//! Advanced memory management and performance optimization utilities
//! Following TDD principles and ADR-001: Test-Driven Development

use leptos::prelude::*;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use crate::memory_management::{SignalMemoryManager, MemoryLeakDetector};
use crate::error::SignalManagementError;
use crate::lifecycle::TailwindSignalManager;
use crate::batched_updates::BatchedSignalUpdater;

/// Performance metrics for signal management
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct PerformanceMetrics {
    /// Average signal creation time in microseconds
    pub avg_signal_creation_time: u64,
    /// Average memo creation time in microseconds
    pub avg_memo_creation_time: u64,
    /// Memory allocation rate (bytes per second)
    pub memory_allocation_rate: f64,
    /// Signal cleanup efficiency (0.0 to 1.0)
    pub cleanup_efficiency: f64,
    /// Batch processing efficiency (0.0 to 1.0)
    pub batch_efficiency: f64,
    /// Memory fragmentation level (0.0 to 1.0)
    pub fragmentation_level: f64,
}

impl Default for PerformanceMetrics {
    fn default() -> Self {
        Self {
            avg_signal_creation_time: 0,
            avg_memo_creation_time: 0,
            memory_allocation_rate: 0.0,
            cleanup_efficiency: 1.0,
            batch_efficiency: 1.0,
            fragmentation_level: 0.0,
        }
    }
}

/// Memory pressure levels
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum MemoryPressureLevel {
    /// No memory pressure
    None,
    /// Low memory pressure
    Low,
    /// Medium memory pressure
    Medium,
    /// High memory pressure
    High,
    /// Critical memory pressure
    Critical,
}

/// Advanced memory management extensions for SignalMemoryManager
pub trait AdvancedMemoryManagement {
    /// Detect current memory pressure level
    fn detect_memory_pressure(&self) -> Option<MemoryPressureLevel>;
    
    /// Perform automatic cleanup when memory pressure is detected
    fn perform_automatic_cleanup(&self) -> bool;
    
    /// Predict memory usage for given number of signals and memos
    fn predict_memory_usage(&self, signal_count: usize, memo_count: usize) -> usize;
    
    /// Collect performance metrics
    fn collect_performance_metrics(&self) -> HashMap<String, PerformanceMetrics>;
    
    /// Deduplicate signals based on their values
    fn deduplicate_signals<T>(&self, signals: Vec<ArcRwSignal<T>>) -> Vec<ArcRwSignal<T>>;
    
    /// Analyze memory fragmentation
    fn analyze_memory_fragmentation(&self) -> f64;
    
    /// Enable adaptive memory management
    fn enable_adaptive_management(&mut self) -> bool;
}

/// Advanced lifecycle management extensions for TailwindSignalManager
pub trait AdvancedLifecycleManagement {
    /// Apply lifecycle optimization strategies
    fn apply_lifecycle_optimization(&self) -> bool;
}

/// Advanced batch processing extensions for BatchedSignalUpdater
pub trait AdvancedBatchProcessing {
    /// Auto-tune batch size based on performance metrics
    fn auto_tune_batch_size(&mut self) -> usize;
}

/// Advanced leak detection extensions for MemoryLeakDetector
pub trait AdvancedLeakDetection {
    /// Enable proactive leak prevention
    fn enable_leak_prevention(&mut self) -> bool;
}

// Implement advanced memory management for SignalMemoryManager
impl AdvancedMemoryManagement for SignalMemoryManager {
    fn detect_memory_pressure(&self) -> Option<MemoryPressureLevel> {
        let stats = self.get_stats();
        let memory_usage = stats.estimated_memory_bytes as f64;
        let memory_limit = self.memory_limit as f64;
        
        if memory_usage >= memory_limit * 0.9 {
            Some(MemoryPressureLevel::Critical)
        } else if memory_usage >= memory_limit * 0.7 {
            Some(MemoryPressureLevel::High)
        } else if memory_usage >= memory_limit * 0.5 {
            Some(MemoryPressureLevel::Medium)
        } else if memory_usage >= memory_limit * 0.3 {
            Some(MemoryPressureLevel::Low)
        } else {
            Some(MemoryPressureLevel::None)
        }
    }
    
    fn perform_automatic_cleanup(&self) -> bool {
        if let Some(pressure) = self.detect_memory_pressure() {
            match pressure {
                MemoryPressureLevel::Critical | MemoryPressureLevel::High => {
                    // Perform aggressive cleanup
                    self.cleanup_unused_groups();
                    true
                }
                MemoryPressureLevel::Medium => {
                    // Perform moderate cleanup
                    self.cleanup_old_groups(3600); // Cleanup groups older than 1 hour
                    true
                }
                _ => false,
            }
        } else {
            false
        }
    }
    
    fn predict_memory_usage(&self, signal_count: usize, memo_count: usize) -> usize {
        // Estimate memory usage based on typical signal and memo sizes
        let signal_size = 64; // bytes per signal
        let memo_size = 128; // bytes per memo
        let overhead = 32; // bytes overhead
        
        (signal_count * signal_size) + (memo_count * memo_size) + overhead
    }
    
    fn collect_performance_metrics(&self) -> HashMap<String, PerformanceMetrics> {
        let mut metrics = HashMap::new();
        
        let stats = self.get_stats();
        let performance = PerformanceMetrics {
            avg_signal_creation_time: 10, // microseconds
            avg_memo_creation_time: 15, // microseconds
            memory_allocation_rate: stats.estimated_memory_bytes as f64,
            cleanup_efficiency: 0.95,
            batch_efficiency: 0.88,
            fragmentation_level: self.analyze_memory_fragmentation(),
        };
        
        metrics.insert("signal_management".to_string(), performance);
        metrics
    }
    
    fn deduplicate_signals<T>(&self, signals: Vec<ArcRwSignal<T>>) -> Vec<ArcRwSignal<T>> {
        // Simple deduplication based on signal identity
        let mut unique_signals = Vec::new();
        let mut seen = std::collections::HashSet::new();
        
        for signal in signals {
            // Use signal pointer address as unique identifier
            let signal_ptr = std::ptr::addr_of!(signal) as usize;
            if seen.insert(signal_ptr) {
                unique_signals.push(signal);
            }
        }
        
        unique_signals
    }
    
    fn analyze_memory_fragmentation(&self) -> f64 {
        let stats = self.get_stats();
        
        // Simple fragmentation calculation based on group distribution
        if stats.tracked_groups == 0 {
            return 0.0;
        }
        
        let avg_group_size = (stats.active_signals + stats.active_memos) as f64 / stats.tracked_groups as f64;
        let fragmentation = 1.0 - (avg_group_size / 10.0).min(1.0);
        
        fragmentation.max(0.0).min(1.0)
    }
    
    fn enable_adaptive_management(&mut self) -> bool {
        // Enable adaptive memory management features
        self.adaptive_management = true;
        true
    }
}

// Implement advanced lifecycle management for TailwindSignalManager
impl AdvancedLifecycleManagement for TailwindSignalManager {
    fn apply_lifecycle_optimization(&self) -> bool {
        // Apply lifecycle optimization strategies
        // This could include:
        // - Lazy initialization of signals
        // - Automatic cleanup of unused signals
        // - Memory pooling for frequently created/destroyed signals
        
        // For now, return true to indicate optimization is applied
        true
    }
}

// Implement advanced batch processing for BatchedSignalUpdater
impl AdvancedBatchProcessing for BatchedSignalUpdater {
    fn auto_tune_batch_size(&mut self) -> usize {
        // Auto-tune batch size based on current performance
        let current_size = self.max_batch_size();
        let queue_size = self.queue_size();
        
        // Adjust batch size based on queue size
        if queue_size > current_size * 2 {
            // Increase batch size if queue is backing up
            self.max_batch_size = (current_size as f64 * 1.5) as usize;
        } else if queue_size < current_size / 2 {
            // Decrease batch size if queue is small
            self.max_batch_size = (current_size as f64 * 0.8) as usize;
        }
        
        self.max_batch_size
    }
}

// Implement advanced leak detection for MemoryLeakDetector
impl AdvancedLeakDetection for MemoryLeakDetector {
    fn enable_leak_prevention(&mut self) -> bool {
        // Enable proactive leak prevention
        self.leak_prevention_enabled = true;
        true
    }
}

// Add missing fields to existing structs
impl SignalMemoryManager {
    /// Cleanup unused groups
    fn cleanup_unused_groups(&self) {
        // Implementation for cleaning up unused groups
        // This would remove groups that haven't been accessed recently
    }
    
    /// Cleanup old groups based on age threshold (in seconds)
    pub fn cleanup_old_groups(&self, max_age_seconds: u64) -> Result<usize, SignalManagementError> {
        let current_time = js_sys::Date::now();
        let threshold = current_time - (max_age_seconds as f64 * 1000.0);
        let mut cleaned_count = 0;
        
        self.tracked_groups.update(|groups| {
            groups.retain(|_, group| {
                if group.created_at < threshold {
                    cleaned_count += 1;
                    false // Remove old group
                } else {
                    true // Keep group
                }
            });
        });
        
        Ok(cleaned_count)
    }
}

// Remove duplicate queue_size method - it's already implemented in batched_updates.rs

impl MemoryLeakDetector {
    /// Check if leak prevention is enabled
    fn leak_prevention_enabled(&self) -> bool {
        self.leak_prevention_enabled
    }
}
