added oauth flow to get authorization code

internal/handlers/login.go

@@ -0,0 +1,48 @@
+package handlers
+
+import (
+	"net/http"
+
+	"git.haelnorr.com/h/golib/hws"
+	"git.haelnorr.com/h/oslstats/internal/config"
+	"git.haelnorr.com/h/oslstats/internal/discord"
+	"git.haelnorr.com/h/oslstats/pkg/oauth"
+)
+
+func Login(server *hws.Server, cfg *config.Config) http.Handler {
+	return http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			state, uak, err := oauth.GenerateState(cfg.OAuth, "login")
+			if err != nil {
+				err = server.ThrowError(w, r, hws.HWSError{
+					StatusCode:      http.StatusInternalServerError,
+					Message:         "Failed to generate state token",
+					Error:           err,
+					Level:           hws.ErrorLevel("error"),
+					RenderErrorPage: true,
+				})
+				if err != nil {
+					server.ThrowFatal(w, err)
+				}
+				return
+			}
+			oauth.SetStateCookie(w, uak, cfg.HWSAuth.SSL)
+
+			link, err := discord.GetOAuthLink(cfg.Discord, state, cfg.HWSAuth.TrustedHost)
+			if err != nil {
+				err = server.ThrowError(w, r, hws.HWSError{
+					StatusCode:      http.StatusInternalServerError,
+					Message:         "An error occured trying to generate the login link",
+					Error:           err,
+					Level:           hws.ErrorLevel("error"),
+					RenderErrorPage: true,
+				})
+				if err != nil {
+					server.ThrowFatal(w, err)
+				}
+				return
+			}
+			http.Redirect(w, r, link, http.StatusSeeOther)
+		},
+	)
+}