Merge pull request #180 from mbland/go-template-download

Download release file instead of cloning repo in go-template (continued from #179)

Author: mbland

go-template

@@ -6,9 +6,9 @@
 # description. You may remove any other comments from this template as well.
 #
 # This template automatically checks for the presence of the go-script-bash
-# sources and makes a shallow clone of the the go-script-bash repository if
-# necessary before dispatching commands. (If you prefer, you can change the
-# logic to create a regular clone instead.) This allows users to set up the
+# sources and downloads the go-script-bash repository contents if necessary
+# before dispatching commands. (If you prefer, you can change the logic to 
+# create a shallow or regular clone instead.) This allows users to set up the
 # framework without taking any extra steps when running the command for the
 # first time, without the need to commit the framework to your repository.
 #
@@ -43,15 +43,81 @@ declare GO_SCRIPT_BASH_CORE_DIR="${GO_SCRIPT_BASH_CORE_DIR:-${0%/*}/$GO_SCRIPTS_
 # The URL of the go-script-bash framework sources
 declare GO_SCRIPT_BASH_REPO_URL="${GO_SCRIPT_BASH_REPO_URL:-https://github.com/mbland/go-script-bash.git}"
 
-if [[ ! -e "$GO_SCRIPT_BASH_CORE_DIR/go-core.bash" ]]; then
+# URL with the release files
+declare GO_SCRIPT_BASH_DOWNLOAD_URL="${GO_SCRIPT_BASH_DOWNLOAD_URL:-${GO_SCRIPT_BASH_REPO_URL%.git}/archive}/$GO_SCRIPT_BASH_VERSION.tar.gz"
+
+# Downloads `GO_SCRIPT_BASH_VERSION` as a tar.gz file and unpacks it.
+download_go_script_bash_tarball() {
+  # GitHub removes the leading 'v' from the archive's output directory.
+  local unpacked_dir="go-script-bash-${GO_SCRIPT_BASH_VERSION#v}"
+  local unpacked_core="$unpacked_dir/go-core.bash"
+  local core_dir_parent="${GO_SCRIPT_BASH_CORE_DIR%/*}"
+  local url="$GO_SCRIPT_BASH_DOWNLOAD_URL"
+  local protocol="${url%%://*}"
+  local download_cmd=()
+
+  if [[ "$protocol" == "$url" ]]; then
+    printf 'GO_SCRIPT_BASH_DOWNLOAD_URL has no protocol: %s\n' "$url" >&2
+    return 1
+  elif [[ "$(git --version)" =~ windows && "$protocol" == 'file' ]]; then
+    url="file://$(cygpath -m "${url#file://}")"
+  fi
+
+  if command -v curl >/dev/null; then
+    download_cmd=(curl -LfsS "$url")
+  elif command -v fetch >/dev/null; then
+    download_cmd=(fetch -o - "$url")
+  elif [[ "$protocol" == 'file' ]] && command -v cat; then
+    # `wget` can't handle 'file://' urls. Though input redirection would work
+    # below, this method is consistent with the process substitution logic.
+    download_cmd=(cat "${url#file://}")
+  elif command -v wget >/dev/null; then
+    download_cmd=(wget -O - "$url")
+  else
+    printf "Failed to find cURL, wget, or fetch\n" >&2
+    return 1
+  fi
+
+  if ! command -v tar >/dev/null; then
+    printf "Failed to find tar\n" >&2
+    return 1
+  fi
+  printf "Downloading framework from '%s'...\n" "$url"
+
+  if ! tar -xzf <("${download_cmd[@]}") || [[ ! -f "$unpacked_core" ]]; then
+    printf "Failed to download from '%s'.\n" "$url" >&2
+    return 1
+  elif [[ ! -d "$core_dir_parent" ]] && ! mkdir -p "$core_dir_parent" ; then
+    printf "Failed to create scripts dir '%s'\n" "$core_dir_parent" >&2
+    rm -rf "$unpacked_dir"
+    return 1
+  elif ! mv "$unpacked_dir" "$GO_SCRIPT_BASH_CORE_DIR"; then
+    printf "Failed to install downloaded directory in '%s'\n" \
+      "$GO_SCRIPT_BASH_CORE_DIR" >&2
+    rm -rf "$unpacked_dir"
+    return 1
+  fi
+  printf "Download of '%s' successful.\n\n" "$url"
+}
+
+git_clone_go_script_bash() {
   printf "Cloning framework from '%s'...\n" "$GO_SCRIPT_BASH_REPO_URL"
   if ! git clone --depth 1 -c advice.detachedHead=false \
       -b "$GO_SCRIPT_BASH_VERSION" "$GO_SCRIPT_BASH_REPO_URL" \
       "$GO_SCRIPT_BASH_CORE_DIR"; then
     printf "Failed to clone '%s'; aborting.\n" "$GO_SCRIPT_BASH_REPO_URL" >&2
-    exit 1
+    return 1
   fi
   printf "Clone of '%s' successful.\n\n" "$GO_SCRIPT_BASH_REPO_URL"
+}
+
+if [[ ! -e "$GO_SCRIPT_BASH_CORE_DIR/go-core.bash" ]]; then
+  if ! download_go_script_bash_tarball; then
+    printf "Using git clone as fallback\n"
+    if ! git_clone_go_script_bash; then
+      exit 1
+    fi
+  fi
 fi
 
 . "$GO_SCRIPT_BASH_CORE_DIR/go-core.bash" "$GO_SCRIPTS_DIR"