<#
.SYNOPSIS
  Builds the video repair engine (untrunc compiled to WebAssembly, as packaged
  by FootageRescue's engine) and copies it to frontend/vendor/local/untrunc@1/,
  where the site serves it from /vendor/.

  The engine is GPL-2.0-or-later. The page talks to it only through its Web
  Worker's messages. Everything it is built from is published at
  /source/untrunc/: the engine repository at the pinned commit (source/engine/)
  and the FFmpeg release it compiles in (source/ffmpeg-3.3.9.tar.xz).

  Nothing is installed on this machine; Docker Desktop and git must be available.
#>
$ErrorActionPreference = 'Continue'
Set-Location $PSScriptRoot
$Repo = 'https://github.com/aletripodi/footagerescue-engine'
$Commit = '179bf09cc8db7ec9a29de14ffa7a9ddf3a2924e3'
$FfmpegUrl = 'https://www.ffmpeg.org/releases/ffmpeg-3.3.9.tar.xz'
$FfmpegSha = 'ae34f14fffa65a1a59b256737ca9af7bf4e296b7c4320d42512350126ce06c84'

$work = Join-Path $PSScriptRoot 'dist'
if (Test-Path $work) { Remove-Item -Recurse -Force $work }
New-Item -ItemType Directory -Force $work | Out-Null
$src = Join-Path $work 'engine'
& git -c core.autocrlf=false clone -q $Repo $src
& git -C $src checkout -q $Commit
$head = (& git -C $src rev-parse HEAD).Trim()
if ($head -ne $Commit) { throw "engine checkout is $head, expected $Commit" }

$out = Join-Path $work 'out'
& docker build --build-arg "ENGINE_COMMIT=$Commit" --output "type=local,dest=$out" $src
if ($LASTEXITCODE -ne 0) { throw 'docker build failed' }

$dest = Join-Path $PSScriptRoot '..\..\vendor\local\untrunc@1'
New-Item -ItemType Directory -Force $dest | Out-Null
foreach ($f in 'untrunc.mjs', 'untrunc.wasm', 'LICENSE.txt', 'SOURCE.txt') {
  Copy-Item (Join-Path $out $f) $dest -Force
}

# johnmcm.com's one change to the engine (GPL-2.0 section 2(a) notice below):
# two more methods in the worker, so the page can pass untrunc's own "-sv"
# option, which stretches the picture to the sound's length - the fix for
# phones that record at a variable frame rate.
$worker = [IO.File]::ReadAllText((Join-Path $out 'untrunc-worker.js'))
$from = "`t""s"": [""-s""],"
if (-not $worker.Contains($from)) { throw 'worker METHOD_ARGS not found: update the patch' }
$worker = $worker.Replace($from, "$from`n`t""sv"": [""-sv""],`n`t""s-sv"": [""-s"", ""-sv""],")
$notice = "// Modified by johnmcm.com on 6 Oct 2026: added the ""sv"" and ""s-sv"" methods (untrunc's -sv,`n// with and without -s) to METHOD_ARGS. Otherwise as built from the engine commit in SOURCE.txt.`n"
[IO.File]::WriteAllText((Join-Path $dest 'untrunc-worker.js'), $notice + $worker)

# The published source: the engine as built (without its git history), plus FFmpeg.
$pub = Join-Path $PSScriptRoot 'source'
if (Test-Path $pub) { Remove-Item -Recurse -Force $pub }
New-Item -ItemType Directory -Force $pub | Out-Null
Remove-Item -Recurse -Force (Join-Path $src '.git')
Copy-Item -Recurse $src (Join-Path $pub 'engine')
$tar = Join-Path $pub 'ffmpeg-3.3.9.tar.xz'
Invoke-WebRequest -Uri $FfmpegUrl -OutFile $tar -UseBasicParsing
$sha = (Get-FileHash -Algorithm SHA256 $tar).Hash.ToLower()
if ($sha -ne $FfmpegSha) { throw "FFmpeg tarball hash $sha, expected $FfmpegSha" }
Get-ChildItem $dest | Format-Table Name, Length