<#
.SYNOPSIS
  Collects every mod currently enabled in tModLoader (Windows) into one folder,
  ready to copy into /opt/terraria/<instance>/data/ on the Linux server.

.DESCRIPTION
  Output layout (mirrors the server's data/ folder):
    <Out>\Mods\*.tmod
    <Out>\Mods\enabled.json      (only lists mods that were actually found)
    <Out>\ModConfigs\*.json

  .tmod files are taken from Steam's Workshop folder (all Steam libraries are
  searched), falling back to Documents\My Games\Terraria\tModLoader\Mods for
  mods you installed manually or built yourself.

.PARAMETER Out
  Where to put the export. Default: Desktop\tmod-export

.PARAMETER TmlDir
  tModLoader's save folder. Default: Documents\My Games\Terraria\tModLoader
  For the preview branch use ...\My Games\Terraria\tModLoader-preview

.PARAMETER MaxVersion
  Optional. Your tModLoader version as year.month (e.g. 2025.3), shown at the
  bottom-left of the tModLoader main menu. Workshop builds made for a newer
  tModLoader than this are skipped.

.EXAMPLE
  powershell -ExecutionPolicy Bypass -File .\export-tmod-mods.ps1
  powershell -ExecutionPolicy Bypass -File .\export-tmod-mods.ps1 -MaxVersion 2025.3
#>
param(
    [string]$Out = (Join-Path ([Environment]::GetFolderPath('Desktop')) 'tmod-export'),
    [string]$TmlDir = (Join-Path ([Environment]::GetFolderPath('MyDocuments')) 'My Games\Terraria\tModLoader'),
    [version]$MaxVersion
)
$ErrorActionPreference = 'Stop'

# --- Which mods are enabled? ------------------------------------------------
$enabledJson = Join-Path $TmlDir 'Mods\enabled.json'
if (-not (Test-Path $enabledJson)) {
    throw "Can't find $enabledJson. Has tModLoader been run? For the preview branch pass -TmlDir ...\tModLoader-preview"
}
$enabled = @(Get-Content $enabledJson -Raw | ConvertFrom-Json)
if ($enabled.Count -eq 0) { throw "No mods are enabled in $enabledJson" }

# --- Find Steam Workshop folders for tModLoader (app 1281930) ----------------
$steamPath = (Get-ItemProperty 'HKCU:\Software\Valve\Steam' -ErrorAction SilentlyContinue).SteamPath
if (-not $steamPath) { $steamPath = 'C:\Program Files (x86)\Steam' }
$libraries = @($steamPath)
$vdf = Join-Path $steamPath 'steamapps\libraryfolders.vdf'
if (Test-Path $vdf) {
    $libraries += Select-String -Path $vdf -Pattern '"path"\s+"([^"]+)"' |
        ForEach-Object { $_.Matches[0].Groups[1].Value -replace '\\\\', '\' }
}
$workshopDirs = @($libraries |
    ForEach-Object { Join-Path $_ 'steamapps\workshop\content\1281930' } |
    Where-Object { Test-Path $_ } |
    ForEach-Object { (Resolve-Path $_).Path } |
    Sort-Object -Unique)
if ($workshopDirs.Count -eq 0) { Write-Warning "No Steam Workshop folder for tModLoader found; only local mods will be exported." }

function Get-FolderVersion([string]$dir) {
    # Workshop items keep builds in folders named after the tModLoader version, e.g. 2024.3
    $v = $null
    if ([version]::TryParse((Split-Path $dir -Leaf), [ref]$v)) { return $v }
    return $null
}

# --- Collect ------------------------------------------------------------------
$modsOut = Join-Path $Out 'Mods'
New-Item -ItemType Directory -Force -Path $modsOut | Out-Null
$exported = @()
$missing  = @()

foreach ($mod in $enabled) {
    $candidates = @()
    foreach ($w in $workshopDirs) {
        $candidates += @(Get-ChildItem -Path $w -Recurse -File -Filter "$mod.tmod" -ErrorAction SilentlyContinue)
    }

    $pick = $null
    if ($candidates.Count -gt 0) {
        $withVer = $candidates | ForEach-Object {
            [pscustomobject]@{ File = $_; Version = (Get-FolderVersion $_.DirectoryName) }
        }
        # Newest version folder that isn't newer than -MaxVersion
        $best = @($withVer |
            Where-Object { $_.Version -and (-not $MaxVersion -or $_.Version -le $MaxVersion) } |
            Sort-Object Version -Descending)
        if ($best.Count -gt 0) {
            $pick = $best[0].File
        } else {
            # Build stored at the item's top level (no version folder)
            $root = @($withVer | Where-Object { -not $_.Version } |
                Sort-Object { $_.File.LastWriteTime } -Descending)
            if ($root.Count -gt 0) { $pick = $root[0].File }
        }
    }

    if (-not $pick) {
        $local = Join-Path $TmlDir "Mods\$mod.tmod"
        if (Test-Path $local) { $pick = Get-Item $local }
    }

    if ($pick) {
        Copy-Item $pick.FullName $modsOut -Force
        $exported += $mod
        Write-Host ("  {0,-28} {1}" -f $mod, $pick.FullName)
    } else {
        $missing += $mod
        Write-Warning "$mod is enabled but no .tmod file was found; skipped."
    }
}

# enabled.json listing only what we exported (a missing mod would stop the server loading)
$json = ConvertTo-Json -InputObject @($exported)
[IO.File]::WriteAllText((Join-Path $modsOut 'enabled.json'), $json, (New-Object Text.UTF8Encoding $false))

# Mod settings (server-side configs matter; client-side ones are harmless)
$cfgSrc = Join-Path $TmlDir 'ModConfigs'
if (Test-Path $cfgSrc) {
    $cfgOut = Join-Path $Out 'ModConfigs'
    New-Item -ItemType Directory -Force -Path $cfgOut | Out-Null
    Copy-Item (Join-Path $cfgSrc '*') $cfgOut -Recurse -Force
}

Write-Host ""
Write-Host "Exported $($exported.Count) mod(s) to $Out"
if ($missing.Count -gt 0) { Write-Warning "Missing: $($missing -join ', ')" }