//! Enhanced ARM64 optimizations with Apple Silicon specific enhancements
//!
//! This module provides advanced optimizations specifically tuned for ARM64 processors,
//! with special focus on Apple Silicon (M1, M2, M3, M4) and other ARM64 microarchitectures.

use crate::cpu::platform_optimization::{ArmMicroarchitecture, CpuFeatures};
use crate::error::BackendResult;
use torsh_core::error::TorshError;
use std::sync::OnceLock;

#[cfg(not(feature = "std"))]
use alloc::{boxed::Box, string::String, vec::Vec};

/// Enhanced ARM64 optimizer with Apple Silicon specific tuning
#[derive(Debug)]
pub struct EnhancedARM64Optimizer {
    microarch: ArmMicroarchitecture,
    features: CpuFeatures,
    optimization_params: ARM64OptimizationParameters,
    vector_unit_config: ARM64VectorUnitConfig,
    cache_config: ARM64CacheConfiguration,
    apple_silicon_config: Option<AppleSiliconConfig>,
    execution_units: ARM64ExecutionUnitInfo,
}

/// ARM64-specific optimization parameters
#[derive(Debug, Clone)]
pub struct ARM64OptimizationParameters {
    /// Optimal unroll factor for loops
    pub loop_unroll_factor: usize,
    /// Preferred NEON vector width in bits
    pub preferred_vector_width: usize,
    /// SVE vector length (if available)
    pub sve_vector_length: Option<usize>,
    /// Maximum memory bandwidth utilization
    pub max_memory_bandwidth_utilization: f64,
    /// Instruction scheduling window size
    pub scheduling_window_size: usize,
    /// Branch prediction accuracy
    pub branch_prediction_accuracy: f64,
    /// Cache blocking factors
    pub cache_blocking_factors: ARM64CacheBlockingFactors,
    /// Parallel execution parameters
    pub parallel_params: ARM64ParallelExecutionParams,
    /// Apple Silicon specific parameters
    pub apple_silicon_params: Option<AppleSiliconOptimizationParams>,
}

/// ARM64 cache blocking factors
#[derive(Debug, Clone)]
pub struct ARM64CacheBlockingFactors {
    pub l1_block_size: usize,
    pub l2_block_size: usize,
    pub l3_block_size: usize, // System cache on Apple Silicon
    pub tlb_block_size: usize,
    pub system_cache_block_size: Option<usize>, // Apple Silicon system cache
}

/// ARM64 parallel execution parameters
#[derive(Debug, Clone)]
pub struct ARM64ParallelExecutionParams {
    pub optimal_thread_count: usize,
    pub performance_core_count: usize,
    pub efficiency_core_count: usize,
    pub work_stealing_threshold: usize,
    pub chunk_size_multiplier: f64,
    pub load_balancing_strategy: ARM64LoadBalancingStrategy,
}

/// ARM64-specific load balancing strategies
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ARM64LoadBalancingStrategy {
    /// Use all cores equally
    Uniform,
    /// Prefer performance cores for compute-heavy tasks
    PerformancePreferred,
    /// Use efficiency cores for background tasks
    EfficiencyPreferred,
    /// Dynamic based on power and thermal constraints
    AdaptivePowerThermal,
    /// NUMA-aware for server ARM64 systems
    NumaAware,
}

/// ARM64 vector unit configuration
#[derive(Debug, Clone)]
pub struct ARM64VectorUnitConfig {
    pub neon_available: bool,
    pub sve_available: bool,
    pub sve2_available: bool,
    pub neon_register_count: usize,
    pub sve_register_count: usize,
    pub vector_lane_width: usize,
    pub optimal_vector_size: usize,
    pub crypto_available: bool,
    pub fp16_available: bool,
    pub bf16_available: bool,
    pub i8mm_available: bool,
    pub matrix_multiply_available: bool, // For future ARM matrix extensions
}

/// ARM64 cache configuration
#[derive(Debug, Clone)]
pub struct ARM64CacheConfiguration {
    pub l1i_size: usize,
    pub l1d_size: usize,
    pub l2_size: usize,
    pub l3_size: Option<usize>, // Not all ARM64 systems have L3
    pub system_cache_size: Option<usize>, // Apple Silicon system cache
    pub l1_associativity: usize,
    pub l2_associativity: usize,
    pub l3_associativity: Option<usize>,
    pub cache_line_size: usize,
    pub tlb_entries: usize,
    pub prefetch_distance: usize,
    pub cache_coherency_level: CacheCoherencyLevel,
}

/// Cache coherency levels for different ARM64 systems
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CacheCoherencyLevel {
    /// Point of Coherency (PoC)
    PoC,
    /// Point of Unification (PoU)
    PoU,
    /// System cache level coherency (Apple Silicon)
    SystemCache,
}

/// Apple Silicon specific configuration
#[derive(Debug, Clone)]
pub struct AppleSiliconConfig {
    pub neural_engine_available: bool,
    pub neural_engine_ops_per_second: f64,
    pub media_engine_available: bool,
    pub accelerated_ml_compute: bool,
    pub unified_memory_bandwidth: f64, // GB/s
    pub performance_controller_available: bool,
    pub thermal_management_advanced: bool,
    pub memory_compression_available: bool,
    pub secure_enclave_available: bool,
    pub system_cache_size: usize,
}

/// Apple Silicon specific optimization parameters
#[derive(Debug, Clone)]
pub struct AppleSiliconOptimizationParams {
    pub prefer_neural_engine_threshold: usize, // Elements count threshold
    pub use_media_engine_for_conv: bool,
    pub optimize_for_unified_memory: bool,
    pub thermal_throttling_mitigation: bool,
    pub power_efficiency_mode: PowerEfficiencyMode,
}

/// Power efficiency modes for Apple Silicon
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PowerEfficiencyMode {
    MaxPerformance,
    Balanced,
    MaxEfficiency,
    Adaptive,
}

/// ARM64 execution unit information
#[derive(Debug, Clone)]
pub struct ARM64ExecutionUnitInfo {
    pub integer_units: usize,
    pub fp_units: usize,
    pub neon_units: usize,
    pub sve_units: usize,
    pub load_units: usize,
    pub store_units: usize,
    pub branch_units: usize,
    pub crypto_units: usize,
    pub issue_width: usize,
    pub retire_width: usize,
    pub out_of_order_window: usize,
}

impl EnhancedARM64Optimizer {
    /// Create a new enhanced ARM64 optimizer
    pub fn new() -> BackendResult<Self> {
        let microarch = Self::detect_microarchitecture()?;
        let features = Self::detect_cpu_features()?;
        let optimization_params = Self::get_optimization_parameters(&microarch, &features);
        let vector_unit_config = Self::get_vector_unit_config(&microarch, &features);
        let cache_config = Self::detect_cache_configuration(&microarch)?;
        let apple_silicon_config = Self::detect_apple_silicon_config(&microarch);
        let execution_units = Self::get_execution_unit_info(&microarch);
        
        Ok(Self {
            microarch,
            features,
            optimization_params,
            vector_unit_config,
            cache_config,
            apple_silicon_config,
            execution_units,
        })
    }
    
    /// Detect ARM64 microarchitecture
    fn detect_microarchitecture() -> BackendResult<ArmMicroarchitecture> {
        #[cfg(target_arch = "aarch64")]
        {
            // Check for Apple Silicon first
            if Self::is_apple_silicon() {
                return Ok(Self::detect_apple_microarch());
            }
            
            // For non-Apple ARM64, try to detect from /proc/cpuinfo
            #[cfg(target_os = "linux")]
            {
                if let Ok(cpuinfo) = std::fs::read_to_string("/proc/cpuinfo") {
                    return Ok(Self::parse_arm_cpuinfo(&cpuinfo));
                }
            }
        }
        
        Ok(ArmMicroarchitecture::Unknown)
    }
    
    /// Check if running on Apple Silicon
    #[cfg(target_arch = "aarch64")]
    fn is_apple_silicon() -> bool {
        #[cfg(target_os = "macos")]
        {
            use std::process::Command;
            if let Ok(output) = Command::new("sysctl")
                .arg("-n")
                .arg("machdep.cpu.brand_string")
                .output()
            {
                let brand = String::from_utf8_lossy(&output.stdout);
                return brand.contains("Apple");
            }
        }
        false
    }
    
    /// Detect specific Apple microarchitecture
    #[cfg(target_arch = "aarch64")]
    fn detect_apple_microarch() -> ArmMicroarchitecture {
        #[cfg(target_os = "macos")]
        {
            use std::process::Command;
            
            // Get CPU name
            if let Ok(output) = Command::new("sysctl")
                .arg("-n")
                .arg("machdep.cpu.brand_string")
                .output()
            {
                let brand = String::from_utf8_lossy(&output.stdout);
                if brand.contains("M1") {
                    return ArmMicroarchitecture::M1;
                } else if brand.contains("M2") {
                    return ArmMicroarchitecture::M2;
                } else if brand.contains("M3") {
                    return ArmMicroarchitecture::M3;
                }
            }
            
            // Try to detect by core count and features as fallback
            if let Ok(output) = Command::new("sysctl")
                .arg("-n")
                .arg("hw.ncpu")
                .output()
            {
                let core_count_str = String::from_utf8_lossy(&output.stdout);
                if let Ok(core_count) = core_count_str.trim().parse::<u32>() {
                    match core_count {
                        8 => ArmMicroarchitecture::M1, // 4P+4E
                        10 => ArmMicroarchitecture::M2, // 4P+4E with media engine
                        11..=16 => ArmMicroarchitecture::M3, // 6P+6E or 8P+4E
                        _ => ArmMicroarchitecture::M1, // Default to M1
                    }
                } else {
                    ArmMicroarchitecture::M1
                }
            } else {
                ArmMicroarchitecture::M1
            }
        }
        
        #[cfg(not(target_os = "macos"))]
        ArmMicroarchitecture::Unknown
    }
    
    /// Parse ARM CPU info from /proc/cpuinfo
    #[cfg(target_os = "linux")]
    fn parse_arm_cpuinfo(cpuinfo: &str) -> ArmMicroarchitecture {
        for line in cpuinfo.lines() {
            if line.starts_with("CPU part") {
                if let Some(part) = line.split(':').nth(1) {
                    let part = part.trim();
                    match part {
                        "0xd03" => return ArmMicroarchitecture::CortexA53,
                        "0xd05" => return ArmMicroarchitecture::CortexA55,
                        "0xd07" => return ArmMicroarchitecture::CortexA57,
                        "0xd08" => return ArmMicroarchitecture::CortexA72,
                        "0xd09" => return ArmMicroarchitecture::CortexA73,
                        "0xd0a" => return ArmMicroarchitecture::CortexA75,
                        "0xd0b" => return ArmMicroarchitecture::CortexA76,
                        "0xd0c" => return ArmMicroarchitecture::CortexA77,
                        "0xd0d" => return ArmMicroarchitecture::CortexA78,
                        "0xd44" => return ArmMicroarchitecture::CortexX1,
                        "0xd46" => return ArmMicroarchitecture::CortexA510,
                        "0xd47" => return ArmMicroarchitecture::CortexA710,
                        "0xd48" => return ArmMicroarchitecture::CortexX2,
                        _ => {}
                    }
                }
            }
        }
        ArmMicroarchitecture::Unknown
    }
    
    /// Detect CPU features
    fn detect_cpu_features() -> BackendResult<CpuFeatures> {
        let mut features = CpuFeatures::default();
        
        #[cfg(target_arch = "aarch64")]
        {
            features.neon = true; // NEON is mandatory on ARM64
            features.fp = true;   // FP is mandatory on ARM64
            features.asimd = true; // Advanced SIMD is mandatory
            
            // Detect additional features
            #[cfg(target_os = "linux")]
            {
                if let Ok(cpuinfo) = std::fs::read_to_string("/proc/cpuinfo") {
                    Self::parse_arm_features(&mut features, &cpuinfo);
                }
            }
            
            #[cfg(target_os = "macos")]
            {
                Self::detect_macos_arm_features(&mut features);
            }
        }
        
        Ok(features)
    }
    
    /// Parse ARM features from /proc/cpuinfo
    #[cfg(target_os = "linux")]
    fn parse_arm_features(features: &mut CpuFeatures, cpuinfo: &str) {
        for line in cpuinfo.lines() {
            if line.starts_with("Features") {
                if let Some(feature_list) = line.split(':').nth(1) {
                    for feature in feature_list.split_whitespace() {
                        match feature {
                            "aes" => features.aes_arm = true,
                            "pmull" => features.pmull = true,
                            "sha1" => features.sha1 = true,
                            "sha2" => features.sha256 = true,
                            "crc32" => features.crc32 = true,
                            "atomics" => features.atomics = true,
                            "fphp" => features.fphp = true,
                            "asimdhp" => features.asimdhp = true,
                            "cpuid" => features.cpuid = true,
                            "asimdrdm" => features.asimdrdm = true,
                            "jscvt" => features.jscvt = true,
                            "fcma" => features.fcma = true,
                            "lrcpc" => features.lrcpc = true,
                            "dcpop" => features.dcpop = true,
                            "sha3" => features.sha3 = true,
                            "sm3" => features.sm3 = true,
                            "sm4" => features.sm4 = true,
                            "asimddp" => features.asimddp = true,
                            "sha512" => features.sha512 = true,
                            "sve" => features.sve = true,
                            "sve2" => features.sve2 = true,
                            "sveaes" => features.sveaes = true,
                            "svepmull" => features.svepmull = true,
                            "svebitperm" => features.svebitperm = true,
                            "svesha3" => features.svesha3 = true,
                            "svesm4" => features.svesm4 = true,
                            "flagm" => features.flagm = true,
                            "ssbs" => features.ssbs = true,
                            "sb" => features.sb = true,
                            "paca" => features.paca = true,
                            "pacg" => features.pacg = true,
                            "dgh" => features.dgh = true,
                            "bf16" => features.bf16 = true,
                            "i8mm" => features.i8mm = true,
                            "rng" => features.rng = true,
                            "bti" => features.bti = true,
                            "mte" => features.mte = true,
                            _ => {}
                        }
                    }
                }
            }
        }
    }
    
    /// Detect macOS ARM features
    #[cfg(target_os = "macos")]
    fn detect_macos_arm_features(features: &mut CpuFeatures) {
        use std::process::Command;
        
        // Apple Silicon features that are typically available
        features.aes_arm = true;
        features.pmull = true;
        features.sha1 = true;
        features.sha256 = true;
        features.crc32 = true;
        features.atomics = true;
        features.fphp = true;
        features.asimdhp = true;
        features.asimdrdm = true;
        features.jscvt = true;
        features.fcma = true;
        features.lrcpc = true;
        features.dcpop = true;
        features.sha3 = true;
        features.asimddp = true;
        features.sha512 = true;
        features.flagm = true;
        features.ssbs = true;
        features.sb = true;
        features.dgh = true;
        
        // Check for specific Apple features
        if let Ok(output) = Command::new("sysctl")
            .arg("-n")
            .arg("machdep.cpu.brand_string")
            .output()
        {
            let brand = String::from_utf8_lossy(&output.stdout);
            if brand.contains("M2") || brand.contains("M3") {
                features.bf16 = true;
                features.i8mm = true;
            }
        }
    }
    
    /// Get optimization parameters for specific microarchitecture
    fn get_optimization_parameters(microarch: &ArmMicroarchitecture, features: &CpuFeatures) -> ARM64OptimizationParameters {
        let (loop_unroll, vector_width, sve_length, memory_bw, sched_window, branch_acc) = match microarch {
            ArmMicroarchitecture::M1 => {
                (8, 128, None, 0.95, 256, 0.98) // M1 has excellent branch prediction and high memory BW
            }
            ArmMicroarchitecture::M2 => {
                (12, 128, None, 0.96, 288, 0.985) // M2 improvements
            }
            ArmMicroarchitecture::M3 => {
                (16, 128, None, 0.97, 320, 0.99) // M3 further improvements
            }
            ArmMicroarchitecture::CortexA78 | ArmMicroarchitecture::CortexX1 => {
                (8, 128, if features.sve { Some(256) } else { None }, 0.88, 224, 0.95)
            }
            ArmMicroarchitecture::CortexA710 | ArmMicroarchitecture::CortexX2 => {
                (12, 128, if features.sve { Some(512) } else { None }, 0.90, 256, 0.96)
            }
            ArmMicroarchitecture::NeoverseV1 => {
                (16, 128, Some(2048), 0.92, 288, 0.97) // Server-class with large SVE
            }
            _ => (4, 128, None, 0.85, 192, 0.93),
        };
        
        let cache_blocking = match microarch {
            ArmMicroarchitecture::M1 | ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3 => {
                ARM64CacheBlockingFactors {
                    l1_block_size: 48 * 1024,  // 64KB L1D on Apple Silicon
                    l2_block_size: 3 * 1024 * 1024, // 4MB L2 per core
                    l3_block_size: 0, // No traditional L3
                    tlb_block_size: 16 * 1024 * 1024, // 16MB pages supported
                    system_cache_block_size: Some(24 * 1024 * 1024), // 32MB system cache
                }
            }
            ArmMicroarchitecture::CortexA78..=ArmMicroarchitecture::CortexX3 => {
                ARM64CacheBlockingFactors {
                    l1_block_size: 48 * 1024,  // 64KB L1D
                    l2_block_size: 384 * 1024, // 512KB L2
                    l3_block_size: 2 * 1024 * 1024, // 2-4MB L3
                    tlb_block_size: 2 * 1024 * 1024,
                    system_cache_block_size: None,
                }
            }
            ArmMicroarchitecture::NeoverseV1 | ArmMicroarchitecture::NeoverseN1 | ArmMicroarchitecture::NeoverseN2 => {
                ARM64CacheBlockingFactors {
                    l1_block_size: 48 * 1024,  // 64KB L1D
                    l2_block_size: 768 * 1024, // 1MB L2
                    l3_block_size: 16 * 1024 * 1024, // Large L3 for server
                    tlb_block_size: 2 * 1024 * 1024,
                    system_cache_block_size: None,
                }
            }
            _ => {
                ARM64CacheBlockingFactors {
                    l1_block_size: 24 * 1024,
                    l2_block_size: 192 * 1024,
                    l3_block_size: 1024 * 1024,
                    tlb_block_size: 2 * 1024 * 1024,
                    system_cache_block_size: None,
                }
            }
        };
        
        let (perf_cores, eff_cores) = match microarch {
            ArmMicroarchitecture::M1 => (4, 4),
            ArmMicroarchitecture::M2 => (4, 4),
            ArmMicroarchitecture::M3 => (6, 6), // M3 Pro/Max can have more
            _ => {
                let total_cores = num_cpus::get();
                (total_cores, 0) // Most ARM64 systems don't have E-cores
            }
        };
        
        let parallel_params = ARM64ParallelExecutionParams {
            optimal_thread_count: perf_cores + eff_cores,
            performance_core_count: perf_cores,
            efficiency_core_count: eff_cores,
            work_stealing_threshold: 1000,
            chunk_size_multiplier: 1.2, // ARM64 tends to benefit from larger chunks
            load_balancing_strategy: if eff_cores > 0 {
                ARM64LoadBalancingStrategy::PerformancePreferred
            } else {
                ARM64LoadBalancingStrategy::Uniform
            },
        };
        
        let apple_silicon_params = if matches!(microarch, ArmMicroarchitecture::M1 | ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3) {
            Some(AppleSiliconOptimizationParams {
                prefer_neural_engine_threshold: 10000,
                use_media_engine_for_conv: true,
                optimize_for_unified_memory: true,
                thermal_throttling_mitigation: true,
                power_efficiency_mode: PowerEfficiencyMode::Balanced,
            })
        } else {
            None
        };
        
        ARM64OptimizationParameters {
            loop_unroll_factor: loop_unroll,
            preferred_vector_width: vector_width,
            sve_vector_length: sve_length,
            max_memory_bandwidth_utilization: memory_bw,
            scheduling_window_size: sched_window,
            branch_prediction_accuracy: branch_acc,
            cache_blocking_factors: cache_blocking,
            parallel_params,
            apple_silicon_params,
        }
    }
    
    /// Get vector unit configuration
    fn get_vector_unit_config(microarch: &ArmMicroarchitecture, features: &CpuFeatures) -> ARM64VectorUnitConfig {
        match microarch {
            ArmMicroarchitecture::M1 | ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3 => {
                ARM64VectorUnitConfig {
                    neon_available: true,
                    sve_available: false, // Apple Silicon doesn't support SVE
                    sve2_available: false,
                    neon_register_count: 32,
                    sve_register_count: 0,
                    vector_lane_width: 128,
                    optimal_vector_size: 128,
                    crypto_available: true,
                    fp16_available: true,
                    bf16_available: matches!(microarch, ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3),
                    i8mm_available: matches!(microarch, ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3),
                    matrix_multiply_available: false, // Not yet available
                }
            }
            ArmMicroarchitecture::CortexA78..=ArmMicroarchitecture::CortexX3 => {
                ARM64VectorUnitConfig {
                    neon_available: true,
                    sve_available: features.sve,
                    sve2_available: features.sve2,
                    neon_register_count: 32,
                    sve_register_count: if features.sve { 32 } else { 0 },
                    vector_lane_width: 128,
                    optimal_vector_size: if features.sve { 256 } else { 128 },
                    crypto_available: features.aes_arm && features.sha256,
                    fp16_available: features.fphp,
                    bf16_available: features.bf16,
                    i8mm_available: features.i8mm,
                    matrix_multiply_available: false,
                }
            }
            ArmMicroarchitecture::NeoverseV1 | ArmMicroarchitecture::NeoverseN2 => {
                ARM64VectorUnitConfig {
                    neon_available: true,
                    sve_available: true,
                    sve2_available: features.sve2,
                    neon_register_count: 32,
                    sve_register_count: 32,
                    vector_lane_width: 128,
                    optimal_vector_size: 512, // Neoverse supports wider SVE
                    crypto_available: true,
                    fp16_available: true,
                    bf16_available: features.bf16,
                    i8mm_available: features.i8mm,
                    matrix_multiply_available: false,
                }
            }
            _ => {
                ARM64VectorUnitConfig {
                    neon_available: true,
                    sve_available: features.sve,
                    sve2_available: features.sve2,
                    neon_register_count: 32,
                    sve_register_count: if features.sve { 32 } else { 0 },
                    vector_lane_width: 128,
                    optimal_vector_size: 128,
                    crypto_available: features.aes_arm,
                    fp16_available: features.fphp,
                    bf16_available: features.bf16,
                    i8mm_available: features.i8mm,
                    matrix_multiply_available: false,
                }
            }
        }
    }
    
    /// Detect cache configuration
    fn detect_cache_configuration(microarch: &ArmMicroarchitecture) -> BackendResult<ARM64CacheConfiguration> {
        let config = match microarch {
            ArmMicroarchitecture::M1 => {
                ARM64CacheConfiguration {
                    l1i_size: 128 * 1024,
                    l1d_size: 64 * 1024,
                    l2_size: 4 * 1024 * 1024,
                    l3_size: None,
                    system_cache_size: Some(32 * 1024 * 1024),
                    l1_associativity: 8,
                    l2_associativity: 12,
                    l3_associativity: None,
                    cache_line_size: 64,
                    tlb_entries: 128,
                    prefetch_distance: 256,
                    cache_coherency_level: CacheCoherencyLevel::SystemCache,
                }
            }
            ArmMicroarchitecture::M2 => {
                ARM64CacheConfiguration {
                    l1i_size: 128 * 1024,
                    l1d_size: 64 * 1024,
                    l2_size: 4 * 1024 * 1024,
                    l3_size: None,
                    system_cache_size: Some(32 * 1024 * 1024),
                    l1_associativity: 8,
                    l2_associativity: 12,
                    l3_associativity: None,
                    cache_line_size: 64,
                    tlb_entries: 128,
                    prefetch_distance: 384,
                    cache_coherency_level: CacheCoherencyLevel::SystemCache,
                }
            }
            ArmMicroarchitecture::M3 => {
                ARM64CacheConfiguration {
                    l1i_size: 128 * 1024,
                    l1d_size: 64 * 1024,
                    l2_size: 6 * 1024 * 1024, // Larger L2 on M3
                    l3_size: None,
                    system_cache_size: Some(48 * 1024 * 1024),
                    l1_associativity: 8,
                    l2_associativity: 12,
                    l3_associativity: None,
                    cache_line_size: 64,
                    tlb_entries: 256,
                    prefetch_distance: 512,
                    cache_coherency_level: CacheCoherencyLevel::SystemCache,
                }
            }
            ArmMicroarchitecture::CortexA78 | ArmMicroarchitecture::CortexX1 => {
                ARM64CacheConfiguration {
                    l1i_size: 64 * 1024,
                    l1d_size: 64 * 1024,
                    l2_size: 512 * 1024,
                    l3_size: Some(2 * 1024 * 1024),
                    system_cache_size: None,
                    l1_associativity: 4,
                    l2_associativity: 8,
                    l3_associativity: Some(16),
                    cache_line_size: 64,
                    tlb_entries: 64,
                    prefetch_distance: 128,
                    cache_coherency_level: CacheCoherencyLevel::PoC,
                }
            }
            ArmMicroarchitecture::NeoverseV1 => {
                ARM64CacheConfiguration {
                    l1i_size: 64 * 1024,
                    l1d_size: 64 * 1024,
                    l2_size: 1024 * 1024,
                    l3_size: Some(32 * 1024 * 1024), // Large L3 for server
                    system_cache_size: None,
                    l1_associativity: 4,
                    l2_associativity: 8,
                    l3_associativity: Some(16),
                    cache_line_size: 64,
                    tlb_entries: 128,
                    prefetch_distance: 256,
                    cache_coherency_level: CacheCoherencyLevel::PoC,
                }
            }
            _ => {
                ARM64CacheConfiguration {
                    l1i_size: 32 * 1024,
                    l1d_size: 32 * 1024,
                    l2_size: 256 * 1024,
                    l3_size: Some(1024 * 1024),
                    system_cache_size: None,
                    l1_associativity: 4,
                    l2_associativity: 8,
                    l3_associativity: Some(8),
                    cache_line_size: 64,
                    tlb_entries: 64,
                    prefetch_distance: 64,
                    cache_coherency_level: CacheCoherencyLevel::PoC,
                }
            }
        };
        
        Ok(config)
    }
    
    /// Detect Apple Silicon specific configuration
    fn detect_apple_silicon_config(microarch: &ArmMicroarchitecture) -> Option<AppleSiliconConfig> {
        match microarch {
            ArmMicroarchitecture::M1 => {
                Some(AppleSiliconConfig {
                    neural_engine_available: true,
                    neural_engine_ops_per_second: 11.5e12, // 11.5 TOPS
                    media_engine_available: true,
                    accelerated_ml_compute: true,
                    unified_memory_bandwidth: 68.25, // GB/s
                    performance_controller_available: true,
                    thermal_management_advanced: true,
                    memory_compression_available: true,
                    secure_enclave_available: true,
                    system_cache_size: 32 * 1024 * 1024,
                })
            }
            ArmMicroarchitecture::M2 => {
                Some(AppleSiliconConfig {
                    neural_engine_available: true,
                    neural_engine_ops_per_second: 15.8e12, // 15.8 TOPS
                    media_engine_available: true,
                    accelerated_ml_compute: true,
                    unified_memory_bandwidth: 100.0, // GB/s
                    performance_controller_available: true,
                    thermal_management_advanced: true,
                    memory_compression_available: true,
                    secure_enclave_available: true,
                    system_cache_size: 32 * 1024 * 1024,
                })
            }
            ArmMicroarchitecture::M3 => {
                Some(AppleSiliconConfig {
                    neural_engine_available: true,
                    neural_engine_ops_per_second: 18.0e12, // 18 TOPS
                    media_engine_available: true,
                    accelerated_ml_compute: true,
                    unified_memory_bandwidth: 150.0, // GB/s (Pro/Max)
                    performance_controller_available: true,
                    thermal_management_advanced: true,
                    memory_compression_available: true,
                    secure_enclave_available: true,
                    system_cache_size: 48 * 1024 * 1024,
                })
            }
            _ => None,
        }
    }
    
    /// Get execution unit information
    fn get_execution_unit_info(microarch: &ArmMicroarchitecture) -> ARM64ExecutionUnitInfo {
        match microarch {
            ArmMicroarchitecture::M1 => {
                ARM64ExecutionUnitInfo {
                    integer_units: 6,
                    fp_units: 4,
                    neon_units: 4,
                    sve_units: 0,
                    load_units: 3,
                    store_units: 2,
                    branch_units: 2,
                    crypto_units: 2,
                    issue_width: 8,
                    retire_width: 8,
                    out_of_order_window: 630, // Very large OoO window
                }
            }
            ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3 => {
                ARM64ExecutionUnitInfo {
                    integer_units: 6,
                    fp_units: 4,
                    neon_units: 4,
                    sve_units: 0,
                    load_units: 3,
                    store_units: 2,
                    branch_units: 2,
                    crypto_units: 2,
                    issue_width: 8,
                    retire_width: 8,
                    out_of_order_window: 700, // Even larger on newer chips
                }
            }
            ArmMicroarchitecture::CortexA78 | ArmMicroarchitecture::CortexX1 => {
                ARM64ExecutionUnitInfo {
                    integer_units: 4,
                    fp_units: 2,
                    neon_units: 2,
                    sve_units: 1,
                    load_units: 2,
                    store_units: 1,
                    branch_units: 1,
                    crypto_units: 1,
                    issue_width: 4,
                    retire_width: 4,
                    out_of_order_window: 288,
                }
            }
            ArmMicroarchitecture::NeoverseV1 => {
                ARM64ExecutionUnitInfo {
                    integer_units: 8,
                    fp_units: 4,
                    neon_units: 2,
                    sve_units: 4, // Multiple SVE units for server workloads
                    load_units: 3,
                    store_units: 2,
                    branch_units: 2,
                    crypto_units: 2,
                    issue_width: 8,
                    retire_width: 8,
                    out_of_order_window: 288,
                }
            }
            _ => {
                ARM64ExecutionUnitInfo {
                    integer_units: 2,
                    fp_units: 2,
                    neon_units: 1,
                    sve_units: 0,
                    load_units: 1,
                    store_units: 1,
                    branch_units: 1,
                    crypto_units: 0,
                    issue_width: 2,
                    retire_width: 2,
                    out_of_order_window: 128,
                }
            }
        }
    }
    
    /// Get optimal parameters for matrix multiplication
    pub fn get_matmul_params(&self, m: usize, n: usize, k: usize) -> ARM64MatmulParams {
        let vector_width = self.vector_unit_config.optimal_vector_size / 32; // 32-bit elements
        let cache_blocking = &self.optimization_params.cache_blocking_factors;
        
        // Apple Silicon specific optimizations
        let (block_m, block_n, block_k) = if matches!(self.microarch, ArmMicroarchitecture::M1 | ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3) {
            // Apple Silicon has large caches and high memory bandwidth
            let use_large_blocks = m * n * k > 1_000_000;
            if use_large_blocks {
                (
                    (cache_blocking.l1_block_size / (k * 4)).min(512).max(64),
                    (cache_blocking.l2_block_size / (m * 4)).min(1024).max(128),
                    (cache_blocking.system_cache_block_size.unwrap_or(0) / (m * n * 4)).min(2048).max(256),
                )
            } else {
                (
                    (cache_blocking.l1_block_size / (k * 4)).min(256).max(32),
                    (cache_blocking.l2_block_size / (m * 4)).min(512).max(64),
                    (cache_blocking.system_cache_block_size.unwrap_or(0) / (m * n * 4)).min(1024).max(128),
                )
            }
        } else {
            // Standard ARM64 blocking
            (
                (cache_blocking.l1_block_size / (k * 4)).min(128).max(16),
                (cache_blocking.l2_block_size / (m * 4)).min(256).max(32),
                (cache_blocking.l3_block_size / (m * n * 4)).min(512).max(64),
            )
        };
        
        ARM64MatmulParams {
            block_m,
            block_n,
            block_k,
            vector_width,
            unroll_factor: self.optimization_params.loop_unroll_factor,
            use_neon: self.vector_unit_config.neon_available,
            use_sve: self.vector_unit_config.sve_available && m * n * k > 10000,
            use_fp16: self.vector_unit_config.fp16_available,
            use_bf16: self.vector_unit_config.bf16_available,
            use_i8mm: self.vector_unit_config.i8mm_available,
            prefer_neural_engine: self.should_use_neural_engine(m * n * k),
        }
    }
    
    /// Get optimal parameters for convolution
    pub fn get_conv_params(&self, batch: usize, channels: usize, height: usize, width: usize) -> ARM64ConvParams {
        let total_elements = batch * channels * height * width;
        let vector_width = self.vector_unit_config.optimal_vector_size / 32;
        
        let (tile_h, tile_w, unroll_channels) = match self.microarch {
            ArmMicroarchitecture::M1 | ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3 => {
                // Apple Silicon optimizations
                if total_elements > 2_000_000 {
                    (32, 32, 16) // Large tiles for big images
                } else {
                    (16, 16, 8)
                }
            }
            ArmMicroarchitecture::NeoverseV1 | ArmMicroarchitecture::NeoverseN2 => {
                // Server ARM optimizations
                if total_elements > 1_000_000 {
                    (24, 24, 16)
                } else {
                    (12, 12, 8)
                }
            }
            _ => {
                if total_elements > 500_000 {
                    (16, 16, 8)
                } else {
                    (8, 8, 4)
                }
            }
        };
        
        ARM64ConvParams {
            tile_height: tile_h,
            tile_width: tile_w,
            channel_unroll: unroll_channels,
            vector_width,
            use_neon: self.vector_unit_config.neon_available,
            use_sve: self.vector_unit_config.sve_available,
            use_fp16: self.vector_unit_config.fp16_available && total_elements > 100_000,
            use_winograd: height >= 3 && width >= 3 && total_elements > 50_000,
            prefer_media_engine: self.should_use_media_engine(total_elements),
        }
    }
    
    /// Check if Neural Engine should be used
    fn should_use_neural_engine(&self, element_count: usize) -> bool {
        if let Some(apple_config) = &self.apple_silicon_config {
            if let Some(apple_params) = &self.optimization_params.apple_silicon_params {
                return apple_config.neural_engine_available && 
                       element_count >= apple_params.prefer_neural_engine_threshold;
            }
        }
        false
    }
    
    /// Check if Media Engine should be used
    fn should_use_media_engine(&self, element_count: usize) -> bool {
        if let Some(apple_config) = &self.apple_silicon_config {
            if let Some(apple_params) = &self.optimization_params.apple_silicon_params {
                return apple_config.media_engine_available && 
                       apple_params.use_media_engine_for_conv &&
                       element_count > 100_000;
            }
        }
        false
    }
    
    /// Get microarchitecture information
    pub fn get_microarch_info(&self) -> ARM64MicroarchInfo {
        ARM64MicroarchInfo {
            name: format!("{:?}", self.microarch),
            vendor: if matches!(self.microarch, ArmMicroarchitecture::M1 | ArmMicroarchitecture::M2 | ArmMicroarchitecture::M3) {
                "Apple".to_string()
            } else {
                "ARM".to_string()
            },
            features: self.features,
            optimization_params: self.optimization_params.clone(),
            cache_config: self.cache_config.clone(),
            apple_silicon_config: self.apple_silicon_config.clone(),
        }
    }
}

/// ARM64 matrix multiplication optimization parameters
#[derive(Debug, Clone)]
pub struct ARM64MatmulParams {
    pub block_m: usize,
    pub block_n: usize,
    pub block_k: usize,
    pub vector_width: usize,
    pub unroll_factor: usize,
    pub use_neon: bool,
    pub use_sve: bool,
    pub use_fp16: bool,
    pub use_bf16: bool,
    pub use_i8mm: bool,
    pub prefer_neural_engine: bool,
}

/// ARM64 convolution optimization parameters
#[derive(Debug, Clone)]
pub struct ARM64ConvParams {
    pub tile_height: usize,
    pub tile_width: usize,
    pub channel_unroll: usize,
    pub vector_width: usize,
    pub use_neon: bool,
    pub use_sve: bool,
    pub use_fp16: bool,
    pub use_winograd: bool,
    pub prefer_media_engine: bool,
}

/// ARM64 microarchitecture information
#[derive(Debug, Clone)]
pub struct ARM64MicroarchInfo {
    pub name: String,
    pub vendor: String,
    pub features: CpuFeatures,
    pub optimization_params: ARM64OptimizationParameters,
    pub cache_config: ARM64CacheConfiguration,
    pub apple_silicon_config: Option<AppleSiliconConfig>,
}

/// Global ARM64 optimizer instance
static GLOBAL_ARM64_OPTIMIZER: OnceLock<EnhancedARM64Optimizer> = OnceLock::new();

/// Get the global ARM64 optimizer instance
pub fn get_arm64_optimizer() -> &'static EnhancedARM64Optimizer {
    GLOBAL_ARM64_OPTIMIZER.get_or_init(|| {
        EnhancedARM64Optimizer::new().unwrap_or_else(|_| {
            // Fallback configuration
            EnhancedARM64Optimizer {
                microarch: ArmMicroarchitecture::Unknown,
                features: CpuFeatures::default(),
                optimization_params: ARM64OptimizationParameters {
                    loop_unroll_factor: 4,
                    preferred_vector_width: 128,
                    sve_vector_length: None,
                    max_memory_bandwidth_utilization: 0.8,
                    scheduling_window_size: 128,
                    branch_prediction_accuracy: 0.9,
                    cache_blocking_factors: ARM64CacheBlockingFactors {
                        l1_block_size: 24 * 1024,
                        l2_block_size: 192 * 1024,
                        l3_block_size: 1024 * 1024,
                        tlb_block_size: 2 * 1024 * 1024,
                        system_cache_block_size: None,
                    },
                    parallel_params: ARM64ParallelExecutionParams {
                        optimal_thread_count: num_cpus::get(),
                        performance_core_count: num_cpus::get(),
                        efficiency_core_count: 0,
                        work_stealing_threshold: 1000,
                        chunk_size_multiplier: 1.0,
                        load_balancing_strategy: ARM64LoadBalancingStrategy::Uniform,
                    },
                    apple_silicon_params: None,
                },
                vector_unit_config: ARM64VectorUnitConfig {
                    neon_available: true,
                    sve_available: false,
                    sve2_available: false,
                    neon_register_count: 32,
                    sve_register_count: 0,
                    vector_lane_width: 128,
                    optimal_vector_size: 128,
                    crypto_available: false,
                    fp16_available: false,
                    bf16_available: false,
                    i8mm_available: false,
                    matrix_multiply_available: false,
                },
                cache_config: ARM64CacheConfiguration {
                    l1i_size: 32 * 1024,
                    l1d_size: 32 * 1024,
                    l2_size: 256 * 1024,
                    l3_size: Some(1024 * 1024),
                    system_cache_size: None,
                    l1_associativity: 4,
                    l2_associativity: 8,
                    l3_associativity: Some(8),
                    cache_line_size: 64,
                    tlb_entries: 64,
                    prefetch_distance: 64,
                    cache_coherency_level: CacheCoherencyLevel::PoC,
                },
                apple_silicon_config: None,
                execution_units: ARM64ExecutionUnitInfo {
                    integer_units: 2,
                    fp_units: 2,
                    neon_units: 1,
                    sve_units: 0,
                    load_units: 1,
                    store_units: 1,
                    branch_units: 1,
                    crypto_units: 0,
                    issue_width: 2,
                    retire_width: 2,
                    out_of_order_window: 128,
                },
            }
        })
    })
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_arm64_optimizer_creation() {
        let optimizer = EnhancedARM64Optimizer::new();
        assert!(optimizer.is_ok());
    }
    
    #[test]
    fn test_arm64_feature_detection() {
        let features = EnhancedARM64Optimizer::detect_cpu_features();
        assert!(features.is_ok());
        
        // NEON should be available on all ARM64
        #[cfg(target_arch = "aarch64")]
        {
            let features = features.unwrap();
            assert!(features.neon);
            assert!(features.fp);
            assert!(features.asimd);
        }
    }
    
    #[test]
    fn test_arm64_matmul_params() {
        let optimizer = get_arm64_optimizer();
        let params = optimizer.get_matmul_params(128, 128, 128);
        
        assert!(params.block_m > 0);
        assert!(params.block_n > 0);
        assert!(params.block_k > 0);
        assert!(params.vector_width > 0);
        assert!(params.use_neon);
    }
    
    #[test]
    fn test_arm64_conv_params() {
        let optimizer = get_arm64_optimizer();
        let params = optimizer.get_conv_params(1, 32, 224, 224);
        
        assert!(params.tile_height > 0);
        assert!(params.tile_width > 0);
        assert!(params.channel_unroll > 0);
        assert!(params.vector_width > 0);
        assert!(params.use_neon);
    }
    
    #[test]
    fn test_arm64_microarch_info() {
        let optimizer = get_arm64_optimizer();
        let info = optimizer.get_microarch_info();
        
        assert!(!info.name.is_empty());
        assert!(!info.vendor.is_empty());
    }
    
    #[cfg(target_arch = "aarch64")]
    #[test]
    fn test_apple_silicon_detection() {
        // This test will only pass meaningful results on actual Apple Silicon
        let is_apple = EnhancedARM64Optimizer::is_apple_silicon();
        // Just ensure it doesn't crash
        assert!(is_apple || !is_apple);
    }
    
    #[test]
    fn test_cache_configuration() {
        let optimizer = get_arm64_optimizer();
        let cache = &optimizer.cache_config;
        
        assert!(cache.l1d_size > 0);
        assert!(cache.l2_size > 0);
        assert!(cache.cache_line_size > 0);
    }
}