<?php
// ============================================================================
// Dynamic ATS-Optimized CV Generator (Backend)
// ============================================================================

// Allow CORS from browser extension
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST, OPTIONS');
header('Access-Control-Allow-Headers: Content-Type');

if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(200);
    exit;
}

// Ensure composer dependencies are installed
$autoloadPath = __DIR__ . '/vendor/autoload.php';
if (!file_exists($autoloadPath)) {
    http_response_code(500);
    echo json_encode(["error" => "Vendor folder not found. Please run 'composer install' in the server directory."]);
    exit;
}

require_once $autoloadPath;
use Dompdf\Dompdf;
use Dompdf\Options;

// 1. Get POST Data
$rawData = file_get_contents('php://input');
$data = json_decode($rawData, true);

$jobDescription = $data['jobDescription'] ?? '';
$apiKey = $data['apiKey'] ?? '';

if (empty($jobDescription) || empty($apiKey)) {
    http_response_code(400);
    echo json_encode(["error" => "Missing jobDescription or apiKey in POST payload."]);
    exit;
}

// 2. Build Gemini API Request
$model = "gemini-2.5-flash";
$geminiUrl = "https://generativelanguage.googleapis.com/v1beta/models/{$model}:generateContent?key=" . $apiKey;

$prompt = "You are an expert ATS CV tailor. Read the following job description and generate tailored content for my CV to maximize my chances of getting an interview.
Return ONLY a valid JSON object with EXACTLY three keys: 'headline', 'summary', and 'skills'.
The 'headline' should be a 5-6 word professional title relevant to the job.
The 'summary' should be a 3-sentence powerful paragraph highlighting skills relevant to the job.
The 'skills' should be a comma-separated list of 10 highly relevant ATS keywords.
Do NOT use markdown blocks like ```json, just return raw JSON text.

Job Description:
" . substr($jobDescription, 0, 4000);

$payload = json_encode([
    "contents" => [
        ["parts" => [["text" => $prompt]]]
    ],
    "generationConfig" => [
        "temperature" => 0.2, // Low temperature for consistent JSON
        "responseMimeType" => "application/json" // Force JSON output
    ]
]);

// 3. Call Google Gemini via cURL
$ch = curl_init($geminiUrl);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
$response = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($httpCode !== 200) {
    http_response_code(500);
    echo json_encode(["error" => "Gemini API Error", "statusCode" => $httpCode, "details" => json_decode($response)]);
    exit;
}

// 4. Parse Gemini Response
$responseData = json_decode($response, true);
$aiText = $responseData['candidates'][0]['content']['parts'][0]['text'] ?? '{}';

// Clean markdown if Gemini still wrapped it in ```json ... ```
$aiText = str_replace(['```json', '```'], '', $aiText);
$aiText = trim($aiText);

$parsedJson = json_decode($aiText, true);

$headline = $parsedJson['headline'] ?? "Solutions Architect & Technical Leader";
$summary = $parsedJson['summary'] ?? "Experienced professional with a strong background in software engineering and system architecture.";
$skills = $parsedJson['skills'] ?? "Architecture, APIs, Cloud, Backend Systems, System Design";

// 5. Load HTML Template and Inject Data
// Note: Put cv_template.html in the same directory as this script on your server
$templatePath = __DIR__ . '/cv_template.html';
if (!file_exists($templatePath)) {
    http_response_code(500);
    echo json_encode(["error" => "cv_template.html not found on server."]);
    exit;
}

$html = file_get_contents($templatePath);
$html = str_replace('{{JOB_HEADLINE}}', htmlspecialchars($headline), $html);
$html = str_replace('{{TAILORED_SUMMARY}}', htmlspecialchars($summary), $html);
$html = str_replace('{{DYNAMIC_SKILLS}}', htmlspecialchars($skills), $html);

// 6. Generate PDF via Dompdf
try {
    $options = new Options();
    $options->set('isHtml5ParserEnabled', true);
    $options->set('defaultFont', 'Helvetica');
    $options->set('isRemoteEnabled', true);

    $dompdf = new Dompdf($options);
    $dompdf->loadHtml($html);
    $dompdf->setPaper('A4', 'portrait');
    $dompdf->render();

    // 7. Return PDF as Base64 encoded string to the frontend
    $pdfOutput = $dompdf->output();
    $base64Pdf = base64_encode($pdfOutput);

    echo json_encode([
        "success" => true,
        "pdf" => $base64Pdf,
        "filename" => "Hamza_Ayed_Tailored_CV.pdf"
    ]);

} catch (Exception $e) {
    http_response_code(500);
    echo json_encode(["error" => "PDF Generation Failed", "details" => $e->getMessage()]);
}