watch.ps1

#
# Watch for changes
#
function watch {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [string[]]$Watch,
        
        [Parameter(Mandatory = $true)]
        [scriptblock]$Action
    )

    function Resolve-GlobPattern {
        param (
            [string]$Pattern
        )

        $isGlob = $Pattern -match '[*?]'
        if (-not $isGlob) {
            return @($Pattern)
        }
        
        $isRecursive = $Pattern -match '\*\*'
        if (-not $isRecursive) {
            $items = Get-ChildItem $Pattern -File -ErrorAction SilentlyContinue
            return $items
        }

        $items = Get-ChildItem $Pattern -Recurse -ErrorAction SilentlyContinue | %{ $_.FullName }
        return @($items);
    }
    
    $filesToWatch = @()
    foreach ($pattern in $Watch) {
        $resolvedFiles = Resolve-GlobPattern -Pattern $pattern
        $filesToWatch += $resolvedFiles
    }
    $filesToWatch = $filesToWatch | Select-Object -Unique
    
    Write-Host "Watching $($filesToWatch.Count) files for changes..." -ForegroundColor Cyan
    $filesToWatch | ForEach-Object { Write-Host "  - $_" -ForegroundColor Cyan }
    Write-Host ""

    # Keep track of last write times
    $lastWriteTimes = @{}
    $filesToWatch | ForEach-Object {
        if (Test-Path -Path $_) {
            $lastWriteTimes[$_] = (Get-Item -Path $_).LastWriteTime
        }
    }
    
    # First execution
    $executionScope = New-Module -ScriptBlock {
        param($scriptBlock, $filesToWatch)
        $global:ChangedFiles = $filesToWatch
        & $scriptBlock
        Remove-Variable -Name ChangedFiles -Scope Global -ErrorAction SilentlyContinue
    } -ArgumentList $Action, $filesToWatch
    
    Write-Host ""

    try {
        while ($true) {
            $changedFiles = @()
            
            foreach ($file in $filesToWatch) {
                if (Test-Path -Path $file) {
                    $currentWriteTime = (Get-Item -Path $file).LastWriteTime
                    if ($lastWriteTimes.ContainsKey($file) -and $currentWriteTime -gt $lastWriteTimes[$file]) {
                        $changedFiles += $file
                        $lastWriteTimes[$file] = $currentWriteTime
                    }
                    elseif (-not $lastWriteTimes.ContainsKey($file)) {
                        $changedFiles += $file
                        $lastWriteTimes[$file] = $currentWriteTime
                    }
                }
                elseif ($lastWriteTimes.ContainsKey($file)) {
                    $changedFiles += $file
                    $lastWriteTimes.Remove($file)
                }
            }
            
            # If files have changed, execute the action
            if ($changedFiles.Count -gt 0) {
                Clear-Host

                Write-Host "`nChanges detected in $($changedFiles.Count) files:" -ForegroundColor Yellow
                $changedFiles | ForEach-Object { Write-Host "  - $_" -ForegroundColor Yellow }
                Write-Host ""

                $executionScope = New-Module -ScriptBlock {
                    param($scriptBlock, $changedFiles)
                    $global:ChangedFiles = $changedFiles
                    & $scriptBlock
                    Remove-Variable -Name ChangedFiles -Scope Global -ErrorAction SilentlyContinue
                } -ArgumentList $Action, $changedFiles

                Write-Host ""
            }
            
            # Check for new files that match the patterns
            $newFilesToWatch = @()
            foreach ($pattern in $Watch) {
                $resolvedFiles = Resolve-GlobPattern -Pattern $pattern
                $newFilesToWatch += $resolvedFiles
            }
            $newFilesToWatch = $newFilesToWatch | Select-Object -Unique
            
            # Add new files to watch list
            foreach ($file in $newFilesToWatch) {
                if (-not $filesToWatch.Contains($file)) {
                    $filesToWatch += $file
                    if (Test-Path -Path $file) {
                        $lastWriteTimes[$file] = (Get-Item -Path $file).LastWriteTime
                    }
                    Write-Host "Now watching new file: $file" -ForegroundColor Cyan
                }
            }
            
            Start-Sleep -Milliseconds 1000
        }
    }
    catch {
        Write-Error "Error in watch function: $_"
    }
    finally {
        Write-Host "Watch stopped." -ForegroundColor Cyan
    }
}