<?php
namespace Domain\Tasks;

class TaskTitleGenerator
{
  private const ENDPOINT = 'https://api.openai.com/v1/chat/completions';
  private const CONTENT_LIMIT = 3000;
  private const TITLE_LIMIT = 120;

  public function generate( $api_key, $model, $task_text )
  {
    $api_key = trim( (string)$api_key );
    $model = trim( (string)$model );
    $task_text = $this -> prepareTaskText( $task_text );

    if ( $api_key === '' )
      return $this -> error( 'Brak klucza API OpenAI.' );

    if ( $model === '' )
      $model = 'gpt-5-nano';

    if ( $task_text === '' )
      return $this -> error( 'Brak tresci zadania do wygenerowania tytulu.' );

    if ( !function_exists( 'curl_init' ) )
      return $this -> error( 'Brak rozszerzenia cURL.' );

    $payload = $this -> buildPayload( $model, $task_text );
    $response = $this -> sendRequest( $api_key, $payload );
    if ( $response['status'] !== 'success' )
      return $response;

    $title = $this -> extractTitle( $response['body'] );
    if ( $title === '' )
      return $this -> error( 'OpenAI nie zwrocil poprawnego tytulu.' );

    return [
      'status' => 'success',
      'title' => $title
    ];
  }

  private function buildPayload( $model, $task_text )
  {
    $payload = [
      'model' => $model,
      'messages' => [
        [
          'role' => 'system',
          'content' => 'Tworzysz bardzo krotkie, bezosobowe tytuly zadan w CRM. Odpowiadasz tylko tytulem, bez komentarza.'
        ],
        [
          'role' => 'user',
          'content' => "Na podstawie tresci zadania zaproponuj jeden skrocony tytul po polsku.\n" .
                       "Wymagania:\n" .
                       "- maksymalnie 6 slow,\n" .
                       "- forma bezosobowa rzeczownikowa, np. \"Usuniecie bloku o firmie\",\n" .
                       "- bez trybu rozkazujacego i bez form typu \"usun\", \"dodaj\", \"popraw\",\n" .
                       "- bez cudzyslowow,\n" .
                       "- bez kropki na koncu,\n" .
                       "- bez ogolnikow typu \"zadanie\" lub \"sprawa\".\n\n" .
                       "Tresc zadania:\n" . $task_text
        ]
      ]
    ];

    if ( stripos( $model, 'gpt-5' ) === 0 )
    {
      $payload['reasoning_effort'] = 'minimal';
      $payload['max_completion_tokens'] = 500;
    }
    else
    {
      $payload['temperature'] = 0.2;
      $payload['max_tokens'] = 80;
    }

    return $payload;
  }

  private function sendRequest( $api_key, array $payload )
  {
    $ch = curl_init( self::ENDPOINT );
    curl_setopt_array( $ch, [
      CURLOPT_RETURNTRANSFER => true,
      CURLOPT_POST => true,
      CURLOPT_POSTFIELDS => json_encode( $payload ),
      CURLOPT_HTTPHEADER => [
        'Content-Type: application/json',
        'Authorization: Bearer ' . $api_key
      ],
      CURLOPT_TIMEOUT => 20
    ] );

    $body = curl_exec( $ch );
    $curl_error = curl_error( $ch );
    $http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
    curl_close( $ch );

    if ( $body === false )
      return $this -> error( 'Blad polaczenia z OpenAI: ' . $curl_error );

    if ( (int)$http_code !== 200 )
      return $this -> error( 'OpenAI zwrocil blad HTTP ' . (int)$http_code . ': ' . $this -> extractApiErrorMessage( $body ) );

    if ( trim( (string)$body ) === '' )
      return $this -> error( 'Pusta odpowiedz z OpenAI.' );

    return [
      'status' => 'success',
      'body' => (string)$body
    ];
  }

  private function extractTitle( $response_body )
  {
    $data = json_decode( (string)$response_body, true );
    if ( !is_array( $data ) )
      return '';

    if ( isset( $data['error']['message'] ) )
      return '';

    $content = '';
    if ( isset( $data['choices'][0]['message']['content'] ) )
      $content = $this -> normalizeContent( $data['choices'][0]['message']['content'] );

    $content = trim( preg_replace( '/\s+/', ' ', $content ) );
    $content = trim( $content, " \t\n\r\0\x0B\"'`." );

    if ( $content === '' )
      return '';

    return mb_substr( $content, 0, self::TITLE_LIMIT );
  }

  private function normalizeContent( $content )
  {
    if ( is_string( $content ) )
      return $content;

    if ( !is_array( $content ) )
      return '';

    $parts = [];
    foreach ( $content as $item )
    {
      if ( is_string( $item ) )
        $parts[] = $item;
      elseif ( is_array( $item ) && isset( $item['text'] ) && is_string( $item['text'] ) )
        $parts[] = $item['text'];
      elseif ( is_array( $item ) && isset( $item['text']['value'] ) && is_string( $item['text']['value'] ) )
        $parts[] = $item['text']['value'];
    }

    return implode( ' ', $parts );
  }

  private function prepareTaskText( $task_text )
  {
    $task_text = html_entity_decode( (string)$task_text, ENT_QUOTES, 'UTF-8' );
    $task_text = preg_replace( '/<script\b[^>]*>.*?<\/script>/is', ' ', $task_text );
    $task_text = preg_replace( '/<style\b[^>]*>.*?<\/style>/is', ' ', $task_text );
    $task_text = strip_tags( $task_text );
    $task_text = preg_replace( '/\s+/', ' ', $task_text );
    $task_text = trim( $task_text );

    if ( $task_text === '' )
      return '';

    return mb_substr( $task_text, 0, self::CONTENT_LIMIT );
  }

  private function extractApiErrorMessage( $response_body )
  {
    $data = json_decode( (string)$response_body, true );
    if ( is_array( $data ) && isset( $data['error']['message'] ) )
      return (string)$data['error']['message'];

    return mb_substr( trim( (string)$response_body ), 0, 300 );
  }

  private function error( $message )
  {
    return [
      'status' => 'error',
      'msg' => (string)$message
    ];
  }
}