<?php

namespace App\Services\Public;

use App\Models\Application;
use App\Models\Position;
use App\Models\PositionQuota;
use App\Models\PusatMengundi;
use App\Models\SaluranMengundi;
use App\Models\StaffAssignment;
use App\Models\User;
use Illuminate\Database\Eloquent\Collection as EloquentCollection;
use Illuminate\Support\Collection;

class KtmVacancyService
{
    private const RESERVED_APPLICATION_STATUSES = [
        'submitted',
        'under_ppm_review',
        'approved',
    ];

    /**
     * @param  array<int, string>  $roleCodes
     * @return array<string, array<int, array{id: int, label: string, remaining: int}>>
     */
    public function optionsForRoles(PusatMengundi $pusatMengundi, array $roleCodes = ['KP', 'KPDP'], ?int $ignoreApplicationId = null): array
    {
        $options = [];

        foreach ($roleCodes as $roleCode) {
            $options[$roleCode] = $this->availableKtmAssignments($pusatMengundi, $roleCode, $ignoreApplicationId)
                ->map(function (StaffAssignment $assignment) use ($roleCode, $ignoreApplicationId): array {
                    $user = $assignment->user;
                    $saluranMengundi = $assignment->saluranMengundi;

                    return [
                        'id' => $assignment->id,
                        'label' => trim(
                            ($user instanceof User ? $user->name : 'KTM tanpa nama')
                            .' - Saluran '
                            .($saluranMengundi instanceof SaluranMengundi ? $saluranMengundi->number : '-'),
                        ),
                        'remaining' => $this->remainingVacancy($assignment, $roleCode, $ignoreApplicationId),
                    ];
                })
                ->values()
                ->all();
        }

        return $options;
    }

    public function hasVacancyForAssignment(int $assignmentId, PusatMengundi $pusatMengundi, string $roleCode, ?int $ignoreApplicationId = null): bool
    {
        $ktmPosition = Position::query()->where('code', 'KTM')->first();

        if ($ktmPosition === null) {
            return false;
        }

        $assignment = StaffAssignment::query()
            ->with(['saluranMengundi', 'user'])
            ->where('id', $assignmentId)
            ->where('election_id', $pusatMengundi->election_id)
            ->where('pusat_mengundi_id', $pusatMengundi->id)
            ->where('position_id', $ktmPosition->id)
            ->where('status', 'active')
            ->whereNotNull('saluran_mengundi_id')
            ->first();

        return $assignment instanceof StaffAssignment
            && $this->remainingVacancy($assignment, $roleCode, $ignoreApplicationId) > 0;
    }

    public function remainingForAssignment(StaffAssignment $assignment, string $roleCode, ?int $ignoreApplicationId = null): int
    {
        return $this->remainingVacancy($assignment, $roleCode, $ignoreApplicationId);
    }

    /**
     * @return Collection<int, StaffAssignment>
     */
    private function availableKtmAssignments(PusatMengundi $pusatMengundi, string $roleCode, ?int $ignoreApplicationId = null): Collection
    {
        return $this->ktmAssignments($pusatMengundi)
            ->filter(fn (StaffAssignment $assignment): bool => $this->remainingVacancy($assignment, $roleCode, $ignoreApplicationId) > 0)
            ->values();
    }

    /**
     * @return EloquentCollection<int, StaffAssignment>
     */
    private function ktmAssignments(PusatMengundi $pusatMengundi): EloquentCollection
    {
        $ktmPosition = Position::query()->where('code', 'KTM')->first();

        if ($ktmPosition === null) {
            return new EloquentCollection;
        }

        return StaffAssignment::query()
            ->with(['saluranMengundi', 'user'])
            ->where('election_id', $pusatMengundi->election_id)
            ->where('pusat_mengundi_id', $pusatMengundi->id)
            ->where('position_id', $ktmPosition->id)
            ->where('status', 'active')
            ->whereNotNull('saluran_mengundi_id')
            ->whereNotNull('user_id')
            ->orderBy('saluran_mengundi_id')
            ->get();
    }

    private function remainingVacancy(StaffAssignment $ktmAssignment, string $roleCode, ?int $ignoreApplicationId = null): int
    {
        $position = Position::query()->where('code', $roleCode)->first();

        if ($position === null || $ktmAssignment->saluran_mengundi_id === null) {
            return 0;
        }

        $quota = PositionQuota::query()
            ->where('election_id', $ktmAssignment->election_id)
            ->where('pusat_mengundi_id', $ktmAssignment->pusat_mengundi_id)
            ->where('saluran_mengundi_id', $ktmAssignment->saluran_mengundi_id)
            ->where('position_id', $position->id)
            ->value('quota');

        if ($quota === null) {
            return 0;
        }

        $assignedCount = StaffAssignment::query()
            ->where('reports_to_assignment_id', $ktmAssignment->id)
            ->where('position_id', $position->id)
            ->where('status', 'active')
            ->count();

        $reservedQuery = Application::query()
            ->where('selected_ktm_assignment_id', $ktmAssignment->id)
            ->where('requested_position_id', $position->id)
            ->whereIn('status', self::RESERVED_APPLICATION_STATUSES);

        if ($ignoreApplicationId !== null) {
            $reservedQuery->where('id', '!=', $ignoreApplicationId);
        }

        $reservedCount = $reservedQuery->count();

        return max(0, (int) $quota - $assignedCount - $reservedCount);
    }
}