<?php

namespace App\Services\Admin\Master;

use App\Models\Department;
use App\Models\DepartmentLeadership;
use App\Models\Lecturer;
use Illuminate\Contracts\Pagination\LengthAwarePaginator;
use Illuminate\Database\Eloquent\Collection;

class DepartmentService
{
    public function getAllForSelect(): Collection
    {
        return Department::select(['id', 'code', 'name', 'degree_level'])->get();
    }

    public function paginated(int $perPage = 25, string $search = ''): LengthAwarePaginator
    {
        return Department::query()
            ->select(['id', 'code', 'name', 'degree_level'])
            ->with(['currentLeader.lecturer.user.profile'])
            ->when($search, fn ($q) => $q->where('name', 'like', "%{$search}%")->orWhere('code', 'like', "%{$search}%"))
            ->latest()
            ->paginate($perPage);
    }

    public function create(array $data): Department
    {
        $department = Department::create([
            'code' => $data['code'],
            'name' => $data['name'],
            'degree_level' => $data['degree_level'] ?? null,
        ]);

        $this->syncLeadership($department, $data['lecturer_id'] ?? null, $data['leadership_started_at'] ?? null);

        return $department;
    }

    public function update(Department $department, array $data): Department
    {
        $department->code = $data['code'];
        $department->name = $data['name'];
        $department->degree_level = $data['degree_level'] ?? null;
        $department->update();

        $this->syncLeadership($department, $data['lecturer_id'] ?? null, $data['leadership_started_at'] ?? null);

        return $department;
    }

    private function syncLeadership(Department $department, ?int $lecturerId, ?string $startedAt): void
    {
        $currentLeader = DepartmentLeadership::query()
            ->where('department_id', $department->id)
            ->whereNull('ended_at')
            ->first();

        if (! $lecturerId) {
            if ($currentLeader) {
                $currentLeader->update(['ended_at' => now()]);
                $this->revokeKaprodiRoleIfNoLongerLeading($currentLeader->lecturer_id);
            }

            return;
        }

        if ($currentLeader && $currentLeader->lecturer_id === $lecturerId) {
            $currentLeader->update(['started_at' => $startedAt ?? $currentLeader->started_at]);
            $this->grantKaprodiRole($lecturerId);

            return;
        }

        if ($currentLeader) {
            $currentLeader->update(['ended_at' => now()]);
            $this->revokeKaprodiRoleIfNoLongerLeading($currentLeader->lecturer_id);
        }

        $department->leaderships()->create([
            'lecturer_id' => $lecturerId,
            'started_at' => $startedAt ?? now(),
        ]);

        $this->grantKaprodiRole($lecturerId);
    }

    private function grantKaprodiRole(int $lecturerId): void
    {
        $user = Lecturer::find($lecturerId)?->user;

        if ($user && ! $user->hasRole('kaprodi')) {
            $user->assignRole('kaprodi');
        }
    }

    private function revokeKaprodiRoleIfNoLongerLeading(int $lecturerId): void
    {
        $stillLeadsAnyDepartment = DepartmentLeadership::query()
            ->where('lecturer_id', $lecturerId)
            ->whereNull('ended_at')
            ->exists();

        if (! $stillLeadsAnyDepartment) {
            Lecturer::find($lecturerId)?->user?->removeRole('kaprodi');
        }
    }

    public function delete(Department $department): bool
    {
        return $department->delete();
    }
}