<?php

namespace App\Http\Controllers\Web;

use App\Http\Controllers\Controller;
use App\Models\AiAgent;
use App\Models\Store;
use Illuminate\Http\Request;
use Illuminate\Http\StreamedResponse;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use Symfony\Component\HttpFoundation\Response;

/**
 * NPC chat endpoints consumed by the 3D city viewer.
 *
 * The POST endpoint accepts a user message, enqueues the OpenRouter call
 * asynchronously and immediately returns 202 so the UI can show a
 * "thinking" state. The GET endpoint streams agent replies as SSE events.
 * Only simulated city context (never personal data) is sent upstream,
 * as required by RULES.md.
 */
class ChatController extends Controller
{
    /**
     * Send a message to an agent and trigger an asynchronous reply.
     */
    public function send(Request $request, AiAgent $agent): Response
    {
        $data = $request->validate([
            'message' => ['required', 'string', 'max:2000'],
        ]);

        // Persist the conversation in the agent's last_decision for audit
        // and stream the pending state to any connected SSE listener.
        $history = $agent->last_decision ?? [];
        $history[] = ['role' => 'user', 'content' => $data['message'], 'at' => now()->toIso8601String()];
        $agent->update([
            'last_decision' => array_slice($history, -20),
            'status' => 'thinking',
        ]);

        self::publish($agent, ['type' => 'thinking', 'agent_id' => $agent->id, 'status' => 'thinking']);

        // Fire the OpenRouter call without blocking the HTTP response.
        dispatch(function () use ($agent, $data): void {
            self::think($agent, $data['message']);
        });

        return response()->json([
            'status' => 'accepted',
            'agent_id' => $agent->id,
            'message' => __('city.chat_accepted'),
        ], 202);
    }

    /**
     * Stream agent status and replies as Server-Sent Events.
     */
    public function stream(Request $request, AiAgent $agent): StreamedResponse
    {
        $request->session()->save();

        return response()->stream(function () use ($agent): void {
            echo "retry: 3000\n\n";
            flush();

            $last = null;

            while (true) {
                if (connection_aborted()) {
                    break;
                }

                // Poll the cache for a message published by think().
                $payload = cache()->pull("chat.{$agent->id}");

                if ($payload !== null) {
                    $json = json_encode($payload, JSON_UNESCAPED_UNICODE);
                    echo "event: message\n";
                    echo "data: {$json}\n\n";
                    flush();
                    $last = $payload;
                }

                // Heartbeat keeps proxies from closing the stream.
                echo ": ping\n\n";
                flush();

                sleep(2);
            }
        }, 200, [
            'Content-Type' => 'text/event-stream',
            'Cache-Control' => 'no-cache',
            'X-Accel-Buffering' => 'no',
        ]);
    }

    /**
     * Call OpenRouter with the agent persona and simulated city context.
     *
     * Never includes personal data — only city state (RULES.md 2.2).
     */
    private static function think(AiAgent $agent, string $userMessage): void
    {
        try {
            $apiKey = config('ai.openrouter.api_key');

            if (! filled($apiKey)) {
                self::fail($agent, 'OPENROUTER_API_KEY not configured');

                return;
            }

            // Simulated city context only — no PII (RULES.md 2.2).
            $cityContext = [
                'stores' => Store::query()
                    ->get(['name', 'type', 'is_open'])
                    ->map(fn ($s) => ['name' => $s->name, 'type' => $s->type, 'open' => $s->is_open])
                    ->all(),
                'agent_name' => $agent->name,
                'agent_type' => $agent->type,
                'current_goal' => $agent->current_goal,
            ];

            $system = ($agent->system_prompt ?: "Você é {$agent->name}, um habitante da cidade virtual City10.")
                ."\n\nContexto simulado da cidade: ".json_encode($cityContext, JSON_UNESCAPED_UNICODE)
                ."\nResponda de forma curta e natural, em português. Não invente dados pessoais de usuários.";

            // Preferred agent model first, then the configured fallback
            // chain (AI_FALLBACK_MODEL) before failing the turn.
            $models = [$agent->model];
            $fallback = config('ai.fallback_model');
            if (is_string($fallback) && $fallback !== ''
                && $fallback !== $agent->model
                && in_array($fallback, config('ai.allowed_models', []), true)) {
                $models[] = $fallback;
            }

            $response = null;
            foreach ($models as $candidate) {
                try {
                    $response = Http::withHeaders([
                        'Authorization' => 'Bearer '.$apiKey,
                        'HTTP-Referer' => config('ai.openrouter.app_url'),
                        'X-Title' => config('ai.openrouter.app_name'),
                    ])->timeout((int) config('ai.openrouter.timeout', 30))
                        ->post(config('ai.openrouter.base_url').'/chat/completions', [
                            'model' => $candidate,
                            'messages' => [
                                ['role' => 'system', 'content' => $system],
                                ['role' => 'user', 'content' => $userMessage],
                            ],
                            'max_tokens' => 300,
                        ]);
                } catch (\Throwable $e) {
                    Log::warning('NPC think model exception', ['model' => $candidate, 'error' => $e->getMessage()]);
                    $response = null;

                    continue;
                }

                if ($response->failed()) {
                    Log::warning('NPC think model failed', ['model' => $candidate, 'status' => $response->status()]);
                    $response = null;

                    continue;
                }

                break;
            }

            if ($response === null) {
                self::fail($agent, 'all models failed');

                return;
            }

            $reply = $response->json('choices.0.message.content') ?? __('city.chat_error');

            $history = $agent->last_decision ?? [];
            $history[] = ['role' => 'assistant', 'content' => $reply, 'at' => now()->toIso8601String()];

            $agent->update([
                'last_decision' => array_slice($history, -20),
                'status' => 'active',
                'error_count' => 0,
                'last_think_at' => now(),
            ]);

            self::publish($agent, [
                'type' => 'reply',
                'agent_id' => $agent->id,
                'name' => $agent->name,
                'reply' => $reply,
                'status' => 'active',
            ]);
        } catch (\Throwable $e) {
            Log::error('NPC think failed', ['agent' => $agent->id, 'error' => $e->getMessage()]);
            self::fail($agent, $e->getMessage());
        }
    }

    /**
     * Record a failure with exponential backoff (RULES.md 2.4).
     */
    private static function fail(AiAgent $agent, string $reason): void
    {
        $errors = (int) $agent->error_count + 1;
        $backoff = min(300, 2 ** min($errors, 8));

        $agent->update([
            'status' => $errors >= 5 ? 'error' : 'active',
            'error_count' => $errors,
        ]);

        self::publish($agent, [
            'type' => 'error',
            'agent_id' => $agent->id,
            'reply' => __('city.chat_error'),
            'status' => $agent->status,
            'retry_after' => $backoff,
        ]);
    }

    /**
     * Publish a message for the SSE stream to pick up.
     */
    private static function publish(AiAgent $agent, array $payload): void
    {
        cache()->put("chat.{$agent->id}", $payload, now()->addMinutes(5));
    }
}