#Requires -Version 5.1

[CmdletBinding()]
param(
    [switch]$ConfigOnly,
    [switch]$SkipDesktopInstall,
    [switch]$SilentDesktopInstall,
    [string]$GitHubToken = $env:GITHUB_TOKEN,
    [string]$ConfigPath = (Join-Path $env:USERPROFILE ".config\opencode\opencode.json")
)

$ErrorActionPreference = "Stop"
$ProgressPreference = "SilentlyContinue"

$repo = "anomalyco/opencode"
$windowsAssetName = "opencode-desktop-win-x64.exe"
$releaseApiUrl = "https://api.github.com/repos/$repo/releases/latest"
$baseUrl = "https://ai-openwebui.gesis.org/api"

function Write-Step {
    param([string]$Message)
    Write-Host ""
    Write-Host "==> $Message" -ForegroundColor Cyan
}

function ConvertFrom-SecureStringToPlainText {
    param([Parameter(Mandatory = $true)][securestring]$SecureString)

    $bstr = [Runtime.InteropServices.Marshal]::SecureStringToBSTR($SecureString)
    try {
        [Runtime.InteropServices.Marshal]::PtrToStringBSTR($bstr)
    }
    finally {
        if ($bstr -ne [IntPtr]::Zero) {
            [Runtime.InteropServices.Marshal]::ZeroFreeBSTR($bstr)
        }
    }
}

function Invoke-GitHubGet {
    param([Parameter(Mandatory = $true)][string]$Uri)

    $headers = @{
        "Accept" = "application/vnd.github+json"
        "User-Agent" = "GESIS-OpenCode-Installer"
    }

    if (-not [string]::IsNullOrWhiteSpace($GitHubToken)) {
        $headers["Authorization"] = "Bearer $GitHubToken"
    }

    Invoke-RestMethod -Uri $Uri -Headers $headers -Method Get
}

function Install-OpenCodeDesktop {
    if ($SkipDesktopInstall -or $ConfigOnly) {
        Write-Host "Skipping OpenCode Desktop installation."
        return
    }

    if (-not [Environment]::Is64BitOperatingSystem) {
        throw "This installer expects 64-bit Windows because OpenCode publishes a Windows x64 desktop installer."
    }

    Write-Step "Finding latest OpenCode Desktop release"
    $release = Invoke-GitHubGet -Uri $releaseApiUrl
    $asset = $release.assets | Where-Object { $_.name -eq $windowsAssetName } | Select-Object -First 1

    if ($null -eq $asset) {
        throw "Could not find $windowsAssetName in the latest $repo release ($($release.tag_name))."
    }

    Write-Host "Latest release: $($release.tag_name)"
    Write-Host "Downloading: $($asset.name)"

    $downloadPath = Join-Path $env:TEMP $asset.name
    Invoke-WebRequest -Uri $asset.browser_download_url -OutFile $downloadPath -Headers @{ "User-Agent" = "GESIS-OpenCode-Installer" }

    Write-Step "Starting OpenCode Desktop installer"
    if ($SilentDesktopInstall) {
        $process = Start-Process -FilePath $downloadPath -ArgumentList "/S" -Wait -PassThru
    }
    else {
        $process = Start-Process -FilePath $downloadPath -Wait -PassThru
    }

    if ($process.ExitCode -ne 0) {
        throw "OpenCode Desktop installer exited with code $($process.ExitCode)."
    }
}

function New-GesisOpenCodeConfig {
    param([Parameter(Mandatory = $true)][string]$ApiKey)

    [ordered]@{
        '$schema' = 'https://opencode.ai/config.json'
        enabled_providers = @('gesis')
        disabled_providers = @('zen', 'opencode')
        provider = [ordered]@{
            gesis = [ordered]@{
                npm = '@ai-sdk/openai-compatible'
                name = 'GESIS AI Server'
                options = [ordered]@{
                    baseURL = $baseUrl
                    apiKey = $ApiKey
                }
                models = [ordered]@{
                    'gemma3:27b' = @{ name = 'Gemma 3 27B' }
                    'gpt-4.1' = @{ name = 'GPT-4.1' }
                    'gpt-4.1-mini' = @{ name = 'GPT-4.1 Mini' }
                    'llama4:latest' = @{ name = 'Llama 4 Latest' }
                    'o4-mini' = @{ name = 'O4 Mini' }
                    'de-fr' = @{ name = 'De-Fr Translation' }
                    'de-ru' = @{ name = 'De-Ru Translation' }
                    'en-de' = @{ name = 'En-De Translation' }
                    'en-fr' = @{ name = 'En-Fr Translation' }
                    'en-ru' = @{ name = 'En-Ru Translation' }
                    'pdf-extractor' = @{ name = 'PDF Extractor' }
                    'gpt-5' = @{ name = 'GPT-5' }
                    'gpt-5-mini' = @{ name = 'GPT-5 Mini' }
                    'gpt-oss:120b' = @{ name = 'GPT-OSS 120B' }
                    'gpt-oss:latest' = @{ name = 'GPT-OSS Latest' }
                }
            }
        }
    }
}

function Write-OpenCodeConfig {
    Write-Step "Configuring GESIS AI Server"
    $secureApiKey = Read-Host "Enter your personal GESIS AI Server API key" -AsSecureString
    $apiKey = ConvertFrom-SecureStringToPlainText -SecureString $secureApiKey

    if ([string]::IsNullOrWhiteSpace($apiKey)) {
        throw "API key cannot be empty."
    }

    $configDirectory = Split-Path -Parent $ConfigPath
    New-Item -Path $configDirectory -ItemType Directory -Force | Out-Null

    if (Test-Path -LiteralPath $ConfigPath) {
        $timestamp = Get-Date -Format "yyyyMMdd-HHmmss"
        $backupPath = "$ConfigPath.backup-$timestamp"
        Copy-Item -LiteralPath $ConfigPath -Destination $backupPath -Force
        Write-Host "Existing config backed up to: $backupPath"
    }

    $config = New-GesisOpenCodeConfig -ApiKey $apiKey
    $json = $config | ConvertTo-Json -Depth 20

    $utf8NoBom = New-Object System.Text.UTF8Encoding($false)
    [System.IO.File]::WriteAllText($ConfigPath, $json, $utf8NoBom)
    Write-Host "OpenCode config written to: $ConfigPath"
}

try {
    [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

    Install-OpenCodeDesktop
    Write-OpenCodeConfig

    Write-Step "Done"
    Write-Host "OpenCode Desktop is installed and configured for the GESIS AI Server."
}
catch {
    Write-Host ""
    Write-Host "Installation failed: $($_.Exception.Message)" -ForegroundColor Red
    exit 1
}