Add basic web serving and html templating

main.go

@@ -1,7 +1,51 @@
 package main
+
 import (
-	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/alexedwards/scs/v2"
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
 )
+
+var sessionManager *scs.SessionManager
+
+var BaseURL, ClientID, ClientSecret string
+
 func main() {
-	fmt.Println("Hello World!")
+	ClientID = os.Getenv("ARCGIS_CLIENT_ID")
+	if ClientID == "" {
+		log.Println("You must specify a non-empty CLIENT_ID")
+		os.Exit(1)
+	}
+	ClientSecret = os.Getenv("ARCGIS_CLIENT_SECRET")
+	if ClientSecret == "" {
+		log.Println("You must specify a non-empty CLIENT_SECRET")
+		os.Exit(1)
+	}
+	BaseURL = os.Getenv("BASE_URL")
+	if BaseURL == "" {
+		log.Println("You must specify a non-empty BASE_URL")
+		os.Exit(1)
+	}
+	bind := os.Getenv("BIND")
+	if bind == "" {
+		bind = ":9001"
+	}
+
+	log.Println("Starting...")
+	sessionManager = scs.New()
+	sessionManager.Lifetime = 24 * time.Hour
+
+	r := chi.NewRouter()
+	r.Use(middleware.Logger)
+	r.Use(sessionManager.LoadAndSave)
+
+	r.Get("/", getRoot)
+	r.Get("/favicon.ico", getFavicon)
+	log.Printf("Serving on %s", bind)
+	log.Fatal(http.ListenAndServe(bind, r))
 }