<?php

namespace App\Polls;

use App\Models\Poll;
use App\Models\PollLedgerEntry;
use App\Models\PollResponse;
use App\Models\User;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\DB;

/**
 * Remove the votes of a permanently deleted profile: the link to the voter is deleted
 * (poll_responses + poll_answers) and the ballot is withdrawn in the ledger, so the totals
 * change visibly instead of silently. The anonymous ballot itself stays in the chain.
 */
class VoteWithdrawal
{
    public function __construct(private Ledger $ledger)
    {
    }

    /**
     * @return int number of withdrawn votes
     */
    public function withdrawFor(Model $profile): int
    {
        // The profile's own votes
        $responses = PollResponse::where('voter_type', get_class($profile))
            ->where('voter_id', $profile->getKey())
            ->get();

        // A user's own votes on behalf of an organization / bank / admin in "one vote per linked user" polls.
        // In "one vote per profile" polls the vote belongs to that profile and stays.
        if ($profile instanceof User) {
            $responses = $responses->merge(
                PollResponse::where('user_id', $profile->getKey())
                    ->where('voter_type', '!=', User::class)
                    ->whereHas('poll', fn ($query) => $query->where('vote_scope', Poll::VOTE_SCOPE_PER_USER))
                    ->get()
            );
        }

        foreach ($responses as $response) {
            DB::transaction(function () use ($response) {
                if ($response->ledger_sequence) {
                    $this->ledger->append(
                        $response->poll,
                        PollLedgerEntry::WITHDRAW,
                        ['reason' => 'profile_deleted'],
                        null,
                        $response->ledger_sequence
                    );
                }
                $response->delete(); // answers cascade
            });
        }

        return $responses->count();
    }
}