package setup

import (
	"context"
	"errors"
	"fmt"
	"log/slog"

	"github.com/dariuszjaniak/warp/server/internal/appservice"
	"github.com/dariuszjaniak/warp/server/internal/config"
	"github.com/dariuszjaniak/warp/server/internal/matrix/event"
	"github.com/dariuszjaniak/warp/server/internal/roomserver"
	"github.com/dariuszjaniak/warp/server/internal/userapi"
)

// loadAppServices reads the registration files the config names.
func loadAppServices(cfg *config.Config) (*appservice.Registry, error) {
	regs := make([]*appservice.Registration, 0, len(cfg.AppService.ConfigFiles))
	for _, path := range cfg.AppService.ConfigFiles {
		reg, err := appservice.LoadRegistration(path, cfg.Global.ServerName)
		if err != nil {
			return nil, err
		}
		regs = append(regs, reg)
	}
	return appservice.NewRegistry(cfg.Global.ServerName, regs)
}

// ensureAppServiceSenders creates the sender user of every application
// service that does not have one yet. A service acts as its sender
// whenever it does not ask to act as somebody else, so the account has to
// exist before the first request; it has no password, because nobody logs
// in as it.
func ensureAppServiceSenders(ctx context.Context, users *userapi.API, registry *appservice.Registry, log *slog.Logger) error {
	for _, svc := range registry.Services() {
		_, err := users.CreateAccount(ctx, userapi.NewAccountRequest{Localpart: svc.SenderLocalpart})
		switch {
		case err == nil:
			log.Info("created the sender of an application service", "appservice", svc.ID, "user_id", svc.SenderUserID())
		case errors.Is(err, userapi.ErrUserExists):
		default:
			return fmt.Errorf("create the sender of application service %q: %w", svc.ID, err)
		}
	}
	return nil
}

// roomLeaver is the roomserver's side of a deactivation: the user leaves
// every room they are in, rejects every invite and withdraws every knock.
// A room that refuses is logged and skipped; the account is already
// deactivated, and one stuck room must not keep the user in all the
// others.
type roomLeaver struct {
	rooms *roomserver.API
	log   *slog.Logger
}

// AccountDeactivated implements userapi.AccountObserver.
func (l roomLeaver) AccountDeactivated(ctx context.Context, localpart string) {
	userID := "@" + localpart + ":" + l.rooms.ServerName()
	memberships, err := l.rooms.UserMemberships(ctx, userID,
		[]string{event.MembershipJoin, event.MembershipInvite, event.MembershipKnock})
	if err != nil {
		l.log.Error("could not list the rooms of a deactivated user", "user_id", userID, "error", err)
		return
	}
	for _, m := range memberships {
		if err := l.rooms.LeaveRoom(ctx, m.RoomID, userID, ""); err != nil {
			l.log.Warn("a deactivated user could not leave a room", "user_id", userID, "room_id", m.RoomID, "error", err)
		}
	}
}