package api

import (
	"cmp"
	"net/http"
	"slices"
)

// handleChats lists the bot's chats, ordered by id. The bot talks to
// people only one to one, so its chats are its contacts, and a chat's
// id is its contact's.
func (h *handlers) handleChats() http.HandlerFunc {
	type chat struct {
		ID             int64  `json:"id"`
		DisplayName    string `json:"display_name"`
		ContactDeleted bool   `json:"contact_deleted"`
	}

	type response struct {
		Chats []chat `json:"chats"`
	}

	return func(w http.ResponseWriter, r *http.Request) {
		contacts, err := h.client.Contacts(r.Context(), h.userID)
		if err != nil {
			h.log.Error("listing the chats", "error", err)
			h.respondError(w, http.StatusInternalServerError,
				"the chats could not be read")

			return
		}

		chats := make([]chat, 0, len(contacts))
		for _, c := range contacts {
			chats = append(chats, chat{
				ID:             c.ContactID,
				DisplayName:    c.Profile.DisplayName,
				ContactDeleted: c.Deleted(),
			})
		}

		slices.SortFunc(chats, func(a, b chat) int { return cmp.Compare(a.ID, b.ID) })

		h.respond(w, http.StatusOK, response{Chats: chats})
	}
}