// 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 processing

import (
	"context"
	"errors"
	"fmt"

	"github.com/superseriousbusiness/gotosocial/internal/config"
	"github.com/superseriousbusiness/gotosocial/internal/db"
	"github.com/superseriousbusiness/gotosocial/internal/email"
	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
	"github.com/superseriousbusiness/gotosocial/internal/id"
	"github.com/superseriousbusiness/gotosocial/internal/stream"
)

func (p *Processor) notifyStatus(ctx context.Context, status *gtsmodel.Status) error {
	// if there are no mentions in this status then just bail
	if len(status.MentionIDs) == 0 {
		return nil
	}

	if status.Mentions == nil {
		// there are mentions but they're not fully populated on the status yet so do this
		mentions, err := p.state.DB.GetMentions(ctx, status.MentionIDs)
		if err != nil {
			return fmt.Errorf("notifyStatus: error getting mentions for status %s from the db: %s", status.ID, err)
		}

		status.Mentions = mentions
	}

	// now we have mentions as full gtsmodel.Mention structs on the status we can continue
	for _, m := range status.Mentions {
		// make sure this is a local account, otherwise we don't need to create a notification for it
		if m.TargetAccount == nil {
			a, err := p.state.DB.GetAccountByID(ctx, m.TargetAccountID)
			if err != nil {
				// we don't have the account or there's been an error
				return fmt.Errorf("notifyStatus: error getting account with id %s from the db: %s", m.TargetAccountID, err)
			}
			m.TargetAccount = a
		}
		if m.TargetAccount.Domain != "" {
			// not a local account so skip it
			continue
		}

		// make sure a notif doesn't already exist for this mention
		if err := p.state.DB.GetWhere(ctx, []db.Where{
			{Key: "notification_type", Value: gtsmodel.NotificationMention},
			{Key: "target_account_id", Value: m.TargetAccountID},
			{Key: "origin_account_id", Value: m.OriginAccountID},
			{Key: "status_id", Value: m.StatusID},
		}, &gtsmodel.Notification{}); err == nil {
			// notification exists already so just continue
			continue
		} else if err != db.ErrNoEntries {
			// there's a real error in the db
			return fmt.Errorf("notifyStatus: error checking existence of notification for mention with id %s : %s", m.ID, err)
		}

		// if we've reached this point we know the mention is for a local account, and the notification doesn't exist, so create it
		notif := &gtsmodel.Notification{
			ID:               id.NewULID(),
			NotificationType: gtsmodel.NotificationMention,
			TargetAccountID:  m.TargetAccountID,
			TargetAccount:    m.TargetAccount,
			OriginAccountID:  status.AccountID,
			OriginAccount:    status.Account,
			StatusID:         status.ID,
			Status:           status,
		}

		if err := p.state.DB.PutNotification(ctx, notif); err != nil {
			return fmt.Errorf("notifyStatus: error putting notification in database: %s", err)
		}

		// now stream the notification to the user
		apiNotif, err := p.tc.NotificationToAPINotification(ctx, notif)
		if err != nil {
			return fmt.Errorf("notifyStatus: error converting notification to api representation: %s", err)
		}

		if err := p.stream.Notify(apiNotif, m.TargetAccount); err != nil {
			return fmt.Errorf("notifyStatus: error streaming notification to account: %s", err)
		}
	}

	return nil
}

func (p *Processor) notifyFollowRequest(ctx context.Context, followRequest *gtsmodel.FollowRequest) error {
	// make sure we have the target account pinned on the follow request
	if followRequest.TargetAccount == nil {
		a, err := p.state.DB.GetAccountByID(ctx, followRequest.TargetAccountID)
		if err != nil {
			return err
		}
		followRequest.TargetAccount = a
	}
	targetAccount := followRequest.TargetAccount

	// return if this isn't a local account
	if targetAccount.Domain != "" {
		// this isn't a local account so we've got nothing to do here
		return nil
	}

	notif := &gtsmodel.Notification{
		ID:               id.NewULID(),
		NotificationType: gtsmodel.NotificationFollowRequest,
		TargetAccountID:  followRequest.TargetAccountID,
		OriginAccountID:  followRequest.AccountID,
	}

	if err := p.state.DB.PutNotification(ctx, notif); err != nil {
		return fmt.Errorf("notifyFollowRequest: error putting notification in database: %s", err)
	}

	// now stream the notification to the user
	apiNotif, err := p.tc.NotificationToAPINotification(ctx, notif)
	if err != nil {
		return fmt.Errorf("notifyStatus: error converting notification to api representation: %s", err)
	}

	if err := p.stream.Notify(apiNotif, targetAccount); err != nil {
		return fmt.Errorf("notifyStatus: error streaming notification to account: %s", err)
	}

	return nil
}

func (p *Processor) notifyFollow(ctx context.Context, follow *gtsmodel.Follow, targetAccount *gtsmodel.Account) error {
	// return if this isn't a local account
	if targetAccount.Domain != "" {
		return nil
	}

	// first remove the follow request notification
	if err := p.state.DB.DeleteWhere(ctx, []db.Where{
		{Key: "notification_type", Value: gtsmodel.NotificationFollowRequest},
		{Key: "target_account_id", Value: follow.TargetAccountID},
		{Key: "origin_account_id", Value: follow.AccountID},
	}, &gtsmodel.Notification{}); err != nil {
		return fmt.Errorf("notifyFollow: error removing old follow request notification from database: %s", err)
	}

	// now create the new follow notification
	notif := &gtsmodel.Notification{
		ID:               id.NewULID(),
		NotificationType: gtsmodel.NotificationFollow,
		TargetAccountID:  follow.TargetAccountID,
		TargetAccount:    follow.TargetAccount,
		OriginAccountID:  follow.AccountID,
		OriginAccount:    follow.Account,
	}
	if err := p.state.DB.PutNotification(ctx, notif); err != nil {
		return fmt.Errorf("notifyFollow: error putting notification in database: %s", err)
	}

	// now stream the notification to the user
	apiNotif, err := p.tc.NotificationToAPINotification(ctx, notif)
	if err != nil {
		return fmt.Errorf("notifyStatus: error converting notification to api representation: %s", err)
	}

	if err := p.stream.Notify(apiNotif, targetAccount); err != nil {
		return fmt.Errorf("notifyStatus: error streaming notification to account: %s", err)
	}

	return nil
}

func (p *Processor) notifyFave(ctx context.Context, fave *gtsmodel.StatusFave) error {
	// ignore self-faves
	if fave.TargetAccountID == fave.AccountID {
		return nil
	}

	if fave.TargetAccount == nil {
		a, err := p.state.DB.GetAccountByID(ctx, fave.TargetAccountID)
		if err != nil {
			return err
		}
		fave.TargetAccount = a
	}
	targetAccount := fave.TargetAccount

	// just return if target isn't a local account
	if targetAccount.Domain != "" {
		return nil
	}

	notif := &gtsmodel.Notification{
		ID:               id.NewULID(),
		NotificationType: gtsmodel.NotificationFave,
		TargetAccountID:  fave.TargetAccountID,
		TargetAccount:    fave.TargetAccount,
		OriginAccountID:  fave.AccountID,
		OriginAccount:    fave.Account,
		StatusID:         fave.StatusID,
		Status:           fave.Status,
	}

	if err := p.state.DB.PutNotification(ctx, notif); err != nil {
		return fmt.Errorf("notifyFave: error putting notification in database: %s", err)
	}

	// now stream the notification to the user
	apiNotif, err := p.tc.NotificationToAPINotification(ctx, notif)
	if err != nil {
		return fmt.Errorf("notifyStatus: error converting notification to api representation: %s", err)
	}

	if err := p.stream.Notify(apiNotif, targetAccount); err != nil {
		return fmt.Errorf("notifyStatus: error streaming notification to account: %s", err)
	}

	return nil
}

func (p *Processor) notifyAnnounce(ctx context.Context, status *gtsmodel.Status) error {
	if status.BoostOfID == "" {
		// not a boost, nothing to do
		return nil
	}

	if status.BoostOf == nil {
		boostedStatus, err := p.state.DB.GetStatusByID(ctx, status.BoostOfID)
		if err != nil {
			return fmt.Errorf("notifyAnnounce: error getting status with id %s: %s", status.BoostOfID, err)
		}
		status.BoostOf = boostedStatus
	}

	if status.BoostOfAccount == nil {
		boostedAcct, err := p.state.DB.GetAccountByID(ctx, status.BoostOfAccountID)
		if err != nil {
			return fmt.Errorf("notifyAnnounce: error getting account with id %s: %s", status.BoostOfAccountID, err)
		}
		status.BoostOf.Account = boostedAcct
		status.BoostOfAccount = boostedAcct
	}

	if status.BoostOfAccount.Domain != "" {
		// remote account, nothing to do
		return nil
	}

	if status.BoostOfAccountID == status.AccountID {
		// it's a self boost, nothing to do
		return nil
	}

	// make sure a notif doesn't already exist for this announce
	err := p.state.DB.GetWhere(ctx, []db.Where{
		{Key: "notification_type", Value: gtsmodel.NotificationReblog},
		{Key: "target_account_id", Value: status.BoostOfAccountID},
		{Key: "origin_account_id", Value: status.AccountID},
		{Key: "status_id", Value: status.ID},
	}, &gtsmodel.Notification{})
	if err == nil {
		// notification exists already so just bail
		return nil
	}

	// now create the new reblog notification
	notif := &gtsmodel.Notification{
		ID:               id.NewULID(),
		NotificationType: gtsmodel.NotificationReblog,
		TargetAccountID:  status.BoostOfAccountID,
		TargetAccount:    status.BoostOfAccount,
		OriginAccountID:  status.AccountID,
		OriginAccount:    status.Account,
		StatusID:         status.ID,
		Status:           status,
	}

	if err := p.state.DB.PutNotification(ctx, notif); err != nil {
		return fmt.Errorf("notifyAnnounce: error putting notification in database: %s", err)
	}

	// now stream the notification to the user
	apiNotif, err := p.tc.NotificationToAPINotification(ctx, notif)
	if err != nil {
		return fmt.Errorf("notifyStatus: error converting notification to api representation: %s", err)
	}

	if err := p.stream.Notify(apiNotif, status.BoostOfAccount); err != nil {
		return fmt.Errorf("notifyStatus: error streaming notification to account: %s", err)
	}

	return nil
}

func (p *Processor) notifyReport(ctx context.Context, report *gtsmodel.Report) error {
	instance, err := p.state.DB.GetInstance(ctx, config.GetHost())
	if err != nil {
		return fmt.Errorf("notifyReport: error getting instance: %w", err)
	}

	toAddresses, err := p.state.DB.GetInstanceModeratorAddresses(ctx)
	if err != nil {
		if errors.Is(err, db.ErrNoEntries) {
			// No registered moderator addresses.
			return nil
		}
		return fmt.Errorf("notifyReport: error getting instance moderator addresses: %w", err)
	}

	if report.Account == nil {
		report.Account, err = p.state.DB.GetAccountByID(ctx, report.AccountID)
		if err != nil {
			return fmt.Errorf("notifyReport: error getting report account: %w", err)
		}
	}

	if report.TargetAccount == nil {
		report.TargetAccount, err = p.state.DB.GetAccountByID(ctx, report.TargetAccountID)
		if err != nil {
			return fmt.Errorf("notifyReport: error getting report target account: %w", err)
		}
	}

	reportData := email.NewReportData{
		InstanceURL:        instance.URI,
		InstanceName:       instance.Title,
		ReportURL:          instance.URI + "/settings/admin/reports/" + report.ID,
		ReportDomain:       report.Account.Domain,
		ReportTargetDomain: report.TargetAccount.Domain,
	}

	if err := p.emailSender.SendNewReportEmail(toAddresses, reportData); err != nil {
		return fmt.Errorf("notifyReport: error emailing instance moderators: %w", err)
	}

	return nil
}

func (p *Processor) notifyReportClosed(ctx context.Context, report *gtsmodel.Report) error {
	user, err := p.state.DB.GetUserByAccountID(ctx, report.Account.ID)
	if err != nil {
		return fmt.Errorf("notifyReportClosed: db error getting user: %w", err)
	}

	if user.ConfirmedAt.IsZero() || !*user.Approved || *user.Disabled || user.Email == "" {
		// Only email users who:
		// - are confirmed
		// - are approved
		// - are not disabled
		// - have an email address
		return nil
	}

	instance, err := p.state.DB.GetInstance(ctx, config.GetHost())
	if err != nil {
		return fmt.Errorf("notifyReportClosed: db error getting instance: %w", err)
	}

	if report.Account == nil {
		report.Account, err = p.state.DB.GetAccountByID(ctx, report.AccountID)
		if err != nil {
			return fmt.Errorf("notifyReportClosed: error getting report account: %w", err)
		}
	}

	if report.TargetAccount == nil {
		report.TargetAccount, err = p.state.DB.GetAccountByID(ctx, report.TargetAccountID)
		if err != nil {
			return fmt.Errorf("notifyReportClosed: error getting report target account: %w", err)
		}
	}

	reportClosedData := email.ReportClosedData{
		Username:             report.Account.Username,
		InstanceURL:          instance.URI,
		InstanceName:         instance.Title,
		ReportTargetUsername: report.TargetAccount.Username,
		ReportTargetDomain:   report.TargetAccount.Domain,
		ActionTakenComment:   report.ActionTaken,
	}

	return p.emailSender.SendReportClosedEmail(user.Email, reportClosedData)
}

// timelineStatus processes the given new status and inserts it into
// the HOME timelines of accounts that follow the status author.
func (p *Processor) timelineStatus(ctx context.Context, status *gtsmodel.Status) error {
	if status.Account == nil {
		// ensure status fully populated (including account)
		if err := p.state.DB.PopulateStatus(ctx, status); err != nil {
			return fmt.Errorf("timelineStatus: error populating status with id %s: %w", status.ID, err)
		}
	}

	// get local followers of the account that posted the status
	follows, err := p.state.DB.GetAccountLocalFollowers(ctx, status.AccountID)
	if err != nil {
		return fmt.Errorf("timelineStatus: error getting followers for account id %s: %w", status.AccountID, err)
	}

	// If the poster is also local, add a fake entry for them
	// so they can see their own status in their timeline.
	if status.Account.IsLocal() {
		follows = append(follows, &gtsmodel.Follow{
			AccountID: status.AccountID,
			Account:   status.Account,
		})
	}

	var errs gtserror.MultiError

	for _, follow := range follows {
		// Timeline the status for each local following account.
		if err := p.timelineStatusForAccount(ctx, follow.Account, status); err != nil {
			errs.Append(err)
		}
	}

	if len(errs) != 0 {
		return fmt.Errorf("timelineStatus: one or more errors timelining statuses: %w", errs.Combine())
	}

	return nil
}

// timelineStatusForAccount puts the given status in the HOME timeline
// of the account with given accountID, if it's hometimelineable.
//
// If the status was inserted into the home timeline of the given account,
// it will also be streamed via websockets to the user.
func (p *Processor) timelineStatusForAccount(ctx context.Context, account *gtsmodel.Account, status *gtsmodel.Status) error {
	// make sure the status is timelineable
	if timelineable, err := p.filter.StatusHomeTimelineable(ctx, account, status); err != nil {
		return fmt.Errorf("timelineStatusForAccount: error getting timelineability for status for timeline with id %s: %w", account.ID, err)
	} else if !timelineable {
		return nil
	}

	// stick the status in the timeline for the account and then immediately prepare it so they can see it right away
	if inserted, err := p.statusTimelines.IngestAndPrepare(ctx, status, account.ID); err != nil {
		return fmt.Errorf("timelineStatusForAccount: error ingesting status %s: %w", status.ID, err)
	} else if !inserted {
		return nil
	}

	// the status was inserted so stream it to the user
	apiStatus, err := p.tc.StatusToAPIStatus(ctx, status, account)
	if err != nil {
		return fmt.Errorf("timelineStatusForAccount: error converting status %s to frontend representation: %w", status.ID, err)
	}

	if err := p.stream.Update(apiStatus, account, stream.TimelineHome); err != nil {
		return fmt.Errorf("timelineStatusForAccount: error streaming update for status %s: %w", status.ID, err)
	}

	return nil
}

// deleteStatusFromTimelines completely removes the given status from all timelines.
// It will also stream deletion of the status to all open streams.
func (p *Processor) deleteStatusFromTimelines(ctx context.Context, status *gtsmodel.Status) error {
	if err := p.statusTimelines.WipeItemFromAllTimelines(ctx, status.ID); err != nil {
		return err
	}

	return p.stream.Delete(status.ID)
}

// wipeStatus contains common logic used to totally delete a status
// + all its attachments, notifications, boosts, and timeline entries.
func (p *Processor) wipeStatus(ctx context.Context, statusToDelete *gtsmodel.Status, deleteAttachments bool) error {
	// either delete all attachments for this status, or simply
	// unattach all attachments for this status, so they'll be
	// cleaned later by a separate process; reason to unattach rather
	// than delete is that the poster might want to reattach them
	// to another status immediately (in case of delete + redraft)
	if deleteAttachments {
		for _, a := range statusToDelete.AttachmentIDs {
			if err := p.media.Delete(ctx, a); err != nil {
				return err
			}
		}
	} else {
		for _, a := range statusToDelete.AttachmentIDs {
			if _, err := p.media.Unattach(ctx, statusToDelete.Account, a); err != nil {
				return err
			}
		}
	}

	// delete all mention entries generated by this status
	for _, id := range statusToDelete.MentionIDs {
		if err := p.state.DB.DeleteMentionByID(ctx, id); err != nil {
			return err
		}
	}

	// delete all notification entries generated by this status
	if err := p.state.DB.DeleteNotificationsForStatus(ctx, statusToDelete.ID); err != nil {
		return err
	}

	// delete all bookmarks that point to this status
	if err := p.state.DB.DeleteStatusBookmarksForStatus(ctx, statusToDelete.ID); err != nil {
		return err
	}

	// delete all faves of this status
	if err := p.state.DB.DeleteStatusFavesForStatus(ctx, statusToDelete.ID); err != nil {
		return err
	}

	// delete all boosts for this status + remove them from timelines
	if boosts, err := p.state.DB.GetStatusReblogs(ctx, statusToDelete); err == nil {
		for _, b := range boosts {
			if err := p.deleteStatusFromTimelines(ctx, b); err != nil {
				return err
			}
			if err := p.state.DB.DeleteStatusByID(ctx, b.ID); err != nil {
				return err
			}
		}
	}

	// delete this status from any and all timelines
	if err := p.deleteStatusFromTimelines(ctx, statusToDelete); err != nil {
		return err
	}

	// delete the status itself
	if err := p.state.DB.DeleteStatusByID(ctx, statusToDelete.ID); err != nil {
		return err
	}

	return nil
}