Fix Invalid SemVer version generation

when the current branch does not have commits ahead of tag/checked out on a tag

CHANGELOG.md

@@ -3,6 +3,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [1.0.4] - 2019-08-01
+### Fixed
+- Invalid SemVer version generation, when the current branch does not have commits ahead of tag/checked out on a tag
+
 ## [1.0.3] - 2019-07-31
 ### Security
 - OStatus: eliminate the possibility of a protocol downgrade attack.

mix.exs

@@ -189,12 +189,13 @@ defp version(version) do
            tag = String.trim(tag),
            {describe, 0} <- System.cmd("git", ["describe", "--tags", "--abbrev=8"]),
            describe = String.trim(describe),
-           ahead <- String.replace(describe, tag, "") do
+           ahead <- String.replace(describe, tag, ""),
+           ahead <- String.trim_leading(ahead, "-") do
         {String.replace_prefix(tag, "v", ""), if(ahead != "", do: String.trim(ahead))}
       else
         _ ->
           {commit_hash, 0} = System.cmd("git", ["rev-parse", "--short", "HEAD"])
-          {nil, "-0-g" <> String.trim(commit_hash)}
+          {nil, "0-g" <> String.trim(commit_hash)}
       end
 
     if git_tag && version != git_tag do
@@ -206,14 +207,15 @@ defp version(version) do
     # Branch name as pre-release version component, denoted with a dot
     branch_name =
       with {branch_name, 0} <- System.cmd("git", ["rev-parse", "--abbrev-ref", "HEAD"]),
+           branch_name <- String.trim(branch_name),
            branch_name <- System.get_env("PLEROMA_BUILD_BRANCH") || branch_name,
-           true <- branch_name != "master" do
+           true <- branch_name not in ["master", "HEAD"] do
         branch_name =
           branch_name
           |> String.trim()
           |> String.replace(identifier_filter, "-")
 
-        "." <> branch_name
+        branch_name
       end
 
     build_name =
@@ -233,6 +235,17 @@ defp version(version) do
         env_override -> env_override
       end
 
+    # Pre-release version, denoted by appending a hyphen
+    # and a series of dot separated identifiers
+    pre_release =
+      [git_pre_release, branch_name]
+      |> Enum.filter(fn string -> string && string != "" end)
+      |> Enum.join(".")
+      |> (fn
+            "" -> nil
+            string -> "-" <> String.replace(string, identifier_filter, "-")
+          end).()
+
     # Build metadata, denoted with a plus sign
     build_metadata =
       [build_name, env_name]
@@ -243,7 +256,7 @@ defp version(version) do
             string -> "+" <> String.replace(string, identifier_filter, "-")
           end).()
 
-    [version, git_pre_release, branch_name, build_metadata]
+    [version, pre_release, build_metadata]
     |> Enum.filter(fn string -> string && string != "" end)
     |> Enum.join()
   end