feat: added exercises handler/service/repo

internal/api/request/paginated.go

@@ -0,0 +1,58 @@
+package request
+
+import (
+	"errors"
+	"log/slog"
+	"net/http"
+	"strconv"
+)
+
+var (
+	ErrFailedToDecodeRequestQuery = errors.New("failed to decode request query")
+	ErrInvalidPageValue           = errors.New("invalid value for page")
+	ErrInvalidCountValue          = errors.New("invalid value for count")
+)
+
+func ParsePaginatedQueryParams(r *http.Request) (int, int, error) {
+	ctx := r.Context()
+
+	pageStr := r.URL.Query().Get("page")
+	if pageStr == "" {
+		pageStr = "1"
+	}
+	countStr := r.URL.Query().Get("count")
+	if countStr == "" {
+		countStr = "10"
+	}
+
+	page, err := strconv.Atoi(pageStr)
+	if err != nil {
+		slog.ErrorContext(ctx,
+			"failed to read page from query",
+			slog.String("page", pageStr))
+		return 0, 0, ErrFailedToDecodeRequestQuery
+	}
+
+	count, err := strconv.Atoi(countStr)
+	if err != nil {
+		slog.ErrorContext(ctx,
+			"failed to read count from query",
+			slog.String("count", countStr))
+		return 0, 0, ErrFailedToDecodeRequestQuery
+	}
+
+	if page < 1 {
+		slog.ErrorContext(ctx,
+			"page parameter is invalid",
+			slog.Int("page", page))
+		return 0, 0, ErrInvalidPageValue
+	}
+	if count <= 0 {
+		slog.ErrorContext(ctx,
+			"count parameter is invalid",
+			slog.Int("count", count))
+		return 0, 0, ErrInvalidCountValue
+	}
+
+	return page, count, nil
+}