feat(auth): implement yggdrasil authenticate endpoint

internal/api/auth_handler.go

@@ -0,0 +1,51 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"log"
+	"net/http"
+
+	"gitea.mrixs.me/minecraft-platform/backend/internal/core"
+	"gitea.mrixs.me/minecraft-platform/backend/internal/models"
+)
+
+type AuthHandler struct {
+	Service *core.AuthService
+}
+
+// YggdrasilError - стандартный формат ошибки для authserver
+type YggdrasilError struct {
+	Error        string `json:"error"`
+	ErrorMessage string `json:"errorMessage"`
+}
+
+func (h *AuthHandler) Authenticate(w http.ResponseWriter, r *http.Request) {
+	var req models.AuthenticateRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		http.Error(w, "Invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	response, err := h.Service.Authenticate(r.Context(), req)
+	if err != nil {
+		if errors.Is(err, core.ErrInvalidCredentials) {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusForbidden) // 403
+			json.NewEncoder(w).Encode(YggdrasilError{
+				Error:        "ForbiddenOperationException",
+				ErrorMessage: "Invalid credentials. Invalid username or password.",
+			})
+			return
+		}
+
+		// Другие ошибки - внутренние
+		log.Printf("internal server error during authentication: %v", err)
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(response)
+}