<?php

namespace App\Services;

use App\DTOs\ArticleCandidateDTO;
use App\DTOs\ClassificationResultDTO;
use App\Exceptions\OllamaUnavailableException;
use Illuminate\Support\Facades\Http;
use Throwable;

class AIClassifierService
{
    /** @param array<ArticleCandidateDTO> $candidates */
    public function rank(string $ticketMessage, array $candidates): ClassificationResultDTO
    {
        if ($candidates === []) {
            return new ClassificationResultDTO(null, 0.0, 'No article candidates available');
        }

        $articlesBlock = collect($candidates)
            ->map(fn (ArticleCandidateDTO $item, int $idx) => sprintf(
                "%d. article_id=%d\nTitle: %s\nContent: %s",
                $idx + 1,
                $item->articleId,
                $item->title,
                $item->content
            ))
            ->implode("\n\n");

        $prompt = <<<PROMPT
You are a support assistant.

User question:
"{$ticketMessage}"

Articles:
{$articlesBlock}

Task:
- Select the best matching article
- Return:
  - article_id
  - confidence (0-1)
  - short explanation

Respond in JSON ONLY.
PROMPT;

        $baseUrl = rtrim((string) config('services.ollama.base_url'), '/');

        try {
            $response = Http::timeout((int) config('services.ollama.timeout', 30))
                ->post($baseUrl.'/api/generate', [
                    'model' => config('services.ollama.chat_model', 'llama3'),
                    'prompt' => $prompt,
                    'stream' => false,
                ])
                ->throw()
                ->json();
        } catch (Throwable $e) {
            throw new OllamaUnavailableException('Ollama generate endpoint is unavailable', 0, $e);
        }

        $text = (string) ($response['response'] ?? '{}');
        $decoded = json_decode($text, true);

        if (!is_array($decoded)) {
            return new ClassificationResultDTO(
                articleId: $candidates[0]->articleId,
                confidence: 0.35,
                explanation: 'LLM returned invalid JSON; defaulted to top semantic match.',
                rawResponse: ['raw' => $text]
            );
        }

        return new ClassificationResultDTO(
            articleId: isset($decoded['article_id']) ? (int) $decoded['article_id'] : $candidates[0]->articleId,
            confidence: isset($decoded['confidence']) ? (float) $decoded['confidence'] : 0.35,
            explanation: (string) ($decoded['explanation'] ?? 'No explanation provided.'),
            rawResponse: $decoded
        );
    }
}