<#
.SYNOPSIS
  End to end demonstration of llm-gateway.

.DESCRIPTION
  Starts the API server on a spare port, runs a full cycle against it
  (health, models, non-streaming completion, streaming completion, provider
  status, validation, configuration reload) and stops the server.

  Without -Mock the server talks to a real browser: log in first with
  "llm-gateway login chatgpt" and make sure the provider is configured.
  With -Mock everything runs in memory, no browser and no login needed.

.EXAMPLE
  ./demo.ps1 -Mock
  ./demo.ps1 -Port 8099
#>
param(
    [switch]$Mock,
    [int]$Port = 8099,
    [string]$Provider = 'chatgpt'
)

$ErrorActionPreference = 'Stop'
$root = Split-Path -Parent $MyInvocation.MyCommand.Path
Push-Location $root

$stateDir = Join-Path $root '.demo-state'
New-Item -ItemType Directory -Force -Path $stateDir | Out-Null
$env:LLM_GATEWAY_HOME = $stateDir

$backend = if ($Mock) { 'mock' } else { 'browser' }
$base = "http://127.0.0.1:$Port"

Write-Host "== building ==" -ForegroundColor Cyan
cargo build --quiet
if ($LASTEXITCODE -ne 0) { throw 'cargo build failed' }
$exe = Join-Path $root 'target/debug/llm-gateway.exe'

Write-Host "== starting llm-gateway (backend: $backend, port: $Port) ==" -ForegroundColor Cyan
$server = Start-Process -FilePath $exe -ArgumentList @('serve', '--port', "$Port", '--backend', $backend) -PassThru -NoNewWindow

try {
    $health = $null
    foreach ($attempt in 1..60) {
        try {
            $health = Invoke-RestMethod -Uri "$base/health" -TimeoutSec 2
            break
        } catch {
            Start-Sleep -Milliseconds 500
        }
    }
    if (-not $health) { throw "the server did not become healthy on $base" }

    Write-Host "
== /health ==" -ForegroundColor Green
    $health | ConvertTo-Json -Depth 6

    Write-Host "
== /v1/models ==" -ForegroundColor Green
    (Invoke-RestMethod -Uri "$base/v1/models").data | ForEach-Object { "  " + $_.id }

    $payload = @{
        model    = $Provider
        messages = @(@{ role = 'user'; content = 'Say ok and nothing else.' })
    } | ConvertTo-Json -Depth 5

    Write-Host "
== POST /v1/chat/completions (non-streaming) ==" -ForegroundColor Green
    $answer = Invoke-RestMethod -Uri "$base/v1/chat/completions" -Method Post -Body $payload -ContentType 'application/json'
    "  id      : " + $answer.id
    "  model   : " + $answer.model
    "  answer  : " + $answer.choices[0].message.content
    "  usage   : prompt " + $answer.usage.prompt_tokens + ", completion " + $answer.usage.completion_tokens

    Write-Host "
== POST /v1/chat/completions (two completions) ==" -ForegroundColor Green
    $variantsPayload = @{
        model    = $Provider
        n        = 2
        messages = @(@{ role = 'user'; content = 'Answer with one word.' })
    } | ConvertTo-Json -Depth 5
    $variants = Invoke-RestMethod -Uri "$base/v1/chat/completions" -Method Post -Body $variantsPayload -ContentType 'application/json'
    "  choices : " + $variants.choices.Count
    $variants.choices | ForEach-Object { "  [" + $_.index + "] " + $_.message.content }
    if ($variants.x_gateway_warnings) { "  warning : " + $variants.x_gateway_warnings[0] }

    $accounts = ($health.providers | Where-Object { $_.name -eq $Provider }).accounts
    if ($accounts) {
        Write-Host "
== accounts of $Provider ==" -ForegroundColor Green
        $accounts | ForEach-Object {
            "  " + $_.id + "  " + $_.email + $(if ($_.default) { "  (default)" } else { "" })
        }
        $account = $accounts[0].id
        $accountPayload = @{
            model    = "$Provider@$account"
            messages = @(@{ role = 'user'; content = 'Say ok and nothing else.' })
        } | ConvertTo-Json -Depth 5
        $accounted = Invoke-RestMethod -Uri "$base/v1/chat/completions" -Method Post -Body $accountPayload -ContentType 'application/json'
        "  model $Provider@$account answered: " + $accounted.choices[0].message.content
    }

    Write-Host "
== POST /v1/chat/completions (streaming) ==" -ForegroundColor Green
    $streamPayload = @{
        model    = $Provider
        stream   = $true
        messages = @(@{ role = 'user'; content = 'Count from one to five.' })
    } | ConvertTo-Json -Depth 5
    $streamed = Invoke-WebRequest -Uri "$base/v1/chat/completions" -Method Post -Body $streamPayload -ContentType 'application/json'
    $streamed.Content -split "`n" | Select-Object -First 12 | ForEach-Object { "  " + $_ }
    "  ... ($((($streamed.Content -split "`n") | Measure-Object).Count) lines of SSE)"

    Write-Host "
== GET /v1/providers/$Provider/status ==" -ForegroundColor Green
    Invoke-RestMethod -Uri "$base/v1/providers/$Provider/status" | ConvertTo-Json -Depth 5

    Write-Host "
== POST /v1/providers/$Provider/validate ==" -ForegroundColor Green
    Invoke-RestMethod -Uri "$base/v1/providers/$Provider/validate" -Method Post | ConvertTo-Json -Depth 5

    Write-Host "
== POST /v1/admin/reload ==" -ForegroundColor Green
    Invoke-RestMethod -Uri "$base/v1/admin/reload" -Method Post | ConvertTo-Json -Depth 5

    Write-Host "
== dashboard ==" -ForegroundColor Green
    "  $base/dashboard"
    "  state directory: $stateDir"
}
finally {
    Write-Host "
== stopping the server ==" -ForegroundColor Cyan
    if ($server -and -not $server.HasExited) {
        Stop-Process -Id $server.Id -Force
        $server.WaitForExit(5000) | Out-Null
    }
    Pop-Location
}