Deploy a pkgdown site to gh_pages branch

deploy_to_gh_pages.r

## Adapted from r-lib/pkgdown source code from RStudio https://github.com/r-lib/pkgdown

## Helper functions, directly from pkgdown code --------------------------------
git <- function(...) {
  processx::run("git", c(...), echo_cmd = TRUE, echo = TRUE)
}

github_clone <- function(dir, repo_slug) {
  remote_url <- sprintf("git@github.com:%s.git", repo_slug)
  cli::rule("Cloning existing site", line = 1)
  git("clone",
      "--single-branch", "-b", "gh-pages",
      "--depth", "1",
      remote_url,
      dir
  )
}

github_push <- function(dir, commit_message) {
  # force execution before changing working directory
  force(commit_message)
  
  cli::rule("Commiting updated site", line = 1)
  
  withr::with_dir(dir, {
    git("add", "-A", ".")
    git("commit", "--allow-empty", "-m", commit_message)
    
    cli::rule("Deploying to GitHub Pages", line = 1)
    git("remote", "-v")
    git("push", "--force", "origin", "HEAD:gh-pages")
  })
}

## Deploy function, adapted from deploy_local ----------------------------------
deploy_site_github_local <- function(repo, preview = TRUE, delete_previous = FALSE, ...) {
  # repo is the github repository, e.g. "username/repo"
  # preview is to whether to first preview the site before pushing
  # delete_previous is a flag to delete previous gh_pages branch content
  # ... are additional parameters to build_site
  dest_dir <- fs::dir_create(fs::file_temp())
  on.exit(fs::dir_delete(dest_dir))
  
  github_clone(dest_dir, repo)
  if (delete_previous) {
    # This may be necessary if the branch has stuff not built by pkgdown
    fs::dir_map(dest_dir, fs::file_delete)
  }
  pkgdown::build_site(".",
             override = list(destination = dest_dir),
             document = FALSE,
             preview = FALSE,
             ...
  )
  
  if (preview) {
    browseURL(fs::path(dest_dir, "index.html"))
    push <- utils::menu(c("Yes","No"), title = "Push site?") == 1
  } else {
    push <- TRUE
  }
  
  if (push) {
    github_push(dest_dir, "Building new version of pkgdown website")
  }
  
  invisible()
}