#!/usr/bin/env pwsh
# CASAN H5 Governance Harness - PowerShell port of governance-check.sh
# Usage:
#   governance-check.ps1 <input-file> <output-file> [action-name]
#
# Non-interactive. High-risk denied unless env:CASAN_APPROVAL_DECISION=approve + env:CASAN_APPROVER set.
# Exit codes: 0=approved, 2=denied, 64=usage error

param(
    [Parameter(Mandatory=$true, Position=0)][string]$InputFile,
    [Parameter(Mandatory=$true, Position=1)][string]$OutputFile,
    [Parameter(Position=2)][string]$ActionName = "agent_step"
)

$ErrorActionPreference = "Stop"

$scriptDir   = Split-Path $MyInvocation.MyCommand.Path -Parent
$projectRoot = (Resolve-Path (Join-Path $scriptDir "../../..")).Path
$logDir      = Join-Path $projectRoot ".specify/logs"
$traceDir    = Join-Path $logDir "trace"
$auditDir    = Join-Path $logDir "audit"
$auditLog    = Join-Path $auditDir "audit.jsonl"

foreach ($d in @($traceDir, $auditDir, (Split-Path $OutputFile -Parent))) {
    if ($d -and !(Test-Path $d)) { New-Item -ItemType Directory -Force -Path $d | Out-Null }
}

if (!(Test-Path $InputFile)) {
    Write-Error "GOVERNANCE_DENIED: input file not found: $InputFile"
    exit 2
}

function New-TraceId {
    try { return [System.Guid]::NewGuid().ToString("D") } catch { return "trace-$(Get-Date -Format 'yyyyMMddHHmmss')-$PID" }
}

function Get-Sha256 ([string]$text) {
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($text)
    $hash  = [System.Security.Cryptography.SHA256]::Create().ComputeHash($bytes)
    return ($hash | ForEach-Object { $_.ToString("x2") }) -join ""
}

function ConvertTo-JsonArray ([string[]]$arr) {
    if (!$arr -or $arr.Count -eq 0) { return "[]" }
    $escaped = $arr | ForEach-Object { '"' + ($_ -replace '"','\"') + '"' }
    return "[" + ($escaped -join ",") + "]"
}

$traceId          = New-TraceId
$timestamp        = (Get-Date).ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssZ")
$input            = Get-Content $InputFile -Raw -Encoding UTF8
if (!$input) { $input = "" }
$lowerInput       = $input.ToLower()
$actor            = if ($env:CASAN_ACTOR)    { $env:CASAN_ACTOR }    else { "developer" }
$approver         = if ($env:CASAN_APPROVER) { $env:CASAN_APPROVER } else { "" }
$approvalDecision = if ($env:CASAN_APPROVAL_DECISION) { $env:CASAN_APPROVAL_DECISION } else { "auto" }
$agentName        = if ($env:CASAN_AGENT_NAME) { $env:CASAN_AGENT_NAME } else { "unknown" }

$riskLevel = "low"
$reasons   = [System.Collections.Generic.List[string]]::new()

# ── Risk by action name ────────────────────────────────────────────────────
switch -Regex ($ActionName) {
    "^(write_code|write_file|external_api|tool_call)$" {
        $riskLevel = "medium"; $reasons.Add("sensitive-action:$ActionName")
    }
    "^(deploy|launch|migration|db_write)$" {
        $riskLevel = "high"; $reasons.Add("high-risk-action:$ActionName")
    }
}

# ── Tool registry agent whitelist check ───────────────────────────────────
if ($agentName -ne "unknown") {
    if ($agentName -match "okr\.(srs|bd|reviewspec|reviewplan|reviewcode)" -or
        $agentName -match "speckit\.(specify|clarify|plan|tasks)") {
        if ($ActionName -match "^(deploy|migration|db_write)$") {
            $riskLevel = "high"
            $reasons.Add("unauthorized-action-for-agent:$ActionName")
        }
    }
}

# ── Risk by content keywords ───────────────────────────────────────────────
if ($lowerInput -match "(delete|drop table|password|api[_-]?key|secret|token|credential|migration|deploy|external api|shutdown|dump database)") {
    $riskLevel = "high"
    if (!$reasons.Contains("high-risk-content")) { $reasons.Add("high-risk-content") }
} elseif ($lowerInput -match "(internal|config|system|policy|permission)") {
    if ($riskLevel -eq "low") { $riskLevel = "medium"; $reasons.Add("medium-risk-content") }
}

# ── Approval decision ──────────────────────────────────────────────────────
$approvalStatus = "auto_approved"
$decision       = "approved"

if ($riskLevel -eq "medium") { $approvalStatus = "policy_auto_approved_with_audit" }
if ($riskLevel -eq "high") {
    if ($approvalDecision -eq "approve" -and $approver -ne "") {
        $approvalStatus = "human_approved"; $decision = "approved"
    } else {
        $approvalStatus = "approval_required"; $decision = "denied"
    }
}

# ── Hash + chain ───────────────────────────────────────────────────────────
$inputHash  = Get-Sha256 $input
$prevHash   = ""
if (Test-Path $auditLog) {
    $lastLine = Get-Content $auditLog -Tail 1
    if ($lastLine -match '"record_hash":"([^"]+)"') { $prevHash = $Matches[1] }
}

$recordCore = "$timestamp|$traceId|$ActionName|$actor|$riskLevel|$decision|$approvalStatus|$inputHash|$prevHash"
$recordHash = Get-Sha256 $recordCore
$reasonsJson = ConvertTo-JsonArray ($reasons.ToArray())

# ── Trace JSON ─────────────────────────────────────────────────────────────
$traceFile = Join-Path $traceDir "governance-$traceId.json"
@"
{
  "trace_id": "$traceId",
  "timestamp": "$timestamp",
  "harness": "H5-governance",
  "action": "$ActionName",
  "actor": "$actor",
  "risk_level": "$riskLevel",
  "decision": "$decision",
  "approval_status": "$approvalStatus",
  "approver": "$approver",
  "reasons": $reasonsJson,
  "input_hash": "$inputHash",
  "previous_record_hash": "$prevHash",
  "record_hash": "$recordHash"
}
"@ | Set-Content -Path $traceFile -Encoding UTF8

# ── Audit JSONL (append-only) ──────────────────────────────────────────────
$auditLine = "{`"timestamp`":`"$timestamp`",`"trace_id`":`"$traceId`",`"harness`":`"H5-governance`",`"action`":`"$ActionName`",`"actor`":`"$actor`",`"risk_level`":`"$riskLevel`",`"decision`":`"$decision`",`"approval_status`":`"$approvalStatus`",`"approver`":`"$approver`",`"input_hash`":`"$inputHash`",`"previous_record_hash`":`"$prevHash`",`"record_hash`":`"$recordHash`"}"
Add-Content -Path $auditLog -Value $auditLine -Encoding UTF8

# ── Result ─────────────────────────────────────────────────────────────────
if ($decision -ne "approved") {
    Set-Content -Path $OutputFile -Value "" -Encoding UTF8
    Write-Error "GOVERNANCE_DENIED trace_id=$traceId risk=$riskLevel approval_status=$approvalStatus"
    exit 2
}

$input | Set-Content -Path $OutputFile -Encoding UTF8
Write-Output "GOVERNANCE_APPROVED trace_id=$traceId risk=$riskLevel approval_status=$approvalStatus output=$OutputFile"
exit 0