package api

import (
	"errors"
	"net/http"

	"milkway/internal/models"
	"milkway/internal/store"
)

// validateSubscriptionRefs verifies the referenced product and customer both
// belong to the org, and that the morning/evening quantities are whole numbers
// when the product is sold by count (piece/dozen/packet). It returns false (after
// writing an error) on any problem.
func (s *Server) validateSubscriptionRefs(w http.ResponseWriter, r *http.Request, orgID int64, sub models.Subscription) bool {
	if _, err := s.store.GetCustomer(r.Context(), orgID, sub.CustomerID); err != nil {
		if errors.Is(err, store.ErrNotFound) {
			writeError(w, http.StatusBadRequest, "customer not found")
			return false
		}
		internalError(w, err)
		return false
	}
	product, err := s.store.GetProduct(r.Context(), orgID, sub.ProductID)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			writeError(w, http.StatusBadRequest, "product not found")
			return false
		}
		internalError(w, err)
		return false
	}
	if integerUnits[product.Unit] {
		if !isIntegerQty(sub.MorningQty) {
			writeFieldError(w, http.StatusBadRequest, CodeValidation,
				"morning_qty must be a whole number for unit "+product.Unit, "morning_qty")
			return false
		}
		if !isIntegerQty(sub.EveningQty) {
			writeFieldError(w, http.StatusBadRequest, CodeValidation,
				"evening_qty must be a whole number for unit "+product.Unit, "evening_qty")
			return false
		}
	}
	return true
}

func (s *Server) listSubscriptions(w http.ResponseWriter, r *http.Request) {
	orgID, ok := s.requireOrg(w, r)
	if !ok {
		return
	}
	customerID := queryCustomerID(r)
	// By default only active subscriptions are returned; ?all=true includes inactive.
	activeOnly := r.URL.Query().Get("all") != "true"
	q, limit, offset := pageParams(r)
	subs, total, err := s.store.ListSubscriptionsPage(r.Context(), orgID, customerID, activeOnly, q, limit, offset)
	if handleStoreErr(w, err) {
		return
	}
	writeJSON(w, http.StatusOK, models.Page[models.Subscription]{Items: subs, Total: total, Limit: limit, Offset: offset})
}

func (s *Server) getSubscription(w http.ResponseWriter, r *http.Request) {
	orgID, ok := s.requireOrg(w, r)
	if !ok {
		return
	}
	id, ok := pathID(w, r)
	if !ok {
		return
	}
	sub, err := s.store.GetSubscription(r.Context(), orgID, id)
	if handleStoreErr(w, err) {
		return
	}
	writeJSON(w, http.StatusOK, sub)
}

// validateSubscriptionBody validates the user-supplied fields common to create
// and update via the struct validator (gt=0 ids, gte=0 quantities, days_of_week
// in 0..6, optional YYYY-MM-DD start_date). It does not touch ID/OrgID (callers
// set those from trusted input).
func validateSubscriptionBody(w http.ResponseWriter, sub models.Subscription) bool {
	return validateStruct(w, sub)
}

func (s *Server) createSubscription(w http.ResponseWriter, r *http.Request) {
	orgID, ok := s.requireOrg(w, r)
	if !ok {
		return
	}
	var sub models.Subscription
	if !decodeJSON(w, r, &sub) {
		return
	}
	if !validateSubscriptionBody(w, sub) {
		return
	}
	if !s.validateSubscriptionRefs(w, r, orgID, sub) {
		return
	}
	// A standing order with no days never delivers; default to every day.
	if len(sub.DaysOfWeek) == 0 {
		sub.DaysOfWeek = []int{0, 1, 2, 3, 4, 5, 6}
	}
	sub.OrgID = orgID
	sub.Active = true // new subscriptions are active by default
	created, err := s.store.CreateSubscription(r.Context(), sub)
	if handleStoreErr(w, err) {
		return
	}
	s.audit(r, "create", "subscription", created.ID)
	writeJSON(w, http.StatusCreated, created)
}

func (s *Server) updateSubscription(w http.ResponseWriter, r *http.Request) {
	orgID, ok := s.requireOrg(w, r)
	if !ok {
		return
	}
	id, ok := pathID(w, r)
	if !ok {
		return
	}
	var sub models.Subscription
	if !decodeJSON(w, r, &sub) {
		return
	}
	if !validateSubscriptionBody(w, sub) {
		return
	}
	if !s.validateSubscriptionRefs(w, r, orgID, sub) {
		return
	}
	if sub.DaysOfWeek == nil {
		sub.DaysOfWeek = []int{}
	}
	sub.ID = id
	sub.OrgID = orgID
	updated, err := s.store.UpdateSubscription(r.Context(), sub)
	if handleStoreErr(w, err) {
		return
	}
	s.audit(r, "update", "subscription", updated.ID)
	writeJSON(w, http.StatusOK, updated)
}

func (s *Server) deleteSubscription(w http.ResponseWriter, r *http.Request) {
	orgID, ok := s.requireOrg(w, r)
	if !ok {
		return
	}
	id, ok := pathID(w, r)
	if !ok {
		return
	}
	if handleStoreErr(w, s.store.DeleteSubscription(r.Context(), orgID, id)) {
		return
	}
	s.audit(r, "delete", "subscription", id)
	w.WriteHeader(http.StatusNoContent)
}