// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package timeline

import (
	"context"
	"errors"
	"fmt"

	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
	"github.com/superseriousbusiness/gotosocial/internal/db"
	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
	"github.com/superseriousbusiness/gotosocial/internal/log"
	"github.com/superseriousbusiness/gotosocial/internal/oauth"
	"github.com/superseriousbusiness/gotosocial/internal/util"
)

func (p *Processor) NotificationsGet(ctx context.Context, authed *oauth.Auth, maxID string, sinceID string, minID string, limit int, excludeTypes []string) (*apimodel.PageableResponse, gtserror.WithCode) {
	notifs, err := p.state.DB.GetAccountNotifications(ctx, authed.Account.ID, maxID, sinceID, minID, limit, excludeTypes)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		err = fmt.Errorf("NotificationsGet: db error getting notifications: %w", err)
		return nil, gtserror.NewErrorInternalError(err)
	}

	count := len(notifs)
	if count == 0 {
		return util.EmptyPageableResponse(), nil
	}

	var (
		items          = make([]interface{}, 0, count)
		nextMaxIDValue string
		prevMinIDValue string
	)

	for i, n := range notifs {
		// Set next + prev values before filtering and API
		// converting, so caller can still page properly.
		if i == count-1 {
			nextMaxIDValue = n.ID
		}

		if i == 0 {
			prevMinIDValue = n.ID
		}

		visible, err := p.notifVisible(ctx, n, authed.Account)
		if err != nil {
			log.Debugf(ctx, "skipping notification %s because of an error checking notification visibility: %v", n.ID, err)
			continue
		}

		if !visible {
			continue
		}

		item, err := p.converter.NotificationToAPINotification(ctx, n)
		if err != nil {
			log.Debugf(ctx, "skipping notification %s because it couldn't be converted to its api representation: %s", n.ID, err)
			continue
		}

		items = append(items, item)
	}

	return util.PackagePageableResponse(util.PageableResponseParams{
		Items:          items,
		Path:           "api/v1/notifications",
		NextMaxIDValue: nextMaxIDValue,
		PrevMinIDValue: prevMinIDValue,
		Limit:          limit,
	})
}

func (p *Processor) NotificationGet(ctx context.Context, account *gtsmodel.Account, targetNotifID string) (*apimodel.Notification, gtserror.WithCode) {
	notif, err := p.state.DB.GetNotificationByID(ctx, targetNotifID)
	if err != nil {
		if errors.Is(err, db.ErrNoEntries) {
			return nil, gtserror.NewErrorNotFound(err)
		}

		// Real error.
		return nil, gtserror.NewErrorInternalError(err)
	}

	if notifTargetAccountID := notif.TargetAccountID; notifTargetAccountID != account.ID {
		err = fmt.Errorf("account %s does not have permission to view notification belong to account %s", account.ID, notifTargetAccountID)
		return nil, gtserror.NewErrorNotFound(err)
	}

	apiNotif, err := p.converter.NotificationToAPINotification(ctx, notif)
	if err != nil {
		if errors.Is(err, db.ErrNoEntries) {
			return nil, gtserror.NewErrorNotFound(err)
		}

		// Real error.
		return nil, gtserror.NewErrorInternalError(err)
	}

	return apiNotif, nil
}

func (p *Processor) NotificationsClear(ctx context.Context, authed *oauth.Auth) gtserror.WithCode {
	// Delete all notifications of all types that target the authorized account.
	if err := p.state.DB.DeleteNotifications(ctx, nil, authed.Account.ID, ""); err != nil && !errors.Is(err, db.ErrNoEntries) {
		return gtserror.NewErrorInternalError(err)
	}

	return nil
}

func (p *Processor) notifVisible(
	ctx context.Context,
	n *gtsmodel.Notification,
	acct *gtsmodel.Account,
) (bool, error) {
	// If account is set, ensure it's
	// visible to notif target.
	if n.OriginAccount != nil {
		// If this is a new local account sign-up,
		// skip normal visibility checking because
		// origin account won't be confirmed yet.
		if n.NotificationType == gtsmodel.NotificationSignup {
			return true, nil
		}

		visible, err := p.filter.AccountVisible(ctx, acct, n.OriginAccount)
		if err != nil {
			return false, err
		}

		if !visible {
			return false, nil
		}
	}

	// If status is set, ensure it's
	// visible to notif target.
	if n.Status != nil {
		visible, err := p.filter.StatusVisible(ctx, acct, n.Status)
		if err != nil {
			return false, err
		}

		if !visible {
			return false, nil
		}
	}

	return true, nil
}