param(
    [string]$BackupVersion = $null
)

$ErrorActionPreference = "Stop"

$configPath = "D:\EPproject\LabelReplaceServer\deployment\config\deployment-config.json"
$stateFile = "D:\EPproject\LabelReplaceServer\deployment\instance_state.json"
$logFile = "D:\EPproject\LabelReplaceServer\deployment\logs\deployment.log"
$backupDir = "D:\EPproject\LabelReplaceServer\deployment\backups"

function Log {
    param([string]$Message, [string]$Level = "INFO")
    $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
    $logEntry = "[$timestamp] [$Level] [Rollback] $Message"
    Write-Host $logEntry -ForegroundColor $(switch($Level) {
        "ERROR" { "Red" }
        "WARN" { "Yellow" }
        "INFO" { "Green" }
        default { "White" }
    })
    
    $logDirPath = Split-Path -Parent $logFile
    if (!(Test-Path $logDirPath)) {
        New-Item -ItemType Directory -Path $logDirPath -Force | Out-Null
    }
    Add-Content -Path $logFile -Value $logEntry
}

function GetLatestBackup {
    if (!(Test-Path $backupDir)) {
        return $null
    }
    
    $backups = Get-ChildItem -Path $backupDir -Directory | Sort-Object -Property LastWriteTime -Descending
    return $backups[0]
}

function RestoreFromBackup {
    param([string]$BackupPath, [string]$TargetPath)
    
    Log "从备份恢复: $BackupPath -> $TargetPath" "INFO"
    
    if (Test-Path $TargetPath) {
        Log "移除现有实例目录..." "INFO"
        Remove-Item -Path $TargetPath -Recurse -Force
    }
    
    Copy-Item -Path $BackupPath -Destination $TargetPath -Recurse -Force
    Log "已从备份恢复文件" "INFO"
}

function StartInstance {
    param([string]$Instance, [string]$Directory, [int]$Port)
    
    Log "启动 $Instance 实例 (端口: $Port)..." "INFO"
    
    try {
        $exePath = Join-Path $Directory "CONTROLLER.exe"
        
        $env:DEPLOYMENT_INSTANCE = if ($Instance -eq "green") { "green" } else { "blue" }
        $env:SHUTDOWN_TIMEOUT = "30"
        
        $process = Start-Process -FilePath $exePath -WorkingDirectory $Directory -PassThru
        
        Log "$Instance 实例已启动 (PID: $($process.Id))" "INFO"
        Start-Sleep -Seconds 2
        
        return $process.Id
    }
    catch {
        Log "启动实例失败: $_" "ERROR"
        throw
    }
}

function StopInstance {
    param([int]$GracefulTimeout = 30)
    
    try {
        $controller = Get-Process -Name CONTROLLER -ErrorAction SilentlyContinue
        
        if ($null -eq $controller) {
            Log "CONTROLLER 进程未找到" "WARN"
            return $true
        }
        
        Log "停止 CONTROLLER 进程 (PID: $($controller.Id))..." "INFO"
        
        if ($controller.WaitForExit($GracefulTimeout * 1000)) {
            Log "进程已退出" "INFO"
            return $true
        }
        
        Log "强制终止进程..." "WARN"
        $controller | Stop-Process -Force
        
        return $true
    }
    catch {
        Log "停止实例失败: $_" "ERROR"
        return $false
    }
}

try {
    Log "========================================" "INFO"
    Log "开始回滚流程" "INFO"
    Log "========================================" "INFO"
    
    if (!(Test-Path $configPath)) {
        throw "配置文件不存在: $configPath"
    }
    
    $config = Get-Content $configPath | ConvertFrom-Json
    
    if (!(Test-Path $stateFile)) {
        throw "状态文件不存在: $stateFile，无法确定当前实例"
    }
    
    $state = Get-Content $stateFile | ConvertFrom-Json
    $currentInstance = $state.activeInstance
    $previousInstance = if ($currentInstance -eq "blue") { "green" } else { "blue" }
    
    Log "当前活跃实例: $currentInstance" "INFO"
    Log "回滚目标实例: $previousInstance" "INFO"
    
    $backup = GetLatestBackup
    if ($null -eq $backup) {
        throw "没有找到备份文件"
    }
    
    Log "最新备份: $($backup.Name)" "INFO"
    
    $previousConfig = if ($previousInstance -eq "green") {
        $config.GreenInstance
    }
    else {
        $config.BlueInstance
    }
    
    Log "========== 第一步：停止当前实例 ==========" "INFO"
    StopInstance -GracefulTimeout 30
    
    Log "========== 第二步：恢复备份 ==========" "INFO"
    RestoreFromBackup -BackupPath $backup.FullName -TargetPath $previousConfig.Directory
    
    Log "========== 第三步：启动恢复的实例 ==========" "INFO"
    $pid = StartInstance -Instance $previousInstance -Directory $previousConfig.Directory `
        -Port $previousConfig.Port
    
    Log "========== 第四步：健康检查 ==========" "INFO"
    $healthScript = "D:\EPproject\LabelReplaceServer\deployment\scripts\health-check.ps1"
    $healthResult = & $healthScript -Instance $previousInstance -Port $previousConfig.Port
    
    if (!$healthResult) {
        throw "恢复的实例健康检查失败"
    }
    
    Log "========== 第五步：更新活跃实例 ==========" "INFO"
    $newState = @{
        activeInstance = $previousInstance
        lastUpdate = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
        version = $state.version
        rolledBack = $true
    }
    
    $newState | ConvertTo-Json | Set-Content -Path $stateFile -Force
    
    Log "========================================" "INFO"
    Log "回滚完成！" "INFO"
    Log "新活跃实例: $previousInstance (端口: $($previousConfig.Port))" "INFO"
    Log "========================================" "INFO"
}
catch {
    Log "回滚失败: $_" "ERROR"
    Log "错误详情: $($_.Exception.StackTrace)" "ERROR"
    exit 1
}