mirror of
https://github.com/42wim/matterbridge.git
synced 2024-12-04 16:32:02 -08:00
194 lines
5.7 KiB
Go
194 lines
5.7 KiB
Go
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// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
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// See LICENSE.txt for license information.
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package model
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import (
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"encoding/binary"
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"encoding/json"
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"fmt"
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"hash/fnv"
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"net/http"
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"time"
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"unicode/utf8"
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"github.com/dyatlov/go-opengraph/opengraph"
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)
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const (
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LinkMetadataTypeImage LinkMetadataType = "image"
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LinkMetadataTypeNone LinkMetadataType = "none"
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LinkMetadataTypeOpengraph LinkMetadataType = "opengraph"
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LinkMetadataMaxImages int = 5
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)
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type LinkMetadataType string
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// LinkMetadata stores arbitrary data about a link posted in a message. This includes dimensions of linked images
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// and OpenGraph metadata.
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type LinkMetadata struct {
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// Hash is a value computed from the URL and Timestamp for use as a primary key in the database.
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Hash int64
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URL string
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Timestamp int64
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Type LinkMetadataType
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// Data is the actual metadata for the link. It should contain data of one of the following types:
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// - *model.PostImage if the linked content is an image
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// - *opengraph.OpenGraph if the linked content is an HTML document
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// - nil if the linked content has no metadata
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Data interface{}
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}
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// truncateText ensure string is 300 chars, truncate and add ellipsis
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// if it was bigger.
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func truncateText(original string) string {
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if utf8.RuneCountInString(original) > 300 {
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return fmt.Sprintf("%.300s[...]", original)
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}
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return original
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}
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func firstNImages(images []*opengraph.Image, maxImages int) []*opengraph.Image {
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if maxImages < 0 { // don't break stuff, if it's weird, go for sane defaults
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maxImages = LinkMetadataMaxImages
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}
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numImages := len(images)
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if numImages > maxImages {
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return images[0:maxImages]
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}
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return images
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}
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// TruncateOpenGraph ensure OpenGraph metadata doesn't grow too big by
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// shortening strings, trimming fields and reducing the number of
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// images.
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func TruncateOpenGraph(ogdata *opengraph.OpenGraph) *opengraph.OpenGraph {
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if ogdata != nil {
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empty := &opengraph.OpenGraph{}
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ogdata.Title = truncateText(ogdata.Title)
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ogdata.Description = truncateText(ogdata.Description)
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ogdata.SiteName = truncateText(ogdata.SiteName)
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ogdata.Article = empty.Article
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ogdata.Book = empty.Book
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ogdata.Profile = empty.Profile
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ogdata.Determiner = empty.Determiner
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ogdata.Locale = empty.Locale
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ogdata.LocalesAlternate = empty.LocalesAlternate
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ogdata.Images = firstNImages(ogdata.Images, LinkMetadataMaxImages)
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ogdata.Audios = empty.Audios
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ogdata.Videos = empty.Videos
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}
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return ogdata
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}
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func (o *LinkMetadata) PreSave() {
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o.Hash = GenerateLinkMetadataHash(o.URL, o.Timestamp)
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}
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func (o *LinkMetadata) IsValid() *AppError {
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if o.URL == "" {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.url.app_error", nil, "", http.StatusBadRequest)
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}
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if o.Timestamp == 0 || !isRoundedToNearestHour(o.Timestamp) {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.timestamp.app_error", nil, "", http.StatusBadRequest)
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}
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switch o.Type {
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case LinkMetadataTypeImage:
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if o.Data == nil {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.data.app_error", nil, "", http.StatusBadRequest)
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}
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if _, ok := o.Data.(*PostImage); !ok {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.data_type.app_error", nil, "", http.StatusBadRequest)
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}
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case LinkMetadataTypeNone:
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if o.Data != nil {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.data_type.app_error", nil, "", http.StatusBadRequest)
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}
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case LinkMetadataTypeOpengraph:
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if o.Data == nil {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.data.app_error", nil, "", http.StatusBadRequest)
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}
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if _, ok := o.Data.(*opengraph.OpenGraph); !ok {
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.data_type.app_error", nil, "", http.StatusBadRequest)
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}
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default:
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return NewAppError("LinkMetadata.IsValid", "model.link_metadata.is_valid.type.app_error", nil, "", http.StatusBadRequest)
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}
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return nil
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}
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// DeserializeDataToConcreteType converts o.Data from JSON into properly structured data. This is intended to be used
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// after getting a LinkMetadata object that has been stored in the database.
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func (o *LinkMetadata) DeserializeDataToConcreteType() error {
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var b []byte
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switch t := o.Data.(type) {
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case []byte:
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// MySQL uses a byte slice for JSON
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b = t
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case string:
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// Postgres uses a string for JSON
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b = []byte(t)
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}
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if b == nil {
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// Data doesn't need to be fixed
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return nil
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}
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var data interface{}
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var err error
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switch o.Type {
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case LinkMetadataTypeImage:
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image := &PostImage{}
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err = json.Unmarshal(b, &image)
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data = image
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case LinkMetadataTypeOpengraph:
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og := &opengraph.OpenGraph{}
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json.Unmarshal(b, &og)
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data = og
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}
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if err != nil {
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return err
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}
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o.Data = data
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return nil
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}
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// FloorToNearestHour takes a timestamp (in milliseconds) and returns it rounded to the previous hour in UTC.
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func FloorToNearestHour(ms int64) int64 {
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t := time.Unix(0, ms*int64(1000*1000)).UTC()
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return time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, time.UTC).UnixNano() / int64(time.Millisecond)
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}
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// isRoundedToNearestHour returns true if the given timestamp (in milliseconds) has been rounded to the nearest hour in UTC.
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func isRoundedToNearestHour(ms int64) bool {
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return FloorToNearestHour(ms) == ms
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}
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// GenerateLinkMetadataHash generates a unique hash for a given URL and timestamp for use as a database key.
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func GenerateLinkMetadataHash(url string, timestamp int64) int64 {
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hash := fnv.New32()
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// Note that we ignore write errors here because the Hash interface says that its Write will never return an error
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binary.Write(hash, binary.LittleEndian, timestamp)
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hash.Write([]byte(url))
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return int64(hash.Sum32())
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}
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