Find gifs in your Discord cache - WIP

discordgifs.ps1

# Tested with Powershell v7.1
# StackOverflow says the behavior of reading bytes from files changed sometime around v5, so
# this script might not work with the version of Powershell that comes with your computer

# https://stackoverflow.com/a/34559554
function New-TemporaryDirectory {
    $parent = [System.IO.Path]::GetTempPath()
    [string] $name = [System.Guid]::NewGuid()
    New-Item -ItemType Directory -Path (Join-Path $parent $name)
}

$cacheDir = "C:\Users\$env:USERNAME\AppData\Roaming\discord\Cache"

$gifDir = New-TemporaryDirectory

Copy-Item -Path "$cacheDir\*" -Destination $gifDir -Recurse

# Find .mp4 videos - requires ffmpeg to be on your PATH
Get-ChildItem $gifDir | Where-Object { !(ffmpeg -loglevel error -i $_ -map 0:1 -f null - 2>&1) } | Rename-Item -NewName { $_.Name + ".mp4" }

# https://www.garykessler.net/library/file_sigs.html
$magicGifBytes1 = 71,73,70,56,57,97
$magicGifBytes2 = 71,73,70,56,55,97

# Doesn't work yet
$magicWebmBytes = 26,69,123,163

function Is-Gif {
	param ([string]$Path)
    $fileBytes = Get-Content $Path -AsByteStream -TotalCount 7
    !(Compare-Object $fileBytes $magicGifBytes1) -or !(Compare-Object $fileBytes $magicGifBytes2)
}

Get-ChildItem $gifDir | Where-Object { Is-Gif $_ } | Rename-Item -NewName { $_.Name + ".gif" }

Get-ChildItem $gifDir | Where-Object { !$_.Extension } | Remove-Item

explorer.exe $gifDir