<?php

namespace App\Services;

class GeminiService
{
    /**
     * Call Gemini API to generate a response
     */
    public static function generateResponse(string $apiKey, string $systemPrompt, string $userMessage): ?string
    {
        $url = 'https://generativelanguage.googleapis.com/v1beta/models/gemini-flash-lite-latest:generateContent?key=' . $apiKey;

        $payload = json_encode([
            'contents' => [
                [
                    'role' => 'user',
                    'parts' => [
                        ['text' => $userMessage]
                    ]
                ]
            ],
            'systemInstruction' => [
                'parts' => [
                    ['text' => $systemPrompt]
                ]
            ]
        ]);

        $ch = curl_init($url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            'Content-Type: application/json'
        ]);
        curl_setopt($ch, CURLOPT_TIMEOUT, 15);

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

        if ($httpCode !== 200) {
            error_log("[Gemini API Error] HTTP " . $httpCode . " | Response: " . $response);
            return null;
        }

        $data = json_decode($response, true);
        return $data['candidates'][0]['content']['parts'][0]['text'] ?? null;
    }
}