update ps1 to prompt change to different hostname

git-ssh-setup.ps1

@@ -6,6 +6,11 @@
     for the passphrase every time, and signs Gitea's key-verification token.
 
 .DESCRIPTION
+    The script asks which SSH host to set up. The first time the answer is
+    blank; after that it offers the host you used last, so press Enter to keep
+    it or type another one to add a second server. You can type a bare host
+    (git.example.com), host:port, or paste an SSH clone URL.
+
     Safe to re-run: an existing key is reused (unless -Force), a key already in
     the agent is not added again, and an existing Host entry in ~/.ssh/config
     is never modified.
@@ -21,7 +26,8 @@
     powershell -NoProfile -ExecutionPolicy Bypass -File .\git-ssh-setup.ps1
 
 .EXAMPLE
-    powershell -NoProfile -ExecutionPolicy Bypass -File .\git-ssh-setup.ps1 -Comment "you@example.com"
+    # Skip the host prompt.
+    powershell -NoProfile -ExecutionPolicy Bypass -File .\git-ssh-setup.ps1 -HostName git.example.com -Port 2222
 
 .EXAMPLE
     # Verify the key later: click Verify next to it in Gitea and pass the token it shows.
@@ -32,12 +38,14 @@
 #>
 [CmdletBinding()]
 param(
-    # Host to add to ~/.ssh/config and test against. Use -HostName "" to skip both.
+    # SSH host for Git. If omitted, the script asks and remembers the answer.
-    [string]$HostName = "tea.lenrui.net",
+    # Use -HostName "" to skip the ~/.ssh/config entry and the connection test.
+    [string]$HostName,
 
     # SSH user for the host (Gitea, GitHub and GitLab all use "git").
     [string]$User = "git",
 
+    # SSH port. Defaults to 22, or to the port typed as host:port at the prompt.
     [ValidateRange(1, 65535)]
     [int]$Port = 22,
 
@@ -70,6 +78,55 @@ function Stop-Setup([string]$Message) {
     exit 1
 }
 
+# Turns what the user typed into a host name and an optional port. Accepts a
+# bare host, host:port, git@host, git@host:owner/repo.git, or
+# ssh://git@host:port/owner/repo.git. Returns $null if it isn't usable.
+function ConvertTo-SshTarget([string]$Text) {
+    $t = "$Text".Trim()
+    $t = $t -replace '^[A-Za-z][A-Za-z0-9+.-]*://', ''   # ssh:// or https://
+    $t = $t -replace '^[^@/]*@', ''                       # git@
+    $t = ($t -split '/')[0]                               # any path
+    $p = $null
+    if ($t -match '^(.+):(\d+)$') {
+        if ($Matches[2].Length -gt 5) { return $null }
+        $t = $Matches[1]
+        $p = [int]$Matches[2]
+        if ($p -lt 1 -or $p -gt 65535) { return $null }
+    } elseif ($t.Contains(':')) {
+        $t = $t.Substring(0, $t.IndexOf(':'))              # host:owner/repo.git
+    }
+    if ($t -notmatch '^[A-Za-z0-9]([A-Za-z0-9.-]*[A-Za-z0-9])?$') { return $null }
+    return [pscustomobject]@{ HostName = $t.ToLowerInvariant(); Port = $p }
+}
+
+# The last host used is kept in a small file in your user profile.
+$stateDir  = if ($env:APPDATA) { Join-Path $env:APPDATA 'git-ssh-setup' } else { Join-Path $HOME '.git-ssh-setup' }
+$stateFile = Join-Path $stateDir 'last-host.json'
+
+function Read-LastHost {
+    try {
+        if (Test-Path $stateFile) {
+            $saved = Get-Content -Path $stateFile -Raw | ConvertFrom-Json
+            if ($saved.HostName) {
+                $savedPort = 22
+                if ($saved.Port) { $savedPort = [int]$saved.Port }
+                return [pscustomobject]@{ HostName = [string]$saved.HostName; Port = $savedPort }
+            }
+        }
+    } catch { }
+    return $null
+}
+
+function Save-LastHost([string]$Name, [int]$PortNumber) {
+    try {
+        New-Item -ItemType Directory -Path $stateDir -Force | Out-Null
+        $json = [pscustomobject]@{ HostName = $Name; Port = $PortNumber } | ConvertTo-Json
+        [IO.File]::WriteAllText($stateFile, $json, (New-Object Text.UTF8Encoding($false)))
+    } catch {
+        Write-Note "Couldn't remember the host for next time: $($_.Exception.Message)"
+    }
+}
+
 # Signs $Text exactly as given and returns the armored signature, or $null if
 # ssh-keygen failed. The text is written to a file with no trailing newline and
 # no BOM: piping it into ssh-keygen from PowerShell would add a newline and
@@ -96,6 +153,49 @@ if ($Token -and $Token -notmatch '^[0-9a-fA-F]+$') {
     Stop-Setup "-Token should be just the hex string from Gitea's Token box."
 }
 
+# --- 0. SSH host -------------------------------------------------------------
+$target = $null
+if ($PSBoundParameters.ContainsKey('HostName')) {
+    if ($HostName) {
+        $target = ConvertTo-SshTarget $HostName
+        if (-not $target) { Stop-Setup "'$HostName' isn't a host name the script can use." }
+    }
+} else {
+    Write-Step "Choosing the SSH host"
+    $last = Read-LastHost
+    $suggested = ''
+    if ($last) {
+        $suggested = $last.HostName
+        if ($last.Port -ne 22) { $suggested = "$($last.HostName):$($last.Port)" }
+        Write-Host "    Press Enter to keep the last host, or type a different one."
+    } else {
+        Write-Host "    Type the host name from your SSH clone URL, e.g. git.example.com"
+        Write-Host "    (add :port if the server doesn't use 22)."
+    }
+    while ($true) {
+        $label = if ($suggested) { "    SSH host [$suggested]" } else { "    SSH host" }
+        $answer = "$(Read-Host $label)".Trim()
+        if (-not $answer) {
+            if ($suggested) { $answer = $suggested } else { Write-Note "A host name is needed."; continue }
+        }
+        $target = ConvertTo-SshTarget $answer
+        if ($target) {
+            if ($answer -match '^https?://') {
+                Write-Note "That was a web address. Make sure '$($target.HostName)' is the host in your SSH"
+                Write-Note "clone URL; a site behind Cloudflare's proxy won't accept SSH."
+            }
+            break
+        }
+        Write-Note "'$answer' doesn't look like a host name. Try something like git.example.com or git.example.com:2222"
+    }
+}
+if ($target) {
+    $HostName = $target.HostName
+    if ($target.Port -and -not $PSBoundParameters.ContainsKey('Port')) { $Port = $target.Port }
+    Save-LastHost $HostName $Port
+    Write-Ok "Using $User@${HostName}, port $Port"
+}
+
 $openSshDir = Join-Path $env:WINDIR 'System32\OpenSSH'
 $sshExe     = Join-Path $openSshDir 'ssh.exe'
 $keygenExe  = Join-Path $openSshDir 'ssh-keygen.exe'