package main

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

type URLParam struct{}

type W = http.ResponseWriter
type R = *http.Request

var routes = []struct {
    methods []string
    regex   *regexp.Regexp
    handler http.HandlerFunc
}{
    {[]string{"GET"}, URL(""), func(w W, r R) {
        http.ServeFile(w, r, filepath.Join("html", "index.html"))
    }},
    {[]string{"GET"}, URL("/style\\.css"), func(w W, r R) {
        http.ServeFile(w, r, "/html/style.css")
    }},
    {[]string{"GET"}, URL("/static/.+"), func(w W, r R) {
        http.ServeFile(w, r, r.URL.Path)
    }},
    {[]string{"GET"}, URL("/[^/]+"), func(w W, r R) {
        http.ServeFile(w, r, filepath.Join("html", r.URL.Path + ".html"))
    }},
}

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

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,
                )
                fmt.Println(r.Method, r.URL.Path)
            }
            rt.handler(w, r.WithContext(
                context.WithValue(r.Context(), URLParam{}, matches[1:])),
            )
            return
        }
    }
    http.NotFound(w, r)
}