<?php

declare(strict_types=1);

namespace App\Agent;

use App\Context\ContextService;
use App\Context\UrlAnalyzer;
use App\Infrastructure\OllamaClient;
use App\Knowledge\Retrieval\RetrieverInterface;
use Generator;
use Psr\Log\LoggerInterface;
use Throwable;
use App\Agent\StreamChunker;

final readonly class AgentRunner
{
    public function __construct(
        private PromptBuilder      $promptBuilder,
        private ThinkSuppressor    $thinkSuppressor,
        private ContextService     $contextService,
        private UrlAnalyzer        $urlAnalyzer,
        private RetrieverInterface $retriever,
        private OllamaClient       $ollamaClient,
        private LoggerInterface    $agentLogger,
        private bool               $debug,
        private bool               $logPrompt,
        private bool               $logContext,
    ) {}

    public function run(string $prompt, string $userId): Generator
    {
        $prompt = trim($prompt);

        if ($prompt === '') {
            yield '❌ Empty prompt.';
            return;
        }

        $this->agentLogger->info('Agent run started', [
            'userId' => $userId,
        ]);

        try {
            // ---------------------------------------------------------
            // 1) Context strategy
            // ---------------------------------------------------------
            $includeFullContext = false;

            // ---------------------------------------------------------
            // 2) Extract URL content (if present)
            // ---------------------------------------------------------
            $urlContent = $this->urlAnalyzer->extractContentFromPrompt($prompt);

            // ---------------------------------------------------------
            // 3) Retrieve RAG knowledge
            // ---------------------------------------------------------
            $knowledgeChunks = $this->retriever->retrieve($prompt);

            // ---------------------------------------------------------
            // 4) Build final prompt
            // ---------------------------------------------------------
            $finalPrompt = $this->promptBuilder->build(
                prompt: $prompt,
                userId: $userId,
                urlContent: $urlContent,
                knowledgeChunks: $knowledgeChunks,
                fullContext: $includeFullContext
            );

            if ($this->debug && $this->logPrompt) {
                $this->agentLogger->debug($finalPrompt);
            }

            if ($this->debug && $this->logContext) {
                $this->agentLogger->debug('Conversation context snapshot', [
                    'context' => $this->contextService->buildUserContext(
                        $userId,
                        $includeFullContext
                    ),
                ]);
            }

            // ---------------------------------------------------------
            // 5) Stream tokens from the LLM backend (chunked streaming)
            // ---------------------------------------------------------
            $fullOutput = '';
            $chunker = new StreamChunker();

            foreach ($this->ollamaClient->stream($finalPrompt) as $token) {
                $cleanToken = $this->thinkSuppressor->filter($token);

                if ($cleanToken === '') {
                    continue;
                }

                // Vollständige Antwort weiter sammeln (für History)
                $fullOutput .= $cleanToken;

                // ⬇️ Token in Chunker geben
                $chunk = $chunker->push($cleanToken);
                if ($chunk !== null) {
                    yield $chunk;
                }
            }

            // ⬇️ Rest flushen
            $finalChunk = $chunker->flush();
            if ($finalChunk !== null) {
                yield $finalChunk;
            }

            // ---------------------------------------------------------
            // 6) Persist conversation history
            // ---------------------------------------------------------
            $this->contextService->appendHistory(
                $userId,
                $prompt,
                $fullOutput
            );

            $this->agentLogger->info('Agent run finished', [
                'userId'       => $userId,
                'outputLength' => mb_strlen($fullOutput),
                'contextMode'  => 'recent',
            ]);
        } catch (Throwable $e) {
            $this->agentLogger->error('Agent run failed', [
                'userId'    => $userId,
                'exception' => $e,
            ]);

            yield "\n❌ An internal error occurred while processing the request.";
        }
    }
}