//! Intelligent memory management system for FFT operations

use super::types::*;
use crate::error::FFTResult;
use std::collections::{HashMap, VecDeque};
use std::time::{Duration, Instant};

/// Intelligent memory management system
#[derive(Debug)]
#[allow(dead_code)]
pub struct IntelligentMemoryManager {
    /// Memory usage tracking
    pub(crate) memory_tracker: MemoryTracker,
    /// Cache management
    pub(crate) cache_manager: CacheManager,
    /// Memory allocation strategy
    pub allocation_strategy: MemoryAllocationStrategy,
    /// Garbage collection hints
    pub(crate) gc_hints: Vec<GarbageCollectionHint>,
}

/// Memory usage tracking
#[derive(Debug, Default)]
pub struct MemoryTracker {
    /// Current memory usage (bytes)
    pub current_usage: usize,
    /// Peak memory usage (bytes)
    pub peak_usage: usize,
    /// Memory usage history
    pub usage_history: VecDeque<MemoryUsageRecord>,
    /// Memory fragmentation estimate
    pub fragmentation_estimate: f64,
}

/// Memory usage record
#[derive(Debug, Clone)]
pub struct MemoryUsageRecord {
    /// Memory usage (bytes)
    pub usage: usize,
    /// Timestamp
    pub timestamp: Instant,
    /// Operation type that caused the usage
    pub operation: String,
}

/// Cache management system
#[derive(Debug)]
#[allow(dead_code)]
pub struct CacheManager {
    /// Cache hit ratio
    pub(crate) hit_ratio: f64,
    /// Cache size (bytes)
    pub(crate) cache_size: usize,
    /// Eviction policy
    pub(crate) eviction_policy: CacheEvictionPolicy,
    /// Cache access patterns
    pub(crate) access_patterns: HashMap<String, CacheAccessPattern>,
}

/// Cache eviction policy
#[derive(Debug, Clone)]
pub enum CacheEvictionPolicy {
    /// Least Recently Used
    LRU,
    /// Least Frequently Used
    LFU,
    /// Time-based expiration
    TimeBasedExpiration { ttl: Duration },
    /// Size-based eviction
    SizeBasedEviction { max_size: usize },
    /// Adaptive policy
    Adaptive,
}

/// Cache access pattern
#[derive(Debug, Clone)]
pub struct CacheAccessPattern {
    /// Access frequency
    pub frequency: f64,
    /// Last access time
    pub last_access: Instant,
    /// Access recency score
    pub recency_score: f64,
    /// Temporal locality score
    pub temporal_locality: f64,
}

/// Garbage collection hint
#[derive(Debug, Clone)]
pub struct GarbageCollectionHint {
    /// Priority level (1-10)
    pub priority: u8,
    /// Memory region to collect
    pub region: String,
    /// Expected memory savings
    pub expected_savings: usize,
}

impl IntelligentMemoryManager {
    pub fn new() -> FFTResult<Self> {
        Ok(Self {
            memory_tracker: MemoryTracker::default(),
            cache_manager: CacheManager::new()?,
            allocation_strategy: MemoryAllocationStrategy::Adaptive,
            gc_hints: Vec::new(),
        })
    }
}

impl CacheManager {
    pub fn new() -> FFTResult<Self> {
        Ok(Self {
            hit_ratio: 0.0,
            cache_size: 0,
            eviction_policy: CacheEvictionPolicy::Adaptive,
            access_patterns: HashMap::new(),
        })
    }
}
