[CmdletBinding()]
param(
    [switch]$Restart
)

$ErrorActionPreference = "Stop"
$ProjectRoot = $PSScriptRoot
$BackendDir = Join-Path $ProjectRoot "backend"
$EnvFile = Join-Path $ProjectRoot ".env"

function Get-MatchingProcesses {
    param([string]$Pattern)

    return @(Get-CimInstance Win32_Process | Where-Object {
        $_.CommandLine -and $_.CommandLine -match $Pattern
    })
}

function Stop-MatchingProcesses {
    param([string]$Name, [string]$Pattern)

    $processes = Get-MatchingProcesses -Pattern $Pattern
    if (-not $processes) {
        return
    }
    $hasStaleEnvironment = @($processes | Where-Object {
        $_.CreationDate -lt $script:EnvLastWriteTime
    }).Count -gt 0
    if (-not $Restart -and -not $hasStaleEnvironment) {
        Write-Host "[skip] $Name 已运行" -ForegroundColor Yellow
        return
    }
    foreach ($process in $processes) {
        Stop-Process -Id $process.ProcessId -Force -ErrorAction SilentlyContinue
    }
    $reason = if ($Restart) { "显式重启" } else { ".env 晚于进程启动时间" }
    Write-Host "[restart] 已停止旧 $Name 进程（$reason）" -ForegroundColor Yellow
}

function Start-PythonProcess {
    param(
        [string]$Name,
        [string]$Pattern,
        [string]$Command
    )

    if (Get-MatchingProcesses -Pattern $Pattern) {
        return
    }
    $escapedDirectory = $BackendDir.Replace("'", "''")
    $windowCommand = "Set-Location -LiteralPath '$escapedDirectory'; `$Host.UI.RawUI.WindowTitle = '$Name'; $Command"
    Start-Process powershell.exe -ArgumentList @("-NoExit", "-Command", $windowCommand)
    Write-Host "[start] $Name" -ForegroundColor Green
}

if (-not (Test-Path -LiteralPath $EnvFile)) {
    throw "未找到 $EnvFile，请先复制 .env.example 并完成配置。"
}
if (-not (Get-Command python -ErrorAction SilentlyContinue)) {
    throw "未找到 python，请先安装 Python 3.12 并加入 PATH。"
}
$script:EnvLastWriteTime = (Get-Item -LiteralPath $EnvFile).LastWriteTime

Push-Location $ProjectRoot
try {
    python -c "from cryptography.fernet import Fernet; from dotenv import dotenv_values; key=dotenv_values('.env').get('AI_CREDENTIAL_ENCRYPTION_KEY',''); Fernet(key.encode()); print('[ok] AI credential encryption key is valid')"
    if ($LASTEXITCODE -ne 0) {
        throw ".env 中的 AI_CREDENTIAL_ENCRYPTION_KEY 缺失或不是有效 Fernet 密钥。"
    }

    Stop-MatchingProcesses -Name "Django API" -Pattern "manage\.py runserver 0\.0\.0\.0:8000"
    Stop-MatchingProcesses -Name "Celery Worker" -Pattern "celery.*-A config\.celery worker"
    Stop-MatchingProcesses -Name "Celery Beat" -Pattern "celery.*-A config\.celery beat"

    Start-PythonProcess -Name "AI Ticket - Django API" `
        -Pattern "manage\.py runserver 0\.0\.0\.0:8000" `
        -Command "python manage.py runserver 0.0.0.0:8000"
    Start-PythonProcess -Name "AI Ticket - Celery Worker" `
        -Pattern "celery.*-A config\.celery worker" `
        -Command "python -m celery -A config.celery worker -l info -P solo"
    Start-PythonProcess -Name "AI Ticket - Celery Beat" `
        -Pattern "celery.*-A config\.celery beat" `
        -Command "python -m celery -A config.celery beat -l info"

    Write-Host ""
    Write-Host "Python 后端程序已启动：" -ForegroundColor Cyan
    Write-Host "  Django API     http://localhost:8000/api/docs"
    Write-Host "  Celery Worker  已启动"
    Write-Host "  Celery Beat    已启动"
    Write-Host ""
    Write-Host "修改 .env 后可执行：.\start-backend.ps1 -Restart" -ForegroundColor Yellow
}
finally {
    Pop-Location
}