<?php

declare(strict_types=1);

namespace App\Services\AI;

use App\Services\AI\Contracts\{AIProviderInterface, ExtractionResultDTO};
use GuzzleHttp\Client;
use Exception;

final class GeminiProvider implements AIProviderInterface
{
    private Client $client;
    private string $apiKey;
    private string $model;

    public function __construct()
    {
        $this->client = new Client();
        $this->apiKey = $_ENV['GEMINI_API_KEY'] ?? '';
        $this->model = $_ENV['GEMINI_MODEL'] ?? 'gemini-2.0-flash';
    }

    public function extractFromFile(string $filePath, string $mimeType): ExtractionResultDTO
    {
        $fileData = base64_encode(file_get_contents($filePath));
        
        $prompt = "Extract invoice data from this file. Return ONLY valid JSON (no markdown). " .
                 "Fields: invoice_number, invoice_date (YYYY-MM-DD), supplier_name, supplier_tin, supplier_address, " .
                 "buyer_name, buyer_tin, lines (description, quantity, unit_price, line_total, tax_rate), " .
                 "subtotal, tax_amount, grand_total, currency (JOD), confidence (0-1).";

        $response = $this->client->post("https://generativelanguage.googleapis.com/v1beta/models/{$this->model}:generateContent?key={$this->apiKey}", [
            'json' => [
                'contents' => [
                    [
                        'parts' => [
                            ['text' => $prompt],
                            [
                                'inline_data' => [
                                    'mime_type' => $mimeType,
                                    'data' => $fileData
                                ]
                            ]
                        ]
                    ]
                ],
                'generationConfig' => [
                    'response_mime_type' => 'application/json'
                ]
            ]
        ]);

        $data = json_decode($response->getBody()->getContents(), true);
        $jsonStr = $data['candidates'][0]['content']['parts'][0]['text'] ?? '{}';
        $result = json_decode($jsonStr, true);

        return new ExtractionResultDTO(
            $result['invoice_number'] ?? '',
            $result['invoice_date'] ?? '',
            $result['supplier_name'] ?? '',
            $result['supplier_tin'] ?? null,
            $result['supplier_address'] ?? '',
            $result['buyer_name'] ?? null,
            $result['buyer_tin'] ?? null,
            $result['lines'] ?? [],
            (float)($result['subtotal'] ?? 0),
            (float)($result['tax_amount'] ?? 0),
            (float)($result['grand_total'] ?? 0),
            $result['currency'] ?? 'JOD',
            (float)($result['confidence'] ?? 0),
            $data['usageMetadata'] ?? []
        );
    }

    public function getProviderName(): string { return 'gemini'; }
}