Dereference remote replies (#132)

* decided where to put reply dereferencing

* fiddling with dereferencing threads

* further adventures

* tidy up some stuff

* move dereferencing functionality

* a bunch of refactoring

* go fmt

* more refactoring

* bleep bloop

* docs and linting

* start implementing replies collection on gts side

* fiddling around

* allow dereferencing our replies

* lint, fmt

internal/ap/extract.go

@@ -0,0 +1,614 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 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 ap contains models and utilities for working with activitypub/activitystreams representations.
+//
+// It is built on top of go-fed/activity.
+package ap
+
+import (
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/go-fed/activity/pub"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// ExtractPreferredUsername returns a string representation of an interface's preferredUsername property.
+func ExtractPreferredUsername(i WithPreferredUsername) (string, error) {
+	u := i.GetActivityStreamsPreferredUsername()
+	if u == nil || !u.IsXMLSchemaString() {
+		return "", errors.New("preferredUsername was not a string")
+	}
+	if u.GetXMLSchemaString() == "" {
+		return "", errors.New("preferredUsername was empty")
+	}
+	return u.GetXMLSchemaString(), nil
+}
+
+// ExtractName returns a string representation of an interface's name property.
+func ExtractName(i WithName) (string, error) {
+	nameProp := i.GetActivityStreamsName()
+	if nameProp == nil {
+		return "", errors.New("activityStreamsName not found")
+	}
+
+	// take the first name string we can find
+	for iter := nameProp.Begin(); iter != nameProp.End(); iter = iter.Next() {
+		if iter.IsXMLSchemaString() && iter.GetXMLSchemaString() != "" {
+			return iter.GetXMLSchemaString(), nil
+		}
+	}
+
+	return "", errors.New("activityStreamsName not found")
+}
+
+// ExtractInReplyToURI extracts the inReplyToURI property (if present) from an interface.
+func ExtractInReplyToURI(i WithInReplyTo) *url.URL {
+	inReplyToProp := i.GetActivityStreamsInReplyTo()
+	if inReplyToProp == nil {
+		// the property just wasn't set
+		return nil
+	}
+	for iter := inReplyToProp.Begin(); iter != inReplyToProp.End(); iter = iter.Next() {
+		if iter.IsIRI() {
+			if iter.GetIRI() != nil {
+				return iter.GetIRI()
+			}
+		}
+	}
+	// couldn't find a URI
+	return nil
+}
+
+// ExtractURLItems extracts a slice of URLs from a property that has withItems.
+func ExtractURLItems(i WithItems) []*url.URL {
+	urls := []*url.URL{}
+	items := i.GetActivityStreamsItems()
+	if items == nil || items.Len() == 0 {
+		return urls
+	}
+
+	for iter := items.Begin(); iter != items.End(); iter = iter.Next() {
+		if iter.IsIRI() {
+			urls = append(urls, iter.GetIRI())
+		}
+	}
+	return urls
+}
+
+// ExtractTos returns a list of URIs that the activity addresses as To.
+func ExtractTos(i WithTo) ([]*url.URL, error) {
+	to := []*url.URL{}
+	toProp := i.GetActivityStreamsTo()
+	if toProp == nil {
+		return nil, errors.New("toProp was nil")
+	}
+	for iter := toProp.Begin(); iter != toProp.End(); iter = iter.Next() {
+		if iter.IsIRI() {
+			if iter.GetIRI() != nil {
+				to = append(to, iter.GetIRI())
+			}
+		}
+	}
+	return to, nil
+}
+
+// ExtractCCs returns a list of URIs that the activity addresses as CC.
+func ExtractCCs(i WithCC) ([]*url.URL, error) {
+	cc := []*url.URL{}
+	ccProp := i.GetActivityStreamsCc()
+	if ccProp == nil {
+		return cc, nil
+	}
+	for iter := ccProp.Begin(); iter != ccProp.End(); iter = iter.Next() {
+		if iter.IsIRI() {
+			if iter.GetIRI() != nil {
+				cc = append(cc, iter.GetIRI())
+			}
+		}
+	}
+	return cc, nil
+}
+
+// ExtractAttributedTo returns the URL of the actor that the withAttributedTo is attributed to.
+func ExtractAttributedTo(i WithAttributedTo) (*url.URL, error) {
+	attributedToProp := i.GetActivityStreamsAttributedTo()
+	if attributedToProp == nil {
+		return nil, errors.New("attributedToProp was nil")
+	}
+	for iter := attributedToProp.Begin(); iter != attributedToProp.End(); iter = iter.Next() {
+		if iter.IsIRI() {
+			if iter.GetIRI() != nil {
+				return iter.GetIRI(), nil
+			}
+		}
+	}
+	return nil, errors.New("couldn't find iri for attributed to")
+}
+
+// ExtractPublished extracts the publication time of an activity.
+func ExtractPublished(i WithPublished) (time.Time, error) {
+	publishedProp := i.GetActivityStreamsPublished()
+	if publishedProp == nil {
+		return time.Time{}, errors.New("published prop was nil")
+	}
+
+	if !publishedProp.IsXMLSchemaDateTime() {
+		return time.Time{}, errors.New("published prop was not date time")
+	}
+
+	t := publishedProp.Get()
+	if t.IsZero() {
+		return time.Time{}, errors.New("published time was zero")
+	}
+	return t, nil
+}
+
+// ExtractIconURL extracts a URL to a supported image file from something like:
+//   "icon": {
+//     "mediaType": "image/jpeg",
+//     "type": "Image",
+//     "url": "http://example.org/path/to/some/file.jpeg"
+//   },
+func ExtractIconURL(i WithIcon) (*url.URL, error) {
+	iconProp := i.GetActivityStreamsIcon()
+	if iconProp == nil {
+		return nil, errors.New("icon property was nil")
+	}
+
+	// icon can potentially contain multiple entries, so we iterate through all of them
+	// here in order to find the first one that meets these criteria:
+	// 1. is an image
+	// 2. has a URL so we can grab it
+	for iter := iconProp.Begin(); iter != iconProp.End(); iter = iter.Next() {
+		// 1. is an image
+		if !iter.IsActivityStreamsImage() {
+			continue
+		}
+		imageValue := iter.GetActivityStreamsImage()
+		if imageValue == nil {
+			continue
+		}
+
+		// 2. has a URL so we can grab it
+		url, err := ExtractURL(imageValue)
+		if err == nil && url != nil {
+			return url, nil
+		}
+	}
+	// if we get to this point we didn't find an icon meeting our criteria :'(
+	return nil, errors.New("could not extract valid image from icon")
+}
+
+// ExtractImageURL extracts a URL to a supported image file from something like:
+//   "image": {
+//     "mediaType": "image/jpeg",
+//     "type": "Image",
+//     "url": "http://example.org/path/to/some/file.jpeg"
+//   },
+func ExtractImageURL(i WithImage) (*url.URL, error) {
+	imageProp := i.GetActivityStreamsImage()
+	if imageProp == nil {
+		return nil, errors.New("icon property was nil")
+	}
+
+	// icon can potentially contain multiple entries, so we iterate through all of them
+	// here in order to find the first one that meets these criteria:
+	// 1. is an image
+	// 2. has a URL so we can grab it
+	for iter := imageProp.Begin(); iter != imageProp.End(); iter = iter.Next() {
+		// 1. is an image
+		if !iter.IsActivityStreamsImage() {
+			continue
+		}
+		imageValue := iter.GetActivityStreamsImage()
+		if imageValue == nil {
+			continue
+		}
+
+		// 2. has a URL so we can grab it
+		url, err := ExtractURL(imageValue)
+		if err == nil && url != nil {
+			return url, nil
+		}
+	}
+	// if we get to this point we didn't find an image meeting our criteria :'(
+	return nil, errors.New("could not extract valid image from image property")
+}
+
+// ExtractSummary extracts the summary/content warning of an interface.
+func ExtractSummary(i WithSummary) (string, error) {
+	summaryProp := i.GetActivityStreamsSummary()
+	if summaryProp == nil {
+		return "", errors.New("summary property was nil")
+	}
+
+	for iter := summaryProp.Begin(); iter != summaryProp.End(); iter = iter.Next() {
+		if iter.IsXMLSchemaString() && iter.GetXMLSchemaString() != "" {
+			return iter.GetXMLSchemaString(), nil
+		}
+	}
+
+	return "", errors.New("could not extract summary")
+}
+
+// ExtractDiscoverable extracts the Discoverable boolean of an interface.
+func ExtractDiscoverable(i WithDiscoverable) (bool, error) {
+	if i.GetTootDiscoverable() == nil {
+		return false, errors.New("discoverable was nil")
+	}
+	return i.GetTootDiscoverable().Get(), nil
+}
+
+// ExtractURL extracts the URL property of an interface.
+func ExtractURL(i WithURL) (*url.URL, error) {
+	urlProp := i.GetActivityStreamsUrl()
+	if urlProp == nil {
+		return nil, errors.New("url property was nil")
+	}
+
+	for iter := urlProp.Begin(); iter != urlProp.End(); iter = iter.Next() {
+		if iter.IsIRI() && iter.GetIRI() != nil {
+			return iter.GetIRI(), nil
+		}
+	}
+
+	return nil, errors.New("could not extract url")
+}
+
+// ExtractPublicKeyForOwner extracts the public key from an interface, as long as it belongs to the specified owner.
+// It will return the public key itself, the id/URL of the public key, or an error if something goes wrong.
+func ExtractPublicKeyForOwner(i WithPublicKey, forOwner *url.URL) (*rsa.PublicKey, *url.URL, error) {
+	publicKeyProp := i.GetW3IDSecurityV1PublicKey()
+	if publicKeyProp == nil {
+		return nil, nil, errors.New("public key property was nil")
+	}
+
+	for iter := publicKeyProp.Begin(); iter != publicKeyProp.End(); iter = iter.Next() {
+		pkey := iter.Get()
+		if pkey == nil {
+			continue
+		}
+
+		pkeyID, err := pub.GetId(pkey)
+		if err != nil || pkeyID == nil {
+			continue
+		}
+
+		if pkey.GetW3IDSecurityV1Owner() == nil || pkey.GetW3IDSecurityV1Owner().Get() == nil || pkey.GetW3IDSecurityV1Owner().Get().String() != forOwner.String() {
+			continue
+		}
+
+		if pkey.GetW3IDSecurityV1PublicKeyPem() == nil {
+			continue
+		}
+
+		pkeyPem := pkey.GetW3IDSecurityV1PublicKeyPem().Get()
+		if pkeyPem == "" {
+			continue
+		}
+
+		block, _ := pem.Decode([]byte(pkeyPem))
+		if block == nil || block.Type != "PUBLIC KEY" {
+			return nil, nil, errors.New("could not decode publicKeyPem to PUBLIC KEY pem block type")
+		}
+
+		p, err := x509.ParsePKIXPublicKey(block.Bytes)
+		if err != nil {
+			return nil, nil, fmt.Errorf("could not parse public key from block bytes: %s", err)
+		}
+		if p == nil {
+			return nil, nil, errors.New("returned public key was empty")
+		}
+
+		if publicKey, ok := p.(*rsa.PublicKey); ok {
+			return publicKey, pkeyID, nil
+		}
+	}
+	return nil, nil, errors.New("couldn't find public key")
+}
+
+// ExtractContent returns a string representation of the interface's Content property.
+func ExtractContent(i WithContent) (string, error) {
+	contentProperty := i.GetActivityStreamsContent()
+	if contentProperty == nil {
+		return "", errors.New("content property was nil")
+	}
+	for iter := contentProperty.Begin(); iter != contentProperty.End(); iter = iter.Next() {
+		if iter.IsXMLSchemaString() && iter.GetXMLSchemaString() != "" {
+			return iter.GetXMLSchemaString(), nil
+		}
+	}
+	return "", errors.New("no content found")
+}
+
+// ExtractAttachments returns a slice of attachments on the interface.
+func ExtractAttachments(i WithAttachment) ([]*gtsmodel.MediaAttachment, error) {
+	attachments := []*gtsmodel.MediaAttachment{}
+	attachmentProp := i.GetActivityStreamsAttachment()
+	if attachmentProp == nil {
+		return attachments, nil
+	}
+	for iter := attachmentProp.Begin(); iter != attachmentProp.End(); iter = iter.Next() {
+		t := iter.GetType()
+		if t == nil {
+			continue
+		}
+		attachmentable, ok := t.(Attachmentable)
+		if !ok {
+			continue
+		}
+		attachment, err := ExtractAttachment(attachmentable)
+		if err != nil {
+			continue
+		}
+		attachments = append(attachments, attachment)
+	}
+	return attachments, nil
+}
+
+// ExtractAttachment returns a gts model of an attachment from an attachmentable interface.
+func ExtractAttachment(i Attachmentable) (*gtsmodel.MediaAttachment, error) {
+	attachment := &gtsmodel.MediaAttachment{
+		File: gtsmodel.File{},
+	}
+
+	attachmentURL, err := ExtractURL(i)
+	if err != nil {
+		return nil, err
+	}
+	attachment.RemoteURL = attachmentURL.String()
+
+	mediaType := i.GetActivityStreamsMediaType()
+	if mediaType == nil {
+		return nil, errors.New("no media type")
+	}
+	if mediaType.Get() == "" {
+		return nil, errors.New("no media type")
+	}
+	attachment.File.ContentType = mediaType.Get()
+	attachment.Type = gtsmodel.FileTypeImage
+
+	name, err := ExtractName(i)
+	if err == nil {
+		attachment.Description = name
+	}
+
+	attachment.Processing = gtsmodel.ProcessingStatusReceived
+
+	return attachment, nil
+}
+
+// func extractBlurhash(i withBlurhash) (string, error) {
+// 	if i.GetTootBlurhashProperty() == nil {
+// 		return "", errors.New("blurhash property was nil")
+// 	}
+// 	if i.GetTootBlurhashProperty().Get() == "" {
+// 		return "", errors.New("empty blurhash string")
+// 	}
+// 	return i.GetTootBlurhashProperty().Get(), nil
+// }
+
+// ExtractHashtags returns a slice of tags on the interface.
+func ExtractHashtags(i WithTag) ([]*gtsmodel.Tag, error) {
+	tags := []*gtsmodel.Tag{}
+	tagsProp := i.GetActivityStreamsTag()
+	if tagsProp == nil {
+		return tags, nil
+	}
+	for iter := tagsProp.Begin(); iter != tagsProp.End(); iter = iter.Next() {
+		t := iter.GetType()
+		if t == nil {
+			continue
+		}
+
+		if t.GetTypeName() != "Hashtag" {
+			continue
+		}
+
+		hashtaggable, ok := t.(Hashtaggable)
+		if !ok {
+			continue
+		}
+
+		tag, err := ExtractHashtag(hashtaggable)
+		if err != nil {
+			continue
+		}
+
+		tags = append(tags, tag)
+	}
+	return tags, nil
+}
+
+// ExtractHashtag returns a gtsmodel tag from a hashtaggable.
+func ExtractHashtag(i Hashtaggable) (*gtsmodel.Tag, error) {
+	tag := &gtsmodel.Tag{}
+
+	hrefProp := i.GetActivityStreamsHref()
+	if hrefProp == nil || !hrefProp.IsIRI() {
+		return nil, errors.New("no href prop")
+	}
+	tag.URL = hrefProp.GetIRI().String()
+
+	name, err := ExtractName(i)
+	if err != nil {
+		return nil, err
+	}
+	tag.Name = strings.TrimPrefix(name, "#")
+
+	return tag, nil
+}
+
+// ExtractEmojis returns a slice of emojis on the interface.
+func ExtractEmojis(i WithTag) ([]*gtsmodel.Emoji, error) {
+	emojis := []*gtsmodel.Emoji{}
+	tagsProp := i.GetActivityStreamsTag()
+	if tagsProp == nil {
+		return emojis, nil
+	}
+	for iter := tagsProp.Begin(); iter != tagsProp.End(); iter = iter.Next() {
+		t := iter.GetType()
+		if t == nil {
+			continue
+		}
+
+		if t.GetTypeName() != "Emoji" {
+			continue
+		}
+
+		emojiable, ok := t.(Emojiable)
+		if !ok {
+			continue
+		}
+
+		emoji, err := ExtractEmoji(emojiable)
+		if err != nil {
+			continue
+		}
+
+		emojis = append(emojis, emoji)
+	}
+	return emojis, nil
+}
+
+// ExtractEmoji ...
+func ExtractEmoji(i Emojiable) (*gtsmodel.Emoji, error) {
+	emoji := &gtsmodel.Emoji{}
+
+	idProp := i.GetJSONLDId()
+	if idProp == nil || !idProp.IsIRI() {
+		return nil, errors.New("no id for emoji")
+	}
+	uri := idProp.GetIRI()
+	emoji.URI = uri.String()
+	emoji.Domain = uri.Host
+
+	name, err := ExtractName(i)
+	if err != nil {
+		return nil, err
+	}
+	emoji.Shortcode = strings.Trim(name, ":")
+
+	if i.GetActivityStreamsIcon() == nil {
+		return nil, errors.New("no icon for emoji")
+	}
+	imageURL, err := ExtractIconURL(i)
+	if err != nil {
+		return nil, errors.New("no url for emoji image")
+	}
+	emoji.ImageRemoteURL = imageURL.String()
+
+	return emoji, nil
+}
+
+// ExtractMentions extracts a slice of gtsmodel Mentions from a WithTag interface.
+func ExtractMentions(i WithTag) ([]*gtsmodel.Mention, error) {
+	mentions := []*gtsmodel.Mention{}
+	tagsProp := i.GetActivityStreamsTag()
+	if tagsProp == nil {
+		return mentions, nil
+	}
+	for iter := tagsProp.Begin(); iter != tagsProp.End(); iter = iter.Next() {
+		t := iter.GetType()
+		if t == nil {
+			continue
+		}
+
+		if t.GetTypeName() != "Mention" {
+			continue
+		}
+
+		mentionable, ok := t.(Mentionable)
+		if !ok {
+			continue
+		}
+
+		mention, err := ExtractMention(mentionable)
+		if err != nil {
+			continue
+		}
+
+		mentions = append(mentions, mention)
+	}
+	return mentions, nil
+}
+
+// ExtractMention extracts a gts model mention from a Mentionable.
+func ExtractMention(i Mentionable) (*gtsmodel.Mention, error) {
+	mention := &gtsmodel.Mention{}
+
+	mentionString, err := ExtractName(i)
+	if err != nil {
+		return nil, err
+	}
+
+	// just make sure the mention string is valid so we can handle it properly later on...
+	username, domain, err := util.ExtractMentionParts(mentionString)
+	if err != nil {
+		return nil, err
+	}
+	if username == "" || domain == "" {
+		return nil, errors.New("username or domain was empty")
+	}
+	mention.NameString = mentionString
+
+	// the href prop should be the AP URI of a user we know, eg https://example.org/users/whatever_user
+	hrefProp := i.GetActivityStreamsHref()
+	if hrefProp == nil || !hrefProp.IsIRI() {
+		return nil, errors.New("no href prop")
+	}
+	mention.MentionedAccountURI = hrefProp.GetIRI().String()
+	return mention, nil
+}
+
+// ExtractActor extracts the actor ID/IRI from an interface WithActor.
+func ExtractActor(i WithActor) (*url.URL, error) {
+	actorProp := i.GetActivityStreamsActor()
+	if actorProp == nil {
+		return nil, errors.New("actor property was nil")
+	}
+	for iter := actorProp.Begin(); iter != actorProp.End(); iter = iter.Next() {
+		if iter.IsIRI() && iter.GetIRI() != nil {
+			return iter.GetIRI(), nil
+		}
+	}
+	return nil, errors.New("no iri found for actor prop")
+}
+
+// ExtractObject extracts a URL object from a WithObject interface.
+func ExtractObject(i WithObject) (*url.URL, error) {
+	objectProp := i.GetActivityStreamsObject()
+	if objectProp == nil {
+		return nil, errors.New("object property was nil")
+	}
+	for iter := objectProp.Begin(); iter != objectProp.End(); iter = iter.Next() {
+		if iter.IsIRI() && iter.GetIRI() != nil {
+			return iter.GetIRI(), nil
+		}
+	}
+	return nil, errors.New("no iri found for object prop")
+}