# Sync standards snapshot to project root.
# - Copies <snapshot>/.agents/<AGENTS_NS> -> <project-root>/.agents/<AGENTS_NS>
# - Updates <project-root>/.gitattributes (managed block by default)
# Existing targets are backed up before overwrite.
[CmdletBinding()]
param(
  # Sync multiple rulesets in one run:
  #   -Langs tsl,cpp
  #   -Langs @("tsl","cpp")
  [Parameter(Mandatory = $false)]
  [string[]]$Langs
)

$ErrorActionPreference = "Stop"
$ScriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
$Src = (Resolve-Path (Join-Path $ScriptDir "..")).Path

$Root = (git -C $ScriptDir rev-parse --show-toplevel 2>$null)
if (-not $Root) { $Root = (Get-Location).Path }
$Root = (Resolve-Path $Root).Path

$AgentsSrcRoot = Join-Path $Src ".agents"
$GitAttrSrc = Join-Path $Src ".gitattributes"

if (-not (Test-Path $AgentsSrcRoot)) {
  throw "Standards snapshot not found at $AgentsSrcRoot. Run: git subtree add --prefix docs/standards/playbook <url> <branch> --squash"
}

$timestamp = Get-Date -Format "yyyyMMddHHmmss"

# Multi rulesets: only on the outer invocation.
if (-not $env:SYNC_STANDARDS_INNER -and $Langs -and $Langs.Count -gt 0) {
  $oldInner = $env:SYNC_STANDARDS_INNER
  $oldAgentsNs = $env:AGENTS_NS
  $oldMode = $env:SYNC_GITATTR_MODE

  $syncModeFirst = $env:SYNC_GITATTR_MODE
  if (-not $syncModeFirst) { $syncModeFirst = "block" }

  $first = $true
  foreach ($ns in $Langs) {
    if (-not $ns) { continue }

    $env:SYNC_STANDARDS_INNER = "1"
    $env:AGENTS_NS = $ns
    if ($first) {
      $first = $false
      $env:SYNC_GITATTR_MODE = $syncModeFirst
    } else {
      $env:SYNC_GITATTR_MODE = "skip"
    }

    & $MyInvocation.MyCommand.Path
  }

  $env:SYNC_STANDARDS_INNER = $oldInner
  $env:AGENTS_NS = $oldAgentsNs
  $env:SYNC_GITATTR_MODE = $oldMode
  exit 0
}

$AgentsNs = $env:AGENTS_NS
if (-not $AgentsNs) { $AgentsNs = "tsl" }
if ($AgentsNs -match '[\\/]' -or $AgentsNs -match '\.\.') {
  throw "Invalid AGENTS_NS=$AgentsNs"
}
$AgentsSrc = Join-Path $AgentsSrcRoot $AgentsNs
if (-not (Test-Path $AgentsSrc)) {
  # Backward-compatible fallback: older snapshots used <snapshot>/.agents/* directly.
  if ((Test-Path (Join-Path $AgentsSrcRoot "index.md")) -and (Test-Path (Join-Path $AgentsSrcRoot "auth.md"))) {
    $AgentsSrc = $AgentsSrcRoot
  } else {
    throw "Agents ruleset not found: $AgentsSrc (set AGENTS_NS to one of the subdirs under $AgentsSrcRoot, e.g. tsl/cpp)."
  }
}
$AgentsRoot = Join-Path $Root ".agents"
$AgentsDst = Join-Path $AgentsRoot $AgentsNs

if ($Src -ieq $Root) {
  Write-Host "Skip: snapshot root equals project root."
  Write-Host "Done."
  exit 0
}

New-Item -ItemType Directory -Path $AgentsRoot -Force | Out-Null

if (Test-Path $AgentsDst) {
  $bak = (Join-Path $AgentsRoot "$AgentsNs.bak.$timestamp")
  Move-Item $AgentsDst $bak
  Write-Host "Backed up existing $AgentsNs agents -> $(Split-Path -Leaf $bak)"
}

New-Item -ItemType Directory -Path $AgentsDst -Force | Out-Null
Copy-Item (Join-Path $AgentsSrc "*") $AgentsDst -Recurse -Force
Write-Host "Synced .agents/$AgentsNs from standards."

$AgentsIndex = Join-Path $AgentsRoot "index.md"
if (-not (Test-Path $AgentsIndex)) {
@'
# .agents（多语言）

本目录用于存放仓库级/语言级的代理规则集。

建议约定：

- `.agents/tsl/`：TSL 相关规则集（由 `sync_standards.*` 同步；适用于 `.tsl`/`.tsf`）
- `.agents/cpp/`：C++ 相关规则集（由 `sync_standards.*` 同步；适用于 C++23/Modules）
- `.agents/python/` 等：其他语言的规则集（按需增加）

规则发生冲突时，建议以“更靠近代码的目录规则更具体”为准。

入口建议从：

- `.agents/tsl/index.md`（TSL 规则集入口）
- `.agents/cpp/index.md`（C++ 规则集入口）
- `docs/standards/playbook/docs/`（人类开发规范快照：`tsl/`、`cpp/`、`python/`、`common/`）
'@ | Set-Content -Path $AgentsIndex -Encoding UTF8
  Write-Host "Created .agents/index.md"
}

$GitAttrDst = Join-Path $Root ".gitattributes"
if (Test-Path $GitAttrSrc) {
  $mode = $env:SYNC_GITATTR_MODE
  if (-not $mode) { $mode = "block" }
  switch ($mode.ToLowerInvariant()) {
    "skip" {
      Write-Host "Skip: .gitattributes sync (SYNC_GITATTR_MODE=skip)."
      break
    }
    "overwrite" {
      if ($GitAttrSrc -ieq $GitAttrDst) {
        Write-Host "Skip: .gitattributes source equals destination."
        break
      }
      if (Test-Path $GitAttrDst) {
        $bak = "$GitAttrDst.bak.$timestamp"
        Move-Item $GitAttrDst $bak
        Write-Host "Backed up existing .gitattributes -> $bak"
      }
      Copy-Item $GitAttrSrc $GitAttrDst -Force
      Write-Host "Synced .gitattributes from standards (overwrite)."
      break
    }
    "block" {
      $begin = "# BEGIN playbook .gitattributes"
      $end = "# END playbook .gitattributes"
      $beginOld = "# BEGIN tsl-playbook .gitattributes"
      $endOld = "# END tsl-playbook .gitattributes"
      $src = Get-Content -Path $GitAttrSrc -Raw
      $block = $begin + "`r`n" + $src.TrimEnd() + "`r`n" + $end + "`r`n"

      $dst = ""
      if (Test-Path $GitAttrDst) {
        $bak = "$GitAttrDst.bak.$timestamp"
        Move-Item $GitAttrDst $bak
        Write-Host "Backed up existing .gitattributes -> $bak"
        $dst = Get-Content -Path $bak -Raw
      }

      $pattern = "(?ms)^(" + [regex]::Escape($begin) + "|" + [regex]::Escape($beginOld) + ")\\R.*?^(" + [regex]::Escape($end) + "|" + [regex]::Escape($endOld) + ")\\R?"
      if ($dst -and ($dst -match $pattern)) {
        $new = [regex]::Replace($dst, $pattern, $block)
      } elseif ($dst) {
        $new = $dst.TrimEnd() + "`r`n`r`n" + $block
      } else {
        $new = $block
      }

      $new | Set-Content -Path $GitAttrDst -Encoding UTF8
      Write-Host "Updated .gitattributes from standards (managed block)."
      break
    }
    default {
      throw "Invalid SYNC_GITATTR_MODE=$mode (use block|overwrite|skip)"
    }
  }
}

Write-Host "Done."