scrabble-game/backend/internal/server/handlers.go

package server

import (
	"errors"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"go.uber.org/zap"

	"scrabble/backend/internal/account"
	"scrabble/backend/internal/engine"
	"scrabble/backend/internal/game"
	"scrabble/backend/internal/lobby"
	"scrabble/backend/internal/session"
	"scrabble/backend/internal/social"
)

// registerRoutes wires the Stage 6 REST handlers onto the /api/v1 groups. The
// internal group is gateway-only (the gateway authenticates and forwards); the
// user group requires X-User-ID; the admin group is reached through the gateway's
// Basic-Auth proxy. This is the representative vertical slice — further domain
// operations follow the same pattern (PLAN.md Stage 6).
func (s *Server) registerRoutes() {
	if s.sessions != nil && s.accounts != nil {
		in := s.internal
		in.POST("/sessions/telegram", s.handleTelegramAuth)
		in.POST("/sessions/guest", s.handleGuestAuth)
		in.POST("/sessions/email/request", s.handleEmailRequest)
		in.POST("/sessions/email/login", s.handleEmailLogin)
		in.POST("/sessions/resolve", s.handleResolveSession)
		in.POST("/sessions/revoke", s.handleRevokeSession)
	}
	u := s.user
	if s.accounts != nil {
		u.GET("/profile", s.handleProfile)
	}
	if s.games != nil {
		u.POST("/games/:id/play", s.handleSubmitPlay)
		u.GET("/games/:id/state", s.handleGameState)
	}
	if s.matchmaker != nil {
		u.POST("/lobby/enqueue", s.handleEnqueue)
		u.GET("/lobby/poll", s.handlePoll)
	}
	if s.social != nil {
		u.POST("/games/:id/chat", s.handleChatPost)
	}
	s.admin.GET("/ping", s.handleAdminPing)
}

// userID returns the authenticated account id stored by RequireUserID. The user
// group always runs that middleware, so absence is a programming error.
func userID(c *gin.Context) (uuid.UUID, bool) {
	return UserIDFromContext(c.Request.Context())
}

// gameIDParam parses the :id path parameter as a game UUID.
func gameIDParam(c *gin.Context) (uuid.UUID, bool) {
	id, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return uuid.UUID{}, false
	}
	return id, true
}

// clientIP returns the originating client IP the gateway forwarded in
// X-Forwarded-For (the first hop), falling back to the direct peer.
func clientIP(c *gin.Context) string {
	if xff := c.GetHeader("X-Forwarded-For"); xff != "" {
		if i := strings.IndexByte(xff, ','); i >= 0 {
			return strings.TrimSpace(xff[:i])
		}
		return strings.TrimSpace(xff)
	}
	return c.ClientIP()
}

// abortBadRequest rejects a malformed request body or parameter.
func abortBadRequest(c *gin.Context, msg string) {
	c.AbortWithStatusJSON(http.StatusBadRequest, errorResponse{Error: errorBody{Code: "bad_request", Message: msg}})
}

// abortErr maps a domain error to its HTTP status and a stable code. Server-side
// (5xx) errors are logged with the real cause and reported generically.
func (s *Server) abortErr(c *gin.Context, err error) {
	status, code := statusForError(err)
	msg := err.Error()
	if status >= http.StatusInternalServerError {
		s.log.Error("request failed", zap.String("path", c.FullPath()), zap.Error(err))
		msg = "internal error"
	}
	c.AbortWithStatusJSON(status, errorResponse{Error: errorBody{Code: code, Message: msg}})
}

// statusForError maps a known domain sentinel to an HTTP status and code,
// defaulting to 500/internal for anything unrecognised.
func statusForError(err error) (int, string) {
	switch {
	case errors.Is(err, game.ErrNotFound), errors.Is(err, account.ErrNotFound):
		return http.StatusNotFound, "not_found"
	case errors.Is(err, game.ErrNotAPlayer), errors.Is(err, social.ErrNotParticipant):
		return http.StatusForbidden, "not_a_player"
	case errors.Is(err, game.ErrNotYourTurn), errors.Is(err, social.ErrNudgeOnOwnTurn):
		return http.StatusConflict, "not_your_turn"
	case errors.Is(err, game.ErrFinished), errors.Is(err, social.ErrGameNotActive):
		return http.StatusConflict, "game_finished"
	case errors.Is(err, lobby.ErrAlreadyQueued):
		return http.StatusConflict, "already_queued"
	case errors.Is(err, game.ErrInvalidConfig):
		return http.StatusBadRequest, "invalid_config"
	case errors.Is(err, game.ErrHintsDisabled), errors.Is(err, game.ErrNoHintsLeft), errors.Is(err, game.ErrNoHintAvailable):
		return http.StatusConflict, "hint_unavailable"
	case errors.Is(err, engine.ErrIllegalPlay), errors.Is(err, engine.ErrTilesNotOnRack), errors.Is(err, engine.ErrGameOver):
		return http.StatusUnprocessableEntity, "illegal_play"
	case errors.Is(err, account.ErrEmailTaken):
		return http.StatusConflict, "email_taken"
	case errors.Is(err, account.ErrInvalidEmail):
		return http.StatusBadRequest, "invalid_email"
	case errors.Is(err, account.ErrCodeMismatch), errors.Is(err, account.ErrCodeExpired),
		errors.Is(err, account.ErrNoPendingCode), errors.Is(err, account.ErrTooManyAttempts):
		return http.StatusUnauthorized, "code_invalid"
	case errors.Is(err, session.ErrNotFound):
		return http.StatusUnauthorized, "session_invalid"
	case errors.Is(err, social.ErrChatBlocked), errors.Is(err, social.ErrMessageTooLong),
		errors.Is(err, social.ErrEmptyMessage), errors.Is(err, social.ErrForbiddenContent),
		errors.Is(err, social.ErrNudgeTooSoon):
		return http.StatusUnprocessableEntity, "chat_rejected"
	default:
		return http.StatusInternalServerError, "internal"
	}
}