<?php
/**
 * Import Google Form API
 * POST ?action=importFromUrl   - Import survey structure from Google Form URL
 * POST ?action=importFromJson  - Import survey structure from JSON
 */

require_once __DIR__ . '/../config/database.php';
require_once __DIR__ . '/../config/auth.php';

header('Content-Type: application/json; charset=utf-8');
requireLogin();

$action = $_GET['action'] ?? '';

switch ($action) {
    case 'importFromUrl':
        importFromUrl();
        break;
    case 'importFromJson':
        importFromJson();
        break;
    default:
        jsonResponse(['error' => 'Invalid action'], 400);
}

function importFromUrl() {
    $input = json_decode(file_get_contents('php://input'), true);
    $url = trim($input['url'] ?? '');
    $projectId = !empty($input['project_id']) ? (int)$input['project_id'] : null;

    if (empty($url)) {
        jsonResponse(['error' => 'กรุณาระบุ URL หรือ Link ของ Google Form'], 400);
    }

    // Extract Form ID or viewform URL
    if (!preg_match('/docs\.google\.com\/forms\/d\/e?\/([^\/]+)/i', $url, $matches) && !preg_match('/docs\.google\.com\/forms\/d\/([^\/]+)/i', $url, $matches)) {
        jsonResponse(['error' => 'รูปแบบ URL ของ Google Form ไม่ถูกต้อง'], 400);
    }

    // Attempt to fetch the public viewform HTML
    $fetchUrl = $url;
    if (strpos($fetchUrl, '/viewform') === false && strpos($fetchUrl, '/edit') === false) {
        $fetchUrl = rtrim($fetchUrl, '/') . '/viewform';
    }

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $fetchUrl);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36');
    curl_setopt($ch, CURLOPT_TIMEOUT, 15);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    $html = curl_exec($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($httpCode !== 200 || empty($html)) {
        jsonResponse(['error' => 'ไม่สามารถดึงข้อมูลจาก Google Form URL นี้ได้ โปรดตรวจสอบว่าเปิดเป็นสาธารณะ (Public) หรือไม่'], 400);
    }

    // Parse FB_PUBLIC_LOAD_DATA_
    if (!preg_match('/FB_PUBLIC_LOAD_DATA_\s*=\s*(.+?);<\/script>/s', $html, $dataMatches)) {
        jsonResponse(['error' => 'ไม่พบโครงสร้างแบบสอบถามใน Google Form นี้'], 400);
    }

    $formData = json_decode($dataMatches[1], true);
    if (!$formData || !isset($formData[1])) {
        jsonResponse(['error' => 'โครงสร้างข้อมูล Google Form ไม่ถูกต้อง'], 400);
    }

    $parsedSurvey = parseGoogleFormData($formData);
    $surveyId = saveParsedSurveyToDB($parsedSurvey, $projectId);

    jsonResponse([
        'success' => true,
        'message' => 'นำเข้าโครงสร้างแบบสอบถามจาก Google Form เรียบร้อยแล้ว',
        'survey_id' => $surveyId,
        'title' => $parsedSurvey['title']
    ]);
}

function importFromJson() {
    $input = json_decode(file_get_contents('php://input'), true);
    $projectId = !empty($input['project_id']) ? (int)$input['project_id'] : null;
    $surveyData = $input['survey_data'] ?? null;

    if (!$surveyData || empty($surveyData['title'])) {
        jsonResponse(['error' => 'ข้อมูล JSON ไม่ถูกต้อง หรือขาดชื่อแบบสอบถาม'], 400);
    }

    $surveyId = saveParsedSurveyToDB($surveyData, $projectId);

    jsonResponse([
        'success' => true,
        'message' => 'นำเข้าแบบสอบถามเรียบร้อยแล้ว',
        'survey_id' => $surveyId,
        'title' => $surveyData['title']
    ]);
}

/**
 * Helper: Parse Google Forms FB_PUBLIC_LOAD_DATA_ structure
 */
function parseGoogleFormData($data) {
    $title = $data[1][8] ?? $data[1][1] ?? $data[3] ?? 'แบบสอบถามจาก Google Forms';
    $description = $data[1][0] ?? '';
    
    $rawItems = $data[1][1] ?? [];
    
    $sections = [];
    $currentSection = [
        'section_number' => 1,
        'title' => 'ส่วนที่ 1 ข้อมูลทั่วไป',
        'description' => '',
        'category' => 'general',
        'questions' => []
    ];

    $sectionCount = 1;

    foreach ($rawItems as $item) {
        if (!is_array($item)) continue;

        $qTitle = $item[1] ?? '';
        $qDesc = $item[2] ?? '';
        $qTypeNum = $item[3] ?? 0;
        $qDetails = $item[4][0] ?? [];

        if (empty($qTitle) && $qTypeNum != 8) continue; // Skip empty items except section breaks

        // Type 8 = Section Break in Google Forms
        if ($qTypeNum == 8) {
            if (!empty($currentSection['questions'])) {
                $sections[] = $currentSection;
            }
            $sectionCount++;
            $currentSection = [
                'section_number' => $sectionCount,
                'title' => $qTitle ?: ('ส่วนที่ ' . $sectionCount),
                'description' => $qDesc,
                'category' => 'rating',
                'questions' => []
            ];
            continue;
        }

        $qType = 'radio';
        $options = [];
        $scaleMin = 1;
        $scaleMax = 5;

        // Map Google Forms Item Type numbers:
        // 0: Short Text, 1: Paragraph
        // 2: Radio (Multiple Choice), 3: Dropdown, 4: Checkbox
        // 5: Linear Scale (1-5)
        // 7: Grid / Matrix
        switch ($qTypeNum) {
            case 0:
            case 1:
                $qType = 'text';
                break;
            case 2:
                $qType = 'radio';
                if (isset($qDetails[1]) && is_array($qDetails[1])) {
                    foreach ($qDetails[1] as $opt) {
                        if (isset($opt[0])) $options[] = $opt[0];
                    }
                }
                break;
            case 3:
                $qType = 'dropdown';
                if (isset($qDetails[1]) && is_array($qDetails[1])) {
                    foreach ($qDetails[1] as $opt) {
                        if (isset($opt[0])) $options[] = $opt[0];
                    }
                }
                break;
            case 4:
                $qType = 'checkbox';
                if (isset($qDetails[1]) && is_array($qDetails[1])) {
                    foreach ($qDetails[1] as $opt) {
                        if (isset($opt[0])) $options[] = $opt[0];
                    }
                }
                break;
            case 5:
                $qType = 'radio'; // Rating Scale
                $scaleMin = 1;
                $scaleMax = 5;
                break;
            default:
                $qType = 'text';
                break;
        }

        $isRequired = isset($qDetails[2]) && $qDetails[2] == 1 ? 1 : 0;

        $questionObj = [
            'question_text' => $qTitle,
            'question_type' => $qType,
            'is_required' => $isRequired,
            'description' => $qDesc,
            'options' => count($options) > 0 ? $options : null,
            'scale_min' => $scaleMin,
            'scale_max' => $scaleMax
        ];

        $currentSection['questions'][] = $questionObj;
    }

    if (!empty($currentSection['questions'])) {
        $sections[] = $currentSection;
    }

    if (empty($sections)) {
        $sections[] = [
            'section_number' => 1,
            'title' => 'ส่วนที่ 1 ข้อมูลและข้อคำถาม',
            'description' => 'นำเข้าจาก Google Forms',
            'category' => 'general',
            'questions' => []
        ];
    }

    return [
        'title' => $title,
        'description' => $description ?: 'แบบสอบถามที่นำเข้าจาก Google Forms',
        'sections' => $sections
    ];
}

/**
 * Save parsed survey structure into database
 */
function saveParsedSurveyToDB($parsedSurvey, $projectId = null) {
    $db = getDB();
    $uniqueLink = bin2hex(random_bytes(16));

    $db->beginTransaction();
    try {
        $stmt = $db->prepare("INSERT INTO surveys (user_id, project_id, title, description, unique_link, status) VALUES (?, ?, ?, ?, ?, 'active')");
        $stmt->execute([
            $_SESSION['user_id'],
            $projectId,
            $parsedSurvey['title'],
            $parsedSurvey['description'] ?? '',
            $uniqueLink
        ]);
        $surveyId = $db->lastInsertId();

        $sections = $parsedSurvey['sections'] ?? [];
        $secNum = 1;

        foreach ($sections as $sec) {
            $stmt = $db->prepare("INSERT INTO survey_sections (survey_id, section_number, title, description, category) VALUES (?, ?, ?, ?, ?)");
            $stmt->execute([
                $surveyId,
                $sec['section_number'] ?? $secNum,
                $sec['title'] ?? ('ส่วนที่ ' . $secNum),
                $sec['description'] ?? '',
                $sec['category'] ?? 'rating'
            ]);
            $sectionId = $db->lastInsertId();

            $orderNum = 1;
            foreach ($sec['questions'] as $q) {
                $optionsJson = !empty($q['options']) ? json_encode($q['options'], JSON_UNESCAPED_UNICODE) : null;
                $stmtQ = $db->prepare("INSERT INTO survey_questions (section_id, question_text, question_type, is_required, order_num, options, scale_min, scale_max, description) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)");
                $stmtQ->execute([
                    $sectionId,
                    $q['question_text'],
                    $q['question_type'] ?? 'radio',
                    $q['is_required'] ?? 1,
                    $orderNum++,
                    $optionsJson,
                    $q['scale_min'] ?? 1,
                    $q['scale_max'] ?? 5,
                    $q['description'] ?? null
                ]);
            }
            $secNum++;
        }

        $db->commit();
        return $surveyId;
    } catch (Exception $e) {
        $db->rollBack();
        jsonResponse(['error' => 'เกิดข้อผิดพลาดในการบันทึกแบบสอบถาม: ' . $e->getMessage()], 500);
    }
}