package utils

import (
	"log"
	"runtime"
	"time"
)

// MemoryMonitor 内存监控器
type MemoryMonitor struct {
	maxHeapMB      uint64 // 最大堆内存阈值(MB)
	maxGoroutines  int    // 最大goroutine数量阈值
	checkInterval  time.Duration // 检查间隔
	running        bool   // 是否运行中
	stopChan       chan bool
}

// NewMemoryMonitor 创建新的内存监控器
func NewMemoryMonitor(maxHeapMB uint64, maxGoroutines int, checkInterval time.Duration) *MemoryMonitor {
	return &MemoryMonitor{
		maxHeapMB:     maxHeapMB,
		maxGoroutines: maxGoroutines,
		checkInterval: checkInterval,
		stopChan:      make(chan bool, 1),
	}
}

// Start 启动内存监控
func (mm *MemoryMonitor) Start() {
	if mm.running {
		return
	}
	
	mm.running = true
	go mm.monitor()
}

// Stop 停止内存监控
func (mm *MemoryMonitor) Stop() {
	if !mm.running {
		return
	}
	
	mm.running = false
	select {
	case mm.stopChan <- true:
	default:
	}
}

// monitor 监控循环
func (mm *MemoryMonitor) monitor() {
	ticker := time.NewTicker(mm.checkInterval)
	defer ticker.Stop()
	
	for {
		select {
		case <-ticker.C:
			mm.checkMemory()
		case <-mm.stopChan:
			return
		}
	}
}

// checkMemory 检查内存使用情况
func (mm *MemoryMonitor) checkMemory() {
	var m runtime.MemStats
	runtime.ReadMemStats(&m)
	
	heapMB := m.HeapInuse / 1024 / 1024
	goroutineCount := runtime.NumGoroutine()
	
	// 检查堆内存使用
	if heapMB > mm.maxHeapMB {
		log.Printf("[WARN] 内存使用警告: 堆内存使用过高 %d MB (阈值: %d MB)", heapMB, mm.maxHeapMB)
		
		// 尝试触发GC
		runtime.GC()
		
		// 再次检查
		runtime.ReadMemStats(&m)
		heapMBAfterGC := m.HeapInuse / 1024 / 1024
		log.Printf("[INFO] GC后堆内存: %d MB", heapMBAfterGC)
	}
	
	// 检查goroutine数量
	if goroutineCount > mm.maxGoroutines {
		log.Printf("[WARN] Goroutine数量警告: 当前数量 %d (阈值: %d)", goroutineCount, mm.maxGoroutines)
	}
}

// GetMemoryStats 获取当前内存统计信息
func (mm *MemoryMonitor) GetMemoryStats() map[string]interface{} {
	var m runtime.MemStats
	runtime.ReadMemStats(&m)
	
	return map[string]interface{}{
		"heap_inuse_mb":    m.HeapInuse / 1024 / 1024,
		"heap_alloc_mb":    m.HeapAlloc / 1024 / 1024,
		"sys_mb":           m.Sys / 1024 / 1024,
		"num_gc":           m.NumGC,
		"num_goroutines":   runtime.NumGoroutine(),
		"last_gc_time":     time.Unix(0, int64(m.LastGC)),
	}
}

// ForceGC 强制执行垃圾回收
func (mm *MemoryMonitor) ForceGC() {
	before := mm.getHeapSize()
	runtime.GC()
	after := mm.getHeapSize()
	
	// 使用log包直接输出，避免undefined common错误
	log.Printf("[INFO] 强制GC: 释放内存 %d MB", (before-after)/1024/1024)
}

// getHeapSize 获取当前堆大小
func (mm *MemoryMonitor) getHeapSize() uint64 {
	var m runtime.MemStats
	runtime.ReadMemStats(&m)
	return m.HeapInuse
}

// 默认内存监控器实例
var DefaultMemMonitor = NewMemoryMonitor(
	512,             // 最大堆内存512MB
	1000,            // 最大1000个goroutines
	30*time.Second,  // 30秒检查一次
)

// StartDefaultMonitor 启动默认内存监控器
func StartDefaultMonitor() {
	DefaultMemMonitor.Start()
}

// StopDefaultMonitor 停止默认内存监控器
func StopDefaultMonitor() {
	DefaultMemMonitor.Stop()
}