<?php
session_start();
require_once(__DIR__ . '/../inc/config.inc.php');
require_once(__DIR__ . '/../inc/functions.inc.php');
require_once(__DIR__ . '/../inc/vacation_absence.inc.php');

ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
error_reporting(E_ALL);

if (!function_exists('vacationApiTableHasColumn')) {
    function vacationApiTableHasColumn(PDO $pdo, string $table, string $column): bool
    {
        $stmt = $pdo->prepare(
            "SELECT COUNT(*)
             FROM information_schema.COLUMNS
             WHERE TABLE_SCHEMA = DATABASE()
               AND TABLE_NAME = :table_name
               AND COLUMN_NAME = :column_name"
        );
        $stmt->execute([
            'table_name' => $table,
            'column_name' => $column,
        ]);
        return (int)$stmt->fetchColumn() > 0;
    }
}

if (!function_exists('vacationApiLower')) {
    function vacationApiLower(?string $value): string
    {
        $value = trim((string)$value);
        if ($value === '') {
            return '';
        }

        if (function_exists('mb_strtolower')) {
            return mb_strtolower($value, 'UTF-8');
        }

        return strtolower($value);
    }
}

if (!function_exists('vacationApiNormalizeAbsenceType')) {
    function vacationApiNormalizeAbsenceType(?string $type): string
    {
        $type = vacationApiLower($type);
        if ($type === '') {
            return vacationAbsenceDefaultReason();
        }

        $type = strtr($type, [
            'ä' => 'ae',
            'ö' => 'oe',
            'ü' => 'ue',
            'ß' => 'ss',
        ]);

        $type = preg_replace('/[^a-z0-9]+/u', '_', $type);
        $type = trim((string)$type, '_');

        $map = [
            'urlaub' => 'urlaub',
            'urlaubsantrag' => 'urlaub',
            'krankheit_mit_attest' => 'krankheit_mit_atest',
            'krankheit_mit_atest' => 'krankheit_mit_atest',
            'krank_mit_attest' => 'krankheit_mit_atest',
            'krankheit_ohne_attest' => 'krankheit_ohne_atest',
            'krankheit_ohne_atest' => 'krankheit_ohne_atest',
            'krank_ohne_attest' => 'krankheit_ohne_atest',
            'berufsschule' => 'berufsschule',
            'weiterbildung' => 'weiterbildung',
            'persoenliche_gruende' => 'persoenliche_gruende',
            'persoenliche_gruende_' => 'persoenliche_gruende',
            'persoenliche_gruende_mit' => 'persoenliche_gruende',
            'sonstiges' => 'sonstiges',
        ];

        return vacationAbsenceNormalizeReason($map[$type] ?? $type);
    }
}

if (!function_exists('vacationApiNormalizeStatus')) {
    function vacationApiNormalizeStatus(?string $status): string
    {
        $status = vacationApiLower($status);
        if ($status === '') {
            return 'beantragt';
        }

        $status = preg_replace('/\s+/u', ' ', $status);
        return $status;
    }
}

if (!function_exists('vacationApiTypeLabel')) {
    function vacationApiTypeLabel(string $type): string
    {
        return vacationAbsenceReasonLabel($type);
    }
}

if (!function_exists('vacationApiStatusLabel')) {
    function vacationApiStatusLabel(string $status): string
    {
        $labels = [
            'genehmigt' => 'Genehmigt',
            'beantragt' => 'Beantragt',
            'abgelehnt' => 'Abgelehnt',
        ];

        return $labels[$status] ?? ucfirst($status);
    }
}

if (!function_exists('vacationApiStatusColor')) {
    function vacationApiStatusColor(string $status): string
    {
        $colors = [
            'genehmigt' => '#28a745',
            'beantragt' => '#f0ad4e',
            'abgelehnt' => '#6c757d',
        ];

        return $colors[$status] ?? '#17a2b8';
    }
}

if (!function_exists('vacationApiTypeColor')) {
    function vacationApiTypeColor(string $type): string
    {
        $colors = [
            'urlaub' => '#2f9e44',
            'krankheit_mit_atest' => '#d9480f',
            'krankheit_ohne_atest' => '#c92a2a',
            'berufsschule' => '#1971c2',
            'weiterbildung' => '#5f3dc4',
            'persoenliche_gruende' => '#e67700',
            'sonstiges' => '#495057',
        ];

        return $colors[$type] ?? '#0d6efd';
    }
}

if (!function_exists('vacationApiRequestedTypes')) {
    function vacationApiRequestedTypes(?string $rawTypes, string $scope): ?array
    {
        $rawTypes = trim((string)$rawTypes);
        if ($rawTypes === '') {
            if ($scope === 'team') {
                return ['urlaub'];
            }

            return null;
        }

        $normalized = vacationApiLower($rawTypes);
        if (in_array($normalized, ['all', '*'], true)) {
            return null;
        }

        $types = [];
        foreach (preg_split('/\s*,\s*/', $rawTypes) as $rawType) {
            $normalizedType = vacationApiNormalizeAbsenceType($rawType);
            if ($normalizedType !== '') {
                $types[$normalizedType] = true;
            }
        }

        $types = array_keys($types);
        sort($types);

        return $types;
    }
}

if (!function_exists('vacationApiStatusAllowed')) {
    function vacationApiStatusAllowed(string $status, string $mode): bool
    {
        $mode = vacationApiLower($mode);
        $status = vacationApiNormalizeStatus($status);

        switch ($mode) {
            case 'approved':
                return $status === 'genehmigt';
            case 'open':
                return $status === 'beantragt' || $status === '';
            case 'active':
                return $status === 'genehmigt' || $status === 'beantragt' || $status === '';
            case 'rejected':
                return $status === 'abgelehnt';
            case 'all':
            default:
                return true;
        }
    }
}

$user = check_user();
$isAdmin = is_admin_user();

$start = trim((string)($_GET['start'] ?? ''));
$end = trim((string)($_GET['end'] ?? ''));

if ($start === '' || $end === '') {
    http_response_code(400);
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode(['error' => 'start and end required']);
    exit;
}

$onlyApproved = isset($_GET['only_approved']) && ($_GET['only_approved'] == '1' || $_GET['only_approved'] === 'true');
$public = isset($_GET['public']) && ($_GET['public'] == '1' || $_GET['public'] === 'true');
$includeRejected = isset($_GET['include_rejected']) && ($_GET['include_rejected'] == '1' || $_GET['include_rejected'] === 'true');
$onlyPersonal = isset($_GET['only_personal']) && ($_GET['only_personal'] == '1' || $_GET['only_personal'] === 'true');
$publicAll = isset($_GET['public_all']) && ($_GET['public_all'] == '1' || $_GET['public_all'] === 'true');

$scope = strtolower(trim((string)($_GET['scope'] ?? '')));
if ($scope === '') {
    if ($onlyPersonal) {
        $scope = 'personal';
    } elseif ($public || $publicAll) {
        $scope = 'team';
    } elseif ($isAdmin) {
        $scope = 'team';
    } else {
        $scope = 'personal';
    }
}

if (!in_array($scope, ['personal', 'team', 'admin_all'], true)) {
    $scope = 'personal';
}

if ($scope === 'admin_all' && !$isAdmin) {
    $scope = 'personal';
}

$statusMode = strtolower(trim((string)($_GET['status_filter'] ?? '')));
if ($statusMode === '') {
    if ($onlyApproved) {
        $statusMode = 'approved';
    } elseif ($includeRejected) {
        $statusMode = 'all';
    } elseif ($scope === 'personal' || $scope === 'admin_all') {
        $statusMode = 'all';
    } else {
        $statusMode = 'active';
    }
}

$includeCompany = !isset($_GET['include_company']) || $_GET['include_company'] === '1' || $_GET['include_company'] === 'true';
$requestedTypes = vacationApiRequestedTypes($_GET['absence_types'] ?? null, $scope);

$hasAbsenceReasonColumn = vacationApiTableHasColumn($pdo, 'vacations', 'absence_reason');
$absenceTypeSelect = $hasAbsenceReasonColumn ? 'v.absence_reason' : "'" . vacationAbsenceDefaultReason() . "'";

$selectColumns = "
    SELECT
        v.id,
        v.user_id,
        v.start_date,
        v.end_date,
        v.days,
        v.status,
        v.comment_user,
        u.vorname,
        u.nachname,
        {$absenceTypeSelect} AS absence_type
    FROM vacations v
    JOIN users u ON v.user_id = u.id
    WHERE v.start_date <= ?
      AND v.end_date >= ?
";

$params = [$end, $start];

if ($scope === 'personal') {
    $selectColumns .= " AND v.user_id = ?";
    $params[] = $_SESSION['userid'];
} elseif ($scope === 'team' || $scope === 'admin_all') {
    // No further restriction here. Scope filters are applied in PHP so
    // the query remains flexible for future admin and team views.
}

$selectColumns .= " ORDER BY v.start_date ASC, v.id ASC";

$stmt = $pdo->prepare($selectColumns);
$stmt->execute($params);
$vacations = $stmt->fetchAll(PDO::FETCH_ASSOC);

$events = [];

foreach ($vacations as $v) {
    $absenceType = vacationApiNormalizeAbsenceType($v['absence_type'] ?? '');
    $status = vacationApiNormalizeStatus($v['status'] ?? '');

    if ($scope === 'team' && $absenceType !== 'urlaub') {
        continue;
    }

    if ($requestedTypes !== null && !in_array($absenceType, $requestedTypes, true)) {
        continue;
    }

    if (!vacationApiStatusAllowed($status, $statusMode)) {
        continue;
    }

    $employeeName = trim((string)($v['vorname'] ?? '') . ' ' . (string)($v['nachname'] ?? ''));
    $typeLabel = vacationApiTypeLabel($absenceType);
    $statusLabel = vacationApiStatusLabel($status);

    if ($scope === 'personal') {
        $title = $typeLabel;
    } elseif ($employeeName !== '') {
        $title = $employeeName . ' - ' . $typeLabel;
    } else {
        $title = $typeLabel;
    }

    if ($status !== '' && $status !== 'genehmigt') {
        $title .= ' (' . $statusLabel . ')';
    }

    try {
        $endInclusive = (new DateTime($v['end_date']))->modify('+1 day')->format('Y-m-d');
    } catch (Exception $e) {
        $endInclusive = $v['start_date'];
    }

    $backgroundColor = vacationApiTypeColor($absenceType);
    if ($status === 'abgelehnt') {
        $backgroundColor = vacationApiStatusColor($status);
    }

    $events[] = [
        'id' => 'vac_' . $v['id'],
        'title' => $title,
        'start' => $v['start_date'],
        'end' => $endInclusive,
        'allDay' => true,
        'backgroundColor' => $backgroundColor,
        'borderColor' => $backgroundColor,
        'textColor' => '#ffffff',
        'extendedProps' => [
            'type' => 'user',
            'user_id' => $v['user_id'],
            'employee_name' => $employeeName,
            'absence_type' => $absenceType,
            'absence_label' => $typeLabel,
            'status' => $v['status'],
            'status_label' => $statusLabel,
            'comment' => $v['comment_user'] ?? '',
            'scope' => $scope,
        ],
    ];
}

if ($includeCompany) {
    $stmt = $pdo->prepare("SELECT id, start_date, end_date, description, vertretung, vertretertelefon, vertreteradresse, vertreterurl FROM company_holidays WHERE start_date <= ? AND end_date >= ? ORDER BY start_date");
    $stmt->execute([$end, $start]);
    $holidays = $stmt->fetchAll(PDO::FETCH_ASSOC);

    foreach ($holidays as $h) {
        try {
            $endInclusive = (new DateTime($h['end_date']))->modify('+1 day')->format('Y-m-d');
        } catch (Exception $e) {
            $endInclusive = $h['start_date'];
        }

        $description = trim((string)($h['description'] ?? ''));
        $title = $description !== '' ? $description : 'Betriebsurlaub';

        $events[] = [
            'id' => 'com_' . $h['id'],
            'title' => $title,
            'start' => $h['start_date'],
            'end' => $endInclusive,
            'allDay' => true,
            'backgroundColor' => '#0b7285',
            'borderColor' => '#0b7285',
            'textColor' => '#ffffff',
            'extendedProps' => [
                'type' => 'company',
                'description' => $description,
                'vertretung' => $h['vertretung'] ?? '',
                'vertretertelefon' => $h['vertretertelefon'] ?? '',
                'vertreteradresse' => $h['vertreteradresse'] ?? '',
                'vertreterurl' => $h['vertreterurl'] ?? '',
            ],
        ];
    }
}

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

$json = json_encode(
    $events,
    JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_INVALID_UTF8_SUBSTITUTE
);

if ($json === false) {
    http_response_code(500);
    echo json_encode([
        'error' => 'Kalenderdaten konnten nicht kodiert werden.',
        'json_error' => json_last_error_msg(),
    ], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

echo $json;
?>