portfoliowai/api/chat.php

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

// Start session for simple rate limiting
if (session_status() === PHP_SESSION_NONE) {
    session_start();
}

// Simple rate limiting: max 30 requests per minute
if (!isset($_SESSION['chat_requests'])) {
    $_SESSION['chat_requests'] = [];
}
$now = time();
// Keep only requests from the last 60 seconds
$_SESSION['chat_requests'] = array_filter($_SESSION['chat_requests'], function($timestamp) use ($now) {
    return ($now - $timestamp) < 60;
});
if (count($_SESSION['chat_requests']) >= 30) {
    http_response_code(429);
    echo json_encode(['error' => 'Too many requests. Please wait a minute before sending another message.']);
    exit;
}
$_SESSION['chat_requests'][] = $now;

// Load DB connection which also loads environment variables
require_once __DIR__ . '/../config/db.php';

$apiKey = getenv('GEMINI_API_KEY') ?: ($_ENV['GEMINI_API_KEY'] ?? '');
if (empty($apiKey)) {
    http_response_code(500);
    echo json_encode(['error' => 'API Key configuration is missing. Please configure GEMINI_API_KEY in your .env file.']);
    exit;
}

// Get the raw POST data
$inputData = json_decode(file_get_contents('php://input'), true);
if (!$inputData || !isset($inputData['message'])) {
    http_response_code(400);
    echo json_encode(['error' => 'Invalid request data.']);
    exit;
}

$userMessage = trim($inputData['message']);
if (empty($userMessage)) {
    http_response_code(400);
    echo json_encode(['error' => 'Message cannot be empty.']);
    exit;
}

// Fetch context data from database to construct system instructions
// 1. Settings / About
$settingsQuery = $mysqli->query("SELECT * FROM settings WHERE id = 1");
$settings = $settingsQuery ? $settingsQuery->fetch_assoc() : null;

// 2. Projects
$projectsQuery = $mysqli->query("SELECT title, des, techstack, url FROM projects");
$projects = [];
if ($projectsQuery) {
    while ($row = $projectsQuery->fetch_assoc()) {
        $projects[] = $row;
    }
}

// 3. Certifications
$certsQuery = $mysqli->query("SELECT title, issuer, date_issued FROM certifications");
$certs = [];
if ($certsQuery) {
    while ($row = $certsQuery->fetch_assoc()) {
        $certs[] = $row;
    }
}

// 4. Articles
$articlesQuery = $mysqli->query("SELECT title, excerpt, date_published, tag, url FROM articles");
$articles = [];
if ($articlesQuery) {
    while ($row = $articlesQuery->fetch_assoc()) {
        $articles[] = $row;
    }
}

// Build the System Instruction
$systemPrompt = "You are a friendly, professional, and intelligent AI assistant built into the personal portfolio website of Cris Charles Garcia.\n";
$systemPrompt .= "Your role is to represent Cris, assist recruiters, potential clients, and visitors, and answer questions about his background, experience, skills, and projects.\n\n";

$systemPrompt .= "Cris's Profile & Biography:\n";
if ($settings) {
    $systemPrompt .= "- Bio Paragraph 1: " . $settings['about_text_1'] . "\n";
    $systemPrompt .= "- Bio Paragraph 2: " . $settings['about_text_2'] . "\n";
    $systemPrompt .= "- Years coding: " . $settings['years_coding'] . "\n";
    $systemPrompt .= "- Projects completed: " . $settings['projects_count'] . "\n";
    $systemPrompt .= "- Certifications: " . $settings['certifications_count'] . "\n";
    $systemPrompt .= "- Github: " . $settings['github_url'] . "\n";
    $systemPrompt .= "- LinkedIn: " . $settings['linkedin_url'] . "\n";
    $systemPrompt .= "- Instagram: " . $settings['instagram_url'] . "\n";
    $systemPrompt .= "- Facebook: " . $settings['facebook_url'] . "\n";
    $systemPrompt .= "- TikTok: " . $settings['tiktok_url'] . "\n";
} else {
    $systemPrompt .= "- Cris is a senior IT student majoring in Software Development based in Laguna, Philippines.\n";
}

$systemPrompt .= "\nCris's Projects:\n";
foreach ($projects as $p) {
    $systemPrompt .= "- **" . $p['title'] . "**: " . $p['des'] . " (Tech: " . $p['techstack'] . "). Link: " . $p['url'] . "\n";
}

$systemPrompt .= "\nCris's Certifications:\n";
foreach ($certs as $c) {
    $systemPrompt .= "- " . $c['title'] . " by " . $c['issuer'] . " (Issued: " . $c['date_issued'] . ")\n";
}

$systemPrompt .= "\nCris's Latest Articles/Blog Posts:\n";
foreach ($articles as $a) {
    $systemPrompt .= "- \"" . $a['title'] . "\": " . $a['excerpt'] . " [Tag: " . $a['tag'] . ", Date: " . $a['date_published'] . ", Link: " . $a['url'] . "]\n";
}

$systemPrompt .= "\nGuidelines for your responses:\n";
$systemPrompt .= "1. Respond in first-person (e.g., \"I am a senior IT student...\" or \"In my project UniMarket...\") or as a dedicated assistant of Cris. Represent Cris accurately, warmly, and professionally.\n";
$systemPrompt .= "2. Keep responses brief, engaging, and directly related to the question. Recruiters appreciate concise answers.\n";
$systemPrompt .= "3. If asked about contact options or hiring, point them to his contact form at the bottom of the page or his professional links (Github, LinkedIn).\n";
$systemPrompt .= "4. Do not make up facts or external projects not listed in the context. If you don't know the answer, politely invite the user to contact Cris directly.\n";
$systemPrompt .= "5. Format your output using simple markdown (like bolding or bullet points) to make it readable.\n";

// Map chat history
$contents = [];
if (isset($inputData['history']) && is_array($inputData['history'])) {
    foreach ($inputData['history'] as $msg) {
        if (isset($msg['role']) && isset($msg['text'])) {
            $role = ($msg['role'] === 'user') ? 'user' : 'model';
            $contents[] = [
                'role' => $role,
                'parts' => [['text' => $msg['text']]]
            ];
        }
    }
}
// Add the current user message
$contents[] = [
    'role' => 'user',
    'parts' => [['text' => $userMessage]]
];

// Setup request body
$requestPayload = [
    'contents' => $contents,
    'systemInstruction' => [
        'parts' => [['text' => $systemPrompt]]
    ],
    'generationConfig' => [
        'temperature' => 0.7,
        'maxOutputTokens' => 800
    ]
];

// Call Gemini API via cURL
$url = "https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:generateContent?key=" . urlencode($apiKey);

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($requestPayload));
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);

if (curl_errno($ch)) {
    $errorMsg = curl_error($ch);
    curl_close($ch);
    http_response_code(500);
    echo json_encode(['error' => 'cURL error: ' . $errorMsg]);
    exit;
}
curl_close($ch);

if ($httpCode !== 200) {
    http_response_code($httpCode);
    $errorDetails = json_decode($response, true);
    $errMsg = isset($errorDetails['error']['message']) ? $errorDetails['error']['message'] : 'Failed to retrieve response from Gemini.';
    echo json_encode(['error' => $errMsg, 'raw' => $response]);
    exit;
}

$responseData = json_decode($response, true);
$reply = '';
if (isset($responseData['candidates'][0]['content']['parts'][0]['text'])) {
    $reply = $responseData['candidates'][0]['content']['parts'][0]['text'];
} else {
    http_response_code(502);
    echo json_encode(['error' => 'Invalid response structure from Gemini API.', 'raw' => $responseData]);
    exit;
}

echo json_encode(['reply' => $reply]);