[CmdletBinding()]
param(
    [string]$SourceBackupPath = "D:\work\code\PayrollManagementSystem\db\ceshi20261026.bak",
    [string]$TPlusRoot = "D:\work\app\tplus-sqlserver"
)

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

function Assert-OnDDrive([string]$Path) {
    $full = [IO.Path]::GetFullPath($Path)
    if (-not $full.StartsWith("D:\", [StringComparison]::OrdinalIgnoreCase)) {
        throw "T+ 数据目录必须位于 D 盘：$full"
    }
}

Assert-OnDDrive $TPlusRoot
if (-not (Test-Path -LiteralPath $SourceBackupPath -PathType Leaf)) {
    throw "找不到客户备份文件：$SourceBackupPath"
}

$dataDir = Join-Path $TPlusRoot "data"
$logDir = Join-Path $TPlusRoot "log"
$backupDir = Join-Path $TPlusRoot "backup"
$scriptsDir = Join-Path $TPlusRoot "scripts"
foreach ($dir in @($dataDir, $logDir, $backupDir, $scriptsDir)) {
    New-Item -ItemType Directory -Path $dir -Force | Out-Null
}

$destination = Join-Path $backupDir (Split-Path $SourceBackupPath -Leaf)
$sourceHash = (Get-FileHash -LiteralPath $SourceBackupPath -Algorithm SHA256).Hash

if (Test-Path -LiteralPath $destination -PathType Leaf) {
    $destinationHash = (Get-FileHash -LiteralPath $destination -Algorithm SHA256).Hash
    if ($destinationHash -ne $sourceHash) {
        throw "D 盘已有同名备份，但 SHA-256 不一致：$destination"
    }
    Write-Host "备份已存在且校验一致：$destination"
} else {
    Write-Host "正在把备份复制到 D 盘，源文件不会被修改……"
    Copy-Item -LiteralPath $SourceBackupPath -Destination $destination -Force
    $destinationHash = (Get-FileHash -LiteralPath $destination -Algorithm SHA256).Hash
    if ($destinationHash -ne $sourceHash) {
        throw "复制完成后 SHA-256 校验失败：$destination"
    }
    Write-Host "备份复制完成：$destination"
}

$hashFile = "$destination.sha256"
"$destinationHash  $(Split-Path $destination -Leaf)" | Set-Content -LiteralPath $hashFile -Encoding utf8
Write-Host "SHA-256：$destinationHash"
Write-Host "SQL Server 数据、日志和备份目录已准备在：$TPlusRoot"