add frontend template + GET /users/{userRef} route

backend/routes/auth/discord.go

@@ -1,12 +1,18 @@
 package auth
 
 import (
+	"net/http"
 	"os"
 
+	"github.com/bwmarrin/discordgo"
+	"github.com/go-chi/render"
+	"gitlab.com/1f320/pronouns/backend/db"
+	"gitlab.com/1f320/pronouns/backend/log"
+	"gitlab.com/1f320/pronouns/backend/server"
 	"golang.org/x/oauth2"
 )
 
-var oauthConfig = oauth2.Config{
+var discordOAuthConfig = oauth2.Config{
 	ClientID:     os.Getenv("DISCORD_CLIENT_ID"),
 	ClientSecret: os.Getenv("DISCORD_CLIENT_SECRET"),
 	Endpoint: oauth2.Endpoint{
@@ -16,3 +22,80 @@ var oauthConfig = oauth2.Config{
 	},
 	Scopes: []string{"identify"},
 }
+
+type oauthCallbackRequest struct {
+	Code  string `json:"code"`
+	State string `json:"state"`
+}
+
+type discordCallbackResponse struct {
+	HasAccount bool `json:"has_account"` // if true, Token and User will be set. if false, Ticket and Discord will be set
+
+	Token string   `json:"token,omitempty"`
+	User  *db.User `json:"user,omitempty"`
+
+	Discord string `json:"discord,omitempty"` // username, for UI purposes
+	Ticket  string `json:"ticket,omitempty"`
+}
+
+func (s *Server) discordCallback(w http.ResponseWriter, r *http.Request) error {
+	ctx := r.Context()
+
+	decoded, err := Decode[oauthCallbackRequest](r)
+	if err != nil {
+		return server.APIError{Code: server.ErrBadRequest}
+	}
+
+	// if the state can't be validated, return
+	if valid, err := s.validateCSRFState(ctx, decoded.State); !valid {
+		if err != nil {
+			return err
+		}
+
+		return server.APIError{Code: server.ErrInvalidState}
+	}
+
+	token, err := discordOAuthConfig.Exchange(r.Context(), decoded.Code)
+	if err != nil {
+		log.Errorf("exchanging oauth code: %v", err)
+
+		return server.APIError{Code: server.ErrInvalidOAuthCode}
+	}
+
+	dg, _ := discordgo.New(token.Type() + " " + token.AccessToken)
+	du, err := dg.User("@me")
+	if err != nil {
+		return err
+	}
+
+	u, err := s.DB.DiscordUser(ctx, du.ID)
+	if err == nil {
+		err = u.UpdateFromDiscord(ctx, s.DB, du)
+		if err != nil {
+			log.Errorf("updating user %v with Discord info: %v", u.ID, err)
+		}
+
+		token, err := s.Auth.CreateToken(u.ID)
+		if err != nil {
+			return err
+		}
+
+		render.JSON(w, r, discordCallbackResponse{
+			HasAccount: true,
+			Token:      token,
+			User:       &u,
+		})
+	} else if err != db.ErrUserNotFound { // internal error
+		return err
+	}
+
+	// no user found, so save a ticket
+
+	return nil
+}
+
+func Decode[T any](r *http.Request) (T, error) {
+	decoded := *new(T)
+
+	return decoded, render.Decode(r, &decoded)
+}