Initial commit: dating app backend (Go/Gin/GORM/Postgres)

Phone+OTP auth, staged onboarding, admin approval workflow, and a
full discovery/swipe/match/chat system with photo upload and
approximate distance (haversine) based on user location.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/handler/discovery_handler.go

@@ -0,0 +1,101 @@
+package handler
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+
+	"dating-app/internal/dto"
+	"dating-app/internal/models"
+	"dating-app/internal/service"
+	"dating-app/internal/utils"
+)
+
+type DiscoveryHandler struct {
+	discoveryService *service.DiscoveryService
+}
+
+func NewDiscoveryHandler(discoveryService *service.DiscoveryService) *DiscoveryHandler {
+	return &DiscoveryHandler{discoveryService: discoveryService}
+}
+
+// Feed GET /discover?max_distance_km=&min_age=&max_age=
+func (h *DiscoveryHandler) Feed(c *gin.Context) {
+	user, ok := currentUser(c)
+	if !ok {
+		return
+	}
+
+	var maxDistance *float64
+	if raw := c.Query("max_distance_km"); raw != "" {
+		if v, err := strconv.ParseFloat(raw, 64); err == nil {
+			maxDistance = &v
+		}
+	}
+	minAge, _ := strconv.Atoi(c.Query("min_age"))
+	maxAge, _ := strconv.Atoi(c.Query("max_age"))
+
+	candidates, err := h.discoveryService.GetFeed(user, maxDistance, minAge, maxAge)
+	if err != nil {
+		h.handleError(c, err)
+		return
+	}
+	utils.Success(c, http.StatusOK, "", candidates)
+}
+
+// CandidateDetail GET /discover/:id
+func (h *DiscoveryHandler) CandidateDetail(c *gin.Context) {
+	user, ok := currentUser(c)
+	if !ok {
+		return
+	}
+	targetID, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		utils.Fail(c, http.StatusBadRequest, "شناسه نامعتبر است", nil)
+		return
+	}
+	detail, err := h.discoveryService.GetCandidateDetail(user, uint(targetID))
+	if err != nil {
+		utils.Fail(c, http.StatusNotFound, "پروفایل یافت نشد", nil)
+		return
+	}
+	utils.Success(c, http.StatusOK, "", detail)
+}
+
+// Swipe POST /discover/:id/swipe   body: {action: "like"|"pass"|"superlike"}
+func (h *DiscoveryHandler) Swipe(c *gin.Context) {
+	user, ok := currentUser(c)
+	if !ok {
+		return
+	}
+	targetID, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		utils.Fail(c, http.StatusBadRequest, "شناسه نامعتبر است", nil)
+		return
+	}
+	var req dto.SwipeRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		utils.Fail(c, http.StatusBadRequest, "ورودی نامعتبر است", err.Error())
+		return
+	}
+
+	result, err := h.discoveryService.Swipe(user, uint(targetID), models.SwipeAction(req.Action))
+	if err != nil {
+		h.handleError(c, err)
+		return
+	}
+	utils.Success(c, http.StatusOK, "", result)
+}
+
+func (h *DiscoveryHandler) handleError(c *gin.Context, err error) {
+	switch {
+	case errors.Is(err, service.ErrGenderNotSet):
+		utils.Fail(c, http.StatusConflict, err.Error(), nil)
+	case errors.Is(err, service.ErrCannotSwipeSelf), errors.Is(err, service.ErrAlreadySwiped):
+		utils.Fail(c, http.StatusBadRequest, err.Error(), nil)
+	default:
+		utils.Fail(c, http.StatusInternalServerError, "خطای داخلی سرور", nil)
+	}
+}