<#
.SYNOPSIS
    Backup directories
.DESCRIPTION
    Make backup of specified directories, copy backup to several places and execute tasks before and after backup
.PARAMETER configFile
    Config file. Default is %USERPROFILE%\mybackup.config
.PARAMETER verify
    Check whether all directories exist
.EXAMPLE
    mybackup -configFile C:\Temp\mybackup.config
    # Perform backup using config from file C:\Temp\mybackup.config
#>

Param (
    [string] $configFile,
    [switch] $verify
)

Write-Host "Starting..." -ForegroundColor Green
$extension = ".zip"

Write-Host "Getting config..." -ForegroundColor Green
if (!$configFile) { $configFile = Join-Path $env:UserProfile "mybackup.config" }
$config = ([xml](Get-Content $configFile)).mybackup

if ($config.source) {
    Write-Host "Updating config..." -ForegroundColor Green
    try { Copy-Item $config.source $configFile }
    catch { Write-Host "Unable to copy config" -ForegroundColor Green }
    $config = ([xml](Get-Content $configFile)).mybackup
}

if ($verify) {
    Function Verify([array]$items) {
        $items.ChildNodes | ? { $_.LocalName -ne "#comment" } | % {
            if (!(Test-Path $_.path)) {
                Write-Host "Path $($_.path) does not exist" -ForegroundColor Red
                exit
            }
        }
    }

    Verify $config.tasks
    Verify $config.destinations
    Verify $config.items
    exit
}

Write-Host "Executing tasks [before]..." -ForegroundColor Green
$config.tasks.ChildNodes | ? { $_.LocalName -ne "#comment" -and $_.when -eq "before" } | % {
    $name = $_.name
    Write-Host "    > $name"
    Push-Location $_.path
    iex $_.command
    Pop-Location
}

Write-Host "Copying items..." -ForegroundColor Green
$tmpRoot = Join-Path $env:TEMP "mybackup"
New-Item $tmpRoot -Type Directory -Force | Out-Null

$tmpZip = $tmpRoot + $extension

Get-ChildItem $tmpRoot | Remove-Item -Recurse -Force

$config.items.ChildNodes | ? { $_.LocalName -ne "#comment" } | % {
    $name = $_.name
    Write-Host "    > $name"
    
    $path = $_.path.TrimEnd("\")
    $include = $_.include -split "\s*;\s*"
    $exclude = $_.exclude -split "\s*;\s*"
    $recurse = $_.recurse -and ($_.recurse.ToLower() -ne "false")
    
    if (!(Test-Path $path)) {
        throw "Path does not exist for backup item '$name': $path"
    }
    
    $tmpDir = Join-Path $tmpRoot $name
    New-Item $tmpDir -Type Directory -Force | Out-Null
    
    $pathRegex = [regex]::Escape($path)
    $pathFind = $path
    if (!$recurse) { $pathFind = $pathFind + "\*" }

    Get-ChildItem $pathFind -Include $include -Exclude $exclude -Recurse:$recurse -File:(!$recurse) | % {
        $src = $_.FullName
        $dst = $_.FullName -replace $pathRegex, $tmpDir
        $dstParent = Split-Path $dst
        New-Item $dstParent -Type Directory -Force | Out-Null
        Copy-Item $src $dst -Force | Out-Null
    }
}

Write-Host "Compressing..." -ForegroundColor Green
Get-ChildItem $tmpRoot | Compress-Archive -Destination $tmpZip -CompressionLevel Fastest -Force

Write-Host "Saving backup..." -ForegroundColor Green
$config.destinations.ChildNodes | ? { $_.LocalName -ne "#comment" } | % {
    $dstName = ([regex]"\{(.*)\}").Replace($_.format, {(Get-Date).ToString($args[0].Groups[1])})
    $dstPath = Join-Path $_.path $dstName
    
    try {
        if ($_.expiredays) {
            $expireDate = (Get-Date).AddDays(-[int]$_.expiredays)

            Get-ChildItem $_.path | ? { $_.Name.EndsWith($extension) -and $_.LastWriteTime -lt $expireDate } | % {
                Remove-Item $_.FullName -Force
            }
        }
        
        Copy-Item $tmpZip $dstPath
    } catch {
        if (!$_.remote) {
            throw "Cannot copy to $($_.path)"
        }
    }
}

Write-Host "Cleaning up..." -ForegroundColor Green
Remove-Item $tmpZip -Force -Recurse
Remove-Item $tmpRoot -Force -Recurse

Write-Host "Executing tasks [after]..." -ForegroundColor Green
$config.Tasks.ChildNodes | ? { $_.LocalName -ne "#comment" -and $_.when -eq "after" } | % {
    $name = $_.name
    Write-Host "    > $name"
    Push-Location $_.path
    iex $_.command
    Pop-Location
}

Write-Host "Done!" -ForegroundColor Green