go-bootstrap/core/router/router.go

package router

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

type closure func(http.ResponseWriter, *http.Request)
type Middleware func(http.ResponseWriter, *http.Request) (bool, *http.Request)

//Route struct de uma rota
type Route struct {
	Method		string
	Pattern     string
	Handler     closure
	Middlewares []Middleware
}

//Routes array of route
type Routes []Route

var routes Routes

//Match retorna a rota encontrada
func (routes Routes) Match(w http.ResponseWriter, r *http.Request) bool {
	url := r.URL.Path
	for _, element := range routes {
		when := element.Pattern
		pattern := toRegex(when)

		items := regexSubmatch(pattern, url)

		ctx := context.WithValue(r.Context(), "urlParameters", items)
		r = r.WithContext(ctx)

		if items[0] == url {
			if element.Method != r.Method {
				//method not allowed
				w.WriteHeader(405)
				w.Write(nil)
				return false
			}

			if element.Middlewares != nil && len(element.Middlewares) > 0 {
				for _, mid := range element.Middlewares {
					var validator bool
					validator, r = mid(w, r)
					if !validator {
						w.WriteHeader(500)
						w.Write(nil)
						return false
					}
				}
			}
			element.Handler(w, r)
			return true
		}
	}
	w.WriteHeader(404)
	w.Write(nil)
	return false
}

//PatternURL coloca barra no final de url se não tiver
func patternURL(url string) string {
	lastChar := url[len(url)-1:]
	if lastChar != "/" {
		url = url + "/"
	}

	return url
}

//ToRegex converte uma expressao imputada em expressão do go
func toRegex(regex string) *regexp.Regexp {
	return regexp.MustCompile(`(?m)` + regex)
}

//RegexSubmatch cria os matches aplicando a padrão de regex inputado
func regexSubmatch(pattern *regexp.Regexp, str string) []string {
	data := []string{""}

	items := pattern.FindAllStringSubmatch(str, -1)
	if len(items) > 0 {
		data = items[0]
	}

	return data
}

//ReplaceStringsURL alterar a url imputada colocando as variaveis da url inserida
func replaceStringsURL(items []string, urlPattern string) string {
	for index, element := range items {
		urlPattern = strings.Replace(urlPattern, "$"+strconv.Itoa(index), element, -1)
	}

	return urlPattern
}