package log

import (
	"sync"
)

// RingBuffer 内存环形缓冲区
type RingBuffer struct {
	data     []QueryLog
	capacity int
	head     int
	tail     int
	count    int
	mu       sync.RWMutex
}

// NewRingBuffer 创建环形缓冲区
func NewRingBuffer(capacity int) *RingBuffer {
	return &RingBuffer{
		data:     make([]QueryLog, capacity),
		capacity: capacity,
		head:     0,
		tail:     0,
		count:    0,
	}
}

// Push 添加日志到缓冲区
func (rb *RingBuffer) Push(log QueryLog) {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	// 如果缓冲区已满，覆盖最旧的数据
	if rb.count == rb.capacity {
		rb.head = (rb.head + 1) % rb.capacity
	}

	rb.data[rb.tail] = log
	rb.tail = (rb.tail + 1) % rb.capacity

	if rb.count < rb.capacity {
		rb.count++
	}
}

// Query 查询日志
func (rb *RingBuffer) Query(filter LogFilter, page PageParams) ([]QueryLog, int64, error) {
	rb.mu.RLock()
	defer rb.mu.RUnlock()

	// 收集所有符合条件的日志
	var filtered []QueryLog
	for i := 0; i < rb.count; i++ {
		idx := (rb.head + i) % rb.capacity
		log := rb.data[idx]

		// 应用过滤条件
		if rb.matchesFilter(log, filter) {
			filtered = append(filtered, log)
		}
	}

	total := int64(len(filtered))

	// 排序
	rb.sortLogs(filtered, page.SortField, page.SortDirection)

	// 分页
	start := page.Offset
	if start >= len(filtered) {
		return []QueryLog{}, total, nil
	}

	end := start + page.Limit
	if end > len(filtered) {
		end = len(filtered)
	}

	return filtered[start:end], total, nil
}

// matchesFilter 检查日志是否匹配过滤条件
func (rb *RingBuffer) matchesFilter(log QueryLog, filter LogFilter) bool {
	// 结果过滤
	if filter.Result != "" && log.Result != filter.Result {
		return false
	}

	// 查询类型过滤
	if filter.QueryType != "" && log.QueryType != filter.QueryType {
		return false
	}

	// 时间范围过滤
	if !filter.StartTime.IsZero() && log.Timestamp.Before(filter.StartTime) {
		return false
	}
	if !filter.EndTime.IsZero() && log.Timestamp.After(filter.EndTime) {
		return false
	}

	// 搜索过滤
	if filter.SearchTerm != "" {
		if !contains(log.Domain, filter.SearchTerm) && !contains(log.ClientIP, filter.SearchTerm) {
			return false
		}
	}

	return true
}

// contains 检查字符串是否包含子串（不区分大小写）
func contains(s, substr string) bool {
	return len(s) >= len(substr) && (s == substr || containsIgnoreCase(s, substr))
}

// containsIgnoreCase 不区分大小写的包含检查
func containsIgnoreCase(s, substr string) bool {
	s = toLower(s)
	substr = toLower(substr)
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}

// toLower 转换为小写
func toLower(s string) string {
	result := make([]byte, len(s))
	for i := 0; i < len(s); i++ {
		c := s[i]
		if c >= 'A' && c <= 'Z' {
			c = c + ('a' - 'A')
		}
		result[i] = c
	}
	return string(result)
}

// sortLogs 对日志进行排序
func (rb *RingBuffer) sortLogs(logs []QueryLog, sortField, sortDirection string) {
	if sortField == "" {
		sortField = "timestamp"
	}
	if sortDirection == "" {
		sortDirection = "desc"
	}

	// 简单的冒泡排序（适用于小数据量）
	n := len(logs)
	for i := 0; i < n-1; i++ {
		for j := 0; j < n-i-1; j++ {
			shouldSwap := rb.compareLogs(logs[j], logs[j+1], sortField)
			if sortDirection == "desc" {
				shouldSwap = !shouldSwap
			}
			if shouldSwap {
				logs[j], logs[j+1] = logs[j+1], logs[j]
			}
		}
	}
}

// compareLogs 比较两个日志
func (rb *RingBuffer) compareLogs(a, b QueryLog, sortField string) bool {
	switch sortField {
	case "timestamp", "time":
		return a.Timestamp.Before(b.Timestamp)
	case "domain":
		return a.Domain < b.Domain
	case "clientIp", "client_ip":
		return a.ClientIP < b.ClientIP
	case "responseTime", "response_time":
		return a.ResponseTime < b.ResponseTime
	default:
		return a.Timestamp.Before(b.Timestamp)
	}
}

// GetStats 获取统计信息
func (rb *RingBuffer) GetStats(timeRange TimeRange) (*LogStats, error) {
	rb.mu.RLock()
	defer rb.mu.RUnlock()

	stats := &LogStats{
		QueryTypes: make(map[string]int64),
	}

	for i := 0; i < rb.count; i++ {
		idx := (rb.head + i) % rb.capacity
		log := rb.data[idx]

		// 时间范围过滤
		if !timeRange.StartTime.IsZero() && log.Timestamp.Before(timeRange.StartTime) {
			continue
		}
		if !timeRange.EndTime.IsZero() && log.Timestamp.After(timeRange.EndTime) {
			continue
		}

		stats.TotalQueries++
		stats.AvgResponseTime += float64(log.ResponseTime)

		switch log.Result {
		case "blocked":
			stats.BlockedQueries++
		case "allowed":
			stats.AllowedQueries++
		case "error":
			stats.ErrorQueries++
		}

		stats.QueryTypes[log.QueryType]++
	}

	if stats.TotalQueries > 0 {
		stats.AvgResponseTime /= float64(stats.TotalQueries)
	}

	return stats, nil
}

// Count 返回当前缓冲区中的日志数量
func (rb *RingBuffer) Count() int {
	rb.mu.RLock()
	defer rb.mu.RUnlock()
	return rb.count
}

// Clear 清空缓冲区
func (rb *RingBuffer) Clear() {
	rb.mu.Lock()
	defer rb.mu.Unlock()
	rb.head = 0
	rb.tail = 0
	rb.count = 0
}