed memory address
    access_time: Duration, // RAM access latency (500ns)
    selected_register: Option<u8>, // Currently selected register (0-3)
    selected_character: Option<u8>, // Currently selected character (0-79)
    // Unified state machine implementation
    state_machine: Intel400xStateMachine, // Unified state machine for Intel 400x components
    // Clock edge detection
    prev_phi1: PinValue, // Previous Φ1 clock state for edge detection
    prev_phi2: PinValue, // Previous Φ2 clock state for edge detection
    // Operation type for next cycle (determines ReadData vs WriteData vs OutputPort)
    pending_operation: PendingOperation,
}

impl Intel400xClockHandling for Intel4002 {
    fn get_base(&self) -> &BaseComponent {
        &self.base
    }
}

impl Intel400xDataBus for Intel4002 {
    fn get_base(&self) -> &BaseComponent {
        &self.base
    }
}

impl Intel400xAddressHandling for Intel4002 {
    fn get_base(&self) -> &BaseComponent {
        &self.base
    }
}

impl Intel400xControlPins for Intel4002 {
    fn get_base(&self) -> &BaseComponent {
        &self.base
    }
}

impl Intel400xResetHandling for Intel4002 {
    fn get_base(&self) -> &BaseComponent {
        &self.base
    }

    fn perform_reset(&mut self) {
        // Reset operations specific to Intel4002
        // Note: This is called from handle_reset, so we don't need to check reset pin again
        self.state_machine.reset();
        self.tri_state_data_bus();
        self.tri_state_status_pins();

        // Clear RAM content
        self.memory = [0u8; 320];
        self.io_ports = [0u8; 4];
        self.status_character = 0;
        self.selected_register = None;
        self.selected_character = None;

        // Reset clock edge detection state to ensure proper edge detection after reset
        // This is critical for tests that reset the chip between operations
        self.prev_phi1 = PinValue::Low;
        self.prev_phi2 = PinValue::Low;
    }
}

impl Intel400xTimingState for Intel4002 {
    fn get_timing_state(&self) -> TimingState {
        // Convert from Intel400xUnifiedState to TimingState
        match self.state_machine.get_state() {
            Intel400xUnifiedState::Idle => TimingState::Idle,
            Intel400xUnifiedState::AddressPhase => TimingState::AddressPhase,
            Intel400xUnifiedState::WaitLatency => TimingState::WaitLatency,
            Intel400xUnifiedState::DriveData => TimingState::DriveData,
            Intel400xUnifiedState::ReadData => TimingState::DriveData,
            Intel400xUnifiedState::WriteData => TimingState::DriveData,
            Intel400xUnifiedState::OutputPort => TimingState::DriveData,
            // Handle all other states
            _ => TimingState::Idle,
        }
    }

    fn set_timing_state(&mut self, state: TimingState) {
        // Convert from TimingState to Intel400xUnifiedState
        let unified_state = match state {
            TimingState::Idle => Intel400xUnifiedState::Idle,
            TimingState::AddressPhase => Intel400xUnifiedState::AddressPhase,
            TimingState::WaitLatency => Intel400xUnifiedState::WaitLatency,
            TimingState::DriveData => Intel400xUnifiedState::ReadData, // Default to ReadData
        };

        // Use state machine's reset method to transition to new state
        // This is a compatibility method for legacy state handling
        self.state_machine.reset();
        self.state_machine.current_state = unified_state;
    }

    fn get_address_latch_time(&self) -> Option<Instant> {
        self.state_machine.get_address_latch_time()
    }

    fn set_address_latch_time(&mut self, time: Option<Instant>) {
        self.state_machine.set_address_latch_time(time);
    }

    fn get_full_address_ready(&self) -> bool {
        self.state_machine.is_full_address_ready()
    }

    fn set_full_address_ready(&mut self, _ready: bool) {
        // This is handled by state machine, but keep for compatibility
    }

    fn get_address_high_nibble(&self) -> Option<u8> {
        self.state_machine.get_address_high_nibble()
    }

    fn set_address_high_nibble(&mut self, nibble: Option<u8>) {
        self.state_machine.set_address_high_nibble(nibble);
    }

    fn get_address_low_nibble(&self) -> Option<u8> {
        self.state_machine.get_address_low_nibble()
    }

    fn set_address_low_nibble(&mut self, nibble: Option<u8>) {
        self.state_machine.set_address_low_nibble(nibble);
    }

    fn get_access_time(&self) -> Duration {
        self.state_machine.get_access_time()
    }
}

impl Intel400xComponentBehavior for Intel4002 {
    fn get_component_type(&self) -> Intel400xComponentType {
        Intel400xComponentType::Intel4002
    }

    fn on_state_entry(&mut self, state: Intel400xUnifiedState) {
        match state {
            Intel400xUnifiedState::Idle => {
                // Entry actions for Idle state
                self.tri_state_data_bus();
                self.tri_state_status_pins();
            }
            Intel400xUnifiedState::AddressPhase => {
                // Entry actions for AddressPhase state
                // Clear address nibbles to prepare for new address
                self.state_machine.set_address_high_nibble(None);
                self.state_machine.set_address_low_nibble(None);
                self.state_machine.set_address_latch_time(None);
            }
            Intel400xUnifiedState::WaitLatency => {
                // Entry actions for WaitLatency state
                // Address is already latched, start access timer
            }
            Intel400xUnifiedState::ReadData => {
                // Entry actions for ReadData state
                // Data reading will happen in execute_state_logic
            }
            Intel400xUnifiedState::WriteData => {
                // Entry actions for WriteData state
                // Data writing will happen in execute_state_logic
            }
            Intel400xUnifiedState::OutputPort => {
                // Entry actions for OutputPort state
                // Status character output will happen in execute_state_logic
            }
            // Handle all other states
            _ => {}
        }
    }

    fn on_state_exit(&mut self, state: Intel400xUnifiedState) {
        match state {
            Intel400xUnifiedState::ReadData
            | Intel400xUnifiedState::WriteData
            | Intel400xUnifiedState::OutputPort => {
                // Exit actions for data states
                self.tri_state_data_bus();
                self.tri_state_status_pins();
            }
            // Handle all other states
            _ => {}
        }
    }

    fn handle_component_event(&mut self, event: Intel400xEvent) -> bool {
        match event {
            Intel400xEvent::ClockPhi1Rising => {
                // Handle Φ1 rising edge
                self.handle_phi1_rising();
                true // Event was handled
            }
            Intel400xEvent::ClockPhi1Falling => {
                // Handle Φ1 falling edge
                self.handle_phi1_falling();
                true // Event was handled
            }
            Intel400xEvent::ClockPhi2Rising => {
                // Handle Φ2 rising edge
                self.handle_phi2_rising();
                true // Event was handled
            }
            Intel400xEvent::ClockPhi2Falling => {
                // Handle Φ2 falling edge
                self.handle_phi2_falling();
                true // Event was handled
            }
            Intel400xEvent::ResetActive => {
                // Handle reset
                self.perform_reset();
                true // Event was handled
            }
            _ => false, // Let the generic state machine handle other events
        }
    }

    fn execute_state_logic(&mut self, state: Intel400xUnifiedState) {
        match state {
            Intel400xUnifiedState::Idle => {
                // In idle state, ensure bus is tri-stated
                self.tri_state_data_bus();
                self.tri_state_status_pins();
            }
            Intel400xUnifiedState::AddressPhase => {
                // Handle address latching during address phase
                self.handle_address_latching();
            }
            Intel400xUnifiedState::WaitLatency => {
                // Check if latency has elapsed
                if self.state_machine.is_latency_elapsed() {
                    // Transition to ReadData (default for RAM)
                    self.process_latency_elapsed();
                }
            }
            Intel400xUnifiedState::ReadData => {
                // Read data from RAM and drive on bus
                self.handle_ram_read();
            }
            Intel400xUnifiedState::WriteData => {
                // Write data from bus to RAM
                self.handle_ram_write();
            }
            Intel400xUnifiedState::OutputPort => {
                // Output status character on status pins
                self.handle_status_output();
            }
            // Handle other states (not used by Intel 4002)
            _ => {}
        }
    }

    fn responds_to_address(&self) -> bool {
        true // Intel 4002 responds to address transmission
    }
}

impl Intel4002 {
    /// Create a new Intel 4002 RAM with specified access time
    /// Parameters: name - Component identifier, access_time_ns - Memory access time in nanoseconds
    /// Returns: New Intel4002 instance with configurable access timing
    pub fn new(name: String) -> Self {
        Self::new_with_access_time(name, 500) // Default 500ns access time
    }

    /// Create a new Intel 4002 RAM with custom access time (for testing)
    /// Parameters: name - Component identifier, access_time_ns - Memory access time in nanoseconds
    /// Returns: New Intel4002 instance with configurable access timing
    pub fn new_with_access_time(name: String, access_time_ns: u64) -> Self {
        // Intel 4002 has 320 bytes of RAM
        const RAM_SIZE: usize = 320;

        // Intel 4002 pinout (per datasheet):
        // - 4 data pins (D0-D3) for multiplexed address/data
        // - 4 I/O ports (IO0-IO3)
        // - 4 status pins (S0-S3) for status character output
        // - Control pins: SYNC, RESET, CM, CI
        // - Clock pins: Φ1, Φ2 (two-phase clock from 4004 CPU)
        //
        // Control pin behavior:
        // - SYNC: Marks start of instruction cycle
        // - RESET: Clears internal state
        // - CM: Chip select (must be HIGH for RAM access)
        // - CI: I/O select (distinguishes I/O vs memory when chip selected)
        let pin_names = vec![
            "D0", "D1", "D2", "D3", // Data/Address pins
            "IO0", "IO1", "IO2", "IO3", // I/O ports
            "S0", "S1", "S2", "S3",    // Status character pins
            "SYNC",  // Sync signal
            "CM",    // CM-ROM: ROM/RAM Chip Select
            "CI",    // CM-RAM: RAM Chip Select (I/O vs ROM access)
            "RESET", // Reset
            "PHI1",  // Clock phase 1
            "PHI2",  // Clock phase 2
        ];

        let pins = BaseComponent::create_pin_map(&pin_names, &name);

        Intel4002 {
            base: BaseComponent::new(name, pins),
            memory: [0u8; RAM_SIZE],
            io_ports: [0u8; 4],
            status_character: 0,
            last_address: 0,
            access_time: Duration::from_nanos(access_time_ns),
            selected_register: None,
            selected_character: None,
            state_machine: Intel400xStateMachine::new(
                Intel400xComponentType::Intel4002,
                Duration::from_nanos(access_time_ns),
            ),
            prev_phi1: PinValue::Low,
            prev_phi2: PinValue::Low,
            pending_operation: PendingOperation::Read, // Default to read
        }
    }

    /// Set memory access time for simulation
    /// Parameters: access_time_ns - Access time in nanoseconds
    pub fn set_access_time(&mut self, access_time_ns: u64) {
        self.access_time = Duration::from_nanos(access_time_ns);
        self.state_machine
            .set_access_time(Duration::from_nanos(access_time_ns));
    }

    /// Get current memory access time
    /// Returns: Access time in nanoseconds
    pub fn get_access_time(&self) -> u64 {
        self.access_time.as_nanos() as u64
    }

    /// Read a byte from RAM at specified address
    /// Parameters: address - 8-bit address (0-319)
    /// Returns: Some(data) if address valid, None if out of bounds
    pub fn read_ram(&self, address: u8) -> Option<u8> {
        if (address as usize) < self.memory.len() {
            Some(self.memory[address as usize])
        } else {
            None
        }
    }

    /// Write a byte to RAM at specified address
    /// Parameters: address - 8-bit address (0-319), data - Byte to write
    /// Returns: Ok(()) on success, Err(String) on failure
    pub fn write_ram(&mut self, address: u8, data: u8) -> Result<(), String> {
        if (address as usize) < self.memory.len() {
            self.memory[address as usize] = data;
            Ok(())
        } else {
            Err(format!("Address 0x{:02X} out of bounds", address))
        }
    }

    /// Write to a specific I/O port
    /// Parameters: port - I/O port number (0-3), data - 4-bit data to write
    /// Returns: Ok(()) on success, Err(String) on failure
    pub fn write_io_port(&mut self, port: usize, data: u8) -> Result<(), String> {
        if port < 4 {
            self.io_ports[port] = data & 0x0F;
            Ok(())
        } else {
            Err("I/O port number out of range (0-3)".to_string())
        }
    }

    /// Get current status character
    /// Returns: 7-bit status character

    /// Tri-state data bus pins
    fn tri_state_data_bus(&self) {
        for i in 0..4 {
            if let Ok(pin) = self.base.get_pin(&format!("D{}", i)) {
                let mut pin_guard = pin.lock();
                // Use the same driver name as write_data_bus() to properly tri-state
                pin_guard.set_driver(Some(format!("{}_DATA", self.base.name())), PinValue::HighZ);
            }
        }
    }

    /// Tri-state status character pins
    fn tri_state_status_pins(&self) {
        for i in 0..4 {
            if let Ok(pin) = self.base.get_pin(&format!("S{}", i)) {
                let mut pin_guard = pin.lock();
                pin_guard.set_driver(Some(self.base.name()), PinValue::HighZ);
            }
        }
    }

    /// Handle Φ1 rising edge - Address and control phase
    /// Hardware: Φ1 high = CPU drives bus with address/control information
    /// Memory operations start when SYNC goes high during Φ1 rising edge
    /// Focus: Address latching, reset, I/O operations
    fn handle_phi1_rising(&mut self) {
        // Handle system reset first (highest priority)
        self.handle_reset("RESET");

        // Check for memory operation start on Φ1 rising edge with SYNC high
        // Hardware: Memory operations start when SYNC goes high during Φ1
        // Note: SYNC marks instruction fetch start, but exact logic involves CPU cycle state.
        // RAM access: CM=1 (chip_select), CI=1 (io_select)
        let sync = self.read_sync_pin();
        let chip_select = self.read_cm_rom_pin();
        let io_select = self.read_ci_pin();

        if sync && chip_select && io_select {
            // Start memory address phase on Φ1 rising edge (RAM access)
            // Only start a new memory operation if we're currently idle
            if self.state_machine.get_state() == Intel400xUnifiedState::Idle {
                self.process_chip_select();
            }
        }
    }

    /// Handle Φ1 falling edge - Latch address nibbles
    /// Hardware: Φ1 low = CPU has finished driving address, data is stable
    /// RAM latches address nibbles on PHI1 falling edge to ensure data is stable
    fn handle_phi1_falling(&mut self) {
        // Only latch if we're in AddressPhase
        // Note: We do NOT check chip_select here because:
        // 1. Chip select was already verified when we entered AddressPhase
        // 2. CM pin may be lowered between A1 and A2 cycles (this is valid)
        // 3. Once address phase starts, we must complete both nibbles
        // 4. The io_select (CI) pin distinguishes I/O vs memory operations
        if self.state_machine.get_state() == Intel400xUnifiedState::AddressPhase {
            // Latch address nibble on PHI1 falling edge (data is now stable)
            let nibble = self.read_data_bus() & 0x0F;

            if self.state_machine.handle_address_nibble(nibble) {
                // Address is complete (both nibbles latched), transition to latency wait
                self.process_address_complete();
            }
        }
    }

    /// Handle Φ2 rising edge - Data phase
    /// Hardware: Φ2 high = Peripherals drive bus with data
    /// Focus: Data driving operations
    fn handle_phi2_rising(&mut self) {
        // Check for latency elapsed and transition to ReadData/WriteData/OutputPort if needed
        if self.state_machine.get_state() == Intel400xUnifiedState::WaitLatency {
            if self.state_machine.is_latency_elapsed() {
                self.process_latency_elapsed();
            }
        }

        // Drive data if in ReadData/WriteData/OutputPort state
        match self.state_machine.get_state() {
            Intel400xUnifiedState::ReadData => {
                self.handle_ram_read();
            }
            Intel400xUnifiedState::WriteData => {
                self.handle_ram_write();
            }
            Intel400xUnifiedState::OutputPort => {
                self.handle_status_output();
            }
            _ => {}
        }
    }

    /// Handle Φ2 falling edge - End of data phase
    /// Hardware: Φ2 low = End of data driving phase, time to tri-state bus
    /// Data is held on bus during Φ2 high, tri-stated when Φ2 falls
    /// Focus: Clean up and return to idle state
    fn handle_phi2_falling(&mut self) {
        match self.state_machine.get_state() {
            Intel400xUnifiedState::ReadData
            | Intel400xUnifiedState::WriteData
            | Intel400xUnifiedState::OutputPort => {
                // End of data phase - tri-state bus and return to idle
                self.tri_state_data_bus();
                self.tri_state_status_pins();
                self.process_operation_complete();
            }

            Intel400xUnifiedState::Idle
            | Intel400xUnifiedState::AddressPhase
            | Intel400xUnifiedState::WaitLatency => {
                // For other states, just ensure bus is tri-stated
                self.tri_state_data_bus();
                self.tri_state_status_pins();
            }
            // Handle all other states
            _ => {
                // Default behavior for unhandled states
                self.tri_state_data_bus();
                self.tri_state_status_pins();
            }
        }
    }

    /// Handle address nibble latching during address phase
    /// Hardware: CPU provides 8-bit address as two 4-bit nibbles
    fn handle_address_latching(&mut self) {
        // Use common address latching functionality
        let nibble = self.read_data_bus() & 0x0F; // Only 4 bits are valid for address nibbles

        if self.state_machine.handle_address_nibble(nibble) {
            // Address is complete, transition to latency wait
            self.process_address_complete();
        }
    }

    /// Handle RAM read operation
    /// Hardware: RAM drives data bus with requested data
    fn handle_ram_read(&mut self) {
        if self.state_machine.is_full_address_ready() {
            let address = self.state_machine.get_full_address().unwrap_or(0) as u8;
            if let Some(data) = self.read_ram(address) {
                self.write_data_bus(data);
                self.last_address = address as u16;
            } else {
                self.tri_state_data_bus();
            }
        } else {
            self.tri_state_data_bus();
        }
    }

    /// Handle RAM write operation
    /// Hardware: RAM reads data from bus and stores at address
    fn handle_ram_write(&mut self) {
        if self.state_machine.is_full_address_ready() {
            let address = self.state_machine.get_full_address().unwrap_or(0) as u8;
            let data = self.read_data_bus();
            if self.write_ram(address, data).is_ok() {
                self.last_address = address as u16;
            }
        }
    }

    /// Handle output port operation
    /// Hardware: RAM writes data from bus to I/O port based on address
    /// Addresses 0x00-0x4F are RAM data, 0x14-0x17 are output ports
    fn handle_status_output(&mut self) {
        if self.state_machine.is_full_address_ready() {
            let address = self.state_machine.get_full_address().unwrap_or(0) as u8;
            let data = self.read_data_bus();

            // Determine which output port based on address
            // Output ports are at addresses 0x14-0x17 (port 0-3)
            let port = match address {
                0x14 => Some(0),
                0x15 => Some(1),
                0x16 => Some(2),
                0x17 => Some(3),
                _ => None,
            };

            if let Some(port_num) = port {
                // Write to I/O port
                let _ = self.write_io_port(port_num, data);
            }
        }
    }

    /// Helper function to process latency elapsed event
    fn process_latency_elapsed(&mut self) {
        // Determine the target state based on pending operation type
        let target_state = match self.pending_operation {
            PendingOperation::Read => Intel400xUnifiedState::ReadData,
            PendingOperation::Write => Intel400xUnifiedState::WriteData,
            PendingOperation::OutputPort => Intel400xUnifiedState::OutputPort,
            PendingOperation::None => Intel400xUnifiedState::ReadData, // Default to read
        };

        // Transition directly to the target state
        if target_state != self.state_machine.get_state() {
            self.on_state_exit(self.state_machine.get_state());
            self.state_machine.current_state = target_state;
            self.on_state_entry(target_state);
        }
    }

    /// Helper function to process chip select event
    fn process_chip_select(&mut self) {
        let old_state = self.state_machine.get_state();
        let event = Intel400xEvent::ChipSelect;
        let new_state = process_event_direct(&mut self.state_machine, event);

        if new_state != old_state {
            self.on_state_exit(old_state);
            self.on_state_entry(new_state);
        }
    }

    /// Helper function to process operation complete event
    fn process_operation_complete(&mut self) {
        let old_state = self.state_machine.get_state();
        let event = Intel400xEvent::OperationComplete;
        let new_state = process_event_direct(&mut self.state_machine, event);

        if new_state != old_state {
            self.on_state_exit(old_state);
            self.on_state_entry(new_state);
        }
    }

    /// Helper function to process address complete event
    fn process_address_complete(&mut self) {
        let old_state = self.state_machine.get_state();
        let event = Intel400xEvent::AddressComplete;
        let new_state = process_event_direct(&mut self.state_machine, event);

        if new_state != old_state {
            self.on_state_exit(old_state);
            self.on_state_entry(new_state);
        }
    }
}

impl Component for Intel4002 {
    fn name(&self) -> String {
        self.base.name()
    }

    fn pins(&self) -> HashMap<String, Arc<Mutex<Pin>>> {
        self.base.pins()
    }

    fn get_pin(&self, name: &str) -> Result<Arc<Mutex<Pin>>, String> {
        self.base.get_pin(name)
    }

    /// Main update cycle - handles clock edge detection and operation dispatch
    /// Hardware: Responds to Φ1 and Φ2 clock edges from CPU
    fn update(&mut self) {
        if !self.is_running() {
            return;
        }
        // Handle both rising and falling edges for proper two-phase operation
        let phi1_rising = self.is_phi1_rising_edge(self.prev_phi1);
        let phi1_falling = self.is_phi1_falling_edge(self.prev_phi1);
        let phi2_rising = self.is_phi2_rising_edge(self.prev_phi2);
        let phi2_falling = self.is_phi2_falling_edge(self.prev_phi2);

        // Update clock states for next edge detection
        let (phi1, phi2) = self.read_clock_pins();
        self.prev_phi1 = phi1;
        self.prev_phi2 = phi2;

        // Check for reset first (highest priority, independent of clock edges)
        let reset_active = self.read_reset_pin();
        if reset_active {
            self.perform_reset();
            // Skip further processing if reset is active
            return;
        }

        // Process clock events through component-specific handlers
        // These handlers contain the actual logic for chip select, address latching, etc.
        if phi1_rising {
            self.handle_phi1_rising();
        }

        if phi1_falling {
            self.handle_phi1_falling();
        }

        if phi2_rising {
            self.handle_phi2_rising();
        }

        if phi2_falling {
            self.handle_phi2_falling();
        }

        // Note: execute_state_machine() is NOT called here because:
        // 1. Address latching is handled directly in handle_phi1_rising()
        // 2. Data driving is handled directly in handle_phi2_rising()
        // 3. Calling it would cause double-latching of address nibbles
    }

    /// Run component in time-slice mode (manual control)
    /// Hardware: Simulates continuous operation with clock edge detection
    fn run(&mut self) {
        self.base.set_running(true);

        // Initialize clock states for edge detection
        let (phi1, phi2) = self.read_clock_pins();
        self.prev_phi1 = phi1;
        self.prev_phi2 = phi2;

        while self.is_running() {
            self.update();
            // Small delay to prevent busy waiting when no clock is present
            thread::sleep(Duration::from_micros(1));
        }
    }

    /// Stop component and tri-state all outputs
    /// Hardware: Component enters low-power state, all pins high-impedance
    fn stop(&mut self) {
        self.base.set_running(false);

        // Tri-state all outputs when stopped
        self.tri_state_data_bus();
        self.tri_state_status_pins();
    }

    fn is_running(&self) -> bool {
        self.base.is_running()
    }

    fn set_running(&mut self, running: bool) {
        self.base.set_running(running);
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    fn as_any_mut(&mut self) -> &mut dyn Any {
        self
    }
}

impl RunnableComponent for Intel4002 {}

// Intel 4002 specific methods
impl Intel4002 {
    /// Get RAM size in bytes
    /// Returns: Total number of bytes in RAM (320 for 4002)
    pub fn get_ram_size(&self) -> usize {
        self.memory.len()
    }

    /// Read a byte from RAM at specified address
    /// Parameters: address - 8-bit address (0-319)
    /// Returns: Some(data) if address valid, None if out of bounds
    pub fn read_ram_direct(&self, address: u8) -> Option<u8> {
        if (address as usize) < self.memory.len() {
            Some(self.memory[address as usize])
        } else {
            None
        }
    }

    /// Write a byte to RAM at specified address
    /// Parameters: address - 8-bit address (0-319), data - Byte to write
    /// Returns: Ok(()) on success, Err(String) on failure
    pub fn write_ram_direct(&mut self, address: u8, data: u8) -> Result<(), String> {
        if (address as usize) < self.memory.len() {
            self.memory[address as usize] = data;
            self.last_address = address as u16; // Update last address tracking
            Ok(())
        } else {
            Err(format!("Address 0x{:02X} out of bounds", address))
        }
    }

    /// Get I/O port value
    /// Parameters: port - I/O port number (0-3)
    /// Returns: Some(4-bit value) if port valid, None if invalid
    pub fn get_io_port(&self, port: usize) -> Option<u8> {
        if port < 4 {
            Some(self.io_ports[port])
        } else {
            None
        }
    }

    /// Set I/O port value (for testing/debugging)
    /// Parameters: port - I/O port number (0-3), data - 4-bit data to set
    /// Returns: Ok(()) on success, Err(String) on failure
    pub fn set_io_port(&mut self, port: usize, data: u8) -> Result<(), String> {
        if port < 4 {
            self.io_ports[port] = data & 0x0F;
            Ok(())
        } else {
            Err("I/O port number out of range (0-3)".to_string())
        }
    }

    /// Get current status character
    /// Returns: 7-bit status character
    pub fn get_status_character(&self) -> u8 {
        self.status_character
    }

    /// Set status character (for testing/debugging)
    /// Parameters: character - 7-bit status character
    pub fn set_status_character(&mut self, character: u8) {
        self.status_character = character & 0x7F; // Only 7 bits valid
    }

    /// Get last accessed address
    /// Returns: Last address accessed by RAM
    pub fn get_last_address(&self) -> u16 {
        self.last_address
    }

    /// Set the state machine state directly (for testing purposes)
    /// Parameters: state - The unified state to set
    /// Note: This triggers on_state_entry to properly initialize state-specific variables
    pub fn set_state_for_test(&mut self, state: Intel400xUnifiedState) {
        let old_state = self.state_machine.get_state();
        if old_state != state {
            self.on_state_exit(old_state);
            self.state_machine.current_state = state;
            self.on_state_entry(state);
        }
    }

    /// Set the pending operation type (for testing purposes)
    /// Parameters: operation - The operation type for the next memory cycle
    pub fn set_pending_operation(&mut self, operation: PendingOperation) {
        self.pending_operation = operation;
    }

    /// Get the pending operation type (for testing purposes)
    /// Returns: The current pending operation type
    pub fn get_pending_operation(&self) -> PendingOperation {
        self.pending_operation
    }

    /// Debug function to log state transitions for troubleshooting
    /// Parameters: test_name - Name of the test for context
    pub fn debug_state_transitions(&self, test_name: &str) {
        println!(
            "{} - State: {:?}, High: {:?}, Low: {:?}, Address: 0x{:x}, Ready: {}, Latch time: {:?}",
            test_name,
            self.state_machine.get_state(),
            self.state_machine.get_address_high_nibble(),
            self.state_machine.get_address_low_nibble(),
            self.last_address,
            self.state_machine.is_full_address_ready(),
            self.state_machine.get_address_latch_time()
        );
    }
}

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

    #[test]
    fn test_intel4002_creation() {
        let ram = Intel4002::new("RAM_4002".to_string());
        assert_eq!(ram.name(), "RAM_4002");
        assert_eq!(ram.get_ram_size(), 320);
        assert_eq!(ram.get_access_time(), 500); // Default 500ns
        assert!(!ram.is_running());
    }

    #[test]
    fn test_intel4002_ram_operations() {
        let mut ram = Intel4002::new("RAM_4002".to_string());

        // Test RAM read/write operations
        assert!(ram.write_ram_direct(0x00, 0x12).is_ok());
        assert!(ram.write_ram_direct(0x01, 0x34).is_ok());
        assert!(ram.write_ram_direct(0x02, 0x56).is_ok());
        assert!(ram.write_ram_direct(0x03, 0x78).is_ok());

        assert_eq!(ram.read_ram_direct(0x00).unwrap(), 0x12);
        assert_eq!(ram.read_ram_direct(0x01).unwrap(), 0x34);
        assert_eq!(ram.read_ram_direct(0x02).unwrap(), 0x56);
        assert_eq!(ram.read_ram_direct(0x03).unwrap(), 0x78);
    }

    #[test]
    fn test_intel4002_io_ports() {
        let mut ram = Intel4002::new("RAM_4002".to_string());

        // Test I/O port operations
        assert!(ram.set_io_port(0, 0x05).is_ok());
        assert!(ram.set_io_port(1, 0x0A).is_ok());
        assert!(ram.set_io_port(2, 0x0F).is_ok());
        assert!(ram.set_io_port(3, 0x00).is_ok());

        assert_eq!(ram.get_io_port(0).unwrap(), 0x05);
        assert_eq!(ram.get_io_port(1).unwrap(), 0x0A);
        assert_eq!(ram.get_io_port(2).unwrap(), 0x0F);
        assert_eq!(ram.get_io_port(3).unwrap(), 0x00);

        // Test invalid port access
        assert!(ram.set_io_port(4, 0x0F).is_err());
        assert!(ram.get_io_port(4).is_none());
    }

    #[test]
    fn test_intel4002_status_character() {
        let mut ram = Intel4002::new("RAM_4002".to_string());

        // Test status character operations
        ram.set_status_character(0x5A); // Binary 1011010
        assert_eq!(ram.get_status_character(), 0x5A);

        // Test status character bit masking
        ram.set_status_character(0xFF); // Should be masked to 0x7F
        assert_eq!(ram.get_status_character(), 0x7F);
    }

    #[test]
    fn test_intel4002_state_transitions() {
        let mut ram = Intel4002::new_with_access_time("StateTestRAM".to_string(), 1);

        // Test all state transitions
        let states = vec![
            TimingState::Idle,
            TimingState::AddressPhase,
            TimingState::WaitLatency,
            TimingState::DriveData,
        ];

        for &state in &states {
            ram.set_timing_state(state);
            assert_eq!(ram.get_timing_state(), state);
        }

        // Test return to idle
        ram.set_timing_state(TimingState::Idle);
        assert_eq!(ram.get_timing_state(), TimingState::Idle);
    }

    #[test]
    fn test_intel4002_address_handling() {
        let mut ram = Intel4002::new_with_access_time("AddressTestRAM".to_string(), 1);

        // Test address nibble handling
        ram.set_address_high_nibble(Some(0x12));
        ram.set_address_low_nibble(Some(0x34));
        ram.set_full_address_ready(true);

        assert_eq!(ram.get_address_high_nibble(), Some(0x12));
        assert_eq!(ram.get_address_low_nibble(), Some(0x34));
        assert_eq!(ram.state_machine.is_full_address_ready(), true);

        // Test clearing
        ram.set_address_high_nibble(None);
        ram.set_address_low_nibble(None);
        ram.set_full_address_ready(false);

        assert_eq!(ram.get_address_high_nibble(), None);
        assert_eq!(ram.get_address_low_nibble(), None);
        assert_eq!(ram.state_machine.is_full_address_ready(), false);
    }

    #[test]
    fn test_intel4002_error_conditions() {
        let mut ram = Intel4002::new("ErrorTestRAM".to_string());

        // Test invalid memory access
        assert_eq!(ram.read_ram_direct(0xFF), Some(0x00)); // Default value for unmapped memory

        // Test invalid data loading
        assert!(ram.write_ram_direct(0x00, 0x12).is_ok()); // Valid
        assert!(ram.write_ram_direct(0xFF, 0x34).is_ok()); // Valid - 0xFF is within 320-byte RAM

        // Note: Since write_ram_direct takes u8 for address, we can't test addresses > 0xFF
        // The actual implementation should handle this correctly for the full 320-byte range
    }

    #[test]
    fn test_intel4002_io_port_operations() {
        let mut ram = Intel4002::new("IOTestRAM".to_string());

        // Test I/O port initialization
        assert_eq!(ram.get_io_port(0).unwrap(), 0);
        assert_eq!(ram.get_io_port(1).unwrap(), 0);
        assert_eq!(ram.get_io_port(2).unwrap(), 0);
        assert_eq!(ram.get_io_port(3).unwrap(), 0);

        // Test setting I/O port values
        assert!(ram.set_io_port(0, 0x05).is_ok());
        assert_eq!(ram.get_io_port(0).unwrap(), 0x05);

        // Test invalid port access
        assert!(ram.set_io_port(4, 0x0F).is_err());
        assert!(ram.get_io_port(4).is_none());
    }

    #[test]
    fn test_intel4002_status_character_operations() {
        let mut ram = Intel4002::new("StatusTestRAM".to_string());

        // Test status character initialization
        assert_eq!(ram.get_status_character(), 0);

        // Test setting status character
        ram.set_status_character(0x5A);
        assert_eq!(ram.get_status_character(), 0x5A);

        // Test status character bit masking
        ram.set_status_character(0xFF); // Should be masked to 0x7F
        assert_eq!(ram.get_status_character(), 0x7F);
    }

    #[test]
    fn test_intel4002_reset_behavior() {
        let mut ram = Intel4002::new("ResetTestRAM".to_string());

        // Set up some state first
        ram.set_io_port(0, 0x05).unwrap();
        ram.set_io_port(1, 0x0A).unwrap();
        ram.set_status_character(0x5A);

        // Verify state is set
        assert_eq!(ram.get_io_port(0).unwrap(), 0x05);
        assert_eq!(ram.get_io_port(1).unwrap(), 0x0A);
        assert_eq!(ram.get_status_character(), 0x5A);

        // Perform reset
        ram.perform_reset();

        // Verify all state is cleared
        assert_eq!(ram.get_io_port(0).unwrap(), 0);
        assert_eq!(ram.get_io_port(1).unwrap(), 0);
        assert_eq!(ram.get_status_character(), 0);

        // Verify RAM is cleared
        for i in 0..320 {
            assert_eq!(ram.read_ram_direct(i as u8).unwrap(), 0x00);
        }
    }

    #[test]
    fn test_intel4002_last_address_tracking() {
        let mut ram = Intel4002::new("AddressTrackTestRAM".to_string());

        // Initially should be 0
        assert_eq!(ram.get_last_address(), 0);

        // Perform some operations
        ram.write_ram_direct(0x10, 0x12).unwrap();
        assert_eq!(ram.get_last_address(), 0x10);

        ram.write_ram_direct(0x20, 0x34).unwrap();
        assert_eq!(ram.get_last_address(), 0x20);

        ram.write_ram_direct(0x30, 0x56).unwrap();
        assert_eq!(ram.get_last_address(), 0x30);
    }

    #[test]
    fn test_intel4002_debug_function() {
        let mut ram = Intel4002::new("DebugTestRAM".to_string());

        // Test debug state transitions
        ram.set_address_high_nibble(Some(0x12));
        ram.set_address_low_nibble(Some(0x34));
        ram.set_full_address_ready(true);

        // Call debug function
        ram.debug_state_transitions("TestDebug");

        // Should not panic or crash
        assert_eq!(ram.get_address_high_nibble(), Some(0x12));
        assert_eq!(ram.get_address_low_nibble(), Some(0x34));
        assert_eq!(ram.state_machine.is_full_address_ready(), true);
    }
}