<?php
require_once __DIR__ . '/../core/security.php';
require_once __DIR__ . '/../core/logger.php';
$pdo    = require __DIR__ . '/../core/db.php';
require_once __DIR__ . '/../models/Paste.php';
require_once __DIR__ . '/../models/Analytics.php';
$config = require __DIR__ . '/../config/config.php';

$logger    = new Logger('view');
$analytics = new Analytics($pdo);

$id = preg_replace('/[^a-f0-9]/i', '', $_GET['id'] ?? '');

if ($id === '') {
    $logger->warning('View request with invalid or missing paste ID', ['raw_id' => $_GET['id'] ?? '']);
    $analytics->record('paste_not_found', null, ['reason' => 'invalid_id']);
    $errorCode    = 404;
    $errorMessage = 'Invalid paste ID.';
    require __DIR__ . '/../../public/error.php';
    exit;
}

$paste = new Paste($pdo);
$data  = $paste->get($id);

if (!$data) {
    $logger->info('Paste not found', ['id' => $id]);
    $analytics->record('paste_not_found', $id);
    $errorCode    = 404;
    $errorMessage = 'Paste not found.';
    require __DIR__ . '/../../public/error.php';
    exit;
}

if ($data['expire_time'] !== null && time() > (int)$data['expire_time']) {
    $logger->info('Expired paste accessed', ['id' => $id, 'expired_at' => $data['expire_time']]);
    $analytics->record('paste_expired', $id, ['expired_at' => $data['expire_time']]);
    $errorCode    = 410;
    $errorMessage = 'This paste has expired.';
    require __DIR__ . '/../../public/error.php';
    exit;
}

$needsPassword = (bool)$data['password_hash'];
$wrongPassword = false;
$decrypted     = null;

if ($needsPassword) {
    $submitted = $_POST['password'] ?? null;
    if ($submitted !== null) {
        if (password_verify($submitted, $data['password_hash'])) {
            $needsPassword = false;
            $logger->info('Paste unlocked successfully', ['id' => $id]);
            $analytics->record('paste_unlocked', $id);
        } else {
            $wrongPassword = true;
            $logger->warning('Failed password attempt for paste', ['id' => $id]);
            $analytics->record('paste_failed_password', $id);
        }
    } else {
        $analytics->record('paste_password_prompt', $id);
    }
}

if (!$needsPassword) {
    $decrypted = decryptText($data['encrypted_text'], $data['iv'], $config['app']['master_key']);
    if ($decrypted === false) {
        $logger->error('Decryption failed for paste', ['id' => $id]);
        $analytics->record('paste_decrypt_error', $id);
        $errorCode    = 500;
        $errorMessage = 'Decryption failed. The paste may be corrupted.';
        require __DIR__ . '/../../public/error.php';
        exit;
    }

    $logger->info('Paste viewed', ['id' => $id, 'char_count' => mb_strlen($decrypted, 'UTF-8')]);
    $analytics->record('paste_viewed', $id, [
        'char_count'  => mb_strlen($decrypted, 'UTF-8'),
        'has_expiry'  => $data['expire_time'] !== null,
    ]);
}