package config

import (
	"fmt"
	"sync"

	"github.com/BurntSushi/toml"
	"github.com/fsnotify/fsnotify"
	"go.uber.org/zap"
)

// Config 应用配置结构
type Config struct {
	Server   ServerConfig   `toml:"server"`
	Log      LogConfig      `toml:"log"`
	Protocol ProtocolConfig `toml:"protocol"`
}

// ServerConfig 服务器配置
type ServerConfig struct {
	Host string `toml:"host"`
	Port int    `toml:"port"`
}

// LogConfig 日志配置
type LogConfig struct {
	Level      string `toml:"level"`
	Output     string `toml:"output"`
	MaxSize    int    `toml:"max_size"`
	MaxBackups int    `toml:"max_backups"`
	MaxAge     int    `toml:"max_age"`
}

// ProtocolConfig 协议配置
type ProtocolConfig struct {
	Name    string            `toml:"name"`
	Version string            `toml:"version"`
	Options map[string]string `toml:"options"`
}

// ConfigManager 配置管理器
type ConfigManager struct {
	configPath string
	config     *Config
	logger     *zap.Logger
	mu         sync.RWMutex
	callbacks  []func(*Config)
}

// NewConfigManager 创建配置管理器
func NewConfigManager(configPath string, logger *zap.Logger) *ConfigManager {
	return &ConfigManager{
		configPath: configPath,
		logger:     logger,
		callbacks:  make([]func(*Config), 0),
	}
}

// Load 加载配置文件
func (cm *ConfigManager) Load() error {
	cm.mu.Lock()
	defer cm.mu.Unlock()

	var cfg Config
	if _, err := toml.DecodeFile(cm.configPath, &cfg); err != nil {
		return fmt.Errorf("failed to decode config: %w", err)
	}

	cm.config = &cfg
	cm.logger.Info("Config loaded successfully",
		zap.String("path", cm.configPath),
		zap.String("server", fmt.Sprintf("%s:%d", cfg.Server.Host, cfg.Server.Port)),
	)

	// 触发回调
	for _, cb := range cm.callbacks {
		cb(cm.config)
	}

	return nil
}

// Get 获取当前配置
func (cm *ConfigManager) Get() *Config {
	cm.mu.RLock()
	defer cm.mu.RUnlock()
	return cm.config
}

// Reload 重新加载配置
func (cm *ConfigManager) Reload() error {
	return cm.Load()
}

// RegisterCallback 注册配置变更回调
func (cm *ConfigManager) RegisterCallback(callback func(*Config)) {
	cm.mu.Lock()
	defer cm.mu.Unlock()
	cm.callbacks = append(cm.callbacks, callback)
}

// Watch 监听配置文件变化
func (cm *ConfigManager) Watch() error {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		return fmt.Errorf("failed to create watcher: %w", err)
	}

	if err := watcher.Add(cm.configPath); err != nil {
		return fmt.Errorf("failed to watch config file: %w", err)
	}

	go func() {
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
					return
				}
				if event.Op&fsnotify.Write == fsnotify.Write {
					cm.logger.Info("Config file changed, reloading...",
						zap.String("file", event.Name))
					if err := cm.Reload(); err != nil {
						cm.logger.Error("Failed to reload config",
							zap.Error(err))
					}
				}
			case err, ok := <-watcher.Errors:
				if !ok {
					return
				}
				cm.logger.Error("Watcher error", zap.Error(err))
			}
		}
	}()

	return nil
}

// Close 关闭配置管理器
func (cm *ConfigManager) Close() error {
	return nil
}