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

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;
}

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

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

// Path to the .env file located outside the document root for security
// Assuming script is in /home/user/htdocs/domain.com/cv/server/
// and .env is in /home/user/
$envPath = realpath(__DIR__ . '/../../../..');

if ($envPath && file_exists($envPath . '/.env')) {
    $dotenv = Dotenv::createImmutable($envPath);
    $dotenv->load();
}

$rawData = file_get_contents('php://input');
$data = json_decode($rawData, true);

$action = $data['action'] ?? 'generateText';

// Prioritize API key from .env over frontend payload
$apiKey = $_ENV['GEMINI_API_KEY'] ?? getenv('GEMINI_API_KEY') ?: ($data['apiKey'] ?? '');

if (empty($apiKey)) {
    http_response_code(400);
    echo json_encode(["error" => "Missing apiKey. Please set GEMINI_API_KEY in .env or pass it in request."]);
    exit;
}

$model = "gemini-flash-lite-latest";
// $model = "gemini-2.5-flash";
$geminiUrl = "https://generativelanguage.googleapis.com/v1beta/models/{$model}:generateContent?key=" . $apiKey;

// ==========================================
// ACTION 1: Generate ATS PDF CV
// ==========================================
if ($action === 'generatePdf') {
    $jobDescription = $data['jobDescription'] ?? '';
    
    $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, "responseMimeType" => "application/json"]
    ]);

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

    $responseData = json_decode($response, true);
    $aiText = $responseData['candidates'][0]['content']['parts'][0]['text'] ?? '{}';
    $aiText = str_replace(['```json', '```'], '', $aiText);
    $parsedJson = json_decode(trim($aiText), true);

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

    $templatePath = __DIR__ . '/cv_template.html';
    $html = file_get_contents($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);

    try {
        $options = new Options();
        $options->set('isHtml5ParserEnabled', true);
        $options->set('defaultFont', 'Helvetica');
        $dompdf = new Dompdf($options);
        $dompdf->loadHtml($html);
        $dompdf->setPaper('A4', 'portrait');
        $dompdf->render();

        $pdfOutput = $dompdf->output();
        $rawJobTitle = $data['jobTitle'] ?? 'Job';
        $safeJobTitle = preg_replace('/[^a-zA-Z0-9\-_]/', '_', $rawJobTitle);
        $safeJobTitle = trim($safeJobTitle, '_');
        $fileName = "Hamza_Ayed - {$safeJobTitle}.pdf";

        echo json_encode([
            "success" => true,
            "pdf" => base64_encode($pdfOutput),
            "filename" => $fileName
        ]);
    } catch (Exception $e) {
        http_response_code(500);
        echo json_encode(["error" => "PDF Generation Failed", "details" => $e->getMessage()]);
    }
    exit;
}

// ==========================================
// ACTION 2: Standard Proxy (Text generation)
// ==========================================
if ($action === 'generateText') {
    $prompt = $data['prompt'] ?? '';
    
    $payload = json_encode([
        "contents" => [["parts" => [["text" => $prompt]]]],
        "generationConfig" => ["temperature" => 0.7, "maxOutputTokens" => 8192]
    ]);

    $ch = curl_init($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 ($httpCode !== 200) {
        http_response_code($httpCode);
        echo $response;
        exit;
    }

    // Pass the exact Gemini response back to the extension
    echo $response;
    exit;
}