sklears-simd 0.1.1

//! FPGA (Field-Programmable Gate Array) acceleration support for SIMD operations
//!
//! This module provides FPGA interfaces for custom hardware acceleration of
//! machine learning operations with fallback to CPU SIMD implementations.

use crate::traits::SimdError;

#[cfg(feature = "no-std")]
use alloc::collections::BTreeMap as HashMap;
#[cfg(feature = "no-std")]
use alloc::{
    boxed::Box,
    format,
    string::{String, ToString},
    vec,
    vec::Vec,
};
#[cfg(not(feature = "no-std"))]
use std::collections::HashMap;

#[cfg(feature = "no-std")]
use core::{any::Any, cmp::Ordering, f32::consts::PI};
#[cfg(not(feature = "no-std"))]
use std::{any::Any, cmp::Ordering, f32::consts::PI};

/// FPGA vendor types
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FpgaVendor {
    Intel,
    Xilinx,
    Microsemi,
    Lattice,
    Altera,
}

/// FPGA device information
#[derive(Debug, Clone)]
pub struct FpgaDevice {
    pub id: u32,
    pub name: String,
    pub vendor: FpgaVendor,
    pub part_number: String,
    pub logic_elements: u32,
    pub memory_blocks: u32,
    pub dsp_blocks: u32,
    pub io_pins: u32,
    pub max_frequency_mhz: f64,
    pub power_consumption_w: f64,
}

/// FPGA bitstream configuration
#[derive(Debug, Clone)]
pub struct FpgaBitstream {
    pub name: String,
    pub version: String,
    pub target_device: String,
    pub functionality: Vec<FpgaFunction>,
    pub resource_usage: FpgaResourceUsage,
    pub bitstream_data: Vec<u8>,
}

/// FPGA function types
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FpgaFunction {
    MatrixMultiply,
    Convolution,
    FFT,
    FIR,
    Sorting,
    Reduction,
    Activation,
    Custom(u32),
}

/// FPGA resource usage
#[derive(Debug, Clone)]
pub struct FpgaResourceUsage {
    pub logic_elements: u32,
    pub memory_blocks: u32,
    pub dsp_blocks: u32,
    pub io_pins: u32,
    pub utilization_percent: f64,
}

/// FPGA memory buffer
#[derive(Debug)]
pub struct FpgaBuffer<T> {
    pub ptr: *mut T,
    pub size: usize,
    pub device: FpgaDevice,
    pub memory_type: FpgaMemoryType,
    #[allow(dead_code)] // Reserved for native FPGA buffer handle (Xilinx XRT / Intel OpenCL)
    backend_handle: Option<Box<dyn Any + Send + Sync>>,
}

/// FPGA memory types
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FpgaMemoryType {
    OnChip,
    DDR,
    HBM,
    BRAM,
    URAM,
}

unsafe impl<T: Send> Send for FpgaBuffer<T> {}
unsafe impl<T: Sync> Sync for FpgaBuffer<T> {}

impl<T> Drop for FpgaBuffer<T> {
    fn drop(&mut self) {
        // Free FPGA memory when buffer is dropped
    }
}

/// FPGA context for managing resources
pub struct FpgaContext {
    pub device: FpgaDevice,
    pub loaded_bitstreams: HashMap<String, FpgaBitstream>,
    pub active_functions: Vec<FpgaFunction>,
    #[allow(dead_code)] // Reserved for native FPGA context (Xilinx XRT / Intel OpenCL)
    backend_context: Option<Box<dyn Any + Send + Sync>>,
}

/// FPGA kernel configuration
#[derive(Debug, Clone)]
pub struct FpgaKernelConfig {
    pub function: FpgaFunction,
    pub input_buffers: Vec<u32>,
    pub output_buffers: Vec<u32>,
    pub parameters: HashMap<String, f64>,
    pub pipeline_depth: u32,
    pub parallelism_factor: u32,
}

impl Default for FpgaKernelConfig {
    fn default() -> Self {
        Self {
            function: FpgaFunction::MatrixMultiply,
            input_buffers: vec![0, 1],
            output_buffers: vec![2],
            parameters: HashMap::new(),
            pipeline_depth: 1,
            parallelism_factor: 1,
        }
    }
}

/// FPGA operations interface
pub trait FpgaOperations {
    /// Load bitstream to FPGA
    fn load_bitstream(&mut self, bitstream: &FpgaBitstream) -> Result<(), SimdError>;

    /// Allocate FPGA memory
    fn allocate<T>(
        &self,
        size: usize,
        memory_type: FpgaMemoryType,
    ) -> Result<FpgaBuffer<T>, SimdError>;

    /// Copy data from host to FPGA
    fn copy_to_fpga<T>(
        &self,
        host_data: &[T],
        fpga_buffer: &mut FpgaBuffer<T>,
    ) -> Result<(), SimdError>;

    /// Copy data from FPGA to host
    fn copy_to_host<T>(
        &self,
        fpga_buffer: &FpgaBuffer<T>,
        host_data: &mut [T],
    ) -> Result<(), SimdError>;

    /// Execute FPGA kernel
    fn execute_kernel(
        &self,
        config: &FpgaKernelConfig,
        buffers: &[&FpgaBuffer<u8>],
    ) -> Result<(), SimdError>;

    /// Query FPGA status
    fn get_status(&self) -> Result<FpgaStatus, SimdError>;

    /// Reset FPGA
    fn reset(&self) -> Result<(), SimdError>;
}

/// FPGA status information
#[derive(Debug, Clone)]
pub struct FpgaStatus {
    pub temperature_c: f64,
    pub power_consumption_w: f64,
    pub utilization_percent: f64,
    pub clock_frequency_mhz: f64,
    pub memory_usage_percent: f64,
    pub active_functions: Vec<FpgaFunction>,
}

/// FPGA runtime implementation
pub struct FpgaRuntime {
    devices: Vec<FpgaDevice>,
    contexts: Vec<FpgaContext>,
    bitstream_library: HashMap<String, FpgaBitstream>,
}

impl FpgaRuntime {
    /// Create new FPGA runtime
    pub fn new() -> Result<Self, SimdError> {
        let devices = Self::discover_devices()?;
        let contexts = Vec::new();
        let bitstream_library = Self::load_bitstream_library()?;

        Ok(Self {
            devices,
            contexts,
            bitstream_library,
        })
    }

    /// Discover available FPGA devices
    fn discover_devices() -> Result<Vec<FpgaDevice>, SimdError> {
        // In a real implementation, this would interface with FPGA drivers
        // For now, return empty list or simulated devices
        Ok(vec![])
    }

    /// Load bitstream library
    fn load_bitstream_library() -> Result<HashMap<String, FpgaBitstream>, SimdError> {
        let mut library = HashMap::new();

        // Add pre-built bitstreams for common operations
        library.insert(
            "matmul_f32".to_string(),
            FpgaBitstream {
                name: "Matrix Multiply F32".to_string(),
                version: "1.0.0".to_string(),
                target_device: "xcvu9p".to_string(),
                functionality: vec![FpgaFunction::MatrixMultiply],
                resource_usage: FpgaResourceUsage {
                    logic_elements: 50000,
                    memory_blocks: 100,
                    dsp_blocks: 200,
                    io_pins: 50,
                    utilization_percent: 45.0,
                },
                bitstream_data: vec![],
            },
        );

        library.insert(
            "conv2d_f32".to_string(),
            FpgaBitstream {
                name: "Convolution 2D F32".to_string(),
                version: "1.0.0".to_string(),
                target_device: "xcvu9p".to_string(),
                functionality: vec![FpgaFunction::Convolution],
                resource_usage: FpgaResourceUsage {
                    logic_elements: 75000,
                    memory_blocks: 150,
                    dsp_blocks: 300,
                    io_pins: 75,
                    utilization_percent: 67.0,
                },
                bitstream_data: vec![],
            },
        );

        Ok(library)
    }

    /// Get available FPGA devices
    pub fn devices(&self) -> &[FpgaDevice] {
        &self.devices
    }

    /// Get available bitstreams
    pub fn bitstreams(&self) -> &HashMap<String, FpgaBitstream> {
        &self.bitstream_library
    }

    /// Create context for FPGA device
    pub fn create_context(&mut self, device_id: u32) -> Result<&mut FpgaContext, SimdError> {
        let device = self
            .devices
            .get(device_id as usize)
            .ok_or_else(|| SimdError::InvalidArgument("Invalid FPGA device ID".to_string()))?;

        let context = FpgaContext {
            device: device.clone(),
            loaded_bitstreams: HashMap::new(),
            active_functions: Vec::new(),
            backend_context: None,
        };

        self.contexts.push(context);
        Ok(self.contexts.last_mut().expect("operation should succeed"))
    }

    /// Check if FPGA is available
    pub fn is_available() -> bool {
        // In a real implementation, this would check for FPGA drivers
        false
    }

    /// Get optimal bitstream for function
    pub fn get_optimal_bitstream(&self, function: FpgaFunction) -> Option<&FpgaBitstream> {
        self.bitstream_library
            .values()
            .find(|bs| bs.functionality.contains(&function))
    }
}

/// FPGA-optimized operations
pub mod ops {
    use super::*;

    /// FPGA matrix multiplication
    pub fn fpga_matmul(
        a: &[f32],
        b: &[f32],
        c: &mut [f32],
        m: usize,
        n: usize,
        k: usize,
        device: Option<&FpgaDevice>,
    ) -> Result<(), SimdError> {
        if device.is_none() {
            // Fallback to CPU SIMD - simple implementation
            return matrix_multiply_fallback(a, b, c, m, n, k);
        }

        // FPGA implementation would go here
        // For now, fall back to CPU SIMD
        matrix_multiply_fallback(a, b, c, m, n, k)
    }

    /// FPGA convolution
    pub fn fpga_conv2d(
        _input: &[f32],
        _kernel: &[f32],
        _output: &mut [f32],
        _input_shape: &[usize],
        _kernel_shape: &[usize],
        device: Option<&FpgaDevice>,
    ) -> Result<(), SimdError> {
        if device.is_none() {
            // Fallback to CPU SIMD
            return Err(SimdError::NotImplemented(
                "CPU conv2d not implemented".to_string(),
            ));
        }

        // FPGA implementation would go here
        Err(SimdError::NotImplemented(
            "FPGA conv2d not implemented".to_string(),
        ))
    }

    /// FPGA FFT
    pub fn fpga_fft(
        input: &[f32],
        output: &mut [f32],
        n: usize,
        device: Option<&FpgaDevice>,
    ) -> Result<(), SimdError> {
        if device.is_none() {
            // Fallback to CPU SIMD
            return fft_fallback(input, output, n);
        }

        // FPGA implementation would go here
        fft_fallback(input, output, n)
    }

    /// FPGA sorting
    pub fn fpga_sort(data: &mut [f32], device: Option<&FpgaDevice>) -> Result<(), SimdError> {
        if device.is_none() {
            // Fallback to CPU SIMD
            return quicksort_fallback(data);
        }

        // FPGA implementation would go here
        quicksort_fallback(data)
    }
}

/// FPGA design tools
pub mod design {
    use super::*;

    /// High-level synthesis parameters
    #[derive(Debug, Clone)]
    pub struct HlsConfig {
        pub target_frequency_mhz: f64,
        pub pipeline_depth: u32,
        pub unroll_factor: u32,
        pub data_width: u32,
        pub memory_partitioning: bool,
    }

    impl Default for HlsConfig {
        fn default() -> Self {
            Self {
                target_frequency_mhz: 200.0,
                pipeline_depth: 4,
                unroll_factor: 4,
                data_width: 32,
                memory_partitioning: true,
            }
        }
    }

    /// Generate FPGA design for operation
    pub fn generate_design(
        function: FpgaFunction,
        config: &HlsConfig,
    ) -> Result<String, SimdError> {
        match function {
            FpgaFunction::MatrixMultiply => generate_matmul_design(config),
            FpgaFunction::Convolution => generate_conv_design(config),
            FpgaFunction::FFT => generate_fft_design(config),
            FpgaFunction::FIR => generate_fir_design(config),
            FpgaFunction::Sorting => generate_sort_design(config),
            FpgaFunction::Reduction => generate_reduction_design(config),
            FpgaFunction::Activation => generate_activation_design(config),
            FpgaFunction::Custom(_) => Err(SimdError::NotImplemented(
                "Custom design generation not implemented".to_string(),
            )),
        }
    }

    fn generate_matmul_design(config: &HlsConfig) -> Result<String, SimdError> {
        let design = format!(
            "// Generated FPGA Matrix Multiply Design\n\
             // Target Frequency: {} MHz\n\
             // Pipeline Depth: {}\n\
             // Unroll Factor: {}\n\
             \n\
             module matmul_f32 (\n\
                 input wire clk,\n\
                 input wire rst,\n\
                 input wire [{}:0] a_data,\n\
                 input wire [{}:0] b_data,\n\
                 output reg [{}:0] c_data,\n\
                 input wire start,\n\
                 output reg done\n\
             );\n\
             \n\
             // Implementation would go here\n\
             \n\
             endmodule",
            config.target_frequency_mhz,
            config.pipeline_depth,
            config.unroll_factor,
            config.data_width - 1,
            config.data_width - 1,
            config.data_width - 1
        );

        Ok(design)
    }

    fn generate_conv_design(_config: &HlsConfig) -> Result<String, SimdError> {
        Ok("// Generated FPGA Convolution Design\n// Implementation would go here".to_string())
    }

    fn generate_fft_design(_config: &HlsConfig) -> Result<String, SimdError> {
        Ok("// Generated FPGA FFT Design\n// Implementation would go here".to_string())
    }

    fn generate_fir_design(_config: &HlsConfig) -> Result<String, SimdError> {
        Ok("// Generated FPGA FIR Design\n// Implementation would go here".to_string())
    }

    fn generate_sort_design(_config: &HlsConfig) -> Result<String, SimdError> {
        Ok("// Generated FPGA Sorting Design\n// Implementation would go here".to_string())
    }

    fn generate_reduction_design(_config: &HlsConfig) -> Result<String, SimdError> {
        Ok("// Generated FPGA Reduction Design\n// Implementation would go here".to_string())
    }

    fn generate_activation_design(_config: &HlsConfig) -> Result<String, SimdError> {
        Ok("// Generated FPGA Activation Design\n// Implementation would go here".to_string())
    }
}

/// Simple fallback implementations for missing functions
fn matrix_multiply_fallback(
    a: &[f32],
    b: &[f32],
    c: &mut [f32],
    m: usize,
    n: usize,
    k: usize,
) -> Result<(), SimdError> {
    if a.len() != m * k || b.len() != k * n || c.len() != m * n {
        return Err(SimdError::DimensionMismatch {
            expected: m * n,
            actual: c.len(),
        });
    }

    for i in 0..m {
        for j in 0..n {
            let mut sum = 0.0;
            for ki in 0..k {
                sum += a[i * k + ki] * b[ki * n + j];
            }
            c[i * n + j] = sum;
        }
    }
    Ok(())
}

fn fft_fallback(input: &[f32], output: &mut [f32], n: usize) -> Result<(), SimdError> {
    if input.len() != n || output.len() != n {
        return Err(SimdError::DimensionMismatch {
            expected: n,
            actual: input.len(),
        });
    }

    // Simple DFT fallback (not efficient but works)
    for (k, out_k) in output.iter_mut().enumerate() {
        let mut real_sum = 0.0f32;
        let mut imag_sum = 0.0f32;

        for (j, &inp) in input.iter().enumerate() {
            let angle = -2.0 * PI * (k * j) as f32 / n as f32;
            real_sum += inp * angle.cos();
            imag_sum += inp * angle.sin();
        }

        // For simplicity, just store the magnitude
        *out_k = (real_sum * real_sum + imag_sum * imag_sum).sqrt();
    }

    Ok(())
}

fn quicksort_fallback(data: &mut [f32]) -> Result<(), SimdError> {
    if data.is_empty() {
        return Ok(());
    }

    data.sort_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::Equal));
    Ok(())
}

#[allow(non_snake_case)]
#[cfg(all(test, not(feature = "no-std")))]
mod tests {
    use super::*;

    #[cfg(feature = "no-std")]
    use alloc::{
        boxed::Box,
        string::{String, ToString},
        vec,
        vec::Vec,
    };

    #[test]
    fn test_fpga_runtime_creation() {
        let runtime = FpgaRuntime::new();
        assert!(runtime.is_ok());
    }

    #[test]
    fn test_fpga_availability() {
        // FPGA should not be available in test environment
        assert!(!FpgaRuntime::is_available());
    }

    #[test]
    fn test_fpga_kernel_config_default() {
        let config = FpgaKernelConfig::default();
        assert_eq!(config.function, FpgaFunction::MatrixMultiply);
        assert_eq!(config.pipeline_depth, 1);
        assert_eq!(config.parallelism_factor, 1);
    }

    #[test]
    fn test_fpga_matmul_fallback() {
        let a = vec![1.0, 2.0, 3.0, 4.0];
        let b = vec![5.0, 6.0, 7.0, 8.0];
        let mut c = vec![0.0; 4];

        let result = ops::fpga_matmul(&a, &b, &mut c, 2, 2, 2, None);
        assert!(result.is_ok());
    }

    #[test]
    fn test_fpga_sort_fallback() {
        let mut data = vec![3.0, 1.0, 4.0, 1.0, 5.0];
        let result = ops::fpga_sort(&mut data, None);
        assert!(result.is_ok());
    }

    #[test]
    fn test_hls_config_default() {
        let config = design::HlsConfig::default();
        assert_eq!(config.target_frequency_mhz, 200.0);
        assert_eq!(config.pipeline_depth, 4);
        assert_eq!(config.unroll_factor, 4);
        assert!(config.memory_partitioning);
    }

    #[test]
    fn test_design_generation() {
        let config = design::HlsConfig::default();
        let design = design::generate_design(FpgaFunction::MatrixMultiply, &config);
        assert!(design.is_ok());

        let design_str = design.expect("operation should succeed");
        assert!(design_str.contains("module matmul_f32"));
        assert!(design_str.contains("200"));
    }

    #[test]
    fn test_bitstream_library() {
        let runtime = FpgaRuntime::new().expect("operation should succeed");
        let bitstreams = runtime.bitstreams();
        assert!(bitstreams.contains_key("matmul_f32"));
        assert!(bitstreams.contains_key("conv2d_f32"));
    }

    #[test]
    fn test_optimal_bitstream_selection() {
        let runtime = FpgaRuntime::new().expect("operation should succeed");
        let bitstream = runtime.get_optimal_bitstream(FpgaFunction::MatrixMultiply);
        assert!(bitstream.is_some());

        let bs = bitstream.expect("operation should succeed");
        assert!(bs.functionality.contains(&FpgaFunction::MatrixMultiply));
    }
}