Add user sessions and login

This isn't quite perfect, but gets much of the hard work done.

endpoint.go

@@ -1,8 +1,10 @@
 package main
 
 import (
+	"errors"
 	"log/slog"
 	"net/http"
+	"strings"
 )
 func getFavicon(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-type", "image/x-icon")
@@ -11,9 +13,19 @@ func getFavicon(w http.ResponseWriter, r *http.Request) {
 }
 
 func getRoot(w http.ResponseWriter, r *http.Request) {
-	err := htmlRoot(w, r.URL.Path)
+	user, err := getAuthenticatedUser(r)
+	if err != nil && !errors.Is(err, &NoCredentialsError{}) {
+		respondError(w, "Failed to get root", err, http.StatusInternalServerError)
+		return
+	}
+	if user == nil {
+		errorCode := r.URL.Query().Get("error")
+		err = htmlSignin(w, errorCode)
+	} else {
+		err = htmlDashboard(w, user)
+	}
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
+		respondError(w, "Failed to render root", err, http.StatusInternalServerError)
 	}
 }
 func getSignup(w http.ResponseWriter, r *http.Request) {
@@ -28,6 +40,33 @@ func respondError(w http.ResponseWriter, m string, e error, s int) {
 	http.Error(w, m, http.StatusBadRequest)
 }
 
+func postSignin(w http.ResponseWriter, r *http.Request) {
+	if err := r.ParseForm(); err != nil {
+		respondError(w, "Could not parse form", err, http.StatusBadRequest)
+		return
+	}
+	
+	username := r.FormValue("username")
+	password := r.FormValue("password")
+	
+	slog.Info("Signin", 
+		slog.String("username", username),
+		slog.String("password", strings.Repeat("*", len(password))))
+	
+
+	_, err := signinUser(r, username, password)
+	if err != nil {
+		if errors.Is(err, InvalidCredentials{}) {
+			http.Redirect(w, r, "/?error=invalid-credentials", http.StatusFound)
+			return
+		}
+		respondError(w, "Failed to signin user", err, http.StatusInternalServerError)
+		return
+	}
+
+	http.Redirect(w, r, "/", http.StatusFound)
+}
+
 func postSignup(w http.ResponseWriter, r *http.Request) {
 	if err := r.ParseForm(); err != nil {
 		respondError(w, "Could not parse form", err, http.StatusBadRequest)
@@ -41,7 +80,8 @@ func postSignup(w http.ResponseWriter, r *http.Request) {
 	
 	slog.Info("Signup", 
 		slog.String("username", username),
-		slog.String("name", name))
+		slog.String("name", name),
+		slog.String("password", strings.Repeat("*", len(password))))
 	
 	if terms != "on" {
 		slog.Error("Terms not agreed", slog.String("terms", terms))
@@ -49,10 +89,13 @@ func postSignup(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if err := signupUser(username, name, password); err != nil {
+	user, err := signupUser(username, name, password)
+	if err != nil {
 		respondError(w, "Failed to signup user", err, http.StatusInternalServerError)
 		return
 	}
 
+	addUserSession(r, user)
+
 	http.Redirect(w, r, "/", http.StatusFound)
 }