#Requires -Version 5.1
<#
.SYNOPSIS
    还原 MES Cloud 全量备份（gzip）

.EXAMPLE
    powershell -ExecutionPolicy Bypass -File .\restore-db.ps1
    powershell -ExecutionPolicy Bypass -File .\restore-db.ps1 -BackupFile "E:\MES_DB_Backup\mes_cloud_20260821.sql.gz"
#>
param(
    [string]$BackupFile,
    [switch]$Force
)

$ErrorActionPreference = "Stop"

. (Join-Path $PSScriptRoot "db-config.ps1")
$dbCfg = Read-MesDbConfig
$DbHost = [string]$dbCfg.host
$DbPort = [int]$dbCfg.port
$DbName = [string]$dbCfg.database
$DbUser = [string]$dbCfg.user
$DbPassword = [string]$dbCfg.password
$BackupRoot = "E:\MES_DB_Backup"
$CnfFile = Join-Path $env:TEMP ("mes_restore_{0}.cnf" -f $PID)

function Find-MysqlTool {
    param([string]$Name)
    $cmd = Get-Command $Name -ErrorAction SilentlyContinue
    if ($cmd -and $cmd.Source) { return $cmd.Source }
    $binRoots = @(
        "C:\Program Files\MySQL",
        "C:\Program Files (x86)\MySQL",
        "C:\mysql",
        "D:\MySQL",
        "E:\MySQL",
        "C:\Program Files\MariaDB"
    )
    foreach ($root in $binRoots) {
        if (-not (Test-Path $root)) { continue }
        $hit = Get-ChildItem -Path $root -Filter ($Name + ".exe") -Recurse -ErrorAction SilentlyContinue |
            Where-Object { $_.Directory.Name -eq "bin" } |
            Select-Object -First 1
        if ($hit) { return $hit.FullName }
    }
    return $null
}

try {
    if (-not $BackupFile) {
        $latest = Get-ChildItem -Path $BackupRoot -File -Filter "mes_cloud_*.sql.gz" -ErrorAction SilentlyContinue |
            Sort-Object LastWriteTime -Descending |
            Select-Object -First 1
        if (-not $latest) { throw "找不到备份文件，目录: $BackupRoot" }
        $BackupFile = $latest.FullName
    }
    if (-not (Test-Path $BackupFile)) {
        throw "找不到备份文件: $BackupFile"
    }

    if (-not $Force) {
        Write-Host "即将把备份还原到 ${DbHost}:${DbPort} / $DbName"
        Write-Host "备份文件: $BackupFile"
        Write-Host "现有数据会被覆盖。"
        $ans = Read-Host "确认还原请输入 YES"
        if ($ans -ne "YES") {
            Write-Host "已取消"
            exit 0
        }
    }

    $mysql = Find-MysqlTool "mysql"
    if (-not $mysql) { throw "找不到 mysql.exe，请安装 MySQL 客户端并把 bin 目录加入 PATH" }

    Write-MesMysqlCnf -Config $dbCfg -CnfPath $CnfFile

    $isGzip = $false
    $fsHead = [System.IO.File]::OpenRead($BackupFile)
    try {
        $b0 = $fsHead.ReadByte()
        $b1 = $fsHead.ReadByte()
        $isGzip = ($b0 -eq 0x1F -and $b1 -eq 0x8B)
    } finally {
        $fsHead.Dispose()
    }

    Write-Host $(if ($isGzip) { "正在还原（gzip 压缩包）..." } else { "正在还原（SQL 文本，文件较大时请耐心等待）..." })
    $psi = New-Object System.Diagnostics.ProcessStartInfo
    $psi.FileName = $mysql
    $psi.Arguments = ('"--defaults-extra-file={0}" "--max-allowed-packet=1G" "--default-character-set=utf8mb4"' -f $CnfFile)
    $psi.UseShellExecute = $false
    $psi.RedirectStandardInput = $true
    $psi.RedirectStandardError = $true
    $psi.CreateNoWindow = $true
    $proc = New-Object System.Diagnostics.Process
    $proc.StartInfo = $psi
    if (-not $proc.Start()) { throw "无法启动 mysql" }
    $fs = [System.IO.File]::OpenRead($BackupFile)
    $gz = $null
    try {
        $inStream = $fs
        if ($isGzip) {
            $gz = New-Object System.IO.Compression.GZipStream($fs, [System.IO.Compression.CompressionMode]::Decompress)
            $inStream = $gz
        }
        $inStream.CopyTo($proc.StandardInput.BaseStream)
        $proc.StandardInput.Close()
    } finally {
        if ($gz) { $gz.Dispose() }
        $fs.Dispose()
    }
    $err = $proc.StandardError.ReadToEnd()
    $proc.WaitForExit()
    if ($proc.ExitCode -ne 0) {
        throw ("还原失败: {0}" -f $err)
    }
    Write-Host "还原完成"
    exit 0
} catch {
    Write-Host ("还原失败: {0}" -f $_.Exception.Message) -ForegroundColor Red
    exit 1
} finally {
    if (Test-Path $CnfFile) { Remove-Item $CnfFile -Force -ErrorAction SilentlyContinue }
}