feat(courses): CRUD курсов

Базовая работа с курсами (без уроков — добавятся в следующей итерации).

CourseRepository:
- List с тем же паттерном что TestRepository: ownerFilter +
  onlyPublished + visibleIDs (для будущего access_grants).
- Get / GetBySlug — slug нужен для public-страниц.
- Create — slugify(title) если slug не задан; collision retry до 5 раз
  (UNIQUE constraint courses_slug_key).
- Update / Delete с CASCADE на lessons.
- courseCols + lessons_count subquery, UI получает бейдж без отдельного
  запроса.

CourseHandler — стандартный набор. Гейтит owner для write/delete;
read доступен всем (внутри сервиса), portal проксирует под
service.learning.access.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/handler/course.go

@@ -0,0 +1,142 @@
+package handler
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/google/uuid"
+
+	"learning-service/internal/model"
+	"learning-service/internal/repository"
+)
+
+type CourseHandler struct {
+	repo *repository.CourseRepository
+}
+
+func NewCourseHandler(repo *repository.CourseRepository) *CourseHandler {
+	return &CourseHandler{repo: repo}
+}
+
+// List — GET /courses?mine=true. Поведение зеркально TestHandler.List:
+//
+//	mine=true → только мои (owner_user_id = X-User-Id);
+//	без mine → только опубликованные.
+//
+// В будущей итерации access_grants добавят visibleIDs-фильтр.
+func (h *CourseHandler) List(w http.ResponseWriter, r *http.Request) {
+	uid, ok := userIDFromHeader(r)
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	mine := r.URL.Query().Get("mine") == "true"
+	var ownerFilter *uuid.UUID
+	if mine {
+		ownerFilter = &uid
+	}
+	items, err := h.repo.List(r.Context(), ownerFilter, !mine, nil)
+	if err != nil {
+		writeRepoError(w, r, err, "list courses")
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"items": items})
+}
+
+func (h *CourseHandler) Get(w http.ResponseWriter, r *http.Request) {
+	id, err := parseUUID(chi.URLParam(r, "id"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid id")
+		return
+	}
+	c, err := h.repo.Get(r.Context(), id)
+	if err != nil {
+		writeRepoError(w, r, err, "get course")
+		return
+	}
+	writeJSON(w, http.StatusOK, c)
+}
+
+func (h *CourseHandler) Create(w http.ResponseWriter, r *http.Request) {
+	uid, ok := userIDFromHeader(r)
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	var req model.CreateCourseRequest
+	if err := decodeJSON(r, &req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid body")
+		return
+	}
+	if strings.TrimSpace(req.Title) == "" {
+		writeError(w, http.StatusBadRequest, "title is required")
+		return
+	}
+	c, err := h.repo.Create(r.Context(), uid, req)
+	if err != nil {
+		writeRepoError(w, r, err, "create course")
+		return
+	}
+	writeJSON(w, http.StatusCreated, c)
+}
+
+func (h *CourseHandler) Update(w http.ResponseWriter, r *http.Request) {
+	uid, ok := userIDFromHeader(r)
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	id, err := parseUUID(chi.URLParam(r, "id"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid id")
+		return
+	}
+	existing, err := h.repo.Get(r.Context(), id)
+	if err != nil {
+		writeRepoError(w, r, err, "get course for update")
+		return
+	}
+	if existing.OwnerUserID != uid {
+		writeError(w, http.StatusForbidden, "only owner can edit")
+		return
+	}
+	var req model.UpdateCourseRequest
+	if err := decodeJSON(r, &req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid body")
+		return
+	}
+	c, err := h.repo.Update(r.Context(), id, req)
+	if err != nil {
+		writeRepoError(w, r, err, "update course")
+		return
+	}
+	writeJSON(w, http.StatusOK, c)
+}
+
+func (h *CourseHandler) Delete(w http.ResponseWriter, r *http.Request) {
+	uid, ok := userIDFromHeader(r)
+	if !ok {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	id, err := parseUUID(chi.URLParam(r, "id"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid id")
+		return
+	}
+	existing, err := h.repo.Get(r.Context(), id)
+	if err != nil {
+		writeRepoError(w, r, err, "get course for delete")
+		return
+	}
+	if existing.OwnerUserID != uid {
+		writeError(w, http.StatusForbidden, "only owner can delete")
+		return
+	}
+	if err := h.repo.Delete(r.Context(), id); err != nil {
+		writeRepoError(w, r, err, "delete course")
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}

internal/repository/course.go

@@ -0,0 +1,207 @@
+package repository
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"learning-service/internal/model"
+)
+
+type CourseRepository struct {
+	pool *pgxpool.Pool
+}
+
+func NewCourseRepository(pool *pgxpool.Pool) *CourseRepository {
+	return &CourseRepository{pool: pool}
+}
+
+// courseCols + lessons_count correlated subquery — UI получает «N уроков»
+// без отдельного запроса на каждый курс в списке.
+const courseCols = `
+	c.id, c.title, c.description, c.slug, c.cover_image_key,
+	c.is_published, c.owner_user_id, c.created_at, c.updated_at,
+	(SELECT COUNT(*)::int FROM lessons l WHERE l.course_id = c.id) AS lessons_count
+`
+
+func scanCourse(scan func(...any) error) (*model.Course, error) {
+	var c model.Course
+	if err := scan(
+		&c.ID, &c.Title, &c.Description, &c.Slug, &c.CoverImageKey,
+		&c.IsPublished, &c.OwnerUserID, &c.CreatedAt, &c.UpdatedAt,
+		&c.LessonsCount,
+	); err != nil {
+		return nil, err
+	}
+	return &c, nil
+}
+
+// List — листинг курсов. Семантика та же что у TestRepository.List:
+// ownerFilter — только мои; onlyPublished — только опубликованные;
+// visibleIDs — фильтр по access_grants (resolve'ится в handler'е).
+func (r *CourseRepository) List(ctx context.Context, ownerFilter *uuid.UUID, onlyPublished bool, visibleIDs []uuid.UUID) ([]model.Course, error) {
+	conds := []string{}
+	args := []any{}
+	push := func(cond string, val any) {
+		args = append(args, val)
+		conds = append(conds, strings.Replace(cond, "?", fmt.Sprintf("$%d", len(args)), 1))
+	}
+	if ownerFilter != nil {
+		push("c.owner_user_id = ?", *ownerFilter)
+	}
+	if onlyPublished {
+		conds = append(conds, "c.is_published = TRUE")
+	}
+	if visibleIDs != nil {
+		if len(visibleIDs) == 0 {
+			return []model.Course{}, nil
+		}
+		push("c.id = ANY(?)", visibleIDs)
+	}
+	where := ""
+	if len(conds) > 0 {
+		where = "WHERE " + strings.Join(conds, " AND ")
+	}
+	q := fmt.Sprintf(`SELECT %s FROM courses c %s ORDER BY c.updated_at DESC`, courseCols, where)
+	rows, err := r.pool.Query(ctx, q, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := []model.Course{}
+	for rows.Next() {
+		c, err := scanCourse(rows.Scan)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, *c)
+	}
+	return out, rows.Err()
+}
+
+func (r *CourseRepository) Get(ctx context.Context, id uuid.UUID) (*model.Course, error) {
+	c, err := scanCourse(r.pool.QueryRow(ctx,
+		fmt.Sprintf(`SELECT %s FROM courses c WHERE c.id = $1`, courseCols), id).Scan)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+	return c, nil
+}
+
+func (r *CourseRepository) GetBySlug(ctx context.Context, slug string) (*model.Course, error) {
+	c, err := scanCourse(r.pool.QueryRow(ctx,
+		fmt.Sprintf(`SELECT %s FROM courses c WHERE c.slug = $1`, courseCols), slug).Scan)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+	return c, nil
+}
+
+// slugify — упрощённый ascii-slug: пробелы/непечатные → '-', нижний регистр,
+// удалить лишние '-'. Cyrillic-safe: транслитерация не реализована, иначе
+// нужна большая таблица; вместо этого если slug пустой после фильтра —
+// генерируем 8-символьный uuid (вроде «c-1bbc7b53»).
+var slugSafeRe = regexp.MustCompile(`[^a-z0-9-]+`)
+var slugMultiDashRe = regexp.MustCompile(`-+`)
+
+func slugify(raw string) string {
+	s := strings.ToLower(strings.TrimSpace(raw))
+	s = strings.ReplaceAll(s, " ", "-")
+	s = slugSafeRe.ReplaceAllString(s, "")
+	s = slugMultiDashRe.ReplaceAllString(s, "-")
+	s = strings.Trim(s, "-")
+	return s
+}
+
+func (r *CourseRepository) Create(ctx context.Context, ownerID uuid.UUID, req model.CreateCourseRequest) (*model.Course, error) {
+	slug := slugify(req.Slug)
+	if slug == "" {
+		slug = slugify(req.Title)
+	}
+	if slug == "" {
+		slug = "c-" + uuid.NewString()[:8]
+	}
+	// UNIQUE slug на уровне БД — пробуем вставить, на конфликте суффикс.
+	var id uuid.UUID
+	for attempt := 0; attempt < 5; attempt++ {
+		err := r.pool.QueryRow(ctx, `
+			INSERT INTO courses (title, description, slug, owner_user_id)
+			VALUES ($1, $2, $3, $4) RETURNING id`,
+			req.Title, req.Description, slug, ownerID,
+		).Scan(&id)
+		if err == nil {
+			return r.Get(ctx, id)
+		}
+		if strings.Contains(err.Error(), "courses_slug_key") {
+			slug = slug + "-" + uuid.NewString()[:4]
+			continue
+		}
+		return nil, err
+	}
+	return nil, fmt.Errorf("failed to generate unique slug after 5 attempts")
+}
+
+func (r *CourseRepository) Update(ctx context.Context, id uuid.UUID, req model.UpdateCourseRequest) (*model.Course, error) {
+	sets := []string{}
+	args := []any{}
+	add := func(col string, val any) {
+		args = append(args, val)
+		sets = append(sets, fmt.Sprintf("%s = $%d", col, len(args)))
+	}
+	if req.Title != nil {
+		add("title", *req.Title)
+	}
+	if req.Description != nil {
+		add("description", *req.Description)
+	}
+	if req.Slug != nil {
+		s := slugify(*req.Slug)
+		if s == "" {
+			return nil, fmt.Errorf("slug becomes empty after normalization")
+		}
+		add("slug", s)
+	}
+	if req.CoverImageKey != nil {
+		add("cover_image_key", *req.CoverImageKey)
+	}
+	if req.IsPublished != nil {
+		add("is_published", *req.IsPublished)
+	}
+	if len(sets) == 0 {
+		return r.Get(ctx, id)
+	}
+	sets = append(sets, "updated_at = NOW()")
+	args = append(args, id)
+	q := fmt.Sprintf(`UPDATE courses SET %s WHERE id = $%d`, strings.Join(sets, ", "), len(args))
+	tag, err := r.pool.Exec(ctx, q, args...)
+	if err != nil {
+		return nil, err
+	}
+	if tag.RowsAffected() == 0 {
+		return nil, ErrNotFound
+	}
+	return r.Get(ctx, id)
+}
+
+func (r *CourseRepository) Delete(ctx context.Context, id uuid.UUID) error {
+	tag, err := r.pool.Exec(ctx, `DELETE FROM courses WHERE id = $1`, id)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return ErrNotFound
+	}
+	return nil
+}