package api

import (
	"encoding/json"
	"errors"
	"net/http"

	"github.com/alchemistkay/guestguard/internal/domain"
	"github.com/alchemistkay/guestguard/internal/storage"
)

type guestHandler struct {
	guests   *storage.GuestRepo
	events   *storage.EventRepo
	collabs  *storage.CollaboratorRepo
	enforcer *tierEnforcer
}

type createGuestRequest struct {
	Name         string  `json:"name"`
	Email        *string `json:"email"`
	Phone        *string `json:"phone"`
	PlusOnes     int     `json:"plus_ones"`
	DietaryNotes *string `json:"dietary_notes"`
	TableNumber  *int    `json:"table_number"`
}

func (h *guestHandler) create(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}
	eventID, ok := parseIDParam(w, r, "id")
	if !ok {
		return
	}
	if _, _, ok := requireRole(w, r, h.events, h.collabs, eventID, hostID, domain.RoleEditor); !ok {
		return
	}
	if !h.enforcer.allowGuestCreate(w, r, hostID, eventID) {
		return
	}

	var req createGuestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	if req.Name == "" {
		writeError(w, http.StatusBadRequest, "name is required")
		return
	}
	if req.PlusOnes < 0 {
		writeError(w, http.StatusBadRequest, "plus_ones must be >= 0")
		return
	}

	g, err := h.guests.Create(r.Context(), storage.CreateGuestParams{
		EventID:      eventID,
		Name:         req.Name,
		Email:        req.Email,
		Phone:        req.Phone,
		PlusOnes:     req.PlusOnes,
		DietaryNotes: req.DietaryNotes,
		TableNumber:  req.TableNumber,
	})
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to create guest")
		return
	}
	writeJSON(w, http.StatusCreated, g)
}

type updateGuestRequest struct {
	Name     *string `json:"name"`
	Email    *string `json:"email"`
	Phone    *string `json:"phone"`
	PlusOnes *int    `json:"plus_ones"`
}

// PATCH /events/{id}/guests/{guest_id} — patch a guest's contact info.
// Fields omitted from the body are left untouched. Empty strings for
// email/phone clear those columns to NULL.
func (h *guestHandler) update(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}
	eventID, ok := parseIDParam(w, r, "id")
	if !ok {
		return
	}
	guestID, ok := parseIDParam(w, r, "guest_id")
	if !ok {
		return
	}
	if _, _, ok := requireRole(w, r, h.events, h.collabs, eventID, hostID, domain.RoleEditor); !ok {
		return
	}

	var req updateGuestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	if req.Name != nil && *req.Name == "" {
		writeError(w, http.StatusBadRequest, "name cannot be empty")
		return
	}
	if req.PlusOnes != nil && *req.PlusOnes < 0 {
		writeError(w, http.StatusBadRequest, "plus_ones must be >= 0")
		return
	}

	g, err := h.guests.Update(r.Context(), eventID, guestID, storage.UpdateGuestParams{
		Name:     req.Name,
		Email:    req.Email,
		Phone:    req.Phone,
		PlusOnes: req.PlusOnes,
	})
	if err != nil {
		if errors.Is(err, domain.ErrGuestNotFound) {
			writeError(w, http.StatusNotFound, "guest not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "failed to update guest")
		return
	}
	writeJSON(w, http.StatusOK, g)
}

// DELETE /events/{id}/guests/{guest_id} — remove a guest from an event.
// Cascade-deletes their token, rsvp, access logs, notifications.
func (h *guestHandler) delete(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}
	eventID, ok := parseIDParam(w, r, "id")
	if !ok {
		return
	}
	guestID, ok := parseIDParam(w, r, "guest_id")
	if !ok {
		return
	}
	if _, _, ok := requireRole(w, r, h.events, h.collabs, eventID, hostID, domain.RoleEditor); !ok {
		return
	}
	if err := h.guests.Delete(r.Context(), eventID, guestID); err != nil {
		if errors.Is(err, domain.ErrGuestNotFound) {
			writeError(w, http.StatusNotFound, "guest not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "failed to delete guest")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (h *guestHandler) list(w http.ResponseWriter, r *http.Request) {
	hostID, ok := hostFromContext(w, r)
	if !ok {
		return
	}
	eventID, ok := parseIDParam(w, r, "id")
	if !ok {
		return
	}
	// Listing guests is viewer+. Editing is gated separately at the
	// PATCH/POST/DELETE call sites.
	if _, _, ok := requireRole(w, r, h.events, h.collabs, eventID, hostID, domain.RoleViewer); !ok {
		return
	}

	q := r.URL.Query()
	limit := atoiOr(q.Get("limit"), 100)
	offset := atoiOr(q.Get("offset"), 0)

	guests, err := h.guests.ListByEventWithRSVP(r.Context(), eventID, limit, offset)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list guests")
		return
	}
	if guests == nil {
		guests = []*storage.GuestWithRSVP{}
	}

	stats := struct {
		Total     int `json:"total"`
		Attending int `json:"attending"`
		Declined  int `json:"declined"`
		Maybe     int `json:"maybe"`
		Pending   int `json:"pending"`
	}{Total: len(guests)}
	for _, g := range guests {
		switch {
		case g.RSVPResponse == nil:
			stats.Pending++
		case *g.RSVPResponse == string(domain.RSVPAttending):
			stats.Attending++
		case *g.RSVPResponse == string(domain.RSVPDeclined):
			stats.Declined++
		case *g.RSVPResponse == string(domain.RSVPMaybe):
			stats.Maybe++
		}
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"guests": guests,
		"stats":  stats,
		"limit":  limit,
		"offset": offset,
	})
}