status-im/status-go

package protocol

import (
    "encoding/json"
    "fmt"
    "net/http"
    neturl "net/url"

    "go.uber.org/zap"

    "github.com/status-im/status-go/protocol/common"
    "github.com/status-im/status-go/protocol/protobuf"
)

type OEmbedUnfurler struct {
    logger     *zap.Logger
    httpClient *http.Client
    // oembedEndpoint describes where the consumer may request representations for
    // the supported URL scheme. For example, for YouTube, it is
    // https://www.youtube.com/oembed.
    oembedEndpoint string
    // url is the actual URL to be unfurled.
    url *neturl.URL
}

func NewOEmbedUnfurler(oembedEndpoint string,
    url *neturl.URL,
    logger *zap.Logger,
    httpClient *http.Client) *OEmbedUnfurler {
    return &OEmbedUnfurler{
        oembedEndpoint: oembedEndpoint,
        url:            url,
        logger:         logger,
        httpClient:     httpClient,
    }
}

type OEmbedResponse struct {
    Title        string `json:"title"`
    ThumbnailURL string `json:"thumbnail_url"`
}

func (u *OEmbedUnfurler) newOEmbedURL() (*neturl.URL, error) {
    oembedURL, err := neturl.Parse(u.oembedEndpoint)
    if err != nil {
        return nil, err
    }

    // When format is specified, the provider MUST return data in the requested
    // format, else return an error.
    oembedURL.RawQuery = neturl.Values{
        "url":    {u.url.String()},
        "format": {"json"},
    }.Encode()

    return oembedURL, nil
}

func (u OEmbedUnfurler) Unfurl() (*common.LinkPreview, error) {
    preview := newDefaultLinkPreview(u.url)
    preview.Type = protobuf.UnfurledLink_LINK

    oembedURL, err := u.newOEmbedURL()
    if err != nil {
        return preview, err
    }

    headers := map[string]string{
        "accept":          headerAcceptJSON,
        "accept-language": headerAcceptLanguage,
        "user-agent":      headerUserAgent,
    }
    oembedBytes, err := fetchBody(u.logger, u.httpClient, oembedURL.String(), headers)
    if err != nil {
        return preview, err
    }

    var oembedResponse OEmbedResponse
    if err != nil {
        return preview, err
    }
    err = json.Unmarshal(oembedBytes, &oembedResponse)
    if err != nil {
        return preview, err
    }

    if oembedResponse.Title == "" {
        return preview, fmt.Errorf("missing required title in oEmbed response")
    }

    preview.Title = oembedResponse.Title
    return preview, nil
}