<?php
// ============================================================
// SURVAM — Export Handler
// ============================================================
require_once __DIR__ . '/../includes/config.php';
require_once __DIR__ . '/../includes/db.php';
require_once __DIR__ . '/../includes/auth.php';
require_once __DIR__ . '/../includes/functions.php';

requireLogin();
$user = currentUser();

$surveyId = (int)($_GET['id'] ?? 0);
$fmt      = strtolower($_GET['fmt'] ?? 'csv');

$survey = DB::row("SELECT * FROM surveys WHERE id=?", [$surveyId]);
if (!$survey || ($survey['user_id'] != $user['id'] && !in_array($user['role'], ['super_admin','manager']))) {
    die('Access denied.');
}

// Load questions in order
$questions = DB::all(
    "SELECT sq.* FROM survey_questions sq
     JOIN survey_pages sp ON sq.page_id = sp.id
     WHERE sq.survey_id=? ORDER BY sp.page_number, sq.order_num",
    [$surveyId]
);

// Load responses and answers
$responses = DB::all(
    "SELECT r.id, r.status, r.created_at, r.ip_address, r.device_type, r.time_taken_seconds
     FROM survey_responses r WHERE r.survey_id=? ORDER BY r.created_at DESC",
    [$surveyId]
);
$responseIds = array_column($responses, 'id');

$answers = [];
if ($responseIds) {
    $placeholders = implode(',', array_fill(0, count($responseIds), '?'));
    $rawAnswers = DB::all(
        "SELECT response_id, question_id, answer_text, answer_value, answer_json
         FROM survey_answers WHERE response_id IN ($placeholders) ORDER BY response_id, question_id",
        $responseIds
    );
    foreach ($rawAnswers as $a) {
        $val = $a['answer_json'] ? implode('; ', json_decode($a['answer_json'], true) ?? [])
             : ($a['answer_text'] ?? ($a['answer_value'] !== null ? (string)$a['answer_value'] : ''));
        $answers[$a['response_id']][$a['question_id']] = $val;
    }
}

// Build headers and rows
$headers = ['Response #', 'Submitted At', 'Status', 'Device', 'Time (sec)'];
foreach ($questions as $q) {
    if (in_array($q['type'], ['statement','section_break'])) continue;
    $headers[] = $q['title'];
}

$rows = [];
foreach ($responses as $ri => $resp) {
    $row = [
        $ri + 1,
        $resp['created_at'],
        $resp['status'],
        $resp['device_type'] ?? '',
        $resp['time_taken_seconds'] ?? '',
    ];
    foreach ($questions as $q) {
        if (in_array($q['type'], ['statement','section_break'])) continue;
        $row[] = $answers[$resp['id']][$q['id']] ?? '';
    }
    $rows[] = $row;
}

$safeName = preg_replace('/[^a-z0-9_-]/i', '_', $survey['title']);
$filename = 'survam_' . $safeName . '_' . date('Ymd_His');

switch ($fmt) {

    // ── CSV ───────────────────────────────────────────────────
    case 'csv':
        header('Content-Type: text/csv; charset=UTF-8');
        header("Content-Disposition: attachment; filename=\"$filename.csv\"");
        $out = fopen('php://output', 'w');
        // BOM for Excel UTF-8 compatibility
        fputs($out, "\xEF\xBB\xBF");
        fputcsv($out, $headers);
        foreach ($rows as $row) fputcsv($out, $row);
        fclose($out);
        exit;

    // ── JSON ──────────────────────────────────────────────────
    case 'json':
        header('Content-Type: application/json; charset=UTF-8');
        header("Content-Disposition: attachment; filename=\"$filename.json\"");
        $out = [];
        foreach ($responses as $ri => $resp) {
            $record = [
                'response_num' => $ri + 1,
                'submitted_at' => $resp['created_at'],
                'status'       => $resp['status'],
                'device'       => $resp['device_type'] ?? '',
                'time_seconds' => $resp['time_taken_seconds'],
                'answers'      => [],
            ];
            foreach ($questions as $q) {
                if (in_array($q['type'], ['statement','section_break'])) continue;
                $record['answers'][$q['id']] = [
                    'question' => $q['title'],
                    'type'     => $q['type'],
                    'answer'   => $answers[$resp['id']][$q['id']] ?? null,
                ];
            }
            $out[] = $record;
        }
        echo json_encode(['survey' => $survey['title'], 'exported_at' => date('c'), 'responses' => $out], JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);
        exit;

    // ── XLSX ──────────────────────────────────────────────────
    case 'xlsx':
        if (!file_exists(__DIR__ . '/../vendor/autoload.php')) {
            // Fallback to CSV if PhpSpreadsheet not available
            header('Content-Type: text/csv; charset=UTF-8');
            header("Content-Disposition: attachment; filename=\"$filename.csv\"");
            $out = fopen('php://output', 'w');
            fputs($out, "\xEF\xBB\xBF");
            fputcsv($out, $headers);
            foreach ($rows as $row) fputcsv($out, $row);
            fclose($out);
            exit;
        }
        require __DIR__ . '/../vendor/autoload.php';
        $spreadsheet = new \PhpOffice\PhpSpreadsheet\Spreadsheet();
        $sheet = $spreadsheet->getActiveSheet();
        $sheet->setTitle('Responses');
        // Header row
        foreach ($headers as $ci => $h) {
            $col = \PhpOffice\PhpSpreadsheet\Cell\Coordinate::stringFromColumnIndex($ci + 1);
            $sheet->setCellValue($col . '1', $h);
            $sheet->getStyle($col . '1')->getFont()->setBold(true);
            $sheet->getStyle($col . '1')->getFill()->setFillType(\PhpOffice\PhpSpreadsheet\Style\Fill::FILL_SOLID)->getStartColor()->setARGB('FF1A1A2E');
            $sheet->getStyle($col . '1')->getFont()->getColor()->setARGB('FFFFFFFF');
        }
        // Data rows
        foreach ($rows as $ri => $row) {
            foreach ($row as $ci => $val) {
                $col = \PhpOffice\PhpSpreadsheet\Cell\Coordinate::stringFromColumnIndex($ci + 1);
                $sheet->setCellValue($col . ($ri + 2), $val);
            }
        }
        foreach (range(1, count($headers)) as $ci) {
            $sheet->getColumnDimensionByColumn($ci)->setAutoSize(true);
        }
        $writer = new \PhpOffice\PhpSpreadsheet\Writer\Xlsx($spreadsheet);
        header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
        header("Content-Disposition: attachment; filename=\"$filename.xlsx\"");
        $writer->save('php://output');
        exit;

    // ── PDF ───────────────────────────────────────────────────
    case 'pdf':
        // Render to HTML then print - works without library
        $html = generatePDFHTML($survey, $headers, $rows, $filename);
        header('Content-Type: text/html; charset=UTF-8');
        echo $html;
        exit;

    // ── SPSS ─────────────────────────────────────────────────
    case 'spss':
        // Generate SAV-compatible syntax file (.sps)
        header('Content-Type: text/plain; charset=UTF-8');
        header("Content-Disposition: attachment; filename=\"$filename.sps\"");
        echo generateSPSSsyntax($survey, $questions, $responses, $answers);
        exit;

    default:
        http_response_code(400); die('Unknown format.');
}

function generatePDFHTML(array $survey, array $headers, array $rows, string $filename): string {
    $title = htmlspecialchars($survey['title']);
    $safeH = implode('</th><th>', array_map('htmlspecialchars', $headers));
    $rowsHTML = '';
    foreach ($rows as $row) {
        $cells = implode('</td><td>', array_map('htmlspecialchars', $row));
        $rowsHTML .= "<tr><td>$cells</td></tr>";
    }
    return "<!DOCTYPE html><html><head><meta charset='UTF-8'><title>$title</title>
    <style>
      body{font-family:'DM Sans',Arial,sans-serif;font-size:11px;margin:0;padding:1.5rem;}
      h1{font-size:16px;color:#1a1a2e;margin-bottom:.25rem;}
      .meta{font-size:10px;color:#9aa3b4;margin-bottom:1rem;}
      table{width:100%;border-collapse:collapse;}
      th{background:#1a1a2e;color:white;padding:.4rem .6rem;text-align:left;font-size:10px;}
      td{padding:.35rem .6rem;border-bottom:1px solid #e5e9f0;color:#5a6478;max-width:200px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;}
      tr:nth-child(even){background:#f8f9fc;}
      @page{margin:1.5cm;} @media print{.no-print{display:none;}}
    </style></head>
    <body>
    <div class='no-print' style='margin-bottom:1rem;'><button onclick='window.print()' style='padding:.5rem 1.2rem;background:#e94560;color:white;border:none;border-radius:6px;cursor:pointer;font-size:.9rem;'>🖨 Print / Save PDF</button></div>
    <h1>$title — Survey Responses</h1>
    <p class='meta'>Exported " . date('d M Y H:i') . " · " . count($rows) . " responses · SURVAM by Relevant Reflex Consulting</p>
    <table><thead><tr><th>$safeH</th></tr></thead><tbody>$rowsHTML</tbody></table>
    </body></html>";
}

function generateSPSSsyntax(array $survey, array $questions, array $responses, array $answers): string {
    $out  = "* SURVAM SPSS Export\n";
    $out .= "* Survey: " . $survey['title'] . "\n";
    $out .= "* Exported: " . date('Y-m-d H:i:s') . "\n\n";
    $out .= "DATA LIST FREE\n  /resp_num status device time_sec";
    foreach ($questions as $i => $q) {
        if (in_array($q['type'], ['statement','section_break'])) continue;
        $out .= " q{$i}";
    }
    $out .= " .\n\nBEGIN DATA.\n";
    foreach ($responses as $ri => $resp) {
        $out .= ($ri + 1) . " " . $resp['status'] . " " . ($resp['device_type'] ?? '') . " " . ($resp['time_taken_seconds'] ?? 0);
        foreach ($questions as $i => $q) {
            if (in_array($q['type'], ['statement','section_break'])) continue;
            $val = $answers[$resp['id']][$q['id']] ?? '';
            $val = str_replace(['"', "\n"], ['', ' '], $val);
            $out .= " \"$val\"";
        }
        $out .= "\n";
    }
    $out .= "END DATA.\n\nVARIABLE LABELS\n  resp_num 'Response Number'\n  status 'Response Status'\n  device 'Device Type'\n  time_sec 'Time Taken (seconds)'";
    foreach ($questions as $i => $q) {
        if (in_array($q['type'], ['statement','section_break'])) continue;
        $lbl = addslashes(substr($q['title'], 0, 120));
        $out .= "\n  q{$i} '$lbl'";
    }
    $out .= " .\n\nEXECUTE.\n";
    return $out;
}