$ErrorActionPreference = "Stop"

$BaseUrl = 'https://contact.robinmollah.com'
$ProfileText = ""
$SessionId = ""
$ClientToken = ""
$Cursor = 0
$Running = $true
$Transcript = New-Object System.Collections.Generic.List[string]
$TempDir = Join-Path ([System.IO.Path]::GetTempPath()) ("chat-with-robin-" + [guid]::NewGuid().ToString())

function Test-InteractiveConsole {
  try {
    $null = $Host.UI.RawUI
    return $true
  } catch {
    return $false
  }
}

function Append-Transcript([string]$Line) {
  $script:Transcript.Add($Line) | Out-Null
}

function Write-Banner {
  Write-Host @"
========================================
  ____   ___  ____ ___ _   _
 |  _ \ / _ \| __ )_ _| \ | |
 | |_) | | | |  _ \| ||  \| |
 |  _ <| |_| | |_) | || |\  |
 |_| \_\\___/|____/___|_| \_|

  __  __  ___  _     _        _   _
 |  \/  |/ _ \| |   | |      / \ | |
 | |\/| | | | | |   | |     / _ \| |
 | |  | | |_| | |___| |___ / ___ \ |
 |_|  |_|\___/|_____|_____/_/   \_\_|
========================================
"@
}

function Draw-Ui {
  Clear-Host
  Write-Banner
  Write-Host ""
  Write-Host "Direct terminal contact with Robin."
  Write-Host "Use :about if you want the full profile and links."
  Write-Host ""
  Write-Host "----------------------------------------"
  Write-Host " Conversation"
  Write-Host "----------------------------------------"

  if ($script:Transcript.Count -gt 0) {
    foreach ($line in $script:Transcript) {
      Write-Host $line
    }
  } else {
    Write-Host "No messages yet. Type something and press Enter."
  }

  Write-Host ""
  Write-Host "Commands: :help  :about  :clear  :quit"
  Write-Host ""
}

function Fetch-Profile {
  $script:ProfileText = Invoke-RestMethod -Uri "$BaseUrl/api/profile?format=text" -Method Get
}

function Create-Session([string]$Name) {
  $body = @{ name = $Name } | ConvertTo-Json -Compress
  $response = Invoke-RestMethod -Uri "$BaseUrl/api/session" -Method Post -ContentType "application/json" -Body $body
  $script:SessionId = [string]$response.sessionId
  $script:ClientToken = [string]$response.clientToken
  $script:Cursor = [int]$response.cursor
}

function Get-Headers {
  return @{
    Authorization = "Bearer $script:ClientToken"
  }
}

function Fetch-Events([int]$WaitFlag = 1) {
  $response = Invoke-RestMethod -Uri "$BaseUrl/api/session/$SessionId/events?cursor=$Cursor&wait=$WaitFlag" -Method Get -Headers (Get-Headers)

  foreach ($event in $response.events) {
    $timestamp = [string]$event.timestamp
    $text = [string]$event.text

    switch ([string]$event.kind) {
      "info" {
        Append-Transcript "[$timestamp] info: $text"
      }
      "visitor_message_ack" {
        Append-Transcript "[$timestamp] you: $text"
      }
      "robin_message" {
        Append-Transcript "[$timestamp] robin: $text"
      }
      "session_closed" {
        Append-Transcript "[$timestamp] session: $text"
        $script:Running = $false
      }
      default {
        Append-Transcript "[$timestamp] $([string]$event.kind): $text"
      }
    }
  }

  $script:Cursor = [int]$response.nextCursor
}

function Post-Message([string]$Text) {
  $body = @{ text = $Text } | ConvertTo-Json -Compress
  Invoke-RestMethod -Uri "$BaseUrl/api/session/$SessionId/message" -Method Post -ContentType "application/json" -Headers (Get-Headers) -Body $body | Out-Null
}

function Send-MessageWithProgress([string]$Text) {
  $job = Start-Job -ScriptBlock {
    param($Uri, $Token, $Payload)
    $headers = @{ Authorization = "Bearer $Token" }
    Invoke-RestMethod -Uri $Uri -Method Post -ContentType "application/json" -Headers $headers -Body $Payload | Out-Null
  } -ArgumentList "$BaseUrl/api/session/$SessionId/message", $script:ClientToken, (@{ text = $Text } | ConvertTo-Json -Compress)

  $percent = 10
  while ($job.State -eq "Running") {
    Write-Progress -Activity "Sending message" -Status "Contacting Robin" -PercentComplete $percent
    Start-Sleep -Milliseconds 120
    $percent += 8
    if ($percent -gt 90) {
      $percent = 25
    }
  }

  try {
    Receive-Job -Job $job -Wait -ErrorAction Stop | Out-Null
    Write-Progress -Activity "Sending message" -Completed
    return $true
  } catch {
    Write-Progress -Activity "Sending message" -Completed
    return $false
  } finally {
    Remove-Job -Job $job -Force -ErrorAction SilentlyContinue
  }
}

function Print-Help {
  Append-Transcript "[local] Commands:"
  Append-Transcript "[local]   :help   Show available commands"
  Append-Transcript "[local]   :about  Reprint profile information"
  Append-Transcript "[local]   :clear  Clear the transcript"
  Append-Transcript "[local]   :quit   Close this session"
}

function Handle-Line([string]$Line) {
  switch ($Line) {
    ":help" {
      Print-Help
    }
    ":about" {
      Append-Transcript "[local] Profile"
      foreach ($aboutLine in ($script:ProfileText -split "\r?\n")) {
        Append-Transcript "[local] $aboutLine"
      }
    }
    ":clear" {
      $script:Transcript.Clear()
    }
    ":quit" {
      $script:Running = $false
      Append-Transcript "[local] Closing session."
      Draw-Ui
    }
    "" {
    }
    default {
      if (Send-MessageWithProgress $Line) {
        Fetch-Events
      } else {
        Append-Transcript "[local] Failed to send message."
      }
    }
  }
}

function Main-Loop {
  while ($script:Running) {
    Fetch-Events 0
    Draw-Ui
    $line = Read-Host ">"
    Handle-Line $line.Trim()
  }
}

function Close-Session {
  if ($script:SessionId -and $script:ClientToken) {
    try {
      Invoke-RestMethod -Uri "$BaseUrl/api/session/$SessionId/close" -Method Post -Headers (Get-Headers) | Out-Null
    } catch {
    }
  }

  if (Test-Path $script:TempDir) {
    Remove-Item -Path $script:TempDir -Recurse -Force -ErrorAction SilentlyContinue
  }
}

function Bootstrap {
  if (-not (Test-InteractiveConsole)) {
    throw "This script needs an interactive PowerShell console."
  }

  New-Item -ItemType Directory -Path $script:TempDir -Force | Out-Null
  Fetch-Profile
  Draw-Ui

  $name = ""
  while ([string]::IsNullOrWhiteSpace($name)) {
    $name = Read-Host "Your name"
    $name = $name.Trim()
  }

  Create-Session $name
  Fetch-Events
  Draw-Ui
  Main-Loop
}

try {
  Bootstrap
} finally {
  Close-Session
  Write-Host ""
}