//! 生产环境日志模块
//!
//! 提供生产环境专用的日志功能，包括结构化日志、日志聚合、性能监控等。
#![allow(dead_code)]

use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::Arc;
use std::time::{Duration, SystemTime};
use tokio::sync::RwLock;
use tracing::error;

/// 生产日志管理器
#[derive(Clone)]
pub struct ProductionLogger {
    /// 日志配置
    config: LoggingConfig,
    /// 日志收集器
    collectors: Vec<Arc<dyn LogCollector + Send + Sync>>,
    /// 日志过滤器
    filters: Vec<Arc<dyn LogFilter + Send + Sync>>,
    /// 日志统计
    stats: Arc<RwLock<LoggingStats>>,
    /// 日志缓冲区
    buffer: Arc<RwLock<LogBuffer>>,
}

impl std::fmt::Debug for ProductionLogger {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ProductionLogger")
            .field("config", &self.config)
            .field("collectors_count", &self.collectors.len())
            .field("filters_count", &self.filters.len())
            .finish()
    }
}

/// 日志配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LoggingConfig {
    /// 日志级别
    pub level: LogLevel,
    /// 输出格式
    pub format: LogFormat,
    /// 输出目标
    pub targets: Vec<LogTarget>,
    /// 缓冲配置
    pub buffer_config: BufferConfig,
    /// 轮转配置
    pub rotation_config: RotationConfig,
    /// 采样配置
    pub sampling_config: SamplingConfig,
}

/// 日志级别
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum LogLevel {
    Trace,
    Debug,
    Info,
    Warn,
    Error,
}

/// 日志格式
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum LogFormat {
    /// JSON 格式
    Json,
    /// 纯文本格式
    Text,
    /// 结构化格式
    Structured,
    /// 自定义格式
    Custom(String),
}

/// 日志输出目标
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum LogTarget {
    /// 控制台输出
    Console,
    /// 文件输出
    File { path: String },
    /// 系统日志
    Syslog,
    /// 远程日志服务
    Remote { endpoint: String, api_key: String },
    /// Elasticsearch
    Elasticsearch { url: String, index: String },
    /// 自定义目标
    Custom(String),
}

/// 缓冲配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct BufferConfig {
    /// 缓冲区大小
    pub size: usize,
    /// 刷新间隔
    pub flush_interval: Duration,
    /// 批量大小
    pub batch_size: usize,
    /// 是否启用压缩
    pub enable_compression: bool,
}

/// 轮转配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RotationConfig {
    /// 最大文件大小 (MB)
    pub max_file_size_mb: u64,
    /// 最大文件数量
    pub max_files: u32,
    /// 轮转间隔
    pub rotation_interval: Duration,
    /// 压缩旧文件
    pub compress_old_files: bool,
}

/// 采样配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SamplingConfig {
    /// 是否启用采样
    pub enabled: bool,
    /// 采样率 (0.0-1.0)
    pub rate: f64,
    /// 采样策略
    pub strategy: SamplingStrategy,
}

/// 采样策略
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum SamplingStrategy {
    /// 随机采样
    Random,
    /// 基于时间的采样
    TimeBased,
    /// 基于级别的采样
    LevelBased,
    /// 自适应采样
    Adaptive,
}

/// 日志条目
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LogEntry {
    /// 时间戳
    pub timestamp: SystemTime,
    /// 日志级别
    pub level: LogLevel,
    /// 消息
    pub message: String,
    /// 模块
    pub module: String,
    /// 文件名
    pub file: Option<String>,
    /// 行号
    pub line: Option<u32>,
    /// 字段
    pub fields: HashMap<String, serde_json::Value>,
    /// 跟踪 ID
    pub trace_id: Option<String>,
    /// 跨度 ID
    pub span_id: Option<String>,
}

/// 日志收集器 trait
pub trait LogCollector {
    /// 收集日志
    fn collect(&self, entry: &LogEntry) -> Result<()>;
    /// 刷新缓冲区
    fn flush(&self) -> Result<()>;
    /// 获取收集器名称
    fn name(&self) -> &str;
}

/// 日志过滤器 trait
pub trait LogFilter {
    /// 过滤日志
    fn filter(&self, entry: &LogEntry) -> bool;
    /// 获取过滤器名称
    fn name(&self) -> &str;
}

/// 控制台日志收集器
pub struct ConsoleCollector {
    /// 收集器名称
    name: String,
    /// 格式化器
    formatter: Box<dyn LogFormatter + Send + Sync>,
}

impl std::fmt::Debug for ConsoleCollector {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("ConsoleCollector")
            .field("name", &self.name)
            .finish()
    }
}

/// 文件日志收集器
pub struct FileCollector {
    /// 收集器名称
    name: String,
    /// 文件路径
    file_path: String,
    /// 轮转配置
    rotation_config: RotationConfig,
    /// 格式化器
    formatter: Box<dyn LogFormatter + Send + Sync>,
}

impl std::fmt::Debug for FileCollector {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("FileCollector")
            .field("name", &self.name)
            .field("file_path", &self.file_path)
            .field("rotation_config", &self.rotation_config)
            .finish()
    }
}

/// 远程日志收集器
pub struct RemoteCollector {
    /// 收集器名称
    name: String,
    /// 远程端点
    endpoint: String,
    /// API 密钥
    api_key: String,
    /// HTTP 客户端
    client: reqwest::Client,
}

impl std::fmt::Debug for RemoteCollector {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RemoteCollector")
            .field("name", &self.name)
            .field("endpoint", &self.endpoint)
            .field("api_key", &"<hidden>")
            .finish()
    }
}

/// 日志格式化器 trait
pub trait LogFormatter {
    /// 格式化日志条目
    fn format(&self, entry: &LogEntry) -> Result<String>;
}

/// JSON 格式化器
#[derive(Debug)]
pub struct JsonFormatter;

/// 文本格式化器
#[derive(Debug)]
pub struct TextFormatter {
    /// 时间格式
    time_format: String,
    /// 是否包含颜色
    colored: bool,
}

/// 级别过滤器
#[derive(Debug)]
pub struct LevelFilter {
    /// 最小级别
    min_level: LogLevel,
}

/// 模块过滤器
#[derive(Debug)]
pub struct ModuleFilter {
    /// 允许的模块
    allowed_modules: Vec<String>,
    /// 禁止的模块
    denied_modules: Vec<String>,
}

/// 速率限制过滤器
#[derive(Debug)]
pub struct RateLimitFilter {
    /// 速率限制器
    limiter: Arc<RwLock<HashMap<String, RateLimiter>>>,
    /// 每秒最大日志数
    max_logs_per_second: u32,
}

/// 简单速率限制器
#[derive(Debug)]
struct RateLimiter {
    /// 最后重置时间
    last_reset: SystemTime,
    /// 当前计数
    count: u32,
    /// 限制
    limit: u32,
}

/// 日志缓冲区
#[derive(Debug)]
pub struct LogBuffer {
    /// 缓冲的日志条目
    entries: Vec<LogEntry>,
    /// 缓冲区大小限制
    max_size: usize,
    /// 最后刷新时间
    last_flush: SystemTime,
}

/// 日志统计
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LoggingStats {
    /// 总日志数
    pub total_logs: u64,
    /// 按级别统计
    pub logs_by_level: HashMap<String, u64>,
    /// 按模块统计
    pub logs_by_module: HashMap<String, u64>,
    /// 错误统计
    pub error_count: u64,
    /// 警告统计
    pub warning_count: u64,
    /// 平均处理时间
    pub avg_processing_time: Duration,
    /// 缓冲区使用率
    pub buffer_usage: f64,
    /// 丢弃的日志数
    pub dropped_logs: u64,
}

impl ProductionLogger {
    /// 创建新的生产日志管理器
    pub fn new(config: LoggingConfig) -> Self {
        Self {
            config,
            collectors: Vec::new(),
            filters: Vec::new(),
            stats: Arc::new(RwLock::new(LoggingStats::default())),
            buffer: Arc::new(RwLock::new(LogBuffer::new(1000))),
        }
    }

    /// 添加日志收集器
    pub fn add_collector(&mut self, collector: Arc<dyn LogCollector + Send + Sync>) {
        self.collectors.push(collector);
    }

    /// 添加日志过滤器
    pub fn add_filter(&mut self, filter: Arc<dyn LogFilter + Send + Sync>) {
        self.filters.push(filter);
    }

    /// 记录日志
    pub async fn log(&self, entry: LogEntry) -> Result<()> {
        // 应用过滤器
        for filter in &self.filters {
            if !filter.filter(&entry) {
                return Ok(());
            }
        }

        // 更新统计
        self.update_stats(&entry).await;

        // 添加到缓冲区
        let mut buffer = self.buffer.write().await;
        buffer.add_entry(entry.clone());

        // 检查是否需要刷新
        if buffer.should_flush(&self.config.buffer_config) {
            drop(buffer);
            self.flush_buffer().await?;
        }

        Ok(())
    }

    /// 刷新缓冲区
    pub async fn flush_buffer(&self) -> Result<()> {
        let mut buffer = self.buffer.write().await;
        let entries = buffer.drain_entries();
        drop(buffer);

        // 发送到所有收集器
        for entry in entries {
            for collector in &self.collectors {
                if let Err(e) = collector.collect(&entry) {
                    error!(
                        "Log collector {} processing failed: {}",
                        collector.name(),
                        e
                    );
                }
            }
        }

        // 刷新所有收集器
        for collector in &self.collectors {
            if let Err(e) = collector.flush() {
                error!(
                    "Log collector {} failed to refresh: {}",
                    collector.name(),
                    e
                );
            }
        }

        Ok(())
    }

    /// 更新统计信息
    async fn update_stats(&self, entry: &LogEntry) {
        let mut stats = self.stats.write().await;
        stats.total_logs += 1;

        let level_key = format!("{:?}", entry.level);
        *stats.logs_by_level.entry(level_key).or_insert(0) += 1;

        *stats
            .logs_by_module
            .entry(entry.module.clone())
            .or_insert(0) += 1;

        match entry.level {
            LogLevel::Error => stats.error_count += 1,
            LogLevel::Warn => stats.warning_count += 1,
            _ => {}
        }
    }

    /// 获取统计信息
    pub async fn get_stats(&self) -> LoggingStats {
        self.stats.read().await.clone()
    }

    /// 启动后台任务
    pub async fn start_background_tasks(&self) {
        let buffer = Arc::clone(&self.buffer);
        let config = self.config.clone();
        let logger = self.clone();

        tokio::spawn(async move {
            let mut interval = tokio::time::interval(config.buffer_config.flush_interval);

            loop {
                interval.tick().await;

                let should_flush = {
                    let buffer = buffer.read().await;
                    !buffer.entries.is_empty()
                };

                if should_flush {
                    if let Err(e) = logger.flush_buffer().await {
                        error!("Failed to refresh the log buffer regularly: {}", e);
                    }
                }
            }
        });
    }
}

impl LogCollector for ConsoleCollector {
    fn collect(&self, entry: &LogEntry) -> Result<()> {
        let formatted = self.formatter.format(entry)?;
        println!("{formatted}");
        Ok(())
    }

    fn flush(&self) -> Result<()> {
        // 控制台不需要刷新
        Ok(())
    }

    fn name(&self) -> &str {
        &self.name
    }
}

impl LogCollector for FileCollector {
    fn collect(&self, entry: &LogEntry) -> Result<()> {
        let _formatted = self.formatter.format(entry)?;
        // 这里应该实现文件写入逻辑
        // 包括轮转检查
        Ok(())
    }

    fn flush(&self) -> Result<()> {
        // 刷新文件缓冲区
        Ok(())
    }

    fn name(&self) -> &str {
        &self.name
    }
}

impl LogCollector for RemoteCollector {
    fn collect(&self, _entry: &LogEntry) -> Result<()> {
        // 这里应该实现异步发送到远程服务
        // 可以使用队列缓冲
        Ok(())
    }

    fn flush(&self) -> Result<()> {
        // 刷新远程队列
        Ok(())
    }

    fn name(&self) -> &str {
        &self.name
    }
}

impl LogFormatter for JsonFormatter {
    fn format(&self, entry: &LogEntry) -> Result<String> {
        serde_json::to_string(entry).context("序列化日志条目为 JSON 失败")
    }
}

impl LogFormatter for TextFormatter {
    fn format(&self, entry: &LogEntry) -> Result<String> {
        let timestamp = entry
            .timestamp
            .duration_since(SystemTime::UNIX_EPOCH)
            .unwrap_or_default();

        Ok(format!(
            "[{}] {:5} {}: {}",
            timestamp.as_secs(),
            format!("{:?}", entry.level),
            entry.module,
            entry.message
        ))
    }
}

impl LogFilter for LevelFilter {
    fn filter(&self, entry: &LogEntry) -> bool {
        self.level_to_number(&entry.level) >= self.level_to_number(&self.min_level)
    }

    fn name(&self) -> &str {
        "level_filter"
    }
}

impl LevelFilter {
    fn level_to_number(&self, level: &LogLevel) -> u8 {
        match level {
            LogLevel::Trace => 0,
            LogLevel::Debug => 1,
            LogLevel::Info => 2,
            LogLevel::Warn => 3,
            LogLevel::Error => 4,
        }
    }
}

impl LogFilter for ModuleFilter {
    fn filter(&self, entry: &LogEntry) -> bool {
        if !self.denied_modules.is_empty()
            && self
                .denied_modules
                .iter()
                .any(|m| entry.module.starts_with(m))
        {
            return false;
        }

        if !self.allowed_modules.is_empty() {
            return self
                .allowed_modules
                .iter()
                .any(|m| entry.module.starts_with(m));
        }

        true
    }

    fn name(&self) -> &str {
        "module_filter"
    }
}

impl LogFilter for RateLimitFilter {
    fn filter(&self, _entry: &LogEntry) -> bool {
        // 这里应该实现速率限制逻辑
        // 基于模块或其他标识符
        true
    }

    fn name(&self) -> &str {
        "rate_limit_filter"
    }
}

impl LogBuffer {
    /// 创建新的日志缓冲区
    pub fn new(max_size: usize) -> Self {
        Self {
            entries: Vec::with_capacity(max_size),
            max_size,
            last_flush: SystemTime::now(),
        }
    }

    /// 添加日志条目
    pub fn add_entry(&mut self, entry: LogEntry) {
        if self.entries.len() >= self.max_size {
            // 移除最旧的条目
            self.entries.remove(0);
        }
        self.entries.push(entry);
    }

    /// 检查是否应该刷新
    pub fn should_flush(&self, config: &BufferConfig) -> bool {
        self.entries.len() >= config.batch_size
            || self.last_flush.elapsed().unwrap_or_default() >= config.flush_interval
    }

    /// 排空缓冲区
    pub fn drain_entries(&mut self) -> Vec<LogEntry> {
        self.last_flush = SystemTime::now();
        std::mem::take(&mut self.entries)
    }
}

impl Default for LoggingConfig {
    fn default() -> Self {
        Self {
            level: LogLevel::Info,
            format: LogFormat::Json,
            targets: vec![LogTarget::Console],
            buffer_config: BufferConfig {
                size: 1000,
                flush_interval: Duration::from_secs(5),
                batch_size: 100,
                enable_compression: false,
            },
            rotation_config: RotationConfig {
                max_file_size_mb: 100,
                max_files: 10,
                rotation_interval: Duration::from_secs(3600),
                compress_old_files: true,
            },
            sampling_config: SamplingConfig {
                enabled: false,
                rate: 1.0,
                strategy: SamplingStrategy::Random,
            },
        }
    }
}

impl Default for LoggingStats {
    fn default() -> Self {
        Self {
            total_logs: 0,
            logs_by_level: HashMap::new(),
            logs_by_module: HashMap::new(),
            error_count: 0,
            warning_count: 0,
            avg_processing_time: Duration::from_millis(0),
            buffer_usage: 0.0,
            dropped_logs: 0,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_production_logger() {
        let config = LoggingConfig::default();
        let logger = ProductionLogger::new(config);

        let entry = LogEntry {
            timestamp: SystemTime::now(),
            level: LogLevel::Info,
            message: "测试日志".to_string(),
            module: "test".to_string(),
            file: None,
            line: None,
            fields: HashMap::new(),
            trace_id: None,
            span_id: None,
        };

        logger.log(entry).await.unwrap();

        let stats = logger.get_stats().await;
        assert_eq!(stats.total_logs, 1);
    }

    #[test]
    fn test_level_filter() {
        let filter = LevelFilter {
            min_level: LogLevel::Warn,
        };

        let info_entry = LogEntry {
            timestamp: SystemTime::now(),
            level: LogLevel::Info,
            message: "信息日志".to_string(),
            module: "test".to_string(),
            file: None,
            line: None,
            fields: HashMap::new(),
            trace_id: None,
            span_id: None,
        };

        let error_entry = LogEntry {
            level: LogLevel::Error,
            ..info_entry.clone()
        };

        assert!(!filter.filter(&info_entry));
        assert!(filter.filter(&error_entry));
    }

    #[test]
    fn test_json_formatter() {
        let formatter = JsonFormatter;

        let entry = LogEntry {
            timestamp: SystemTime::now(),
            level: LogLevel::Info,
            message: "测试消息".to_string(),
            module: "test".to_string(),
            file: Some("test.rs".to_string()),
            line: Some(42),
            fields: HashMap::new(),
            trace_id: Some("trace123".to_string()),
            span_id: Some("span456".to_string()),
        };

        let formatted = formatter.format(&entry).unwrap();
        assert!(formatted.contains("测试消息"));
        assert!(formatted.contains("trace123"));
    }
}