Download TeXLive ISO with Aria2 + PowerShell

download-tliso.ps1

<#
This script is for Japanese TeX users.
TeXLive ISO高速ダウンローダー

後日GitHub本体の方でリポジトリ化する予定

Copyright © 2020 Tatsunori Uchino
ライセンス: MIT
#>

function Get-SHA512ISOHash([string]$Repo, [string]$ISOPath) {
  return [Regex]::Match([Text.Encoding]::UTF8.GetString((Invoke-WebRequest "$Repo$ISOPath.sha512").Content), "^[0-9a-fA-F]+").Value
}

if (-not (Get-Command aria2c -ErrorAction Ignore)) {
  Write-Error "本スクリプトの実行にはAria2が必要です。インストールし、パスを通してください。"
  if ($IsWindows -in ($true, $null)) {
    if(Get-Command cinst -ErrorAction Ignore) {
      Write-Error "cinst -y aria2"
    } else if(Get-Command scoop -ErrorAction Ignore) {
      Write-Error "scoop install aria2"
    }
  } else if ($IsMacOS) {
    Write-Error "brew install aria2"
  } else if ($IsLinux) {
    $Cmd =
      if (Get-Command apt -ErrorAction Ignore) { "apt install -y" } else
      if (Get-Command dnf -ErrorAction Ignore) { "dnf install -y" } else
      if (Get-Command yum -ErrorAction Ignore) { "yum instal -y" } else
      if (Get-Command zypper -ErrorAction Ignore) { "zypper in -y" } else
      if (Get-Command pacman -ErrorAction Ignore) { "pacman -S" }
    if ($Cmd -ne $null) {
      Write-Error "$Cmd aria2"
    }
  }
  exit 1
}

$ParentRepo = "http://www.tug.org/texlive/Images/"
$ISOPath = (Invoke-WebRequest $ParentRepo).Links.Href | Where-Object { $_ -match "texlive[0-9]+\.iso$" } | Sort-Object -Descending | Select-Object -f 1
Write-Output "ターゲット: $ISOPath"
$Mirrors = (Invoke-WebRequest "https://texwiki.texjp.org/?TeX Live").Links.Href | ? { $_ -match "https?://.+jp.+/Images/?" }
Write-Output "ミラー合計: $($Mirrors.Length) 個"
# ボトルネック？
# ToDo: PowerShell 7では ForEach-Object -Parallelが使える
$SHA512Lengths = $Mirrors | ForEach-Object {
  (Invoke-WebRequest "$_$ISOPath.sha512" -Method Head).headers["Content-Length"]
}
$CheckSHA512Indices = 0..($Mirrors.Length - 1) | Where-Object {
  $SHA512Lengths[$_] -le 2048
}
$BaseSHA512 = Get-SHA512ISOHash -Repo $Mirrors[$CheckSHA512Indices[0]] -ISOPath $ISOPath
Write-Output "SHA512: $BaseSHA512"
$SameSHA512List = $CheckSHA512Indices | Where-Object { ($_ -eq 0) -or ((Get-SHA512ISOHash -Repo $Mirrors[$_] -ISOPath $ISOPath) -eq $BaseSHA512) }
$VerifiedMirrors = $Mirrors | Select-Object -Index $SameSHA512List
Write-Output "使用ミラー: $($VerifiedMirrors.Length) 個"
# ToDo: -x・-sオプションを指定
$Aria2Args = , "--checksum=sha-512=$BaseSHA512" + ($VerifiedMirrors | ForEach-Object { "$_$ISOPath" })
aria2c $Aria2Args