[CmdletBinding()]
param()

$ErrorActionPreference = "Stop"
$bundleName = "zed-settings-sync.json"
$utf8 = New-Object System.Text.UTF8Encoding($false)

function Require-Command([string]$Name, [string]$InstallHint) {
  if (-not (Get-Command $Name -ErrorAction SilentlyContinue)) {
    throw "$Name is required. Install it first: $InstallHint"
  }
}

function Get-GistId([string]$Value) {
  $matches = [regex]::Matches($Value.Trim(), "[a-fA-F0-9]{8,}")
  if ($matches.Count -eq 0) {
    throw "Enter a valid GitHub Gist ID or URL."
  }
  return $matches[$matches.Count - 1].Value.ToLowerInvariant()
}

function Test-AllowedPath([string]$Path) {
  $fixed = @(
    "settings.json",
    "keymap.json",
    "tasks.json",
    "debug.json",
    "scripts/toggle-file-scan-exclusions.mjs",
    "scripts/file-exclusions.json",
    "scripts/zed-settings-sync.mjs"
  )
  if ($Path.StartsWith("/") -or $Path.Contains("\") -or $Path.Split("/") -contains "..") {
    return $false
  }
  return $fixed -contains $Path -or $Path.StartsWith("snippets/") -or $Path.StartsWith("themes/")
}

function Write-Atomic([string]$Path, [string]$Contents) {
  $directory = Split-Path $Path -Parent
  New-Item -ItemType Directory -Force -Path $directory | Out-Null
  $temporary = Join-Path $directory ".$([IO.Path]::GetFileName($Path)).$PID.tmp"
  try {
    [IO.File]::WriteAllText($temporary, $Contents, $utf8)
    Move-Item -LiteralPath $temporary -Destination $Path -Force
  } finally {
    Remove-Item -LiteralPath $temporary -Force -ErrorAction SilentlyContinue
  }
}

Require-Command "node" "winget install OpenJS.NodeJS.LTS"
if (-not $env:ZED_SETTINGS_BUNDLE_PATH) {
  Require-Command "gh" "winget install GitHub.cli"
  Remove-Item Env:GH_TOKEN,Env:GITHUB_TOKEN -ErrorAction SilentlyContinue
  & gh auth status *> $null
  if ($LASTEXITCODE -ne 0) {
    Write-Host "GitHub authentication is required."
    & gh auth login
    if ($LASTEXITCODE -ne 0) { throw "GitHub authentication failed." }
  }
}

$entered = if ($env:ZED_SETTINGS_GIST_ID) { $env:ZED_SETTINGS_GIST_ID } else { Read-Host "GitHub Gist ID or URL (leave blank to create a new Secret Gist)" }
if ($env:ZED_SETTINGS_BUNDLE_PATH) {
  $gistId = Get-GistId $entered
  $bundleSource = [IO.File]::ReadAllText($env:ZED_SETTINGS_BUNDLE_PATH, [Text.Encoding]::UTF8)
} else {
  $token = (& gh auth token).Trim()
  if ($LASTEXITCODE -ne 0 -or -not $token) { throw "Could not obtain the GitHub authentication token from gh." }
  $headers = @{
    Accept = "application/vnd.github+json"
    Authorization = "Bearer $token"
    "User-Agent" = "zed-settings-bootstrap"
    "X-GitHub-Api-Version" = "2022-11-28"
  }
  if ([string]::IsNullOrWhiteSpace($entered)) {
    $seedUrl = "https://git.okk.cool/purp1e/zed-sync/raw/branch/master/zed-settings-sync.json"
    $bundleSource = (Invoke-WebRequest -UseBasicParsing -Uri $seedUrl).Content
    $payload = @{
      description = "Zed settings sync"
      public = $false
      files = @{ $bundleName = @{ content = $bundleSource } }
    } | ConvertTo-Json -Depth 5
    $created = Invoke-RestMethod -Method Post -Uri "https://api.github.com/gists" -Headers $headers -ContentType "application/json" -Body ([Text.Encoding]::UTF8.GetBytes($payload))
    $gistId = $created.id
    Write-Host "Created Secret Gist: $($created.html_url)"
  } else {
    $gistId = Get-GistId $entered
    $gist = Invoke-RestMethod -Uri "https://api.github.com/gists/$gistId" -Headers $headers
    $remoteFile = $gist.files.$bundleName
    if (-not $remoteFile) { throw "Gist $gistId does not contain $bundleName." }
    if ($remoteFile.truncated) { throw "$bundleName is too large for the Gist API response." }
    $bundleSource = [string]$remoteFile.content
  }
}

try {
  $bundle = $bundleSource | ConvertFrom-Json
} catch {
  throw "The Gist contains invalid JSON: $($_.Exception.Message)"
}

$properties = @($bundle.PSObject.Properties)
foreach ($required in @("settings.json", "keymap.json", "tasks.json")) {
  if (-not ($properties.Name -contains $required)) { throw "The bundle is missing $required." }
}
foreach ($property in $properties) {
  if (-not (Test-AllowedPath $property.Name) -or $property.Value -isnot [string]) {
    throw "Invalid bundle file: $($property.Name)"
  }
}

$target = Join-Path $env:APPDATA "Zed"
$timestamp = Get-Date -Format "yyyyMMdd-HHmmss"
$backup = Join-Path $target "backups\gist-bootstrap-$timestamp"
New-Item -ItemType Directory -Force -Path $target, $backup, (Join-Path $target "scripts") | Out-Null

foreach ($property in $properties) {
  $existing = Join-Path $target ($property.Name.Replace("/", "\"))
  if (Test-Path -LiteralPath $existing) {
    $backupPath = Join-Path $backup ($property.Name.Replace("/", "\"))
    New-Item -ItemType Directory -Force -Path (Split-Path $backupPath -Parent) | Out-Null
    Copy-Item -LiteralPath $existing -Destination $backupPath -Force
  }
}

$toggleScript = (Join-Path $target "scripts\toggle-file-scan-exclusions.mjs").Replace("\", "/")
$syncScript = (Join-Path $target "scripts\zed-settings-sync.mjs").Replace("\", "/")
foreach ($property in $properties) {
  $destination = Join-Path $target ($property.Name.Replace("/", "\"))
  $contents = [string]$property.Value
  if ($property.Name -eq "tasks.json") {
    $contents = $contents.Replace("__TOGGLE_SCRIPT__", $toggleScript).Replace("__SYNC_SCRIPT__", $syncScript)
  }
  Write-Atomic $destination $contents
}

$bytes = $utf8.GetBytes($bundleSource)
$sha = [Security.Cryptography.SHA256]::Create()
try {
  $hash = -join ($sha.ComputeHash($bytes) | ForEach-Object { $_.ToString("x2") })
} finally {
  $sha.Dispose()
}
$syncState = [ordered]@{ gist_id = $gistId; last_synced_hash = $hash } | ConvertTo-Json
Write-Atomic (Join-Path $target "scripts\settings-sync.json") "$syncState`n"

Write-Host "Installed Zed settings from Gist $gistId"
Write-Host "SHA-256: $hash"
Write-Host "Backup: $backup"
Write-Host "Restart Zed to load the synchronized configuration."