# 宿主性能基线：对 BakNRet 的关键路径做可复现的计时。
# 设计原则：所有指标都是"比值"或"固定夹具下的绝对耗时"，可以在同一台机器上重复对比。
param(
    [string]$OutJson = '.scratch\ci-cd\20260928-001722\perf_baseline.json',
    [int]$Repeat = 5,
    [string]$Pwsh = 'pwsh'
)

$ErrorActionPreference = 'Stop'
$root = (Resolve-Path (Join-Path $PSScriptRoot '..\..')).Path
$modulePath = Join-Path $root 'BakNRet\BakNRet.psd1'
$listPath = Join-Path $root 'BackupList.txt'
$cfgPath = Join-Path $root 'BackupConfig.psd1'

function Get-Median([double[]]$Values) {
    $s = $Values | Sort-Object
    $n = $s.Count
    if ($n -eq 0) { return 0 }
    if ($n % 2 -eq 1) { return $s[[int](($n - 1) / 2)] }
    return ($s[$n / 2 - 1] + $s[$n / 2]) / 2
}

function Measure-Once([scriptblock]$Body) {
    $sw = [System.Diagnostics.Stopwatch]::StartNew()
    & $Body | Out-Null
    $sw.Stop()
    return $sw.Elapsed.TotalMilliseconds
}

$results = [ordered]@{
    measuredAt = (Get-Date).ToString('s')
    machine    = $env:COMPUTERNAME
    os         = [System.Environment]::OSVersion.VersionString
    psi        = $PSVersionTable.PSVersion.ToString()
    cpu        = (Get-CimInstance Win32_Processor | Select-Object -First 1 -ExpandProperty Name)
    logicalCpu = [int](Get-CimInstance Win32_ComputerSystem).NumberOfLogicalProcessors
    workdir    = $root
    metrics    = @{}
    notes      = @()
}

# ---------------------------------------------------------------- 夹具（固定内容，避免与真实数据联动）
$fixture = Join-Path $env:TEMP ('baknret-perf-' + [guid]::NewGuid().ToString('N').Substring(0, 8))
New-Item -ItemType Directory -Path $fixture -Force | Out-Null
$srcDir = Join-Path $fixture 'src'
New-Item -ItemType Directory -Path $srcDir -Force | Out-Null

$sw = [System.Diagnostics.Stopwatch]::StartNew()
$rnd = [Random]::new(20260928)
$payload = New-Object byte[] 32768
for ($f = 0; $f -lt 200; $f++) {
    $sub = Join-Path $srcDir ('d{0:D2}' -f ($f % 10))
    if (-not (Test-Path $sub)) { New-Item -ItemType Directory -Path $sub -Force | Out-Null }
    $rnd.NextBytes($payload)
    [System.IO.File]::WriteAllBytes((Join-Path $sub ("f$f.bin")), $payload)
}
$sw.Stop()
$results.fixture = [ordered]@{ files = 200; bytes = 200 * 32768; createMs = [math]::Round($sw.Elapsed.TotalMilliseconds, 1) }

# ---------------------------------------------------------------- 1. 模块导入
$imports = 1..$Repeat | ForEach-Object {
    Measure-Once { & $Pwsh -NoProfile -Command "Import-Module '$modulePath' -Force" }
}
$results.metrics.moduleImportMs = [ordered]@{
    min = [math]::Round(($imports | Measure-Object -Minimum).Minimum, 1)
    median = [math]::Round((Get-Median $imports), 1)
    max = [math]::Round(($imports | Measure-Object -Maximum).Maximum, 1)
    samples = $Repeat
}

# ---------------------------------------------------------------- 2. 清单解析
$parseScript = @"
Import-Module '$modulePath' -Force
1..50 | ForEach-Object { Get-Content -LiteralPath '$listPath' | ForEach-Object { ConvertFrom-BackupListLine -Line `$_ } }
"@
$parseFile = Join-Path $fixture 'parse.ps1'
Set-Content -LiteralPath $parseFile -Value $parseScript -Encoding utf8
$parses = 1..$Repeat | ForEach-Object { Measure-Once { & $Pwsh -NoProfile -File $parseFile } }
$results.metrics.backupListParse50xMs = [ordered]@{
    min = [math]::Round(($parses | Measure-Object -Minimum).Minimum, 1)
    median = [math]::Round((Get-Median $parses), 1)
    max = [math]::Round(($parses | Measure-Object -Maximum).Maximum, 1)
    samples = $Repeat
}

# ---------------------------------------------------------------- 3. 只读干跑（真实清单 + 空间预估 + manifest）
$dryFile = Join-Path $fixture 'dry.ps1'
Set-Content -LiteralPath $dryFile -Encoding utf8 -Value @"
Set-Location '$root'
& '$root\Backup-Data.ps1' -DryRun -BackupDir '$fixture\Backups' -ConfigPath '$cfgPath' *> `$null
exit `$LASTEXITCODE
"@
$dries = 1..$Repeat | ForEach-Object { Measure-Once { & $Pwsh -NoProfile -File $dryFile } }
$results.metrics.dryRunFullListMs = [ordered]@{
    min = [math]::Round(($dries | Measure-Object -Minimum).Minimum, 1)
    median = [math]::Round((Get-Median $dries), 1)
    max = [math]::Round(($dries | Measure-Object -Maximum).Maximum, 1)
    samples = $Repeat
}

# ---------------------------------------------------------------- 4. 7z 压缩吞吐（固定夹具，无压缩）
$sevenZip = (Get-Command 7z -ErrorAction SilentlyContinue).Source
if (-not $sevenZip) {
    foreach ($p in 'C:\Programs\Scoop\shims\7z.exe', 'C:\Program Files\7-Zip\7z.exe') { if (Test-Path $p) { $sevenZip = $p; break } }
}
if ($sevenZip) {
    $archive = Join-Path $fixture 'bench.7z'
    $bench = @()
    foreach ($lvl in 0, 5, 9) {
        if (Test-Path $archive) { Remove-Item $archive -Force }
        $ms = Measure-Once { & $sevenZip a -t7z "-mx=$lvl" -bso0 -bsp0 $archive (Join-Path $srcDir '*') }
        $bench += [pscustomobject]@{ level = $lvl; ms = [math]::Round($ms, 1); archiveBytes = (Get-Item $archive).Length }
    }
    $results.metrics.sevenZipBench = @($bench)
    $results.fixture.compressionInputBytes = 200 * 32768
    $results.metrics.sevenZipVersion = (& $sevenZip | Select-Object -First 2 | Select-Object -Last 1)
}
else {
    $results.notes += '找不到 7z.exe，跳过压缩基准'
}

# ---------------------------------------------------------------- 5. 源树扫描（Get-BakNRetFolderSummary 走真实目录）
$summaryScript = @"
Import-Module '$modulePath' -Force
`$sw = [System.Diagnostics.Stopwatch]::StartNew()
1..3 | ForEach-Object { Get-BakNRetFolderSummary -FolderPath '$srcDir' | Out-Null }
`$sw.Stop()
Write-Output ([math]::Round(`$sw.Elapsed.TotalMilliseconds / 3, 1))
"@
$sumFile = Join-Path $fixture 'summary.ps1'
Set-Content -LiteralPath $sumFile -Value $summaryScript -Encoding utf8
$sumMs = (& $Pwsh -NoProfile -File $sumFile | Select-Object -Last 1)
$results.metrics.folderSummary200Files3xMs = [double]$sumMs

Remove-Item -LiteralPath $fixture -Recurse -Force -ErrorAction SilentlyContinue

$results | ConvertTo-Json -Depth 6 | Set-Content -LiteralPath (Join-Path $root $OutJson) -Encoding utf8
Write-Host ('基线已写入 {0}' -f $OutJson)
$results.metrics | ConvertTo-Json -Depth 6