<?php

declare(strict_types=1);

namespace App\Console\Commands;

use App\Game\StressTestHarness;
use Illuminate\Console\Command;

/**
 * Runs the authoritative simulation stress sweep and reports capacity limits.
 *
 * Measures GameEngine::tick() time and snapshot broadcast payload size at
 * increasing entity counts, then derives the entity count where the average
 * tick exceeds the 60 Hz budget and where the snapshot exceeds Reverb's max
 * message size.
 */
final class GameStressTest extends Command
{
    protected $signature = 'game:stress
        {--scenario=both : zombies, projectiles, or both}
        {--players=2 : number of players in the room}
        {--entities-from=50 : first entity count sampled}
        {--entities-to=400 : last entity count sampled}
        {--step=50 : increment between sampled entity counts}
        {--ticks=600 : simulation ticks measured per sample}
        {--breakpoint-only : print only the derived capacity limits}';

    protected $description = 'Benchmark simulation tick time and snapshot payload size across entity counts';

    public function handle(StressTestHarness $harness): int
    {
        $scenarios = $this->resolveScenarios((string) $this->option('scenario'));
        if ($scenarios === []) {
            $this->error('Unknown scenario. Use zombies, projectiles, or both.');

            return self::FAILURE;
        }

        $from = (int) $this->option('entities-from');
        $to = (int) $this->option('entities-to');
        $step = (int) $this->option('step');
        $players = (int) $this->option('players');
        $ticks = (int) $this->option('ticks');

        if ($step <= 0 || $to < $from) {
            $this->error('Invalid sweep range (--entities-to must be >= --entities-from, --step must be > 0).');

            return self::FAILURE;
        }

        $counts = $this->range($from, $to, $step);

        $tickSamples = [];
        $snapshotSamples = [];
        foreach ($counts as $count) {
            $this->line(sprintf('  sampling %d entities...', $count));
            $tickSamples[$count] = $harness->measureTickTime($count, $players, $ticks, $scenarios);
            $snapshotSamples[$count] = $harness->measureSnapshotBytes($count, $players, $scenarios);
        }

        if ($this->option('breakpoint-only')) {
            $this->printBreakpoints($tickSamples, $snapshotSamples);

            return self::SUCCESS;
        }

        $this->printTables($counts, $scenarios, $tickSamples, $snapshotSamples);
        $this->printBreakpoints($tickSamples, $snapshotSamples);

        return self::SUCCESS;
    }

    /** @return array<int, string> */
    private function resolveScenarios(string $scenario): array
    {
        return match ($scenario) {
            'both' => StressTestHarness::SCENARIOS,
            default => in_array($scenario, StressTestHarness::SCENARIOS, true)
                ? [$scenario]
                : [],
        };
    }

    /** @return array<int, int> */
    private function range(int $from, int $to, int $step): array
    {
        $counts = [];
        for ($i = $from; $i <= $to; $i += $step) {
            $counts[] = $i;
        }

        return $counts;
    }

    private function printTables(array $counts, array $scenarios, array $tickSamples, array $snapshotSamples): void
    {
        $this->newLine();
        $this->info('Tick time per entity count (avg/median/max ms; budget '.round(StressTestHarness::TICK_BUDGET_SECONDS * 1000, 2).' ms):');
        $this->table(
            array_merge(['Entities'], $this->scenarioHeaders($scenarios)),
            array_map(fn (int $count) => array_merge(
                [(string) $count],
                array_map(fn (string $scenario) => sprintf(
                    '%s/%s/%s %s',
                    $tickSamples[$count]['scenarios'][$scenario]['avgMs'],
                    $tickSamples[$count]['scenarios'][$scenario]['medianMs'],
                    $tickSamples[$count]['scenarios'][$scenario]['maxMs'],
                    $tickSamples[$count]['scenarios'][$scenario]['budgetOk'] ? '' : '⚠',
                ), $scenarios),
            ), $counts),
        );

        $this->newLine();
        $this->info('Snapshot broadcast size per entity count (Reverb cap '.StressTestHarness::REVERB_MAX_BYTES.' bytes):');
        $this->table(
            array_merge(['Entities'], $this->scenarioHeaders($scenarios)),
            array_map(fn (int $count) => array_merge(
                [(string) $count],
                array_map(fn (string $scenario) => sprintf(
                    '%d B (%.1f B/ent) %s',
                    $snapshotSamples[$count]['scenarios'][$scenario]['bytes'],
                    $snapshotSamples[$count]['scenarios'][$scenario]['bytesPerEntity'],
                    $snapshotSamples[$count]['scenarios'][$scenario]['exceedsReverb'] ? '⚠' : '',
                ), $scenarios),
            ), $counts),
        );
    }

    private function printBreakpoints(array $tickSamples, array $snapshotSamples): void
    {
        $this->newLine();
        $this->info('Derived capacity limits:');

        $budgetMs = StressTestHarness::TICK_BUDGET_SECONDS * 1000.0;

        $badTick = $this->firstBad('budgetOk', false, $tickSamples);
        if ($badTick !== null) {
            $this->line(sprintf(
                '  Avg tick exceeds %.2f ms budget at %d entities (scenario: %s).',
                $budgetMs,
                $badTick['count'],
                $badTick['scenario'],
            ));
        } else {
            $this->line(sprintf('  Avg tick stays under %.2f ms across all sampled entity counts.', $budgetMs));
        }

        $badSnapshot = $this->firstBad('exceedsReverb', true, $snapshotSamples);
        if ($badSnapshot !== null) {
            $this->line(sprintf(
                '  Snapshot exceeds %d-byte Reverb cap at %d entities (scenario: %s).',
                StressTestHarness::REVERB_MAX_BYTES,
                $badSnapshot['count'],
                $badSnapshot['scenario'],
            ));
        } else {
            $this->line(sprintf('  Snapshot stays under %d-byte Reverb cap across all sampled entity counts.', StressTestHarness::REVERB_MAX_BYTES));
        }
    }

    /**
     * @param  array<int, array<string, mixed>>  $samples
     * @return array{count: int, scenario: string}|null
     */
    private function firstBad(string $key, mixed $target, array $samples): ?array
    {
        foreach ($samples as $count => $sample) {
            foreach (array_keys($sample['scenarios']) as $scenario) {
                if ($sample['scenarios'][$scenario][$key] === $target) {
                    return ['count' => $count, 'scenario' => $scenario];
                }
            }
        }

        return null;
    }

    /** @return array<int, string> */
    private function scenarioHeaders(array $scenarios): array
    {
        return array_map(fn (string $scenario) => ucfirst($scenario), $scenarios);
    }
}