Feat/link preview v2

[nicolasbraun]

Motivation

Aims to fix #758 and allow easier implementation of linkPreviews in the chat.
This relies on the following PR flyerhq/flutter_link_previewer#63 in flutter_link_previewer , I made it there for easier review, but once it's ok we can move it in this monorepo.

LinkPreview

• Made LinkPreview depend on chatcore
• Reworked the methods to return null if no preview since the new model link property is not optional
• Added back the image information
• Reworked the layout to allow to hide specifiy items, especially the linkify text which "repeats" the chatMessage text
• ⚠️ Made width optional (default to infinity) and used a layoutBuilder to constrain the _imageWidget

ChatUi

• Added a builder for the linkPreview
• Adapted FlyerChatMessage and SimpleMessage to display the Preview
• No default implementation => did not want to make them depends on flutter_link_previewer + the logic to fetch or not preview is to be decided by the user.

Implementation example

linkPreviewBuilder: (context, message) {
          final metadataLinkPreviewFetchedKey = 'linkPreviewDataFetched';
          final isLinkPreviewDataFetched =
              message.metadata?.containsKey(metadataLinkPreviewFetchedKey) ??
                  false;

          if (message.linkPreviewData != null || !isLinkPreviewDataFetched) {
            return Column(
              children: [
                Divider(
                  height: 0.5,
                  color: Colors.white,
                ),
                LinkPreview(
                  text: message.text,
                  linkPreviewData: message.linkPreviewData,
                  hideDescription: false,
                  hideText: false,
                  hideTitle: false,
                  linkStyle: TextStyle().copyWith(color: Colors.white),
                  openOnPreviewImageTap: true,
                  openOnPreviewTitleTap: true,
                  onLinkPreviewDataFetched: (linkPreviewData) {
                    _controller?.updateMessage(
                      message,
                      message.copyWith(
                        metadata: {
                          ...message.metadata ?? {},
                          metadataLinkPreviewFetchedKey: true,
                        },
                        linkPreviewData: linkPreviewData,
                      ),
                    );
                  },
                ),
              ],
            );
          }
          return null;
        },
     

Questions / notes

1. Not sure why the display as row is conditionned to the image being square? Maybe we could add an option to force a row/colum render
2. Understanding the layout was quite harsh, I tried to make it a little bit more readable

Screenshots

Preview	Description
	Everything showed
	Hidden text
	Title and image only
	No img
	img only
	fake 1 ratio => row render

[demchenkoalex]

some changes I made after merging: c922a0c