[Console]::OutputEncoding = [Text.Encoding]::UTF8
$ErrorActionPreference = 'Stop'

function Test-Installed {
    $keys = @(
        'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*',
        'HKLM:\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*'
    )
    Get-ItemProperty $keys -ErrorAction SilentlyContinue |
        Where-Object { $_.DisplayName -match 'Thunderbird' } |
        Select-Object -First 1 DisplayName,DisplayVersion,InstallLocation
}

$existing = Test-Installed
if ($existing) {
    Write-Host "[=] Thunderbird already installed: $($existing.DisplayName) $($existing.DisplayVersion)"
    Write-Host "    Location: $($existing.InstallLocation)"
    exit 0
}

$installed = $false

# --- Attempt 1: winget ---
$winget = Get-Command winget -ErrorAction SilentlyContinue
if ($winget) {
    Write-Host "[*] winget found, installing Mozilla.Thunderbird"
    try {
        & winget install --id Mozilla.Thunderbird -e --silent `
            --accept-source-agreements --accept-package-agreements `
            --scope machine 2>&1 | Write-Host
        if ($LASTEXITCODE -eq 0) { $installed = $true }
        else { Write-Host "[!] winget exited $LASTEXITCODE, falling back to direct download" }
    } catch {
        Write-Host "[!] winget failed: $_"
    }
} else {
    Write-Host "[!] winget not available, using direct download"
}

# --- Attempt 2: direct download from Mozilla CDN ---
if (-not $installed) {
    $url = 'https://download.mozilla.org/?product=thunderbird-latest&os=win64&lang=zh-TW'
    $dst = Join-Path $env:TEMP 'thunderbird-setup.exe'

    Write-Host "[*] Downloading installer -> $dst"
    [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
    Invoke-WebRequest -Uri $url -OutFile $dst -UseBasicParsing

    if (-not (Test-Path $dst) -or (Get-Item $dst).Length -lt 10MB) {
        throw "Downloaded file looks wrong (size < 10 MB)"
    }

    Write-Host "[*] Running silent install"
    $proc = Start-Process -FilePath $dst -ArgumentList '/S' -Wait -PassThru
    if ($proc.ExitCode -ne 0) {
        throw "Installer exited with code $($proc.ExitCode)"
    }
    Remove-Item $dst -ErrorAction SilentlyContinue
    $installed = $true
}

# --- Verify ---
Start-Sleep -Seconds 2
$after = Test-Installed
if ($after) {
    Write-Host ""
    Write-Host "[OK] Installed: $($after.DisplayName) $($after.DisplayVersion)"
    Write-Host "     Location:  $($after.InstallLocation)"
    exit 0
} else {
    Write-Host "[FAIL] Thunderbird was not detected in uninstall registry after install"
    exit 1
}