feat(savings): Add savings module with categories, transactions, recurring plans

- Categories: regular, deposits, credits, recurring, multi-user, accounts
- Transactions: deposits and withdrawals with user tracking
- Recurring plans: monthly payment obligations per user
- Stats: overdues calculation with allocation algorithm
- Excludes is_account categories from total sums
- Documentation: docs/SAVINGS.md

internal/handler/habit_freeze.go

@@ -0,0 +1,135 @@
+package handler
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+
+	"github.com/daniil/homelab-api/internal/middleware"
+	"github.com/daniil/homelab-api/internal/model"
+	"github.com/daniil/homelab-api/internal/repository"
+)
+
+type HabitFreezeHandler struct {
+	freezeRepo *repository.HabitFreezeRepository
+	habitRepo  *repository.HabitRepository
+}
+
+func NewHabitFreezeHandler(freezeRepo *repository.HabitFreezeRepository, habitRepo *repository.HabitRepository) *HabitFreezeHandler {
+	return &HabitFreezeHandler{
+		freezeRepo: freezeRepo,
+		habitRepo:  habitRepo,
+	}
+}
+
+func (h *HabitFreezeHandler) Create(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.GetUserID(r.Context())
+	habitID, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+	if err != nil {
+		writeError(w, "invalid habit id", http.StatusBadRequest)
+		return
+	}
+
+	// Verify habit exists and belongs to user
+	if _, err := h.habitRepo.GetByID(habitID, userID); err != nil {
+		if errors.Is(err, repository.ErrHabitNotFound) {
+			writeError(w, "habit not found", http.StatusNotFound)
+			return
+		}
+		writeError(w, "failed to fetch habit", http.StatusInternalServerError)
+		return
+	}
+
+	var req model.CreateHabitFreezeRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, "invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	if req.StartDate == "" || req.EndDate == "" {
+		writeError(w, "start_date and end_date are required", http.StatusBadRequest)
+		return
+	}
+
+	startDate, err := time.Parse("2006-01-02", req.StartDate)
+	if err != nil {
+		writeError(w, "invalid start_date format", http.StatusBadRequest)
+		return
+	}
+
+	endDate, err := time.Parse("2006-01-02", req.EndDate)
+	if err != nil {
+		writeError(w, "invalid end_date format", http.StatusBadRequest)
+		return
+	}
+
+	freeze := &model.HabitFreeze{
+		HabitID:   habitID,
+		UserID:    userID,
+		StartDate: startDate,
+		EndDate:   endDate,
+		Reason:    req.Reason,
+	}
+
+	if err := h.freezeRepo.Create(freeze); err != nil {
+		if errors.Is(err, repository.ErrInvalidDateRange) {
+			writeError(w, "end_date must be after start_date", http.StatusBadRequest)
+			return
+		}
+		writeError(w, "failed to create freeze", http.StatusInternalServerError)
+		return
+	}
+
+	writeJSON(w, freeze, http.StatusCreated)
+}
+
+func (h *HabitFreezeHandler) List(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.GetUserID(r.Context())
+	habitID, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+	if err != nil {
+		writeError(w, "invalid habit id", http.StatusBadRequest)
+		return
+	}
+
+	// Verify habit exists and belongs to user
+	if _, err := h.habitRepo.GetByID(habitID, userID); err != nil {
+		if errors.Is(err, repository.ErrHabitNotFound) {
+			writeError(w, "habit not found", http.StatusNotFound)
+			return
+		}
+		writeError(w, "failed to fetch habit", http.StatusInternalServerError)
+		return
+	}
+
+	freezes, err := h.freezeRepo.GetByHabitID(habitID, userID)
+	if err != nil {
+		writeError(w, "failed to fetch freezes", http.StatusInternalServerError)
+		return
+	}
+
+	writeJSON(w, freezes, http.StatusOK)
+}
+
+func (h *HabitFreezeHandler) Delete(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.GetUserID(r.Context())
+	freezeID, err := strconv.ParseInt(chi.URLParam(r, "freezeId"), 10, 64)
+	if err != nil {
+		writeError(w, "invalid freeze id", http.StatusBadRequest)
+		return
+	}
+
+	if err := h.freezeRepo.Delete(freezeID, userID); err != nil {
+		if errors.Is(err, repository.ErrFreezeNotFound) {
+			writeError(w, "freeze not found", http.StatusNotFound)
+			return
+		}
+		writeError(w, "failed to delete freeze", http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}