package router

import (
	"net/http"
	"regexp"
	"strings"
)

// Route 路由规则
type Route struct {
	// 匹配模式（主机名、路径、正则表达式）
	Pattern string
	// 匹配类型
	Type RouteType
	// 目标地址
	Target string
	// 路径重写规则
	RewritePattern string
	// 请求头修改
	HeaderModifier HeaderModifier
	// 自定义匹配函数
	MatchFunc func(req *http.Request) bool
}

// RouteType 路由类型
type RouteType int

const (
	// HostRoute 主机名路由
	HostRoute RouteType = iota
	// PathRoute 路径路由
	PathRoute
	// RegexRoute 正则表达式路由
	RegexRoute
	// CustomRoute 自定义路由
	CustomRoute
)

// HeaderModifier 头部修改接口
type HeaderModifier interface {
	// ModifyRequest 修改请求头
	ModifyRequest(req *http.Request)
	// ModifyResponse 修改响应头
	ModifyResponse(resp *http.Response)
}

// Router 路由器
type Router struct {
	routes []*Route
}

// NewRouter 创建路由器
func NewRouter() *Router {
	return &Router{
		routes: make([]*Route, 0),
	}
}

// AddRoute 添加路由规则
func (r *Router) AddRoute(route *Route) {
	r.routes = append(r.routes, route)
}

// Match 匹配请求
func (r *Router) Match(req *http.Request) (*Route, bool) {
	for _, route := range r.routes {
		switch route.Type {
		case HostRoute:
			if matchHost(req.Host, route.Pattern) {
				return route, true
			}
		case PathRoute:
			if matchPath(req.URL.Path, route.Pattern) {
				return route, true
			}
		case RegexRoute:
			if matchRegex(req.URL.String(), route.Pattern) {
				return route, true
			}
		case CustomRoute:
			if route.MatchFunc != nil && route.MatchFunc(req) {
				return route, true
			}
		}
	}
	return nil, false
}

// 匹配主机名
func matchHost(host, pattern string) bool {
	return host == pattern || strings.HasSuffix(host, "."+pattern)
}

// 匹配路径
func matchPath(path, pattern string) bool {
	return strings.HasPrefix(path, pattern)
}

// 匹配正则表达式
func matchRegex(url, pattern string) bool {
	matched, _ := regexp.MatchString(pattern, url)
	return matched
}