/*
   GoToSocial
   Copyright (C) 2021-2023 GoToSocial Authors admin@gotosocial.org

   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 typeutils

import (
	"context"
	"errors"
	"fmt"
	"net/url"

	"github.com/miekg/dns"
	"github.com/superseriousbusiness/gotosocial/internal/ap"
	"github.com/superseriousbusiness/gotosocial/internal/config"
	"github.com/superseriousbusiness/gotosocial/internal/db"
	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
	"github.com/superseriousbusiness/gotosocial/internal/log"
	"github.com/superseriousbusiness/gotosocial/internal/uris"
)

func (c *converter) ASRepresentationToAccount(ctx context.Context, accountable ap.Accountable, accountDomain string) (*gtsmodel.Account, error) {
	// first check if we actually already know this account
	uriProp := accountable.GetJSONLDId()
	if uriProp == nil || !uriProp.IsIRI() {
		return nil, errors.New("no id property found on person, or id was not an iri")
	}
	uri := uriProp.GetIRI()

	// we don't know the account, or we're being told to update it, so we need to generate it from the person -- at least we already have the URI!
	acct := &gtsmodel.Account{}
	acct.URI = uri.String()

	// Username aka preferredUsername
	// We need this one so bail if it's not set.
	username, err := ap.ExtractPreferredUsername(accountable)
	if err != nil {
		return nil, fmt.Errorf("couldn't extract username: %s", err)
	}
	acct.Username = username

	// Domain
	if accountDomain != "" {
		acct.Domain = accountDomain
	} else {
		acct.Domain = uri.Host
	}

	// avatar aka icon
	// if this one isn't extractable in a format we recognise we'll just skip it
	if avatarURL, err := ap.ExtractIconURL(accountable); err == nil {
		acct.AvatarRemoteURL = avatarURL.String()
	}

	// header aka image
	// if this one isn't extractable in a format we recognise we'll just skip it
	if headerURL, err := ap.ExtractImageURL(accountable); err == nil {
		acct.HeaderRemoteURL = headerURL.String()
	}

	// display name aka name
	// we default to the username, but take the more nuanced name property if it exists
	if displayName := ap.ExtractName(accountable); displayName != "" {
		acct.DisplayName = displayName
	} else {
		acct.DisplayName = username
	}

	// account emojis (used in bio, display name, fields)
	if emojis, err := ap.ExtractEmojis(accountable); err != nil {
		log.Infof("ASRepresentationToAccount: error extracting account emojis: %s", err)
	} else {
		acct.Emojis = emojis
	}

	// TODO: fields aka attachment array

	// note aka summary
	acct.Note = ap.ExtractSummary(accountable)

	// check for bot and actor type
	switch accountable.GetTypeName() {
	case ap.ActorPerson, ap.ActorGroup, ap.ActorOrganization:
		// people, groups, and organizations aren't bots
		bot := false
		acct.Bot = &bot
		// apps and services are
	case ap.ActorApplication, ap.ActorService:
		bot := true
		acct.Bot = &bot
	default:
		// we don't know what this is!
		return nil, fmt.Errorf("type name %s not recognised or not convertible to ap.ActivityStreamsActor", accountable.GetTypeName())
	}
	acct.ActorType = accountable.GetTypeName()

	// assume not memorial (todo)
	memorial := false
	acct.Memorial = &memorial

	// assume not sensitive (todo)
	sensitive := false
	acct.Sensitive = &sensitive

	// assume not hide collections (todo)
	hideCollections := false
	acct.HideCollections = &hideCollections

	// locked aka manuallyApprovesFollowers
	locked := true
	acct.Locked = &locked // assume locked by default
	maf := accountable.GetActivityStreamsManuallyApprovesFollowers()
	if maf != nil && maf.IsXMLSchemaBoolean() {
		locked = maf.Get()
		acct.Locked = &locked
	}

	// discoverable
	// default to false -- take custom value if it's set though
	discoverable := false
	acct.Discoverable = &discoverable
	d, err := ap.ExtractDiscoverable(accountable)
	if err == nil {
		acct.Discoverable = &d
	}

	// assume not rss feed
	enableRSS := false
	acct.EnableRSS = &enableRSS

	// url property
	url, err := ap.ExtractURL(accountable)
	if err == nil {
		// take the URL if we can find it
		acct.URL = url.String()
	} else {
		// otherwise just take the account URI as the URL
		acct.URL = uri.String()
	}

	// InboxURI
	if accountable.GetActivityStreamsInbox() != nil && accountable.GetActivityStreamsInbox().GetIRI() != nil {
		acct.InboxURI = accountable.GetActivityStreamsInbox().GetIRI().String()
	}

	// SharedInboxURI:
	// only trust shared inbox if it has at least two domains,
	// from the right, in common with the domain of the account
	if sharedInboxURI := ap.ExtractSharedInbox(accountable); // nocollapse
	sharedInboxURI != nil && dns.CompareDomainName(acct.Domain, sharedInboxURI.Host) >= 2 {
		sharedInbox := sharedInboxURI.String()
		acct.SharedInboxURI = &sharedInbox
	}

	// OutboxURI
	if accountable.GetActivityStreamsOutbox() != nil && accountable.GetActivityStreamsOutbox().GetIRI() != nil {
		acct.OutboxURI = accountable.GetActivityStreamsOutbox().GetIRI().String()
	}

	// FollowingURI
	if accountable.GetActivityStreamsFollowing() != nil && accountable.GetActivityStreamsFollowing().GetIRI() != nil {
		acct.FollowingURI = accountable.GetActivityStreamsFollowing().GetIRI().String()
	}

	// FollowersURI
	if accountable.GetActivityStreamsFollowers() != nil && accountable.GetActivityStreamsFollowers().GetIRI() != nil {
		acct.FollowersURI = accountable.GetActivityStreamsFollowers().GetIRI().String()
	}

	// FeaturedURI
	if accountable.GetTootFeatured() != nil && accountable.GetTootFeatured().GetIRI() != nil {
		acct.FeaturedCollectionURI = accountable.GetTootFeatured().GetIRI().String()
	}

	// TODO: FeaturedTagsURI

	// TODO: alsoKnownAs

	// publicKey
	pkey, pkeyURL, err := ap.ExtractPublicKeyForOwner(accountable, uri)
	if err != nil {
		return nil, fmt.Errorf("couldn't get public key for person %s: %s", uri.String(), err)
	}
	acct.PublicKey = pkey
	acct.PublicKeyURI = pkeyURL.String()

	return acct, nil
}

func (c *converter) extractAttachments(i ap.WithAttachment) []*gtsmodel.MediaAttachment {
	attachmentProp := i.GetActivityStreamsAttachment()
	if attachmentProp == nil {
		return nil
	}

	attachments := make([]*gtsmodel.MediaAttachment, 0, attachmentProp.Len())

	for iter := attachmentProp.Begin(); iter != attachmentProp.End(); iter = iter.Next() {
		t := iter.GetType()
		if t == nil {
			continue
		}

		attachmentable, ok := t.(ap.Attachmentable)
		if !ok {
			log.Error("ap attachment was not attachmentable")
			continue
		}

		attachment, err := ap.ExtractAttachment(attachmentable)
		if err != nil {
			log.Errorf("error extracting attachment: %s", err)
			continue
		}

		attachments = append(attachments, attachment)
	}

	return attachments
}

func (c *converter) ASStatusToStatus(ctx context.Context, statusable ap.Statusable) (*gtsmodel.Status, error) {
	status := &gtsmodel.Status{}

	// uri at which this status is reachable
	uriProp := statusable.GetJSONLDId()
	if uriProp == nil || !uriProp.IsIRI() {
		return nil, errors.New("no id property found, or id was not an iri")
	}
	status.URI = uriProp.GetIRI().String()

	l := log.WithField("statusURI", status.URI)

	// web url for viewing this status
	if statusURL, err := ap.ExtractURL(statusable); err == nil {
		status.URL = statusURL.String()
	} else {
		// if no URL was set, just take the URI
		status.URL = status.URI
	}

	// the html-formatted content of this status
	status.Content = ap.ExtractContent(statusable)

	// attachments to dereference and fetch later on (we don't do that here)
	status.Attachments = c.extractAttachments(statusable)

	// hashtags to dereference later on
	if hashtags, err := ap.ExtractHashtags(statusable); err != nil {
		l.Infof("ASStatusToStatus: error extracting status hashtags: %s", err)
	} else {
		status.Tags = hashtags
	}

	// emojis to dereference and fetch later on
	if emojis, err := ap.ExtractEmojis(statusable); err != nil {
		l.Infof("ASStatusToStatus: error extracting status emojis: %s", err)
	} else {
		status.Emojis = emojis
	}

	// mentions to dereference later on
	if mentions, err := ap.ExtractMentions(statusable); err != nil {
		l.Infof("ASStatusToStatus: error extracting status mentions: %s", err)
	} else {
		status.Mentions = mentions
	}

	// cw string for this status
	// prefer Summary, fall back to Name
	if summary := ap.ExtractSummary(statusable); summary != "" {
		status.ContentWarning = summary
	} else {
		status.ContentWarning = ap.ExtractName(statusable)
	}

	// when was this status created?
	published, err := ap.ExtractPublished(statusable)
	if err != nil {
		l.Infof("ASStatusToStatus: error extracting status published: %s", err)
	} else {
		status.CreatedAt = published
		status.UpdatedAt = published
	}

	// which account posted this status?
	// if we don't know the account yet we can dereference it later
	attributedTo, err := ap.ExtractAttributedTo(statusable)
	if err != nil {
		return nil, errors.New("ASStatusToStatus: attributedTo was empty")
	}
	status.AccountURI = attributedTo.String()

	statusOwner, err := c.db.GetAccountByURI(ctx, attributedTo.String())
	if err != nil {
		return nil, fmt.Errorf("ASStatusToStatus: couldn't get status owner from db: %s", err)
	}
	status.AccountID = statusOwner.ID
	status.AccountURI = statusOwner.URI
	status.Account = statusOwner

	// check if there's a post that this is a reply to
	inReplyToURI := ap.ExtractInReplyToURI(statusable)
	if inReplyToURI != nil {
		// something is set so we can at least set this field on the
		// status and dereference using this later if we need to
		status.InReplyToURI = inReplyToURI.String()

		// now we can check if we have the replied-to status in our db already
		if inReplyToStatus, err := c.db.GetStatusByURI(ctx, inReplyToURI.String()); err == nil {
			// we have the status in our database already
			// so we can set these fields here and now...
			status.InReplyToID = inReplyToStatus.ID
			status.InReplyToAccountID = inReplyToStatus.AccountID
			status.InReplyTo = inReplyToStatus
			if status.InReplyToAccount == nil {
				if inReplyToAccount, err := c.db.GetAccountByID(ctx, inReplyToStatus.AccountID); err == nil {
					status.InReplyToAccount = inReplyToAccount
				}
			}
		}
	}

	// visibility entry for this status
	visibility, err := ap.ExtractVisibility(statusable, status.Account.FollowersURI)
	if err != nil {
		return nil, fmt.Errorf("ASStatusToStatus: error extracting visibility: %s", err)
	}
	status.Visibility = visibility

	// advanced visibility for this status
	// TODO: a lot of work to be done here -- a new type needs to be created for this in go-fed/activity using ASTOOL
	// for now we just set everything to true
	pinned := false
	federated := true
	boostable := true
	replyable := true
	likeable := true

	status.Pinned = &pinned
	status.Federated = &federated
	status.Boostable = &boostable
	status.Replyable = &replyable
	status.Likeable = &likeable
	// sensitive
	sensitive := ap.ExtractSensitive(statusable)
	status.Sensitive = &sensitive

	// language
	// we might be able to extract this from the contentMap field

	// ActivityStreamsType
	status.ActivityStreamsType = statusable.GetTypeName()

	return status, nil
}

func (c *converter) ASFollowToFollowRequest(ctx context.Context, followable ap.Followable) (*gtsmodel.FollowRequest, error) {
	idProp := followable.GetJSONLDId()
	if idProp == nil || !idProp.IsIRI() {
		return nil, errors.New("no id property set on follow, or was not an iri")
	}
	uri := idProp.GetIRI().String()

	origin, err := ap.ExtractActor(followable)
	if err != nil {
		return nil, errors.New("error extracting actor property from follow")
	}
	originAccount, err := c.db.GetAccountByURI(ctx, origin.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	target, err := ap.ExtractObject(followable)
	if err != nil {
		return nil, errors.New("error extracting object property from follow")
	}
	targetAccount, err := c.db.GetAccountByURI(ctx, target.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	followRequest := &gtsmodel.FollowRequest{
		URI:             uri,
		AccountID:       originAccount.ID,
		TargetAccountID: targetAccount.ID,
	}

	return followRequest, nil
}

func (c *converter) ASFollowToFollow(ctx context.Context, followable ap.Followable) (*gtsmodel.Follow, error) {
	idProp := followable.GetJSONLDId()
	if idProp == nil || !idProp.IsIRI() {
		return nil, errors.New("no id property set on follow, or was not an iri")
	}
	uri := idProp.GetIRI().String()

	origin, err := ap.ExtractActor(followable)
	if err != nil {
		return nil, errors.New("error extracting actor property from follow")
	}
	originAccount, err := c.db.GetAccountByURI(ctx, origin.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	target, err := ap.ExtractObject(followable)
	if err != nil {
		return nil, errors.New("error extracting object property from follow")
	}
	targetAccount, err := c.db.GetAccountByURI(ctx, target.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	follow := &gtsmodel.Follow{
		URI:             uri,
		AccountID:       originAccount.ID,
		TargetAccountID: targetAccount.ID,
	}

	return follow, nil
}

func (c *converter) ASLikeToFave(ctx context.Context, likeable ap.Likeable) (*gtsmodel.StatusFave, error) {
	idProp := likeable.GetJSONLDId()
	if idProp == nil || !idProp.IsIRI() {
		return nil, errors.New("no id property set on like, or was not an iri")
	}
	uri := idProp.GetIRI().String()

	origin, err := ap.ExtractActor(likeable)
	if err != nil {
		return nil, errors.New("error extracting actor property from like")
	}
	originAccount, err := c.db.GetAccountByURI(ctx, origin.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	target, err := ap.ExtractObject(likeable)
	if err != nil {
		return nil, errors.New("error extracting object property from like")
	}

	targetStatus, err := c.db.GetStatusByURI(ctx, target.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting status with uri %s from the database: %s", target.String(), err)
	}

	var targetAccount *gtsmodel.Account
	if targetStatus.Account != nil {
		targetAccount = targetStatus.Account
	} else {
		a, err := c.db.GetAccountByID(ctx, targetStatus.AccountID)
		if err != nil {
			return nil, fmt.Errorf("error extracting account with id %s from the database: %s", targetStatus.AccountID, err)
		}
		targetAccount = a
	}

	return &gtsmodel.StatusFave{
		AccountID:       originAccount.ID,
		Account:         originAccount,
		TargetAccountID: targetAccount.ID,
		TargetAccount:   targetAccount,
		StatusID:        targetStatus.ID,
		Status:          targetStatus,
		URI:             uri,
	}, nil
}

func (c *converter) ASBlockToBlock(ctx context.Context, blockable ap.Blockable) (*gtsmodel.Block, error) {
	idProp := blockable.GetJSONLDId()
	if idProp == nil || !idProp.IsIRI() {
		return nil, errors.New("ASBlockToBlock: no id property set on block, or was not an iri")
	}
	uri := idProp.GetIRI().String()

	origin, err := ap.ExtractActor(blockable)
	if err != nil {
		return nil, errors.New("ASBlockToBlock: error extracting actor property from block")
	}
	originAccount, err := c.db.GetAccountByURI(ctx, origin.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	target, err := ap.ExtractObject(blockable)
	if err != nil {
		return nil, errors.New("ASBlockToBlock: error extracting object property from block")
	}

	targetAccount, err := c.db.GetAccountByURI(ctx, target.String())
	if err != nil {
		return nil, fmt.Errorf("error extracting account with uri %s from the database: %s", origin.String(), err)
	}

	return &gtsmodel.Block{
		AccountID:       originAccount.ID,
		Account:         originAccount,
		TargetAccountID: targetAccount.ID,
		TargetAccount:   targetAccount,
		URI:             uri,
	}, nil
}

func (c *converter) ASAnnounceToStatus(ctx context.Context, announceable ap.Announceable) (*gtsmodel.Status, bool, error) {
	status := &gtsmodel.Status{}
	isNew := true

	// check if we already have the boost in the database
	idProp := announceable.GetJSONLDId()
	if idProp == nil || !idProp.IsIRI() {
		return nil, isNew, errors.New("no id property set on announce, or was not an iri")
	}
	uri := idProp.GetIRI().String()

	if status, err := c.db.GetStatusByURI(ctx, uri); err == nil {
		// we already have it, great, just return it as-is :)
		isNew = false
		return status, isNew, nil
	}
	status.URI = uri

	// get the URI of the announced/boosted status
	boostedStatusURI, err := ap.ExtractObject(announceable)
	if err != nil {
		return nil, isNew, fmt.Errorf("ASAnnounceToStatus: error getting object from announce: %s", err)
	}

	// set the URI on the new status for dereferencing later
	status.BoostOf = &gtsmodel.Status{
		URI: boostedStatusURI.String(),
	}

	// get the published time for the announce
	published, err := ap.ExtractPublished(announceable)
	if err != nil {
		return nil, isNew, fmt.Errorf("ASAnnounceToStatus: error extracting published time: %s", err)
	}
	status.CreatedAt = published
	status.UpdatedAt = published

	// get the actor's IRI (ie., the person who boosted the status)
	actor, err := ap.ExtractActor(announceable)
	if err != nil {
		return nil, isNew, fmt.Errorf("ASAnnounceToStatus: error extracting actor: %s", err)
	}

	// get the boosting account based on the URI
	// this should have been dereferenced already before we hit this point so we can confidently error out if we don't have it
	boostingAccount, err := c.db.GetAccountByURI(ctx, actor.String())
	if err != nil {
		return nil, isNew, fmt.Errorf("ASAnnounceToStatus: error in db fetching account with uri %s: %s", actor.String(), err)
	}
	status.AccountID = boostingAccount.ID
	status.AccountURI = boostingAccount.URI
	status.Account = boostingAccount

	// these will all be wrapped in the boosted status so set them empty here
	status.AttachmentIDs = []string{}
	status.TagIDs = []string{}
	status.MentionIDs = []string{}
	status.EmojiIDs = []string{}

	visibility, err := ap.ExtractVisibility(announceable, boostingAccount.FollowersURI)
	if err != nil {
		return nil, isNew, fmt.Errorf("ASAnnounceToStatus: error extracting visibility: %s", err)
	}
	status.Visibility = visibility

	// the rest of the fields will be taken from the target status, but it's not our job to do the dereferencing here
	return status, isNew, nil
}

func (c *converter) ASFlagToReport(ctx context.Context, flaggable ap.Flaggable) (*gtsmodel.Report, error) {
	// Extract flag uri.
	idProp := flaggable.GetJSONLDId()
	if idProp == nil || !idProp.IsIRI() {
		return nil, errors.New("ASFlagToReport: no id property set on flaggable, or was not an iri")
	}
	uri := idProp.GetIRI().String()

	// Extract account that created the flag / report.
	// This will usually be an instance actor.
	actor, err := ap.ExtractActor(flaggable)
	if err != nil {
		return nil, fmt.Errorf("ASFlagToReport: error extracting actor: %w", err)
	}
	account, err := c.db.GetAccountByURI(ctx, actor.String())
	if err != nil {
		return nil, fmt.Errorf("ASFlagToReport: error in db fetching account with uri %s: %w", actor.String(), err)
	}

	// Get the content of the report.
	// For Mastodon, this will just be a string, or nothing.
	// In Misskey's case, it may also contain the URLs of
	// one or more reported statuses, so extract these too.
	content := ap.ExtractContent(flaggable)
	statusURIs := []*url.URL{}
	inlineURLs := misskeyReportInlineURLs(content)
	statusURIs = append(statusURIs, inlineURLs...)

	// Extract account and statuses targeted by the flag / report.
	//
	// Incoming flags from mastodon usually have a target account uri as
	// first entry in objects, followed by URIs of one or more statuses.
	// Misskey on the other hand will just contain the target account uri.
	// We shouldn't assume the order of the objects will correspond to this,
	// but we can check that he objects slice contains just one account, and
	// maybe some statuses.
	//
	// Throw away anything that's not relevant to us.
	objects, err := ap.ExtractObjects(flaggable)
	if err != nil {
		return nil, fmt.Errorf("ASFlagToReport: error extracting objects: %w", err)
	}
	if len(objects) == 0 {
		return nil, errors.New("ASFlagToReport: flaggable objects empty, can't create report")
	}

	var targetAccountURI *url.URL
	for _, object := range objects {
		switch {
		case object.Host != config.GetHost():
			// object doesn't belong to us, just ignore it
			continue
		case uris.IsUserPath(object):
			if targetAccountURI != nil {
				return nil, errors.New("ASFlagToReport: flaggable objects contained more than one target account uri")
			}
			targetAccountURI = object
		case uris.IsStatusesPath(object):
			statusURIs = append(statusURIs, object)
		}
	}

	// Make sure we actually have a target account now.
	if targetAccountURI == nil {
		return nil, errors.New("ASFlagToReport: flaggable objects contained no recognizable target account uri")
	}
	targetAccount, err := c.db.GetAccountByURI(ctx, targetAccountURI.String())
	if err != nil {
		if errors.Is(err, db.ErrNoEntries) {
			return nil, fmt.Errorf("ASFlagToReport: account with uri %s could not be found in the db", targetAccountURI.String())
		}
		return nil, fmt.Errorf("ASFlagToReport: db error getting account with uri %s: %w", targetAccountURI.String(), err)
	}

	// If we got some status URIs, try to get them from the db now
	var (
		statusIDs = make([]string, 0, len(statusURIs))
		statuses  = make([]*gtsmodel.Status, 0, len(statusURIs))
	)
	for _, statusURI := range statusURIs {
		statusURIString := statusURI.String()

		// try getting this status by URI first, then URL
		status, err := c.db.GetStatusByURI(ctx, statusURIString)
		if err != nil {
			if !errors.Is(err, db.ErrNoEntries) {
				return nil, fmt.Errorf("ASFlagToReport: db error getting status with uri %s: %w", statusURIString, err)
			}

			status, err = c.db.GetStatusByURL(ctx, statusURIString)
			if err != nil {
				if !errors.Is(err, db.ErrNoEntries) {
					return nil, fmt.Errorf("ASFlagToReport: db error getting status with url %s: %w", statusURIString, err)
				}

				log.Warnf("ASFlagToReport: reported status %s could not be found in the db, skipping it", statusURIString)
				continue
			}
		}

		if status.AccountID != targetAccount.ID {
			// status doesn't belong to this account, ignore it
			continue
		}

		statusIDs = append(statusIDs, status.ID)
		statuses = append(statuses, status)
	}

	// id etc should be handled the caller, so just return what we got
	return &gtsmodel.Report{
		URI:             uri,
		AccountID:       account.ID,
		Account:         account,
		TargetAccountID: targetAccount.ID,
		TargetAccount:   targetAccount,
		Comment:         content,
		StatusIDs:       statusIDs,
		Statuses:        statuses,
	}, nil
}