upd: rewrite and support stdout

scripts/changelog.ps1

@@ -1,40 +1,55 @@
 #!/usr/bin/pwsh -c
-param ([Alias('p')][string]$Path)
-try {
-    [System.IO.Directory]::SetCurrentDirectory("$PSScriptRoot/../")
-    $ROOT_PATH = [System.IO.Directory]::GetCurrentDirectory()
-    $CHANGELOG = [System.IO.Path]::Combine($ROOT_PATH, 'CHANGELOG.md')
-    $readLines = [System.IO.File]::ReadAllLines($CHANGELOG)
-    $header = $readLines -match '^## \[([\d.]+)\] - \d{4}-\d{2}-\d{2}'
-} finally {
-    if ($header[0]) {
-        $writelines = @()
-        foreach ($line in $readLines) {
-            if ($line -eq $header[1]) { break }
-            if ($line -ne $header[0] -and $line.Length -ne 0) {
-                if ($line.StartsWith('[Full Changelog]')) { $writelines += '' }
-                $writelines += $line
-            }
-        }
-        if ($Path -and !([System.IO.File]::Exists($Path))) {
-            $dirPath = [System.IO.Path]::GetDirectoryName($Path)
-            if ([System.IO.Directory]::Exists($dirPath)) {
-                [System.IO.Directory]::CreateDirectory($dirPath) | Out-Null
-            }
-            $fileName = [System.IO.Path]::GetFileName($Path)
-            $newChangelogPath = [System.IO.Path]::Combine($dirPath, $fileName)
-        } else {
-            $newChangelogPath = [System.IO.Path]::Combine($ROOT_PATH, 'CHANGES.MD')
+param (
+    # Save as output to file name.
+    [Alias('o')][string]$OutFile,
+    # Update header date to current date.
+    [Alias('u')][switch]$NowDate
+)
+
+$ROOT_PATH = [System.IO.Path]::GetFullPath("$PSScriptRoot/..")
+$inFileChangelog = [System.IO.Path]::Combine($ROOT_PATH, 'CHANGELOG.md')
+if (!([System.IO.File]::Exists($inFileChangelog))) {
+    "File could not be found '$inFileChangelog'."
+    exit 1
+}
+
+if ($OutFile -and $OutFile.EndsWith('CHANGELOG.md')) {
+    "File cannot be the same as '$inFileChangelog'."
+    exit 1
+}
+
+[System.Console]::InputEncoding = [System.Console]::OutputEncoding = $OutputEncoding = [System.Text.UTF8Encoding]::new()
+$readLines = [System.IO.File]::ReadAllLines($inFileChangelog).Trim()
+$headings = $readLines -match '^##.\[([\d.]+)\].-.\d{4}-\d{2}-\d{2}'
+$footers = $readLines -match '^\[Full Changelog\]\(.*\)'
+$currentDate = [string]::Format('{0:yyyy-MM-dd}', [datetime]::Now)
+
+$startHeader = $headings[0]
+
+if ($startHeader) {
+    $writeLines = [System.Collections.Generic.List[string]]::new()
+    foreach ($line in $readLines) {
+        if ($line -eq $footers[0]) { $writeLines.Add($line); break }
+        if ($line -eq $headings[1]) { break }; $writeLines.Add($line)
+    }
+    if ($NowDate) {
+        $semanticVersion = $startHeader.Split(' ')[1].Trim('[]')
+        $newStartHeader = "## [$semanticVersion] - $currentDate"
+        if ($startHeader -ne $newStartHeader) {
+            $writeLines = $writeLines -replace $startHeader, $newStartHeader
         }
-        [System.IO.File]::WriteAllLines($newChangelogPath, $writelines)
-        # replacing old date to current date
-        $version = $header[0].Split(' ')[1].Trim('[]')
-        $newDate = [string]::Format('{0:yyyy-MM-dd}', [datetime]::Now)
-        $oldHeader = "^## \[$version\] - \d{4}-\d{2}-\d{2}"
-        $newHeader = "## [$version] - $newDate"
-        if ($header[0] -ne $newHeader) {
-            $newChangelogDate = $readLines -replace $oldHeader, $newHeader
-            [System.IO.File]::WriteAllLines($CHANGELOG, $newChangelogDate)
+    }
+    if ($OutFile) {
+        $DirPath = [System.IO.Path]::GetDirectoryName([System.IO.Path]::GetFullPath($OutFile))
+        if (!([System.IO.Directory]::Exists($DirPath))) {
+            [System.IO.Directory]::CreateDirectory($DirPath) | Out-Null
         }
+        [System.IO.File]::WriteAllLines($OutFile, $writeLines)
+    } else {
+        return $writeLines
     }
+} else {
+    "Mismatched heading like '## [semver] - yyyy-MM-dd'."
+    "example heading: ## [1.0.0] - $currentDate"
+    exit 1
 }