feat(backend): implement HTTP API, auth, chat, and admin surfaces

Expose learning, registration controls, mentor chat, realtime WebSocket, and staff administration.

backend/internal/api/leaderboard.go

@@ -0,0 +1,94 @@
+package api
+
+import (
+	"context"
+	"net/http"
+	"strconv"
+	"time"
+
+	"pargar/backend/internal/service"
+)
+
+type lbEntry struct {
+	UserID        int64   `json:"userId"`
+	Name          string  `json:"name"`
+	Email         string  `json:"email"`
+	XP            float64 `json:"xp"`
+	Rank          int     `json:"rank"`
+	AvatarVariant string  `json:"avatarVariant"`
+	AvatarPalette string  `json:"avatarPalette"`
+	AvatarPhoto   string  `json:"avatarPhoto,omitempty"`
+}
+
+func (s *Server) handleWeeklyLeaderboard(w http.ResponseWriter, r *http.Request) {
+	u := currentUser(r)
+	key := "lb:" + service.ISOWeek(time.Now())
+
+	entries := make([]lbEntry, 0, 20)
+	type scored struct {
+		userID int64
+		xp     float64
+	}
+	var scoredList []scored
+
+	if s.redis != nil {
+		z, err := s.redis.ZRevRangeWithScores(context.Background(), key, 0, 19).Result()
+		if err == nil {
+			for _, member := range z {
+				id, _ := strconv.ParseInt(member.Member.(string), 10, 64)
+				scoredList = append(scoredList, scored{userID: id, xp: member.Score})
+			}
+		}
+	}
+
+	// fallback to DB if redis empty (e.g. dev bootstrap)
+	if len(scoredList) == 0 {
+		rows, err := s.store.Pool().Query(context.Background(), `
+			SELECT user_id, xp FROM weekly_leaderboard WHERE week=$1 ORDER BY xp DESC LIMIT 20`,
+			service.ISOWeek(time.Now()))
+		if err == nil {
+			for rows.Next() {
+				var id int64
+				var xp int
+				if rows.Scan(&id, &xp) == nil {
+					scoredList = append(scoredList, scored{userID: id, xp: float64(xp)})
+				}
+			}
+			rows.Close()
+		}
+	}
+
+	for i, sc := range scoredList {
+		usr, err := s.store.GetUserByID(context.Background(), sc.userID)
+		if err != nil {
+			continue
+		}
+		entries = append(entries, lbEntry{
+			UserID: sc.userID, Name: usr.Name, Email: usr.Email, XP: sc.xp, Rank: i + 1,
+			AvatarVariant: usr.AvatarVariant, AvatarPalette: usr.AvatarPalette, AvatarPhoto: usr.AvatarPhoto,
+		})
+	}
+
+	// my position
+	myRank := -1
+	var myXP float64
+	if s.redis != nil {
+		rank, err := s.redis.ZRevRank(context.Background(), key, strconv.FormatInt(u.ID, 10)).Result()
+		if err == nil {
+			myRank = int(rank) + 1
+		}
+		score, err := s.redis.ZScore(context.Background(), key, strconv.FormatInt(u.ID, 10)).Result()
+		if err == nil {
+			myXP = score
+		}
+	}
+
+	if entries == nil {
+		entries = []lbEntry{}
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"week":    service.ISOWeek(time.Now()),
+		"entries": entries,
+		"me":      map[string]any{"rank": myRank, "xp": myXP, "streak": u.StreakCurrent},
+	})
+}