package rule

import (
	"bufio"
	"encoding/json"
	"fmt"
	"log/slog"
	"net"
	"os"
	"strconv"
	"strings"
)

// Loader 规则加载器
type Loader struct {
	manager *Manager
	logger  *slog.Logger
}

// NewLoader 创建规则加载器
func NewLoader(manager *Manager, logger *slog.Logger) *Loader {
	if logger == nil {
		logger = slog.Default()
	}
	return &Loader{
		manager: manager,
		logger:  logger,
	}
}

// LoadFromJSON 从JSON文件加载规则
func (l *Loader) LoadFromJSON(filename string) error {
	data, err := os.ReadFile(filename)
	if err != nil {
		return fmt.Errorf("读取规则文件失败: %w", err)
	}

	var config struct {
		Rules []json.RawMessage `json:"rules"`
	}

	if err := json.Unmarshal(data, &config); err != nil {
		return fmt.Errorf("解析规则文件失败: %w", err)
	}

	for _, ruleData := range config.Rules {
		var baseRule BaseRule
		if err := json.Unmarshal(ruleData, &baseRule); err != nil {
			l.logger.Warn("解析规则基础信息失败",
				"error", err.Error(),
				"rule_data", string(ruleData),
			)
			continue
		}

		var rule Rule
		switch baseRule.Type {
		case RuleTypeDNS:
			var dnsRule DNSRule
			if err := json.Unmarshal(ruleData, &dnsRule); err != nil {
				l.logger.Warn("解析DNS规则失败",
					"error", err.Error(),
					"rule_data", string(ruleData),
				)
				continue
			}
			rule = &dnsRule
		case RuleTypeRewrite:
			var rewriteRule RewriteRule
			if err := json.Unmarshal(ruleData, &rewriteRule); err != nil {
				l.logger.Warn("解析重写规则失败",
					"error", err.Error(),
					"rule_data", string(ruleData),
				)
				continue
			}
			rule = &rewriteRule
		case RuleTypeRoute:
			var routeRule RouteRule
			if err := json.Unmarshal(ruleData, &routeRule); err != nil {
				l.logger.Warn("解析路由规则失败",
					"error", err.Error(),
					"rule_data", string(ruleData),
				)
				continue
			}
			rule = &routeRule
		default:
			l.logger.Warn("未知的规则类型",
				"type", string(baseRule.Type),
				"rule_data", string(ruleData),
			)
			continue
		}

		if err := l.manager.AddRule(rule); err != nil {
			l.logger.Error("添加规则失败",
				"error", err.Error(),
				"rule_id", rule.GetID(),
				"rule_type", string(rule.GetType()),
			)
		}
	}

	return nil
}

// LoadFromHosts 从hosts文件加载DNS规则
func (l *Loader) LoadFromHosts(filename string) error {
	file, err := os.Open(filename)
	if err != nil {
		return fmt.Errorf("打开hosts文件失败: %w", err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	lineNum := 0
	for scanner.Scan() {
		lineNum++
		line := strings.TrimSpace(scanner.Text())

		// 跳过空行和注释
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		fields := strings.Fields(line)
		if len(fields) < 2 {
			l.logger.Warn("无效的hosts行",
				"line_number", lineNum,
				"line", line,
			)
			continue
		}

		// 解析IP和端口
		ipStr := fields[0]
		ip := ipStr
		port := 0

		if strings.Contains(ipStr, ":") {
			parts := strings.Split(ipStr, ":")
			if len(parts) != 2 {
				l.logger.Warn("无效的IP:端口格式",
					"line_number", lineNum,
					"ip_port", ipStr,
				)
				continue
			}
			ip = parts[0]
			if p, err := strconv.Atoi(parts[1]); err == nil {
				port = p
			} else {
				l.logger.Warn("无效的端口号",
					"line_number", lineNum,
					"port", parts[1],
				)
				continue
			}
		}

		// 验证IP地址
		if net.ParseIP(ip) == nil {
			l.logger.Warn("无效的IP地址",
				"line_number", lineNum,
				"ip", ip,
			)
			continue
		}

		// 处理每个域名
		for _, domain := range fields[1:] {
			// 跳过注释
			if strings.HasPrefix(domain, "#") {
				break
			}

			// 创建DNS规则
			matchType := MatchTypeExact
			if strings.Contains(domain, "*") {
				matchType = MatchTypeWildcard
			}

			rule := &DNSRule{
				BaseRule: BaseRule{
					ID:        fmt.Sprintf("hosts-%d-%s", lineNum, domain),
					Type:      RuleTypeDNS,
					Priority:  100,
					Pattern:   domain,
					MatchType: matchType,
					Enabled:   true,
				},
				Targets: []DNSTarget{
					{
						IP:   ip,
						Port: port,
					},
				},
			}

			if err := l.manager.AddRule(rule); err != nil {
				l.logger.Error("添加hosts规则失败",
					"error", err.Error(),
					"domain", domain,
					"ip", ip,
					"port", port,
				)
			}
		}
	}

	if err := scanner.Err(); err != nil {
		return fmt.Errorf("读取hosts文件失败: %w", err)
	}

	return nil
}