param(
    [string]$MysqlDatabaseUrl = $env:MYSQL_DATABASE_URL,
    [string]$MysqlPipPackages = $(if ($env:MYSQL_PIP_PACKAGES) { $env:MYSQL_PIP_PACKAGES } else { "asyncmy==0.2.10" }),
    [string]$CreateDatabase = $(if ($env:CREATE_DATABASE) { $env:CREATE_DATABASE } else { "1" }),
    [string]$DropEmptyTargetSchema = $(if ($env:DROP_EMPTY_TARGET_SCHEMA) { $env:DROP_EMPTY_TARGET_SCHEMA } else { "1" }),
    [string]$TruncateTarget = $(if ($env:TRUNCATE_TARGET) { $env:TRUNCATE_TARGET } else { "0" }),
    [string]$SqliteDb = $(if ($env:SQLITE_DB) { $env:SQLITE_DB } else { "" }),
    [string]$ConfigFile = $(if ($env:DEER_FLOW_CONFIG_PATH) { $env:DEER_FLOW_CONFIG_PATH } else { "" }),
    [string]$EnvFile = $(if ($env:ENV_FILE) { $env:ENV_FILE } else { "" }),
    [string]$PythonExe = $(if ($env:PYTHON_EXE) { $env:PYTHON_EXE } else { "" })
)

$ErrorActionPreference = "Stop"

function Die([string]$Message) {
    Write-Error $Message
    exit 1
}

function Require-Command([string]$Name) {
    if (-not (Get-Command $Name -ErrorAction SilentlyContinue)) {
        Die "command not found: $Name"
    }
}

function Require-File([string]$Path) {
    if (-not (Test-Path -LiteralPath $Path -PathType Leaf)) {
        Die "required file not found: $Path"
    }
}

function Require-Dir([string]$Path) {
    if (-not (Test-Path -LiteralPath $Path -PathType Container)) {
        Die "required directory not found: $Path"
    }
}

function Resolve-ExistingFile([string]$Path) {
    return (Resolve-Path -LiteralPath $Path).Path
}

function Get-EnvFileValue([string]$Path, [string]$Key) {
    if (-not (Test-Path -LiteralPath $Path -PathType Leaf)) {
        return ""
    }
    $line = Get-Content -LiteralPath $Path |
        Where-Object { $_ -match "^\s*$([regex]::Escape($Key))=" } |
        Select-Object -Last 1
    if (-not $line) {
        return ""
    }
    return ($line -replace "^\s*$([regex]::Escape($Key))=", "")
}

function Upsert-EnvFileValue([string]$Path, [string]$Key, [string]$Value) {
    $existing = @()
    if (Test-Path -LiteralPath $Path -PathType Leaf) {
        $existing = Get-Content -LiteralPath $Path | Where-Object { $_ -notmatch "^\s*$([regex]::Escape($Key))=" }
    }
    $existing + "$Key=$Value" | Set-Content -LiteralPath $Path -Encoding UTF8
}

function Is-Enabled([string]$Value) {
    return @("1", "true", "yes", "on") -contains $Value.ToLowerInvariant()
}

function Run-Native([string]$Command, [string[]]$Arguments) {
    & $Command @Arguments
    if ($LASTEXITCODE -ne 0) {
        Die "$Command failed with exit code $LASTEXITCODE"
    }
}

$ScriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
$BackendDir = Join-Path $ScriptDir "backend"
$DefaultDeerFlowHome = Join-Path $BackendDir ".deer-flow"

if (-not $ConfigFile) {
    $ConfigFile = Join-Path $ScriptDir "config.yaml"
}
if (-not $EnvFile) {
    $EnvFile = Join-Path $ScriptDir ".env"
}
if (-not $SqliteDb) {
    $SqliteDb = Join-Path $DefaultDeerFlowHome "data\deerflow.db"
}

if ($PythonExe) {
    Require-File $PythonExe
    $PythonExe = Resolve-ExistingFile $PythonExe
} else {
    Require-Command uv
}
Require-File $EnvFile
Require-File $ConfigFile
Require-File $SqliteDb
Require-File (Join-Path $BackendDir "pyproject.toml")
Require-File (Join-Path $BackendDir "scripts\migrate_business_sqlite_to_mysql.py")
Require-File (Join-Path $BackendDir "scripts\update_database_config.py")
Require-File (Join-Path $ScriptDir "extensions_config.json")
Require-File (Join-Path $ScriptDir "skill_evolution.json")
Require-Dir (Join-Path $ScriptDir "skills")

if (-not $MysqlDatabaseUrl) {
    $MysqlDatabaseUrl = Get-EnvFileValue $EnvFile "MYSQL_DATABASE_URL"
}
if (-not $MysqlDatabaseUrl) {
    Die "MYSQL_DATABASE_URL is required. Example: .\switch_database_to_mysql.ps1 -MysqlDatabaseUrl 'mysql+asyncmy://user:pass@127.0.0.1:3306/deerflow?charset=utf8mb4'"
}

$ConfigFile = Resolve-ExistingFile $ConfigFile
$EnvFile = Resolve-ExistingFile $EnvFile
$SqliteDb = Resolve-ExistingFile $SqliteDb
$DeerFlowHome = if ($env:DEER_FLOW_HOME) { $env:DEER_FLOW_HOME } else { $DefaultDeerFlowHome }
New-Item -ItemType Directory -Force -Path $DeerFlowHome | Out-Null
$DeerFlowHome = (Resolve-Path -LiteralPath $DeerFlowHome).Path

$BackupRoot = Join-Path $DeerFlowHome "backups"
New-Item -ItemType Directory -Force -Path $BackupRoot | Out-Null
$Timestamp = Get-Date -Format "yyyyMMdd_HHmmss"
$BackupDir = Join-Path $BackupRoot "mysql-switch-$Timestamp"
New-Item -ItemType Directory -Force -Path $BackupDir | Out-Null
Copy-Item -LiteralPath $ConfigFile -Destination (Join-Path $BackupDir "config.yaml.bak") -Force
Copy-Item -LiteralPath $EnvFile -Destination (Join-Path $BackupDir "env.bak") -Force
Copy-Item -LiteralPath $SqliteDb -Destination (Join-Path $BackupDir "deerflow.db.bak") -Force

$env:MYSQL_DATABASE_URL = $MysqlDatabaseUrl
$env:DEER_FLOW_PROJECT_ROOT = $ScriptDir
$env:DEER_FLOW_HOME = $DeerFlowHome
$env:DEER_FLOW_CONFIG_PATH = $ConfigFile
$env:DEER_FLOW_EXTENSIONS_CONFIG_PATH = Join-Path $ScriptDir "extensions_config.json"
$env:DEER_FLOW_SKILL_EVOLUTION_CONFIG_PATH = Join-Path $ScriptDir "skill_evolution.json"
$env:DEER_FLOW_SKILLS_PATH = Join-Path $ScriptDir "skills"
$PythonPathParts = @(
    $BackendDir,
    (Join-Path $BackendDir "packages\harness")
)
if ($env:PYTHONPATH) {
    $PythonPathParts += $env:PYTHONPATH
}
$env:PYTHONPATH = ($PythonPathParts -join [IO.Path]::PathSeparator)

Push-Location $BackendDir
try {
    $packages = @($MysqlPipPackages -split "\s+" | Where-Object { $_ })
    if ($PythonExe) {
        if ($packages.Count -gt 0) {
            Write-Host "Installing MySQL driver into selected Python environment: $MysqlPipPackages"
            Run-Native $PythonExe (@("-m", "pip", "install") + $packages)
        }
        Run-Native $PythonExe @("-c", "import asyncmy")
    } else {
        if (-not (Test-Path -LiteralPath (Join-Path $BackendDir ".venv") -PathType Container)) {
            Write-Host "Creating local uv virtual environment..."
            Run-Native "uv" @("venv")
        }

        if ($packages.Count -gt 0) {
            Write-Host "Installing MySQL driver into local backend environment: $MysqlPipPackages"
            Run-Native "uv" (@("pip", "install") + $packages)
        }
        Run-Native "uv" @("run", "--no-sync", "python", "-c", "import asyncmy")
    }

    $migrationArgs = @(
        "scripts\migrate_business_sqlite_to_mysql.py",
        "--sqlite", $SqliteDb,
        "--mysql-url", $MysqlDatabaseUrl
    )
    if (Is-Enabled $CreateDatabase) {
        $migrationArgs += "--create-database"
    }
    if (Is-Enabled $DropEmptyTargetSchema) {
        $migrationArgs += "--drop-empty-target-schema"
    }
    if (Is-Enabled $TruncateTarget) {
        $migrationArgs += "--truncate-target"
    }

    Write-Host "Backups written to: $BackupDir"
    Write-Host "Migrating business tables to MySQL..."
    if ($PythonExe) {
        Run-Native $PythonExe $migrationArgs
    } else {
        Run-Native "uv" (@("run", "--no-sync", "python") + $migrationArgs)
    }

    $configArgs = @(
        "scripts\update_database_config.py",
        "--config", $ConfigFile,
        "--mysql-url-env", "MYSQL_DATABASE_URL",
        "--checkpointer-sqlite", $SqliteDb
    )
    if ($PythonExe) {
        Run-Native $PythonExe $configArgs
    } else {
        Run-Native "uv" (@("run", "--no-sync", "python") + $configArgs)
    }

    Upsert-EnvFileValue $EnvFile "MYSQL_DATABASE_URL" $MysqlDatabaseUrl
}
finally {
    Pop-Location
}

Write-Host ""
Write-Host "MySQL switch completed."
Write-Host "  Config updated: $ConfigFile"
Write-Host "  Env updated:    $EnvFile"
Write-Host "  Backup dir:     $BackupDir"
Write-Host ""
Write-Host "Start the local backend from backend directory, for example:"
Write-Host "  cd backend"
Write-Host "  `$env:PYTHONPATH='.'"
Write-Host "  uv run uvicorn app.gateway.app:app --host 0.0.0.0 --port 8001"