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)
}