<?php

declare(strict_types=1);

namespace App\Services\AI;

use App\Services\AI\Contracts\AIProviderInterface;
use Exception;

final class OpenAIProvider implements AIProviderInterface
{
    private string $apiKey;
    private string $model;

    public function __construct()
    {
        $this->apiKey = $_ENV['OPENAI_API_KEY'] ?? '';
        $this->model = $_ENV['OPENAI_MODEL'] ?? 'gpt-4o-mini';
    }

    public function isConfigured(): bool
    {
        return !empty($this->apiKey);
    }

    public function extractInvoiceData(string $fileContent, string $mimeType, string $prompt): array
    {
        if (!$this->isConfigured()) {
            throw new Exception("OpenAI API Key is missing. Please configure it in .env");
        }

        $base64Data = base64_encode($fileContent);
        
        $payload = [
            'model' => $this->model,
            'messages' => [
                [
                    'role' => 'user',
                    'content' => [
                        [
                            'type' => 'text',
                            'text' => $prompt
                        ],
                        [
                            'type' => 'image_url',
                            'image_url' => [
                                'url' => "data:{$mimeType};base64,{$base64Data}"
                            ]
                        ]
                    ]
                ]
            ],
            'response_format' => ['type' => 'json_object'],
            'temperature' => 0.1
        ];

        $ch = curl_init('https://api.openai.com/v1/chat/completions');
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            'Content-Type: application/json',
            "Authorization: Bearer {$this->apiKey}"
        ]);

        $response = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($httpCode !== 200) {
            throw new Exception("OpenAI Extraction failed. HTTP Code: {$httpCode}. Response: {$response}");
        }

        $result = json_decode($response, true);
        $text = $result['choices'][0]['message']['content'] ?? '{}';
        
        $data = json_decode($text, true);
        if (!is_array($data)) {
            throw new Exception("Failed to parse OpenAI output as JSON: {$text}");
        }

        return $data;
    }
}