package main

import (
    "context"
    "fmt"
    "net/http"
    "regexp"
    "slices"
)

type URLParam struct{}

var routes = []struct {
    methods []string
    regex   *regexp.Regexp
    handler http.HandlerFunc
}{
    {[]string{"GET"}, url(""), index},
    {[]string{"GET"}, url("/static/.+"), static},
    {[]string{"GET"}, url("/(.+\\.css)"), css},
    {[]string{"GET"}, url("/([^/]+)"), html},
}

func url(s string) *regexp.Regexp {
    return regexp.MustCompile("^" + s + "/?$")
}

func getParam(r *http.Request, i int) string {
    return r.Context().Value(URLParam{}).([]string)[i]
}

func route(w http.ResponseWriter, r *http.Request) {
    for _, rt := range routes {
        matches := rt.regex.FindStringSubmatch(r.URL.Path)
        if len(matches) > 0 {
            if !slices.Contains(rt.methods, r.Method) {
                w.Header().Set("Allow", r.Method)
                http.Error(
                    w, "405 method not allowed", http.StatusMethodNotAllowed,
                )
                return
            }
            fmt.Println(r.Method, r.URL.Path)
            rt.handler(w, r.WithContext(
                context.WithValue(r.Context(), URLParam{}, matches[1:]),
            ))
            return
        }
    }
    http.NotFound(w, r)
}