<?php

namespace App\Services\Ktm;

use App\Mail\KtmCreatedApplicantMail;
use App\Models\Application;
use App\Models\Election;
use App\Models\Position;
use App\Models\PusatMengundi;
use App\Models\StaffAssignment;
use App\Models\User;
use App\Services\Public\KtmVacancyService;
use App\Services\RegistrationPeriodService;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Mail;
use Illuminate\Support\Str;
use Illuminate\Validation\ValidationException;

class KtmApplicationService
{
    /**
     * @param  array{name: string, ic_number: string, phone_number: string, email: string, address?: string|null}  $data
     */
    public function registerKp(StaffAssignment $ktmAssignment, User $actor, array $data): Application
    {
        return DB::transaction(function () use ($ktmAssignment, $actor, $data): Application {
            $ktmAssignment->loadMissing(['election.settings', 'pusatMengundi', 'user']);

            if (! app(KtmScopeService::class)->ownsAssignment($actor, $ktmAssignment)) {
                throw ValidationException::withMessages([
                    'assignment' => 'Anda tidak dibenarkan mendaftar KP untuk saluran ini.',
                ]);
            }

            $election = $this->assignmentElection($ktmAssignment);
            $pusatMengundi = $this->assignmentPusat($ktmAssignment);

            if (! app(RegistrationPeriodService::class)->isOpen($election)) {
                throw ValidationException::withMessages([
                    'registration' => app(RegistrationPeriodService::class)->closedMessage($election),
                ]);
            }

            $kpPosition = Position::query()->where('code', 'KP')->firstOrFail();

            if (! app(KtmVacancyService::class)->hasVacancyForAssignment($ktmAssignment->id, $pusatMengundi, 'KP')) {
                throw ValidationException::withMessages([
                    'ktm_assignment_id' => 'Kekosongan KP untuk saluran ini telah penuh.',
                ]);
            }

            // SoftDeletes scope excludes soft-deleted records. whereNotIn covers 'cancelled' records
            // (not soft-deleted) and 'deleted_by_ktm' as an explicit redundant safety layer.
            $existing = Application::query()
                ->where('election_id', $ktmAssignment->election_id)
                ->where('ic_number', $data['ic_number'])
                ->whereNotIn('status', ['cancelled', 'deleted_by_ktm'])
                ->first();

            if ($existing instanceof Application) {
                throw ValidationException::withMessages([
                    'ic_number' => 'No. kad pengenalan ini telah mempunyai rekod permohonan aktif untuk pilihanraya semasa.',
                ]);
            }

            $application = Application::query()->create([
                'election_id' => $ktmAssignment->election_id,
                'pusat_mengundi_id' => $ktmAssignment->pusat_mengundi_id,
                'selected_ktm_assignment_id' => $ktmAssignment->id,
                'public_uuid' => (string) Str::uuid(),
                'source' => 'created_by_ktm',
                'status' => 'submitted',
                'name' => $data['name'],
                'ic_number' => $data['ic_number'],
                'phone_number' => $data['phone_number'],
                'email' => $data['email'],
                'address' => $data['address'] ?? null,
                'requested_position_id' => $kpPosition->id,
                'created_by_user_id' => $actor->id,
            ]);

            $application->statusHistories()->create([
                'to_status' => 'submitted',
                'changed_by_user_id' => $actor->id,
                'note' => 'KP applicant created by KTM.',
                'metadata' => [
                    'source' => 'created_by_ktm',
                    'ktm_assignment_id' => $ktmAssignment->id,
                ],
            ]);

            Mail::to($application->email)->queue(new KtmCreatedApplicantMail($application->load('pusatMengundi'), $ktmAssignment));

            activity('ktm_flow')
                ->performedOn($application)
                ->causedBy($actor)
                ->withProperties([
                    'ktm_assignment_id' => $ktmAssignment->id,
                    'position_code' => 'KP',
                ])
                ->log('kp_applicant_created_by_ktm');

            return $application;
        });
    }

    public function approveKp(Application $application, User $actor): StaffAssignment
    {
        return DB::transaction(function () use ($application, $actor): StaffAssignment {
            $application->loadMissing(['selectedKtmAssignment.pusatMengundi', 'selectedKtmAssignment.election.settings', 'requestedPosition']);
            $ktmAssignment = $application->selectedKtmAssignment;

            if (! $ktmAssignment instanceof StaffAssignment || ! app(KtmScopeService::class)->ownsAssignment($actor, $ktmAssignment)) {
                throw ValidationException::withMessages([
                    'application' => 'Anda tidak dibenarkan meluluskan permohonan ini.',
                ]);
            }

            $election = $this->assignmentElection($ktmAssignment);
            $pusatMengundi = $this->assignmentPusat($ktmAssignment);

            if (! app(RegistrationPeriodService::class)->isOpen($election)) {
                throw ValidationException::withMessages([
                    'registration' => app(RegistrationPeriodService::class)->closedMessage($election),
                ]);
            }

            $kpPosition = Position::query()->where('code', 'KP')->firstOrFail();

            if ((int) $application->requested_position_id !== (int) $kpPosition->id) {
                throw ValidationException::withMessages([
                    'requested_position_id' => 'KTM hanya boleh meluluskan permohonan KP.',
                ]);
            }

            if (! in_array($application->status, ['submitted', 'under_ppm_review', 'approved'], true)) {
                throw ValidationException::withMessages([
                    'status' => 'Status permohonan tidak membenarkan kelulusan KTM.',
                ]);
            }

            if (! app(KtmVacancyService::class)->hasVacancyForAssignment($ktmAssignment->id, $pusatMengundi, 'KP', $application->id)) {
                throw ValidationException::withMessages([
                    'ktm_assignment_id' => 'Kekosongan KP untuk saluran ini telah penuh.',
                ]);
            }

            $previousStatus = $application->status;

            $application->forceFill([
                'status' => 'assigned',
                'approved_position_id' => $kpPosition->id,
                'approved_by_user_id' => $actor->id,
                'approved_at' => now(),
            ])->save();

            $assignment = StaffAssignment::query()->updateOrCreate(
                ['application_id' => $application->id],
                [
                    'election_id' => $application->election_id,
                    'user_id' => $application->user_id,
                    'position_id' => $kpPosition->id,
                    'pusat_mengundi_id' => $application->pusat_mengundi_id,
                    'saluran_mengundi_id' => $ktmAssignment->saluran_mengundi_id,
                    'reports_to_assignment_id' => $ktmAssignment->id,
                    'status' => 'active',
                    'assigned_by_user_id' => $actor->id,
                    'assigned_at' => now(),
                    'source' => 'ktm_approval',
                ],
            );

            $application->statusHistories()->create([
                'from_status' => $previousStatus,
                'to_status' => 'assigned',
                'changed_by_user_id' => $actor->id,
                'note' => 'KP application approved by KTM.',
                'metadata' => [
                    'ktm_assignment_id' => $ktmAssignment->id,
                    'position_code' => 'KP',
                ],
            ]);

            $assignment->histories()->create([
                'to_position_id' => $kpPosition->id,
                'to_pusat_mengundi_id' => $application->pusat_mengundi_id,
                'to_saluran_mengundi_id' => $ktmAssignment->saluran_mengundi_id,
                'to_reports_to_assignment_id' => $ktmAssignment->id,
                'changed_by_user_id' => $actor->id,
                'note' => 'KP assigned by KTM approval.',
            ]);

            activity('ktm_flow')
                ->performedOn($application)
                ->causedBy($actor)
                ->withProperties([
                    'assignment_id' => $assignment->id,
                    'ktm_assignment_id' => $ktmAssignment->id,
                ])
                ->log('kp_application_approved_by_ktm');

            return $assignment;
        });
    }

    public function deleteCreatedApplication(Application $application, User $actor): Application
    {
        return DB::transaction(function () use ($application, $actor): Application {
            if (! app(KtmScopeService::class)->canAccessApplication($actor, $application)) {
                throw ValidationException::withMessages([
                    'application' => 'Anda tidak dibenarkan memadam rekod ini.',
                ]);
            }

            if ($application->source !== 'created_by_ktm') {
                throw ValidationException::withMessages([
                    'application' => 'Hanya rekod yang dicipta oleh KTM boleh dipadam oleh KTM.',
                ]);
            }

            if ($application->status === 'assigned') {
                throw ValidationException::withMessages([
                    'application' => 'Rekod yang telah diassign tidak boleh dipadam oleh KTM.',
                ]);
            }

            $previousStatus = $application->status;

            $application->forceFill([
                'status' => 'deleted_by_ktm',
            ])->save();

            $application->statusHistories()->create([
                'from_status' => $previousStatus,
                'to_status' => 'deleted_by_ktm',
                'changed_by_user_id' => $actor->id,
                'note' => 'KTM deleted pre-created applicant record.',
            ]);

            activity('ktm_flow')
                ->performedOn($application)
                ->causedBy($actor)
                ->withProperties([
                    'from_status' => $previousStatus,
                    'to_status' => 'deleted_by_ktm',
                ])
                ->log('ktm_created_applicant_deleted');

            $application->delete();

            return $application;
        });
    }

    private function assignmentElection(StaffAssignment $assignment): Election
    {
        /** @var Election $election */
        $election = $assignment->election()->with('settings')->firstOrFail();

        return $election;
    }

    private function assignmentPusat(StaffAssignment $assignment): PusatMengundi
    {
        /** @var PusatMengundi $pusatMengundi */
        $pusatMengundi = $assignment->pusatMengundi()->firstOrFail();

        return $pusatMengundi;
    }
}