Support lexicographical sorting

README.md

@@ -10,11 +10,12 @@ It would be more useful to use this with other GitHub Actions' outputs.
 
 ## Inputs
 
-|          NAME          |                                                  DESCRIPTION                                                  |   TYPE   | REQUIRED | DEFAULT  |
-|------------------------|---------------------------------------------------------------------------------------------------------------|----------|----------|----------|
-| `semver_only`          | Whether gets only a tag in the shape of semver. `v` prefix is accepted for tag names.                         | `bool`   | `false`  | `false`  |
-| `initial_version`      | The initial version. Works only when `inputs.with_initial_version` == `true`.                                 | `string` | `false`  | `v0.0.0` |
-| `with_initial_version` | Whether returns `inputs.initial_version` as `outputs.tag` if no tag exists. `true` and `false` are available. | `bool`   | `false`  | `true`   |
+NAME | DESCRIPTION | TYPE | REQUIRED | DEFAULT
+---|---|---|---|---
+`semver_only` | Whether to return only semvar format tags. `v` prefix is accepted for tag names. | `bool` | `false` | `false`
+`initial_version` | The initial version. Works only when `inputs.with_initial_version` is set to `true`. | `string` | `false` | `v0.0.0`
+`with_initial_version` | Whether to return `inputs.initial_version` as `outputs.tag` if no tag exists | `bool` | `false` | `true`
+`sort_by_date` | Whether to sort the tags in chronological order (default) or in lexicographical order | `bool` | `false` | `true`
 
 If `inputs.semver_only` is `true`, the latest tag among tags with semver will be set for `outputs.tag`.
 

action.yml

@@ -14,6 +14,10 @@ inputs:
     description: Whether returns `inputs.initial_version` as `outputs.tag` if no tag exists. `true` and `false` are available.
     required: false
     default: "true"
+  sort_by_date:
+    description: If set to `false`, the tags are sorted in lexicographical order by `refname` (which can return the largest semver tag). Defaults to `true` and returns the tag which was pushed most recently (even though it might not be the largest by semver comparison).
+    required: false
+    default: "true"
 outputs:
   tag:
     description: The latest tag. If no tag exists and `inputs.with_initial_version` == `false`, this value is `''`.

entrypoint.sh

@@ -9,6 +9,12 @@ git fetch --tags
 git fetch --prune --unshallow || true
 
 latest_tag=''
+sort_flag='--sort=-refname'
+
+if [ "${INPUT_SORT_BY_DATE}" = 'true' ]; then
+  # Set the 'sort' flag
+  sort_flag='--sort=-creatordate'
+fi
 
 if [ "${INPUT_SEMVER_ONLY}" = 'false' ]; then
   # Get a actual latest tag.
@@ -25,6 +31,24 @@ else
   done
 fi
 
+# Get a latest tag
+for ref in $(git for-each-ref ${sort_flag} --format '%(refname)' refs/tags); do
+  tag="${ref#refs/tags/}"
+
+  # Return if it is in semver format
+  if echo "${tag}" | grep -Eq '^v?([0-9]+)\.([0-9]+)\.([0-9]+)(?:-([0-9A-Za-z-]+(?:\.[0-9A-Za-z-]+)*))?(?:\+[0-9A-Za-z-]+)?$'; then
+    latest_tag="${tag}"
+    break
+  fi
+
+  # Return if the user didn't ask for semver format
+  if [ "${INPUT_SEMVER_ONLY}" = 'false' ]; then
+    # Get a actual latest tag.
+    latest_tag="${tag}"
+    break
+  fi
+done
+
 if [ "${latest_tag}" = '' ] && [ "${INPUT_WITH_INITIAL_VERSION}" = 'true' ]; then
   latest_tag="${INPUT_INITIAL_VERSION}"
 fi