R markdown templates

[renkun-ken]

What problem did you solve?

Closes #839

This PR implements choosing template and create draft rmd from template via rmarkdown::draft().

The templates are obtained via scanning the R package folders so that the information of all templates are written to a temp JSON file. When user picks a template, saveFileDialog will show up and user needs to find a location to save the file.

Some templates have multiple files. If user specify e.g. draft.Rmd, multi-file templates will create a new folder draft and then put files in it.

(If you have)Screenshot

Kapture.2022-02-09.at.20.15.37.mp4

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1. "R Markdown: New Draft" will let user choose template and choose a location to save file.
2. Then a rmd file or a folder will be created.
3. The rmd file will be open in editor.

[ManuelHentschel]

I'm not very familiar with rmd templates, but the ones that were found in my installed packages (rmarkdown, reprex) were only single-file documents. In these instances it might feel more natural to just create an unsaved editor with the content of the file, instead of having to save it somewhere.

Would it be feasible to do this for the packages that have create_dir = false?

[renkun-ken]

Yes. In my initial implementation, I create untitled documents in all cases, but switched to save before creation when I test with create_dir = true. Using untitled documents for create_dir = false certainly makes good sense, and it is consistent with the behavior of RStudio. I'll implement this soon.

[ManuelHentschel]

The .Rmd extension might be a bit confusing here. I did not find a really clean solution to configure the SaveDialog to specify a folder, but the following could be used:

        let defaultPath = path.join(cwd, 'draft');
        let i = 1;
        while(fs.existsSync(defaultPath)){
            defaultPath = path.join(cwd, `draft_${++i}`);
        }

        const uri = await window.showSaveDialog({
            defaultUri: Uri.file(defaultPath),
            filters: {
                'Folder': ['']
            },
            saveLabel: 'Create Folder',
            title: 'R Markdown: New Draft'
        });

The open dialogue seems to have an option to select only folders, but does not allow to select non-existing folders

[renkun-ken]

Yes, it is something I'm also considering. I tried showOpenDialog with folder-only options, but it didn't work smoothly for saving purpose.

[renkun-ken]

Also, rmarkdown::draft() will throw error if the target file or folder exists, which I have not handled yet.

[renkun-ken]

rmarkdown::draft() will create a folder with last file extension removed. For example, draft.Rmd will become draft; draft.test.Rmd will become draft.test.

I update the code to check if this folder already exists and let user confirm whether to remove it before creating the draft folder.

[renkun-ken]

@ManuelHentschel Any more suggestions?

[ManuelHentschel]

Works nicely, thanks!