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 AccessGrantHandler struct {
	repo       *repository.AccessGrantRepository
	testRepo   *repository.TestRepository
	courseRepo *repository.CourseRepository
}

func NewAccessGrantHandler(
	repo *repository.AccessGrantRepository,
	testRepo *repository.TestRepository,
	courseRepo *repository.CourseRepository,
) *AccessGrantHandler {
	return &AccessGrantHandler{repo: repo, testRepo: testRepo, courseRepo: courseRepo}
}

// authorizeResourceOwner — проверка прав на управление access_grants:
// только owner ресурса (или admin через bypass на портале). Owner
// автоматически имеет доступ ко всему, гранты для него не нужны —
// они только для «других».
func (h *AccessGrantHandler) authorizeResourceOwner(w http.ResponseWriter, r *http.Request, resourceType string, resourceID uuid.UUID) (uuid.UUID, bool) {
	uid, ok := userIDFromHeader(r)
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return uuid.Nil, false
	}
	var owner uuid.UUID
	switch resourceType {
	case "test":
		t, err := h.testRepo.Get(r.Context(), resourceID)
		if err != nil {
			writeRepoError(w, r, err, "get test")
			return uuid.Nil, false
		}
		owner = t.OwnerUserID
	case "course":
		c, err := h.courseRepo.Get(r.Context(), resourceID)
		if err != nil {
			writeRepoError(w, r, err, "get course")
			return uuid.Nil, false
		}
		owner = c.OwnerUserID
	default:
		writeError(w, http.StatusBadRequest, "resource_type must be test|course")
		return uuid.Nil, false
	}
	if owner != uid {
		writeError(w, http.StatusForbidden, "only owner can manage access")
		return uuid.Nil, false
	}
	return uid, true
}

// List — GET /access/{resourceType}/{resourceId}.
func (h *AccessGrantHandler) List(w http.ResponseWriter, r *http.Request) {
	resourceType := strings.ToLower(chi.URLParam(r, "resourceType"))
	resourceID, err := parseUUID(chi.URLParam(r, "resourceId"))
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid resource id")
		return
	}
	if _, ok := h.authorizeResourceOwner(w, r, resourceType, resourceID); !ok {
		return
	}
	items, err := h.repo.List(r.Context(), resourceType, resourceID)
	if err != nil {
		writeRepoError(w, r, err, "list access grants")
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"items": items})
}

// Create — POST /access/{resourceType}/{resourceId} {subject_type, subject_id, can_manage}.
func (h *AccessGrantHandler) Create(w http.ResponseWriter, r *http.Request) {
	resourceType := strings.ToLower(chi.URLParam(r, "resourceType"))
	resourceID, err := parseUUID(chi.URLParam(r, "resourceId"))
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid resource id")
		return
	}
	uid, ok := h.authorizeResourceOwner(w, r, resourceType, resourceID)
	if !ok {
		return
	}
	var req model.CreateAccessGrantRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid body")
		return
	}
	if req.SubjectType != "user" && req.SubjectType != "role" &&
		req.SubjectType != "department" && req.SubjectType != "position" &&
		req.SubjectType != "public" {
		writeError(w, http.StatusBadRequest, "subject_type must be user|role|department|position|public")
		return
	}
	g, err := h.repo.Create(r.Context(), resourceType, resourceID, req, uid)
	if err != nil {
		writeRepoError(w, r, err, "create access grant")
		return
	}
	writeJSON(w, http.StatusCreated, g)
}

// Delete — DELETE /access/{resourceType}/{resourceId}/grants/{grantId}.
// resourceType/resourceId дублируются в URL'е для удобства проверки прав
// (handler читает их из path-params, не из body).
func (h *AccessGrantHandler) Delete(w http.ResponseWriter, r *http.Request) {
	resourceType := strings.ToLower(chi.URLParam(r, "resourceType"))
	resourceID, err := parseUUID(chi.URLParam(r, "resourceId"))
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid resource id")
		return
	}
	grantID, err := parseUUID(chi.URLParam(r, "grantId"))
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid grant id")
		return
	}
	if _, ok := h.authorizeResourceOwner(w, r, resourceType, resourceID); !ok {
		return
	}
	// Дополнительно проверим, что grant действительно принадлежит этому
	// ресурсу — иначе owner ресурса A мог бы удалить грант ресурса B
	// просто подсунув grantId.
	g, err := h.repo.Get(r.Context(), grantID)
	if err != nil {
		writeRepoError(w, r, err, "get grant")
		return
	}
	if g.ResourceType != resourceType || g.ResourceID != resourceID {
		writeError(w, http.StatusBadRequest, "grant does not belong to this resource")
		return
	}
	if err := h.repo.Delete(r.Context(), grantID); err != nil {
		writeRepoError(w, r, err, "delete grant")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}