#!/usr/bin/env pwsh

<#
.SYNOPSIS
    Updates git submodules and generates a commit message with the list of changes
.PARAMETER GitCommitArgs
    Additional arguments to pass into git-commit
.PARAMETER NoCommit
    Make changes without executing git-commit
.PARAMETER Force
    Specified this to make a commit with any changes
#>
[cmdletbinding(SupportsShouldProcess = $true)]
param(
    [string[]]$GitCommitArgs = @(),
    [switch]$NoCommit,
    [switch]$Force
)

$ErrorActionPreference = 'Stop'
Set-StrictMode -Version 2

$RepoRoot = Resolve-Path "$PSScriptRoot\.."
$ModuleDirectory = Join-Path $RepoRoot "modules"

Import-Module "$PSScriptRoot/common.psm1" -Scope Local -Force

function Get-GitChanges([string]$Path) {
    Write-Verbose "git diff --cached --quiet $Path"
    & git diff --cached --quiet $Path | Out-Null
    if ($LastExitCode -ne 0) {
        return $true
    }
    Write-Verbose "git diff --quiet $Path"
    & git diff --quiet $Path | Out-Null
    return $LastExitCode -ne 0
}

Push-Location $RepoRoot | Out-Null
try {
    Assert-Git

    Write-Host "Checking that submodules are in a clean state first..."
    if (Get-GitChanges $ModuleDirectory) {
        Write-Error "$RepoRoot/modules is in an unclean state. Reset submodules first by running ``git submodule update``"
        exit 1
    }

    $submodules = Get-Submodules $RepoRoot -Verbose:$VerbosePreference

    foreach ($submodule in  $submodules) {
        $submodulePath = $submodule.path
        Write-Host "Updating $submodulePath"

        $vcs_name = "BUILD_VCS_NUMBER_" + $submodule.module
        $newCommit = [environment]::GetEnvironmentVariable($vcs_name)

        if (-not $newCommit) {
            Write-Warning "TeamCity env variable '$vcs_name' not found. Pulling the latest submodule branch instead"
            Invoke-Block { & git submodule update --remote $submodulePath }
            Push-Location $submodulePath | Out-Null
            try {
                $newCommit = $(git rev-parse HEAD)
            }
            finally {
                Pop-Location | Out-Null
            }
        }
        else {
            Push-Location $submodulePath | Out-Null
            try {
                Invoke-Block { & git checkout $newCommit }
            }
            finally {
                Pop-Location | Out-Null
            }
        }

        $submodule.newCommit = $newCommit
        if ($newCommit -ne $submodule.commit) {
            $submodule.changed = $true
            Write-Host -ForegroundColor Cyan "`t=> $($submodule.module) updated to $($submodule.newCommit)"
        }
        else {
            Write-Host -ForegroundColor Magenta "`t$($submodule.module) did not change"
        }
    }

    $changes = $submodules `
        | ? { $_.changed } `
        | % {
            Invoke-Block { & git add $_.path }
            "$($_.module) => $($_.newCommit)"
        }

    if ($changes) {
        $shortMessage = "Updating submodule(s) `n`n$( $changes -join "`n" )"
        # add this to the commit message to make it possible to filter commit triggers based on message
        $message = "$shortMessage`n`n[auto-updated: submodules]"
        if (-not $NoCommit -and ($Force -or ($PSCmdlet.ShouldContinue($shortMessage, 'Create a new commit with these changes?')))) {
            Invoke-Block { & git commit -m $message @GitCommitArgs }
        }
        else {
            # If composing this script with others, return the message that would have been used
            return @{
                message = $message
            }
        }
    }
    else {
        Write-Host -ForegroundColor Magenta 'No changes detected in git submodules'
    }
}
finally {
    Pop-Location
}