Interactive Git commands for Far Manager + FarNet.PowerShellFar

FarGit.psm1

<#
Interactive Git commands for Far Manager + FarNet.PowerShellFar
<https://gist.github.com/nightroman/1d4806e4bcd2fae1b852>

HOW TO USE
	Create a directory FarGit in any of $env:PSModulePath. As far as it is for
	PowerShellFar only consider %FARHOME%\FarNet\Modules\PowerShellFar\Modules

	Download FarGit.psm1 to the created directory FarGit.

	Import the module and call its commands in PowerShellFar.
	Or add these commands to your Far Manager user menu:

	h:  Show help (user menu needs Far 3.0.4330+)
		ps: Import-Module FarGit; Show-FarGitHelp #
	s:  Show status
		ps: Import-Module FarGit; Show-FarGitStatus #
	r:  Go to root
		ps: Import-Module FarGit; Set-FarGitRoot #
	e:  Edit config
		ps: Import-Module FarGit; Edit-FarGitConfig #

	:  Branch
	{
	b:  Switch branch
		ps: Import-Module FarGit; Invoke-FarGitCheckoutBranch #
	c:  Create branch
		ps: Import-Module FarGit; Invoke-FarGitBranchCreate #
	m:  Merge branch
		ps: Import-Module FarGit; Invoke-FarGitMergeBranch #
	d:  Delete branch (safe)
		ps: Import-Module FarGit; Invoke-FarGitBranchDelete #
	k:  Delete branch (force)
		ps: Import-Module FarGit; Invoke-FarGitBranchDelete -Force #
	r:  Rename current branch
		ps: Import-Module FarGit; Invoke-FarGitBranchRename #
	}

	:  Stash
	{
	a:  Apply stash
		ps: Import-Module FarGit; Invoke-FarGitStashApply #
	p:  Pop stash
		ps: Import-Module FarGit; Invoke-FarGitStashPop #
	d:  Drop stash
		ps: Import-Module FarGit; Invoke-FarGitStashDrop #
	s:  Show stash
		ps: Import-Module FarGit; Invoke-FarGitStashShow #
	}
#>

$ErrorActionPreference = 'Stop'

### Exported commands.

<#
.Synopsis
	Shows git help for the git command.

.Description
	The command shows HTML help the git command found in the editor, dialog, or
	command line. If 'git command' is not found then the main page is shown.
#>
function Show-FarGitHelp {
	if ($Far.Line.Text -match '\bgit\s+(\S+)') {
		$null = Invoke-Git {git ($matches[1]) --help}
	}
	else {
		Invoke-Item -LiteralPath "$(Invoke-Git {git --html-path})\index.html"
	}
}

<#
.Synopsis
	Opens the current config file in the editor.
#>
function Edit-FarGitConfig {
	try {
		Assert-Git

		$root = Invoke-Git {git rev-parse --git-dir}
		Open-FarEditor $root\config
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Sets the repository root current in the panel.
#>
function Set-FarGitRoot {
	try {
		Assert-Git

		$root = Invoke-Git {git rev-parse --show-toplevel}
		$Far.Panel.CurrentDirectory = $root
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Shows changed files and navigates to a selected.

.Description
	The command shows the list of changed files.
	Select a file to navigate to in the active panel.
#>
function Show-FarGitStatus {
	try {
		Assert-Git

		$info = Invoke-Git {git status --porcelain} | ConvertFrom-Octet | .{process{
			($_ -replace '^ ', '-') -replace '^(.) ', '$1-'
		}} | Out-FarList -Title "On branch $(Get-BranchCurrent)"
		if (!$info) {return}

		if ($info -notmatch '^(..)\s+"?(.+?)"?(?:\s+->\s+"?(.+?)"?)?$') {throw "Unexpected status format: $info"}
		$path = if ($matches[3]) {$matches[3]} else {$matches[2]}
		$Far.Panel.GoToPath("$(Invoke-Git {git rev-parse --show-toplevel})\$path")
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Switches to another branch.

.Description
	The command shows the branch list.
	Select a branch to be set the current.
	If there are no branches the command prompts to create a new branch.
#>
function Invoke-FarGitCheckoutBranch {
	try {
		Assert-Git

		if (!($branch = Get-BranchOther)) {
			if (0 -eq (Show-FarMessage 'No other branches. Create?' -Buttons YesNo)) {
				Invoke-FarGitBranchCreate
			}
			return
		}

		$branch = $branch | Out-FarList -Title "Switch from $(Get-BranchCurrent)"
		if ($branch) {
			Invoke-Git {git checkout $branch}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Merges another branch into the current.

.Description
	The command shows the branch list.
	Select a branch to merge into the current.
#>
function Invoke-FarGitMergeBranch {
	try {
		Assert-Git

		if (!($branch = Get-BranchOther)) {
			Show-FarMessage 'No other branches.'
			return
		}

		$branch = $branch | Out-FarList -Title "Merge to $(Get-BranchCurrent)"
		if ($branch) {
			Invoke-Git {git merge $branch}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Deletes another branch.

.Parameter Force
		Tells to delete a branch irrespective of its merged status.

.Description
	The command shows the branch list.
	Select a branch to be deleted.

	By default the branch must be fully merged in its upstream branch. Use the
	switch Force in order to delete a branch irrespective of its merged status.
#>
function Invoke-FarGitBranchDelete {
	[CmdletBinding()]
	param(
		[switch]$Force
	)
	try {
		Assert-Git

		if (!($branch = Get-BranchOther)) {
			Show-FarMessage 'No other branches.'
			return
		}

		$branch = $branch | Out-FarList -Title 'Delete branch'
		if (!$branch) {return}

		#??
		if ($branch -ceq 'master') {
			Show-FarMessage 'Cannot delete master.'
			return
		}

		$message = if ($Force) {"Delete branch $branch (force)"} else {"Delete branch $branch"}
		if (0 -ne (Show-FarMessage $message -Buttons YesNo -IsWarning:$Force)) {return}
		if ($Force) {
			Invoke-Git {git branch -D $branch}
		}
		else {
			Invoke-Git {git branch -d $branch}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Creates a new branch and switches to it.

.Description
	The command shows the input box.
	Enter the new branch name and press enter.
#>
function Invoke-FarGitBranchCreate {
	try {
		Assert-Git

		$currentBranch = Get-BranchCurrent
		$newBranch = if ($currentBranch -eq 'master') {''} else {$currentBranch}
		$newBranch = $Far.Input('Branch name', 'GitBranch', "New branch from $currentBranch", $newBranch)
		if ($newBranch) {
			Invoke-Git {git checkout -b $newBranch}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Renames the current branch.

.Description
	The command shows the input box with the current branch name.
	Enter the new branch name and press enter.
#>
function Invoke-FarGitBranchRename {
	param (
		[switch]$DatePrefix
	)
	try {
		Assert-Git

		$currentBranch = Get-BranchCurrent
		$newBranch = if ($DatePrefix -and $currentBranch -notmatch '^\d\d\d\d\d\d-') {
			'{0:yyMMdd}-{1}' -f (Get-Date), $currentBranch
		}
		else {
			$currentBranch
		}

		$newBranch = $Far.Input('Branch name', 'GitBranch', "Rename branch $currentBranch", $newBranch)
		if ($newBranch) {
			Invoke-Git {git branch -m $newBranch}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Invokes git stash apply.

.Description
	The command shows the stash list.
	Select a stash to be applied.
#>
function Invoke-FarGitStashApply {
	try {
		Assert-Git

		if ($stash = Select-StashName 'Apply stash') {
			Invoke-Git {git stash apply $stash}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Invokes git stash drop.

.Description
	The command shows the stash list.
	Select a stash to be dropped.
#>
function Invoke-FarGitStashDrop {
	try {
		Assert-Git

		if ($stash = Select-StashName 'Drop stash') {
			Invoke-Git {git stash drop $stash}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Invokes git stash pop.

.Description
	The command shows the stash list.
	Select a stash to be popped.
#>
function Invoke-FarGitStashPop {
	try {
		Assert-Git

		if ($stash = Select-StashName 'Pop stash') {
			Invoke-Git {git stash pop $stash}
		}
	}
	catch {
		Show-Error
	}
}

<#
.Synopsis
	Invokes git stash show.

.Description
	The command shows the stash list.
	Select a stash to show its patch details.
#>
function Invoke-FarGitStashShow {
	try {
		Assert-Git

		if ($stash = Select-StashName 'Show stash') {
			Invoke-Git {git stash show -p $stash}
		}
	}
	catch {
		Show-Error
	}
}

### Internal commands.

# Decodes git strings with octets.
filter ConvertFrom-Octet {
	if (!$_.Contains('\')) {
		return $_
	}
	$bytes = [System.Collections.ArrayList]@()
	foreach($m in ([regex]'\\\d\d\d|.').Matches($_)) {
		$t = $m.ToString()
		if (($b = $t[0]) -eq '\') {
			$b = [Convert]::ToInt32($t.Substring(1), 8)
		}
		$null = $bytes.Add($b)
	}
	[System.Text.Encoding]::UTF8.GetString($bytes)
}

# Gets the current branch name.
function Get-BranchCurrent {
	foreach($branch in Invoke-Git {git branch --list --quiet}) {
		if ($branch -notmatch '^(\*)?\s*(\S+)') {throw "Unexpected branch format: '$branch'."}
		if ($matches[1]) {
			return $matches[2]
		}
	}
}

# Gets branch names except the current.
function Get-BranchOther {
	foreach($branch in Invoke-Git {git branch --list --quiet}) {
		if ($branch -notmatch '^(\*)?\s*(\S+)') {throw "Unexpected branch format: '$branch'."}
		if (!$matches[1]) {
			$matches[2]
		}
	}
}

# Gets stash strings.
function Get-StashText {
	Invoke-Git {git stash list}
}

# Gets the stash name from a string.
function Get-StashName {
	[CmdletBinding()]
	param(
		$Stash
	)

	if ($Stash -notmatch '^(stash@{\d+})') {throw "Unexpected stash format: $Stash."}
	$matches[1]
}

# Shows the stash list and gets the selected stash name.
function Select-StashName {
	[CmdletBinding()]
	param(
		$Title
	)

	if (!($stash = Get-StashText)) {
		Show-FarMessage 'There are no stashes.'
		return
	}

	$stash = $stash | Out-FarList -Title $Title
	if (!$stash) {return}

	Get-StashName $stash
}

# Invokes a native command and checks for $LASTEXITCODE.
function Invoke-Git($Command) {
	${*OutputEncoding} = [Console]::OutputEncoding
	[Console]::OutputEncoding = [System.Text.Encoding]::UTF8
	try {
		. $Command
		if ($LASTEXITCODE) {Write-Error "Exit code: $LASTEXITCODE. Command: $Command" -ErrorAction 1}
	}
	finally {
		[Console]::OutputEncoding = ${*OutputEncoding}
	}
}

# Shows the error $_.
function Show-Error {
	Write-Host $_ -ForegroundColor Red
}

# Throw if not a repo.
function Assert-Git {
	[CmdletBinding()]param()
	$path = $PSCmdlet.GetUnresolvedProviderPathFromPSPath('.')
	do {
		if (Test-Path "$path\.git") {return}
	} while($Path = Split-Path $Path)
	throw 'Not a git repository.'
}

Export-ModuleMember -Function *-FarGit*