chat.php

<?php
require 'db.php';

header('Content-Type: application/json');

$input = json_decode(file_get_contents('php://input'), true);
$message = trim($input['message']);
$model = $input['model'];

// Save user message
$stmt = $db->prepare("INSERT INTO messages (role, content, model) VALUES (?, ?, ?)");
$stmt->execute(['user', $message, $model]);

// Load API key
$env = parse_ini_file('.env');
$apiKey = $env['OPENAI_API_KEY'] ?? die(json_encode(['error' => 'API key not found']));

// Get full conversation
$stmt = $db->prepare("SELECT role, content FROM messages WHERE model = ? ORDER BY timestamp ASC");
$stmt->execute([$model]);
$conversation = $stmt->fetchAll(PDO::FETCH_ASSOC);

// Call OpenAI
$payload = [
    'model' => $model,
    'messages' => $conversation,
];

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

$response = curl_exec($ch);
curl_close($ch);

$data = json_decode($response, true);
$reply = $data['choices'][0]['message']['content'] ?? "No response.";

// Save assistant reply
$stmt = $db->prepare("INSERT INTO messages (role, content, model) VALUES (?, ?, ?)");
$stmt->execute(['assistant', $reply, $model]);

echo json_encode([
    'user' => $message,
    'assistant' => $reply
]);