<?php

namespace App\Jobs\Concerns;

use App\Models\DeviceState;
use Illuminate\Database\UniqueConstraintViolationException;

/**
 * Monotonic, race-safe upsert of a single entity's state. Shared by every ingest path (H4) so
 * the ordering guarantee is written once: concurrent Horizon workers can finish out of order,
 * and an older message must never overwrite a newer one. The guard lives in the WHERE clause,
 * so it holds without row locks.
 */
trait AppliesDeviceState
{
    /**
     * Returns true when this message's state was applied, false when it was stale
     * (an equal-or-newer state is already stored).
     *
     * @param  array<string,mixed>  $state
     */
    protected function applyState(int $entityId, array $state, int $observedAt): bool
    {
        $encoded = json_encode($state);

        // Overwrite an existing row only when this message is newer.
        $updated = DeviceState::query()
            ->where('entity_id', $entityId)
            ->where(fn ($q) => $q->whereNull('observed_at')->orWhere('observed_at', '<', $observedAt))
            ->update(['state' => $encoded, 'observed_at' => $observedAt, 'updated_at' => now()]);

        if ($updated > 0) {
            return true;
        }

        // No row yet → insert (unique(entity_id) guards against a concurrent insert).
        if (! DeviceState::where('entity_id', $entityId)->exists()) {
            try {
                DeviceState::create(['entity_id' => $entityId, 'state' => $state, 'observed_at' => $observedAt]);

                return true;
            } catch (UniqueConstraintViolationException) {
                // Lost the insert race — fall through and retry the conditional update.
                return DeviceState::query()
                    ->where('entity_id', $entityId)
                    ->where(fn ($q) => $q->whereNull('observed_at')->orWhere('observed_at', '<', $observedAt))
                    ->update(['state' => $encoded, 'observed_at' => $observedAt, 'updated_at' => now()]) > 0;
            }
        }

        // Existing row is equal-or-newer → this message is stale.
        return false;
    }
}