<?php

namespace App\Services;

use App\Models\ConfigurationModel;
use App\Models\StaffModel;
use App\Models\UserModel;
use CodeIgniter\Database\BaseConnection;

final class StaffDirectorySyncService
{
    private const WORK_EMAIL_DOMAIN = '@alrahmaisgl.org';

    public function __construct(
        private readonly StaffModel $staffModel,
        private readonly UserModel $userModel,
        private readonly ConfigurationModel $configurationModel,
        private readonly BaseConnection $db,
    ) {
    }

    public function syncAll(): void
    {
        $rows = $this->db->table('users')
            ->select('id')
            ->get()
            ->getResultArray();

        foreach ($rows as $row) {
            $userId = (int) ($row['id'] ?? 0);
            if ($userId > 0) {
                $this->syncUser($userId);
            }
        }
    }

    public function syncUser(int $userId): void
    {
        if ($userId <= 0) {
            return;
        }

        $user = $this->userModel->find($userId);
        if (! $user) {
            return;
        }

        $roles = $this->rolesForUser($userId);
        $staffRoles = array_values(array_filter($roles, static function (array $role): bool {
            return strtolower((string) ($role['name'] ?? '')) !== 'parent';
        }));

        $now = utc_now();
        $schoolYear = (string) ($this->configurationModel->getConfig('school_year') ?? '');
        $roleNames = array_values(array_unique(array_map(
            static fn (array $role): string => strtolower((string) ($role['name'] ?? '')),
            $roles
        )));

        $activeRole = ! empty($staffRoles)
            ? strtolower((string) ($staffRoles[0]['name'] ?? ''))
            : 'inactive';

        $this->staffModel->upsert([
            'user_id'     => $userId,
            'firstname'   => (string) ($user['firstname'] ?? ''),
            'lastname'    => (string) ($user['lastname'] ?? ''),
            'email'       => $this->generateUniqueStaffEmail(
                (string) ($user['firstname'] ?? ''),
                (string) ($user['lastname'] ?? ''),
                $userId
            ),
            'phone'       => (string) ($user['cellphone'] ?? ''),
            'role_name'   => implode(', ', $roleNames),
            'active_role' => $activeRole,
            'school_year' => $schoolYear,
            'updated_at'  => $now,
        ]);
    }

    public function activeStaffForSchoolYear(string $schoolYear): array
    {
        $this->syncAll();

        $staffRows = $this->db->table('users u')
            ->select([
                'u.id AS user_id',
                'u.school_id',
                'u.firstname',
                'u.lastname',
                'u.email AS personal_email',
                'u.cellphone',
                's.id AS staff_id',
                's.email AS work_email',
                's.active_role',
                's.role_name',
                "GROUP_CONCAT(DISTINCT r.name ORDER BY COALESCE(r.priority, 999), r.name SEPARATOR ', ') AS roles",
            ])
            ->join('user_roles ur', 'ur.user_id = u.id', 'inner')
            ->join('roles r', 'r.id = ur.role_id', 'inner')
            ->join('staff s', 's.user_id = u.id', 'left')
            ->where("LOWER(r.name) != 'parent'", null, false)
            ->where('COALESCE(r.is_active, 1) = 1', null, false);

        if ($this->hasField('user_roles', 'deleted_at')) {
            $staffRows->where('ur.deleted_at', null);
        }

        $rows = $staffRows
            ->groupBy('u.id, u.school_id, u.firstname, u.lastname, u.email, u.cellphone, s.id, s.email, s.active_role, s.role_name')
            ->orderBy('u.lastname', 'ASC')
            ->orderBy('u.firstname', 'ASC')
            ->get()
            ->getResultArray();

        $assignments = $this->assignmentsByTeacher($schoolYear);
        $issuesCount = 0;

        foreach ($rows as &$row) {
            $userId = (int) ($row['user_id'] ?? 0);
            $activeRole = strtolower((string) ($row['active_role'] ?? ''));
            $roleText = strtolower((string) ($row['roles'] ?? ''));
            $isTeacher = in_array($activeRole, ['teacher', 'teacher_assistant'], true)
                || str_contains($roleText, 'teacher')
                || preg_match('/(^|, )ta($|,)/', $roleText);

            $labels = $assignments[$userId] ?? [];
            if ($isTeacher) {
                if ($labels !== []) {
                    $row['class_section'] = implode(', ', array_unique($labels));
                    $row['verification_issue'] = false;
                } else {
                    $row['class_section'] = 'No class assigned';
                    $row['verification_issue'] = true;
                    $issuesCount++;
                }
            } else {
                $row['class_section'] = '-';
                $row['verification_issue'] = false;
            }
        }
        unset($row);

        return [
            'staff' => $rows,
            'issues_count' => $issuesCount,
        ];
    }

    private function rolesForUser(int $userId): array
    {
        $builder = $this->db->table('user_roles ur')
            ->select('r.name, r.priority')
            ->join('roles r', 'r.id = ur.role_id', 'inner')
            ->where('ur.user_id', $userId)
            ->where('COALESCE(r.is_active, 1) = 1', null, false)
            ->orderBy('COALESCE(r.priority, 999)', 'ASC', false)
            ->orderBy('r.name', 'ASC');

        if ($this->hasField('user_roles', 'deleted_at')) {
            $builder->where('ur.deleted_at', null);
        }

        return $builder->get()->getResultArray();
    }

    private function assignmentsByTeacher(string $schoolYear): array
    {
        if ($schoolYear === '' || ! $this->db->tableExists('teacher_class')) {
            return [];
        }

        $rows = $this->db->table('teacher_class tc')
            ->select('tc.teacher_id, tc.position, cs.class_section_name')
            ->join('classSection cs', 'cs.class_section_id = tc.class_section_id', 'left')
            ->where('tc.school_year', $schoolYear)
            ->get()
            ->getResultArray();

        $assignments = [];
        foreach ($rows as $row) {
            $teacherId = (int) ($row['teacher_id'] ?? 0);
            $name = trim((string) ($row['class_section_name'] ?? ''));
            $position = strtolower((string) ($row['position'] ?? ''));

            if ($teacherId <= 0 || $name === '' || ! in_array($position, ['main', 'ta'], true)) {
                continue;
            }

            $assignments[$teacherId][] = $name . ' (' . $position . ')';
        }

        return $assignments;
    }

    private function generateUniqueStaffEmail(string $firstname, string $lastname, int $userId): string
    {
        $first = strtolower((string) preg_replace('/[^a-z]/i', '', $firstname));
        $last = strtolower((string) preg_replace('/[^a-z]/i', '', $lastname));

        if ($last === '') {
            $last = 'user' . $userId;
        }

        $base = $last;
        $max = max(1, strlen($first));
        for ($i = 1; $i <= $max; $i++) {
            $base = substr($first, 0, $i) . $last;
            $email = $base . self::WORK_EMAIL_DOMAIN;

            $exists = $this->staffModel
                ->where('email', $email)
                ->where('user_id !=', $userId)
                ->first();

            if (! $exists) {
                return $email;
            }
        }

        return $base . $userId . self::WORK_EMAIL_DOMAIN;
    }

    private function hasField(string $table, string $field): bool
    {
        try {
            return $this->db->tableExists($table) && $this->db->fieldExists($field, $table);
        } catch (\Throwable) {
            return false;
        }
    }
}