<?php

namespace App\Services;

use InvalidArgumentException;
use RuntimeException;
use Throwable;

class LdapUserService
{
    private const USER_FILTER = '(&(objectCategory=person)(objectClass=user))';

    private const ATTRIBUTES = [
        'samaccountname',
        'displayname',
        'mail',
        'useraccountcontrol',
        'lastlogontimestamp',
        'memberof',
        'distinguishedname',
    ];

    private const UF_ACCOUNTDISABLE = 2;

    public function __construct(
        private readonly LdapConnection $ldap
    ) {
    }

    public function listUsers(string $sort, string $dir, string $search = '', string $groupFilter = ''): array
    {
        $connection = null;

        try {
            $connection = $this->ldap->bind();

            $result = @ldap_search(
                $connection,
                config('ldap.base_dn'),
                self::USER_FILTER,
                self::ATTRIBUTES
            );

            if ($result === false) {
                return $this->errorResult('LDAP search failed.');
            }

            $entries = ldap_get_entries($connection, $result);
            $rows = [];

            for ($i = 0; $i < ($entries['count'] ?? 0); $i++) {
                $row = $this->mapUserEntry($entries[$i]);

                if ($row !== null) {
                    $rows[] = $row;
                }
            }

            $allGroups = $this->collectGroupNames($rows);
            $rows = $this->filterAndSort($rows, $sort, $dir, $search, $groupFilter);

            return [
                'rows' => $rows,
                'meta' => array_merge($this->meta(), [
                    'total' => count($rows),
                    'all_groups' => $allGroups,
                ]),
                'error' => null,
            ];
        } catch (Throwable $e) {
            return $this->errorResult($e->getMessage() === 'LDAP bind failed.'
                ? 'LDAP bind failed. Check bind credentials.'
                : 'Unable to load LDAP users. Please check LDAP connectivity.');
        } finally {
            if ($connection !== null) {
                @ldap_unbind($connection);
            }
        }
    }

    public function getUser(string $username): array
    {
        $connection = null;

        try {
            $username = $this->ldap->validateUsername($username);
            $connection = $this->ldap->bind();
            $filter = '(sAMAccountName=' . ldap_escape($username, '', LDAP_ESCAPE_FILTER) . ')';
            $result = @ldap_search($connection, config('ldap.base_dn'), $filter, self::ATTRIBUTES);

            if ($result === false) {
                throw new InvalidArgumentException('LDAP search failed.');
            }

            $entries = ldap_get_entries($connection, $result);

            if (($entries['count'] ?? 0) < 1) {
                throw new InvalidArgumentException('User not found.');
            }

            $user = $this->mapUserEntry($entries[0]);

            if ($user === null) {
                throw new InvalidArgumentException('User not found.');
            }

            $user['protected'] = $this->isProtectedUser($username);

            return $user;
        } finally {
            if ($connection !== null) {
                @ldap_unbind($connection);
            }
        }
    }

    public function updateProfile(string $username, string $displayName, ?string $email): void
    {
        $this->ldap->assertUserWritable($username);
        $connection = null;

        try {
            $connection = $this->ldap->bind();
            $dn = $this->ldap->findUserDn($connection, $username);

            if (! @ldap_mod_replace($connection, $dn, ['displayName' => $displayName])) {
                throw new RuntimeException('Failed to update display name.');
            }

            if ($email !== null && $email !== '') {
                if (! @ldap_mod_replace($connection, $dn, ['mail' => $email])) {
                    throw new RuntimeException('Failed to update email.');
                }
            } else {
                @ldap_mod_del($connection, $dn, ['mail' => []]);
            }
        } finally {
            if ($connection !== null) {
                @ldap_unbind($connection);
            }
        }
    }

    public function setEnabled(string $username, bool $enabled): void
    {
        $this->ldap->assertUserWritable($username);
        $connection = null;

        try {
            $connection = $this->ldap->bind();
            $dn = $this->ldap->findUserDn($connection, $username);
            $result = @ldap_read($connection, $dn, '(objectClass=user)', ['useraccountcontrol']);

            if ($result === false) {
                throw new RuntimeException('Failed to read user status.');
            }

            $entries = ldap_get_entries($connection, $result);
            $uac = (int) ($this->ldap->attributeValue($entries[0] ?? [], 'useraccountcontrol') ?? 0);

            if ($enabled) {
                $uac &= ~self::UF_ACCOUNTDISABLE;
            } else {
                $uac |= self::UF_ACCOUNTDISABLE;
            }

            if (! @ldap_mod_replace($connection, $dn, ['userAccountControl' => (string) $uac])) {
                throw new RuntimeException('Failed to update account status.');
            }
        } finally {
            if ($connection !== null) {
                @ldap_unbind($connection);
            }
        }
    }

    public function resetPassword(string $username, string $password): void
    {
        $this->ldap->assertUserWritable($username);
        $connection = null;

        try {
            $connection = $this->ldap->bind(ssl: true);
            $dn = $this->ldap->findUserDn($connection, $username);
            $encoded = iconv('UTF-8', 'UTF-16LE', '"' . $password . '"');

            if ($encoded === false) {
                throw new InvalidArgumentException('Invalid password encoding.');
            }

            if (! @ldap_mod_replace($connection, $dn, ['unicodePwd' => $encoded])) {
                throw new RuntimeException('Password reset failed. Ensure LDAPS (port 636) is available and password meets AD policy.');
            }
        } finally {
            if ($connection !== null) {
                @ldap_unbind($connection);
            }
        }
    }

    public function isProtectedUser(string $username): bool
    {
        try {
            $this->ldap->assertUserWritable($username);

            return false;
        } catch (InvalidArgumentException) {
            return true;
        }
    }

    private function mapUserEntry(array $entry): ?array
    {
        $username = $this->ldap->attributeValue($entry, 'samaccountname');

        if ($username === null) {
            return null;
        }

        $uac = (int) ($this->ldap->attributeValue($entry, 'useraccountcontrol') ?? 0);
        $groups = $this->groupsList($entry);

        return [
            'username' => $username,
            'display_name' => $this->ldap->attributeValue($entry, 'displayname') ?? '—',
            'email' => $this->ldap->attributeValue($entry, 'mail') ?? '—',
            'enabled' => ! ($uac & self::UF_ACCOUNTDISABLE),
            'last_logon' => $this->filetimeToDate($this->ldap->attributeValue($entry, 'lastlogontimestamp')),
            'groups' => $groups,
            'groups_count' => count($groups),
            'protected' => $this->isProtectedUser($username),
        ];
    }

    private function groupsList(array $entry): array
    {
        if (! isset($entry['memberof']) || ! is_array($entry['memberof'])) {
            return [];
        }

        $groups = [];

        for ($i = 0; $i < ($entry['memberof']['count'] ?? 0); $i++) {
            $dn = $entry['memberof'][$i] ?? '';

            if (preg_match('/^CN=([^,]+)/i', $dn, $matches)) {
                $groups[] = $matches[1];
            }
        }

        sort($groups);

        return $groups;
    }

    private function collectGroupNames(array $rows): array
    {
        $groups = [];

        foreach ($rows as $row) {
            foreach ($row['groups'] as $group) {
                $groups[$group] = true;
            }
        }

        $names = array_keys($groups);
        sort($names, SORT_NATURAL | SORT_FLAG_CASE);

        return $names;
    }

    private function filterAndSort(array $rows, string $sort, string $dir, string $search, string $groupFilter = ''): array
    {
        if ($groupFilter !== '') {
            $rows = array_values(array_filter(
                $rows,
                fn (array $row) => in_array($groupFilter, $row['groups'], true)
            ));
        }

        if ($search !== '') {
            $needle = mb_strtolower($search);
            $rows = array_values(array_filter($rows, function (array $row) use ($needle) {
                if (str_contains(mb_strtolower($row['username']), $needle)
                    || str_contains(mb_strtolower($row['display_name']), $needle)
                    || str_contains(mb_strtolower($row['email']), $needle)) {
                    return true;
                }

                foreach ($row['groups'] as $group) {
                    if (str_contains(mb_strtolower($group), $needle)) {
                        return true;
                    }
                }

                return false;
            }));
        }

        usort($rows, function (array $a, array $b) use ($sort, $dir) {
            if ($sort === 'enabled') {
                $cmp = ($a['enabled'] ? 1 : 0) <=> ($b['enabled'] ? 1 : 0);
            } elseif ($sort === 'groups_count') {
                $cmp = $a['groups_count'] <=> $b['groups_count'];
            } elseif ($sort === 'groups') {
                $cmp = implode(', ', $a['groups']) <=> implode(', ', $b['groups']);
            } else {
                $cmp = ($a[$sort] ?? '') <=> ($b[$sort] ?? '');
            }

            return $dir === 'desc' ? -$cmp : $cmp;
        });

        return $rows;
    }

    private function filetimeToDate(?string $filetime): ?string
    {
        if ($filetime === null || $filetime === '' || $filetime === '0') {
            return null;
        }

        $unix = ((int) $filetime / 10000000) - 11644473600;

        if ($unix <= 0) {
            return null;
        }

        return gmdate('Y-m-d H:i:s', $unix);
    }

    private function meta(): array
    {
        return [
            'total' => 0,
            'server' => config('ldap.host'),
            'domain' => $this->ldap->domainFromBaseDn(),
        ];
    }

    private function errorResult(string $message): array
    {
        return [
            'rows' => [],
            'meta' => array_merge($this->meta(), ['total' => 0, 'all_groups' => []]),
            'error' => $message,
        ];
    }
}