<?php

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

if (!function_exists('vacationSyncTableHasColumn')) {
    function vacationSyncTableHasColumn(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('vacationSyncEnsureSchema')) {
    function vacationSyncEnsureSchema(PDO $pdo): void
    {
        $urlaubExists = vacationSyncTableExists($pdo, 'urlaub');
        $companyHolidaysExists = vacationSyncTableExists($pdo, 'company_holidays');

        if (!$urlaubExists && !$companyHolidaysExists) {
            return;
        }

        if ($urlaubExists && !vacationSyncTableHasColumn($pdo, 'urlaub', 'company_holiday_id')) {
            $pdo->exec("ALTER TABLE urlaub ADD COLUMN company_holiday_id INT NULL AFTER vertreterurl");
        }

        if (!$companyHolidaysExists) {
            return;
        }

        if (!vacationSyncTableHasColumn($pdo, 'company_holidays', 'urlaub_id')) {
            $pdo->exec("ALTER TABLE company_holidays ADD COLUMN urlaub_id INT NULL AFTER created_by");
        }

        if (!vacationSyncTableHasColumn($pdo, 'company_holidays', 'vertretung')) {
            $pdo->exec("ALTER TABLE company_holidays ADD COLUMN vertretung VARCHAR(255) NOT NULL DEFAULT '' AFTER description");
        }

        if (!vacationSyncTableHasColumn($pdo, 'company_holidays', 'vertretertelefon')) {
            $pdo->exec("ALTER TABLE company_holidays ADD COLUMN vertretertelefon VARCHAR(255) NOT NULL DEFAULT '' AFTER vertretung");
        }

        if (!vacationSyncTableHasColumn($pdo, 'company_holidays', 'vertreteradresse')) {
            $pdo->exec("ALTER TABLE company_holidays ADD COLUMN vertreteradresse VARCHAR(1000) NOT NULL DEFAULT '' AFTER vertretertelefon");
        }

        if (!vacationSyncTableHasColumn($pdo, 'company_holidays', 'vertreterurl')) {
            $pdo->exec("ALTER TABLE company_holidays ADD COLUMN vertreterurl VARCHAR(255) NOT NULL DEFAULT '' AFTER vertreteradresse");
        }
    }
}

if (!function_exists('vacationSyncFindCompanyHolidayIdForUrlaub')) {
    function vacationSyncFindCompanyHolidayIdForUrlaub(PDO $pdo, int $urlaubId): int
    {
        if ($urlaubId <= 0) {
            return 0;
        }

        if (!vacationSyncTableExists($pdo, 'urlaub') || !vacationSyncTableExists($pdo, 'company_holidays')) {
            return 0;
        }

        vacationSyncEnsureSchema($pdo);

        $stmt = $pdo->prepare("SELECT company_holiday_id FROM urlaub WHERE urlaubid = :urlaub_id LIMIT 1");
        $stmt->execute(['urlaub_id' => $urlaubId]);
        $linkedId = (int)($stmt->fetchColumn() ?: 0);
        if ($linkedId > 0) {
            return $linkedId;
        }

        $stmt = $pdo->prepare("SELECT id FROM company_holidays WHERE urlaub_id = :urlaub_id LIMIT 1");
        $stmt->execute(['urlaub_id' => $urlaubId]);
        $linkedId = (int)($stmt->fetchColumn() ?: 0);
        if ($linkedId > 0) {
            return $linkedId;
        }

        $stmt = $pdo->prepare("SELECT start, ende FROM urlaub WHERE urlaubid = :urlaub_id LIMIT 1");
        $stmt->execute(['urlaub_id' => $urlaubId]);
        $urlaub = $stmt->fetch(PDO::FETCH_ASSOC);
        if (!$urlaub) {
            return 0;
        }

        $stmt = $pdo->prepare("
            SELECT id
            FROM company_holidays
            WHERE start_date = :start_date
              AND end_date = :end_date
            ORDER BY id ASC
            LIMIT 1
        ");
        $stmt->execute([
            'start_date' => $urlaub['start'],
            'end_date' => $urlaub['ende'],
        ]);
        return (int)($stmt->fetchColumn() ?: 0);
    }
}

if (!function_exists('vacationSyncFindUrlaubIdForCompanyHoliday')) {
    function vacationSyncFindUrlaubIdForCompanyHoliday(PDO $pdo, int $companyHolidayId): int
    {
        if ($companyHolidayId <= 0) {
            return 0;
        }

        if (!vacationSyncTableExists($pdo, 'urlaub') || !vacationSyncTableExists($pdo, 'company_holidays')) {
            return 0;
        }

        vacationSyncEnsureSchema($pdo);

        $stmt = $pdo->prepare("SELECT urlaub_id FROM company_holidays WHERE id = :company_holiday_id LIMIT 1");
        $stmt->execute(['company_holiday_id' => $companyHolidayId]);
        $linkedId = (int)($stmt->fetchColumn() ?: 0);
        if ($linkedId > 0) {
            return $linkedId;
        }

        $stmt = $pdo->prepare("SELECT urlaubid FROM urlaub WHERE company_holiday_id = :company_holiday_id LIMIT 1");
        $stmt->execute(['company_holiday_id' => $companyHolidayId]);
        $linkedId = (int)($stmt->fetchColumn() ?: 0);
        if ($linkedId > 0) {
            return $linkedId;
        }

        $stmt = $pdo->prepare("SELECT start_date, end_date FROM company_holidays WHERE id = :company_holiday_id LIMIT 1");
        $stmt->execute(['company_holiday_id' => $companyHolidayId]);
        $holiday = $stmt->fetch(PDO::FETCH_ASSOC);
        if (!$holiday) {
            return 0;
        }

        $stmt = $pdo->prepare("
            SELECT urlaubid
            FROM urlaub
            WHERE start = :start_date
              AND ende = :end_date
            ORDER BY urlaubid ASC
            LIMIT 1
        ");
        $stmt->execute([
            'start_date' => $holiday['start_date'],
            'end_date' => $holiday['end_date'],
        ]);
        return (int)($stmt->fetchColumn() ?: 0);
    }
}

if (!function_exists('vacationSyncCompanyHolidayFromUrlaub')) {
    function vacationSyncCompanyHolidayFromUrlaub(PDO $pdo, int $urlaubId, ?int $createdBy = null): int
    {
        if ($urlaubId <= 0) {
            return 0;
        }

        if (!vacationSyncTableExists($pdo, 'urlaub') || !vacationSyncTableExists($pdo, 'company_holidays')) {
            return 0;
        }

        vacationSyncEnsureSchema($pdo);

        $stmtUrlaub = $pdo->prepare("
            SELECT urlaubid, start, ende, vertretung, vertretertelefon, vertreteradresse, vertreterurl, company_holiday_id
            FROM urlaub
            WHERE urlaubid = :urlaub_id
            LIMIT 1
        ");
        $stmtUrlaub->execute(['urlaub_id' => $urlaubId]);
        $urlaub = $stmtUrlaub->fetch(PDO::FETCH_ASSOC);
        if (!$urlaub) {
            return 0;
        }

        $companyHolidayId = (int)($urlaub['company_holiday_id'] ?? 0);
        if ($companyHolidayId <= 0) {
            $companyHolidayId = vacationSyncFindCompanyHolidayIdForUrlaub($pdo, $urlaubId);
        }

        $description = 'Betriebsurlaub';
        if ($companyHolidayId > 0) {
            $stmtExisting = $pdo->prepare("SELECT description FROM company_holidays WHERE id = :company_holiday_id LIMIT 1");
            $stmtExisting->execute(['company_holiday_id' => $companyHolidayId]);
            $existingDescription = $stmtExisting->fetchColumn();
            if ($existingDescription !== false && trim((string)$existingDescription) !== '') {
                $description = (string)$existingDescription;
            }
        }

        if ($companyHolidayId > 0) {
            $stmtUpdate = $pdo->prepare("
                UPDATE company_holidays
                SET start_date = :start_date,
                    end_date = :end_date,
                    vertretung = :vertretung,
                    vertretertelefon = :vertretertelefon,
                    vertreteradresse = :vertreteradresse,
                    vertreterurl = :vertreterurl,
                    urlaub_id = :urlaub_id
                WHERE id = :company_holiday_id
            ");
            $stmtUpdate->execute([
                'start_date' => $urlaub['start'],
                'end_date' => $urlaub['ende'],
                'vertretung' => (string)$urlaub['vertretung'],
                'vertretertelefon' => (string)$urlaub['vertretertelefon'],
                'vertreteradresse' => (string)$urlaub['vertreteradresse'],
                'vertreterurl' => (string)$urlaub['vertreterurl'],
                'urlaub_id' => $urlaubId,
                'company_holiday_id' => $companyHolidayId,
            ]);
        } else {
            $stmtInsert = $pdo->prepare("
                INSERT INTO company_holidays (
                    start_date, end_date, description, vertretung, vertretertelefon, vertreteradresse, vertreterurl, created_by, urlaub_id
                )
                VALUES (
                    :start_date, :end_date, :description, :vertretung, :vertretertelefon, :vertreteradresse, :vertreterurl, :created_by, :urlaub_id
                )
            ");
            $stmtInsert->execute([
                'start_date' => $urlaub['start'],
                'end_date' => $urlaub['ende'],
                'description' => $description,
                'vertretung' => (string)$urlaub['vertretung'],
                'vertretertelefon' => (string)$urlaub['vertretertelefon'],
                'vertreteradresse' => (string)$urlaub['vertreteradresse'],
                'vertreterurl' => (string)$urlaub['vertreterurl'],
                'created_by' => $createdBy,
                'urlaub_id' => $urlaubId,
            ]);
            $companyHolidayId = (int)$pdo->lastInsertId();
        }

        if ($companyHolidayId > 0) {
            $stmtLink = $pdo->prepare("UPDATE urlaub SET company_holiday_id = :company_holiday_id WHERE urlaubid = :urlaub_id");
            $stmtLink->execute([
                'company_holiday_id' => $companyHolidayId,
                'urlaub_id' => $urlaubId,
            ]);
        }

        return $companyHolidayId;
    }
}

if (!function_exists('vacationSyncUrlaubFromCompanyHoliday')) {
    function vacationSyncUrlaubFromCompanyHoliday(PDO $pdo, int $companyHolidayId): int
    {
        if ($companyHolidayId <= 0) {
            return 0;
        }

        if (!vacationSyncTableExists($pdo, 'company_holidays') || !vacationSyncTableExists($pdo, 'urlaub')) {
            return 0;
        }

        vacationSyncEnsureSchema($pdo);

        $stmtHoliday = $pdo->prepare("
            SELECT id, start_date, end_date, vertretung, vertretertelefon, vertreteradresse, vertreterurl, urlaub_id
            FROM company_holidays
            WHERE id = :company_holiday_id
            LIMIT 1
        ");
        $stmtHoliday->execute(['company_holiday_id' => $companyHolidayId]);
        $holiday = $stmtHoliday->fetch(PDO::FETCH_ASSOC);
        if (!$holiday) {
            return 0;
        }

        $urlaubId = (int)($holiday['urlaub_id'] ?? 0);
        if ($urlaubId <= 0) {
            $urlaubId = vacationSyncFindUrlaubIdForCompanyHoliday($pdo, $companyHolidayId);
        }

        if ($urlaubId > 0) {
            $stmtUpdate = $pdo->prepare("
                UPDATE urlaub
                SET start = :start_date,
                    ende = :end_date,
                    vertretung = :vertretung,
                    vertretertelefon = :vertretertelefon,
                    vertreteradresse = :vertreteradresse,
                    vertreterurl = :vertreterurl,
                    company_holiday_id = :company_holiday_id
                WHERE urlaubid = :urlaub_id
            ");
            $stmtUpdate->execute([
                'start_date' => $holiday['start_date'],
                'end_date' => $holiday['end_date'],
                'vertretung' => (string)$holiday['vertretung'],
                'vertretertelefon' => (string)$holiday['vertretertelefon'],
                'vertreteradresse' => (string)$holiday['vertreteradresse'],
                'vertreterurl' => (string)$holiday['vertreterurl'],
                'company_holiday_id' => $companyHolidayId,
                'urlaub_id' => $urlaubId,
            ]);
        } else {
            $stmtInsert = $pdo->prepare("
                INSERT INTO urlaub
                    (vertretung, start, ende, vertretertelefon, vertreteradresse, vertreterurl, company_holiday_id)
                VALUES
                    (:vertretung, :start_date, :end_date, :vertretertelefon, :vertreteradresse, :vertreterurl, :company_holiday_id)
            ");
            $stmtInsert->execute([
                'vertretung' => (string)$holiday['vertretung'],
                'start_date' => $holiday['start_date'],
                'end_date' => $holiday['end_date'],
                'vertretertelefon' => (string)$holiday['vertretertelefon'],
                'vertreteradresse' => (string)$holiday['vertreteradresse'],
                'vertreterurl' => (string)$holiday['vertreterurl'],
                'company_holiday_id' => $companyHolidayId,
            ]);
            $urlaubId = (int)$pdo->lastInsertId();
        }

        if ($urlaubId > 0) {
            $stmtLink = $pdo->prepare("UPDATE company_holidays SET urlaub_id = :urlaub_id WHERE id = :company_holiday_id");
            $stmtLink->execute([
                'urlaub_id' => $urlaubId,
                'company_holiday_id' => $companyHolidayId,
            ]);
        }

        return $urlaubId;
    }
}

if (!function_exists('vacationSyncDeleteCompanyHolidayByUrlaub')) {
    function vacationSyncDeleteCompanyHolidayByUrlaub(PDO $pdo, int $urlaubId): void
    {
        if (!vacationSyncTableExists($pdo, 'urlaub') || !vacationSyncTableExists($pdo, 'company_holidays')) {
            return;
        }

        $companyHolidayId = vacationSyncFindCompanyHolidayIdForUrlaub($pdo, $urlaubId);
        if ($companyHolidayId <= 0) {
            return;
        }

        $stmt = $pdo->prepare("DELETE FROM company_holidays WHERE id = :company_holiday_id");
        $stmt->execute(['company_holiday_id' => $companyHolidayId]);
    }
}

if (!function_exists('vacationSyncDeleteUrlaubByCompanyHoliday')) {
    function vacationSyncDeleteUrlaubByCompanyHoliday(PDO $pdo, int $companyHolidayId): void
    {
        if (!vacationSyncTableExists($pdo, 'urlaub') || !vacationSyncTableExists($pdo, 'company_holidays')) {
            return;
        }

        $urlaubId = vacationSyncFindUrlaubIdForCompanyHoliday($pdo, $companyHolidayId);
        if ($urlaubId <= 0) {
            return;
        }

        $stmt = $pdo->prepare("DELETE FROM urlaub WHERE urlaubid = :urlaub_id");
        $stmt->execute(['urlaub_id' => $urlaubId]);
    }
}