<#
.SYNOPSIS
    symlink_downloads.ps1 -- place in the "Sven Co-op" root folder alongside tags.json.

.DESCRIPTION
    1. Scans svencoop_downloads\models\player\ for .mdl files whose name matches a
       model ID in tags.json (case-insensitive).
    2. Creates a relative symlink in svencoop_addon\models\player\ for each match:
         <id>\<id>.mdl  ->  ..\..\..\..\svencoop\models\player\helmet\helmet.mdl
    3. Lists matched folders and prompts to delete them from svencoop_downloads.
       The player\ root itself is never deleted.

.NOTES
    Requires PowerShell 5.1+ and either:
      - Developer Mode enabled  (Settings > For developers)
      - Running as Administrator
#>
[CmdletBinding()]
param(
    [switch]$DryRun
)

Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"

# --- Paths ---
$scriptDir     = $PSScriptRoot
$tagsPath      = Join-Path $scriptDir "tags.json"
$helmetAbs     = Join-Path $scriptDir "svencoop\models\player\helmet\helmet.mdl"
$dlRoot        = Join-Path $scriptDir "svencoop_downloads\models\player"
$addonRoot     = Join-Path $scriptDir "svencoop_addon\models\player"
$symlinkTarget = "..\..\..\..\svencoop\models\player\helmet\helmet.mdl"

# --- Pre-flight checks ---
if (-not (Test-Path $tagsPath)) {
    Write-Error "tags.json not found next to script ($tagsPath)"
    exit 1
}
if (-not (Test-Path $helmetAbs)) {
    Write-Error "helmet.mdl not found: $helmetAbs`nRun from the Sven Co-op root folder."
    exit 1
}
if (-not (Test-Path $dlRoot)) {
    Write-Error "Downloads folder not found: $dlRoot"
    exit 1
}

# Check for symlink privilege on Windows
$isAdmin = ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole(
    [Security.Principal.WindowsBuiltInRole]::Administrator
)
if (-not $isAdmin) {
    $devMode = $false
    try {
        $dm = Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock" -ErrorAction SilentlyContinue
        $devMode = $dm.AllowDevelopmentWithoutDevLicense -eq 1
    } catch {}
    if (-not $devMode) {
        Write-Warning @"
Symlink creation may fail. To fix, either:
  - Enable Developer Mode  (Settings > For developers > Developer Mode)
  - Re-run this script as Administrator
"@
    }
}

# --- Build case-insensitive tag lookup: mdl stem -> canonical ID ---
$tags = Get-Content $tagsPath -Raw -Encoding UTF8 | ConvertFrom-Json
$tagLookup = @{}
foreach ($category in $tags.PSObject.Properties) {
    foreach ($id in $category.Value) {
        $tagLookup[$id] = $id
    }
}

# --- Scan downloads for matching .mdl files ---
$folderMdls = @{}
$matched    = [System.Collections.Generic.List[hashtable]]::new()

Get-ChildItem -Path $dlRoot -Recurse -Filter "*.mdl" | ForEach-Object {
    $dir = $_.DirectoryName
    if ($dir -eq $dlRoot) { return }

    if (-not $folderMdls.ContainsKey($dir)) { $folderMdls[$dir] = @() }
    $folderMdls[$dir] += $_

    $tagsId = $tagLookup[$_.BaseName]
    if ($tagsId) {
        $matched.Add(@{ File = $_; TagsId = $tagsId })
    }
}

if ($matched.Count -eq 0) {
    Write-Host "No downloaded .mdl files matched any model ID in tags.json."
    exit 0
}

# --- Symlink pass ---
$prefix = if ($DryRun) { "[DRY RUN] " } else { "" }
Write-Host "${prefix}Symlinking $($matched.Count) matched model(s):`n"

$counts = @{ created = 0; replaced = 0; ok = 0; error = 0 }

foreach ($m in $matched) {
    $tagsId   = $m.TagsId
    $addonMdl = Join-Path $addonRoot "$tagsId\$tagsId.mdl"
    $addonDir = Split-Path $addonMdl -Parent

    if ($DryRun) {
        $link = Get-Item $addonMdl -ErrorAction SilentlyContinue
        if ($link -and $link.LinkType -and $link.Target -eq $symlinkTarget) {
            $status = "ok"
        } else {
            $status = "would link"
        }
        Write-Host ("  {0,-12} {1}  (from {2})" -f $status, $tagsId, $m.File.FullName.Substring($dlRoot.Length + 1))
        $counts.created++
        continue
    }

    try {
        if (Test-Path $addonMdl) { Remove-Item $addonMdl -Force }
        if (-not (Test-Path $addonDir)) { New-Item -ItemType Directory -Path $addonDir -Force | Out-Null }

        $existing = Get-Item $addonMdl -ErrorAction SilentlyContinue
        if ($existing -and $existing.LinkType -and $existing.Target -eq $symlinkTarget) {
            Write-Host "  already ok   $tagsId"
            $counts.ok++
        } else {
            New-Item -ItemType SymbolicLink -Path $addonMdl -Target $symlinkTarget | Out-Null
            Write-Host "  linked       $tagsId"
            $counts.created++
        }
    } catch {
        Write-Host "  ERROR        ${tagsId}: $_"
        $counts.error++
    }
}

if (-not $DryRun) {
    Write-Host ("`n  $($counts.created) created, $($counts.replaced) replaced, $($counts.ok) already correct, $($counts.error) errors")
}

# --- Cleanup prompt ---
$foldersToClean = @{}
foreach ($m in $matched) {
    $dir = $m.File.DirectoryName
    if (-not $foldersToClean.ContainsKey($dir)) { $foldersToClean[$dir] = @() }
    $foldersToClean[$dir] += $m.File
}

Write-Host "`nFolders to delete from svencoop_downloads ($($foldersToClean.Count)):`n"
foreach ($dir in ($foldersToClean.Keys | Sort-Object)) {
    $matchedHere = $foldersToClean[$dir]
    $matchedPaths = $matchedHere | ForEach-Object { $_.FullName }
    $other = $folderMdls[$dir] | Where-Object { $_.FullName -notin $matchedPaths }
    $relDir = $dir.Substring($scriptDir.Length + 1)
    Write-Host "  $relDir\"
    foreach ($f in $matchedHere) { Write-Host "    [tagged] $($f.Name)" }
    foreach ($f in $other)       { Write-Host "    [extra ] $($f.Name)" }
}

Write-Host ""
if ($DryRun) {
    Write-Host "[DRY RUN] Skipping delete prompt."
    exit 0
}

$answer = Read-Host "Delete these folders from svencoop_downloads? [y/N]"
if ($answer -ne "y") {
    Write-Host "Skipped cleanup."
    exit 0
}

$deleted = 0
foreach ($dir in ($foldersToClean.Keys | Sort-Object)) {
    if ($dir -eq $dlRoot) {
        Write-Host "  SKIP (is player\ root): $dir"
        continue
    }
    try {
        Remove-Item -Path $dir -Recurse -Force
        Write-Host "  deleted $($dir.Substring($scriptDir.Length + 1))\"
        $deleted++
    } catch {
        Write-Host "  ERROR $([System.IO.Path]::GetFileName($dir)): $_"
    }
}

Write-Host "`nDeleted $deleted folder(s)."