package routing

import (
	"net"
	"regexp"
	"strings"

	"github.com/azoic/wormhole-client/internal/config"
	"github.com/azoic/wormhole-client/pkg/logger"
)

// RouteMatcher 路由匹配器
type RouteMatcher struct {
	config          *config.Routing
	bypassDomains   []*regexp.Regexp
	forceDomains    []*regexp.Regexp
	privateNetworks []*net.IPNet
}

// MatchResult 匹配结果
type MatchResult int

const (
	// MatchBypass 直连（绕过代理）
	MatchBypass MatchResult = iota
	// MatchProxy 代理
	MatchProxy
	// MatchAuto 自动决定
	MatchAuto
)

// NewRouteMatcher 创建路由匹配器
func NewRouteMatcher(config *config.Routing) (*RouteMatcher, error) {
	matcher := &RouteMatcher{
		config: config,
	}

	// 编译域名规则
	if err := matcher.compilePatterns(); err != nil {
		return nil, err
	}

	// 初始化私有网络列表
	matcher.initPrivateNetworks()

	logger.Debug("Route matcher initialized with %d bypass domains, %d force domains",
		len(matcher.bypassDomains), len(matcher.forceDomains))

	return matcher, nil
}

// Match 匹配主机地址，返回路由决策
func (rm *RouteMatcher) Match(host string) MatchResult {
	// 去除端口
	if hostOnly, _, err := net.SplitHostPort(host); err == nil {
		host = hostOnly
	}

	logger.Debug("Matching route for host: %s", host)

	// 1. 检查强制代理域名（包括IP地址）
	if rm.matchesForceDomains(host) {
		logger.Debug("Host %s matches force domains - using proxy", host)
		return MatchProxy
	}

	// 2. 检查绕过域名（包括IP地址）
	if rm.matchesBypassDomains(host) {
		logger.Debug("Host %s matches bypass domains - using direct", host)
		return MatchBypass
	}

	// 3. 检查是否为IP地址，进行IP特定的匹配
	if ip := net.ParseIP(host); ip != nil {
		return rm.matchIP(ip)
	}

	// 4. 检查本地域名
	if rm.config.BypassLocal && rm.isLocalDomain(host) {
		logger.Debug("Host %s is local domain - using direct", host)
		return MatchBypass
	}

	// 5. 默认策略：自动决定或代理
	logger.Debug("Host %s no specific rule - using auto", host)
	return MatchAuto
}

// matchesForceDomains 检查是否匹配强制代理域名
func (rm *RouteMatcher) matchesForceDomains(host string) bool {
	for _, pattern := range rm.forceDomains {
		if pattern.MatchString(host) {
			return true
		}
	}
	return false
}

// matchesBypassDomains 检查是否匹配绕过域名
func (rm *RouteMatcher) matchesBypassDomains(host string) bool {
	for _, pattern := range rm.bypassDomains {
		if pattern.MatchString(host) {
			return true
		}
	}
	return false
}

// matchIP 匹配IP地址
func (rm *RouteMatcher) matchIP(ip net.IP) MatchResult {
	// 检查本地IP
	if rm.config.BypassLocal && rm.isLocalIP(ip) {
		logger.Debug("IP %s is local - using direct", ip.String())
		return MatchBypass
	}

	// 检查私有网络
	if rm.config.BypassPrivate && rm.isPrivateIP(ip) {
		logger.Debug("IP %s is private - using direct", ip.String())
		return MatchBypass
	}

	return MatchAuto
}

// isLocalIP 检查是否为本地IP
func (rm *RouteMatcher) isLocalIP(ip net.IP) bool {
	// 环回地址
	if ip.IsLoopback() {
		return true
	}

	// 链路本地地址
	if ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() {
		return true
	}

	return false
}

// isPrivateIP 检查是否为私有IP
func (rm *RouteMatcher) isPrivateIP(ip net.IP) bool {
	for _, network := range rm.privateNetworks {
		if network.Contains(ip) {
			return true
		}
	}
	return false
}

// isLocalDomain 检查是否为本地域名
func (rm *RouteMatcher) isLocalDomain(host string) bool {
	host = strings.ToLower(host)

	// 常见本地域名
	localSuffixes := []string{
		".local",
		".localhost",
		".lan",
		".internal",
		".intranet",
		".home",
		".corp",
	}

	for _, suffix := range localSuffixes {
		if strings.HasSuffix(host, suffix) {
			return true
		}
	}

	// 单词域名（无点）
	if !strings.Contains(host, ".") {
		return true
	}

	return false
}

// compilePatterns 编译域名匹配模式
func (rm *RouteMatcher) compilePatterns() error {
	// 编译绕过域名模式
	for _, domain := range rm.config.BypassDomains {
		pattern, err := rm.domainToRegexp(domain)
		if err != nil {
			return err
		}
		rm.bypassDomains = append(rm.bypassDomains, pattern)
	}

	// 编译强制代理域名模式
	for _, domain := range rm.config.ForceDomains {
		pattern, err := rm.domainToRegexp(domain)
		if err != nil {
			return err
		}
		rm.forceDomains = append(rm.forceDomains, pattern)
	}

	return nil
}

// domainToRegexp 将域名模式转换为正则表达式
func (rm *RouteMatcher) domainToRegexp(domain string) (*regexp.Regexp, error) {
	// 转义特殊字符
	pattern := regexp.QuoteMeta(domain)

	// 替换通配符
	pattern = strings.ReplaceAll(pattern, "\\*", ".*")

	// 添加行开始和结束标记
	pattern = "^" + pattern + "$"

	// 编译正则表达式（不区分大小写）
	return regexp.Compile("(?i)" + pattern)
}

// initPrivateNetworks 初始化私有网络列表
func (rm *RouteMatcher) initPrivateNetworks() {
	privateNetworks := []string{
		"10.0.0.0/8",     // Class A private
		"172.16.0.0/12",  // Class B private
		"192.168.0.0/16", // Class C private
		"169.254.0.0/16", // Link-local
		"127.0.0.0/8",    // Loopback
		"224.0.0.0/4",    // Multicast
		"240.0.0.0/4",    // Reserved
		"::1/128",        // IPv6 loopback
		"fe80::/10",      // IPv6 link-local
		"fc00::/7",       // IPv6 unique local
	}

	for _, network := range privateNetworks {
		if _, ipNet, err := net.ParseCIDR(network); err == nil {
			rm.privateNetworks = append(rm.privateNetworks, ipNet)
		}
	}
}

// GetStats 获取路由统计信息
func (rm *RouteMatcher) GetStats() map[string]interface{} {
	return map[string]interface{}{
		"bypass_domains_count":   len(rm.bypassDomains),
		"force_domains_count":    len(rm.forceDomains),
		"private_networks_count": len(rm.privateNetworks),
		"bypass_local":           rm.config.BypassLocal,
		"bypass_private":         rm.config.BypassPrivate,
	}
}

// ReloadConfig 重新加载配置
func (rm *RouteMatcher) ReloadConfig(config *config.Routing) error {
	rm.config = config
	rm.bypassDomains = nil
	rm.forceDomains = nil

	if err := rm.compilePatterns(); err != nil {
		return err
	}

	logger.Info("Route matcher configuration reloaded")
	return nil
}