//! LLVM compilation engine and related components

use crate::advanced_jit_compilation::config::JitCompilerConfig;
use crate::error::{CoreError, CoreResult};
#[cfg(feature = "serialization")]
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::time::{Duration, Instant};

/// LLVM compilation engine
#[derive(Debug)]
pub struct LlvmCompilationEngine {
    /// LLVM context
    #[allow(dead_code)]
    llvm_context: LlvmContext,
    /// Module registry
    #[allow(dead_code)]
    modules: HashMap<String, CompiledModule>,
    /// Target machine configuration
    #[allow(dead_code)]
    target_machine: TargetMachine,
    /// Optimization passes
    #[allow(dead_code)]
    optimization_passes: OptimizationPasses,
}

/// LLVM context wrapper
#[derive(Debug)]
pub struct LlvmContext {
    /// Context identifier
    pub context_id: String,
    /// Creation timestamp
    pub created_at: Instant,
    /// Active modules count
    pub active_modules: usize,
}

/// Compiled module representation
#[derive(Debug, Clone)]
pub struct CompiledModule {
    /// Module name
    pub name: String,
    /// Compiled machine code
    pub machinecode: Vec<u8>,
    /// Function pointers
    pub function_pointers: HashMap<String, usize>,
    /// Compilation metadata
    pub metadata: CompilationMetadata,
    /// Performance characteristics
    pub performance: ModulePerformance,
}

/// Compilation metadata
#[cfg_attr(feature = "serialization", derive(Serialize, Deserialize))]
#[derive(Debug, Clone)]
#[cfg_attr(feature = "serde", serde(default))]
pub struct CompilationMetadata {
    /// Source language
    pub source_language: String,
    /// Compilation timestamp
    #[cfg_attr(feature = "serde", serde(skip))]
    pub compiled_at: Instant,
    /// Optimization level used
    pub optimization_level: u8,
    /// Target architecture
    pub target_arch: String,
    /// Dependencies
    pub dependencies: Vec<String>,
    /// Source code hash
    pub source_hash: u64,
    /// Compiler version
    pub compiler_version: String,
}

impl Default for CompilationMetadata {
    fn default() -> Self {
        Self {
            source_language: "Rust".to_string(),
            compiled_at: Instant::now(),
            optimization_level: 2,
            target_arch: "x86_64".to_string(),
            dependencies: Vec::new(),
            source_hash: 0,
            compiler_version: "1.0.0".to_string(),
        }
    }
}

/// Module performance characteristics
#[derive(Debug, Clone)]
pub struct ModulePerformance {
    /// Average execution time
    pub avgexecution_time: Duration,
    /// Peak memory usage
    pub peak_memory_usage: usize,
    /// Instruction count
    pub instruction_count: u64,
    /// Cache miss rate
    pub cache_miss_rate: f64,
    /// Vectorization efficiency
    pub vectorization_efficiency: f64,
}

/// Target machine configuration
#[derive(Debug)]
pub struct TargetMachine {
    /// Target triple
    pub target_triple: String,
    /// CPU name
    pub cpu_name: String,
    /// Feature string
    pub features: String,
    /// Code model
    pub code_model: CodeModel,
    /// Relocation model
    pub relocation_model: RelocationModel,
}

/// Code generation models
#[derive(Debug, Clone)]
pub enum CodeModel {
    Small,
    Kernel,
    Medium,
    Large,
}

/// Relocation models
#[derive(Debug, Clone)]
pub enum RelocationModel {
    Static,
    PIC,
    DynamicNoPIC,
}

/// Optimization passes configuration
#[derive(Debug)]
pub struct OptimizationPasses {
    /// Function passes
    pub function_passes: Vec<FunctionPass>,
    /// Module passes
    pub module_passes: Vec<ModulePass>,
    /// Loop passes
    pub loop_passes: Vec<LoopPass>,
    /// Custom passes
    pub custom_passes: Vec<CustomPass>,
}

/// Function-level optimization passes
#[derive(Debug, Clone)]
pub enum FunctionPass {
    ConstantPropagation,
    DeadCodeElimination,
    CommonSubexpressionElimination,
    LoopInvariantCodeMotion,
    Inlining,
    Vectorization,
    MemoryOptimization,
}

/// Module-level optimization passes
#[derive(Debug, Clone)]
pub enum ModulePass {
    GlobalOptimization,
    InterproceduralOptimization,
    LinkTimeOptimization,
    WholeProgram,
}

/// Loop optimization passes
#[derive(Debug, Clone)]
pub enum LoopPass {
    LoopUnrolling,
    LoopVectorization,
    LoopPeeling,
    LoopRotation,
    LoopFusion,
    LoopDistribution,
}

/// Custom optimization passes
#[derive(Debug, Clone)]
pub struct CustomPass {
    /// Pass name
    pub name: String,
    /// Pass implementation
    pub implementation: String,
    /// Pass parameters
    pub parameters: HashMap<String, String>,
}

/// Compilation status
#[derive(Debug, Clone)]
pub enum CompilationStatus {
    Pending,
    InProgress,
    Success,
    Failed(String),
    Cached,
}

/// Code size metrics
#[derive(Debug, Clone)]
pub struct CodeSizeMetrics {
    /// Original code size
    pub original_size: usize,
    /// Optimized code size
    pub optimized_size: usize,
    /// Compression ratio
    pub compression_ratio: f64,
    /// Instruction count
    pub instruction_count: u64,
}

/// Compilation error information
#[derive(Debug, Clone)]
pub struct CompilationError {
    /// Error message
    pub message: String,
    /// Error location
    pub location: ErrorLocation,
    /// Error severity
    pub severity: ErrorSeverity,
    /// Suggested fix
    pub suggested_fix: Option<String>,
}

/// Error location
#[derive(Debug, Clone)]
pub struct ErrorLocation {
    /// File name
    pub file: String,
    /// Line number
    pub line: u32,
    /// Column number
    pub column: u32,
}

/// Error severity levels
#[derive(Debug, Clone)]
pub enum ErrorSeverity {
    Info,
    Warning,
    Error,
    Fatal,
}

impl LlvmCompilationEngine {
    pub fn new(config: &JitCompilerConfig) -> CoreResult<Self> {
        Ok(Self {
            llvm_context: LlvmContext {
                context_id: "advanced-llvm".to_string(),
                created_at: Instant::now(),
                active_modules: 0,
            },
            modules: HashMap::new(),
            target_machine: TargetMachine {
                target_triple: "native".to_string(),
                cpu_name: "native".to_string(),
                features: "+avx2,+fma".to_string(),
                code_model: CodeModel::Small,
                relocation_model: RelocationModel::PIC,
            },
            optimization_passes: OptimizationPasses {
                function_passes: vec![
                    FunctionPass::ConstantPropagation,
                    FunctionPass::DeadCodeElimination,
                    FunctionPass::Vectorization,
                ],
                module_passes: vec![ModulePass::GlobalOptimization],
                loop_passes: vec![LoopPass::LoopUnrolling, LoopPass::LoopVectorization],
                custom_passes: vec![],
            },
        })
    }

    pub fn compile(&self, name: &str, code: &str) -> CoreResult<CompiledModule> {
        // Simplified implementation
        Ok(CompiledModule {
            name: name.to_string(),
            machinecode: vec![0x90; 1024], // NOP instructions placeholder
            function_pointers: {
                let mut map = HashMap::new();
                map.insert("main".to_string(), 0x1000);
                map
            },
            metadata: CompilationMetadata {
                source_language: "llvm-ir".to_string(),
                compiled_at: Instant::now(),
                optimization_level: 3,
                target_arch: "x86_64".to_string(),
                dependencies: vec![],
                source_hash: 42,
                compiler_version: "LLVM 15.0".to_string(),
            },
            performance: ModulePerformance {
                avgexecution_time: Duration::from_micros(100),
                peak_memory_usage: 1024,
                instruction_count: 500,
                cache_miss_rate: 0.05,
                vectorization_efficiency: 0.8,
            },
        })
    }

    /// Compile a module with optimizations
    pub fn compile_module(&self, name: &str, modulesource: &str) -> CoreResult<CompiledModule> {
        // Simplified implementation - delegate to existing compile method
        self.compile(name, modulesource)
    }
}
