sam-kd/chatbot/md_rag/api.php

<?php
// chatbot/md_rag/api.php
require_once($_SERVER['DOCUMENT_ROOT'] . "/session.php");
// Error handling for API
error_reporting(0);
ini_set('display_errors', 0);
ini_set('memory_limit', '512M');
ob_start();

header('Content-Type: application/json; charset=utf-8');

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    ob_clean();
    echo json_encode(['error' => 'Invalid request method']);
    exit;
}

$input = json_decode(file_get_contents('php://input'), true);
$userMessage = $input['message'] ?? '';
$history = $input['history'] ?? [];

if (empty($userMessage)) {
    ob_clean();
    echo json_encode(['error' => 'Empty message']);
    exit;
}

$projectRoot = dirname(__DIR__, 2);
$googleApiKeyPath = $projectRoot . "/apikey/google_vertex_api.txt";
$googleApiKey = trim(file_get_contents($googleApiKeyPath));

// Reuse VectorSearch class but override file path? 
// Or just instantiate it and inject path if possible?
// The current VectorSearch class has hardcoded path. 
// We should modify VectorSearch to accept a path in constructor, 
// OR simpler: we just write a mini-search logic here or a subclass.
// Let's use a modified Include logic or subclassing.
// Actually, modifying `rag/search.php` to accept an optional $customFile path is the BEST architecture.
// But to avoid touching working code during this task, I will clone the logic lightly here or simpler: define a new class in this file.

class MDSearch {
    private $vectors;
    
    public function __construct() {
        $dataFile = __DIR__ . '/data/vectors.json';
        if (file_exists($dataFile)) {
            $this->vectors = json_decode(file_get_contents($dataFile), true);
        } else {
            $this->vectors = [];
        }
    }
    
    private function cosineSimilarity($vecA, $vecB) {
        $dotProduct = 0;
        $normA = 0;
        $normB = 0;
        foreach ($vecA as $i => $val) {
            $dotProduct += $val * $vecB[$i];
            $normA += $val * $val;
            $normB += $val * $val;
        }
        return ($normA * $normB) == 0 ? 0 : $dotProduct / (sqrt($normA) * sqrt($normB));
    }

    public function search($query, $apiKey, $topK = 3) {
        if (empty($this->vectors)) return [];

        // Embed Query
        $url = "https://generativelanguage.googleapis.com/v1beta/models/text-embedding-004:embedContent?key=" . $apiKey;
        $data = ['model' => 'models/text-embedding-004', 'content' => ['parts' => [['text' => $query]]]];
        
        $ch = curl_init($url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
        curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);
        $response = curl_exec($ch);
        curl_close($ch);
        
        $result = json_decode($response, true);
        $queryVector = $result['embedding']['values'] ?? null;
        
        if (!$queryVector) return [];

        // Search
        $scores = [];
        foreach ($this->vectors as $doc) {
            $score = $this->cosineSimilarity($queryVector, $doc['vector']);
            $scores[] = [
                'id' => $doc['id'],
                'score' => $score,
                'text' => $doc['text'],
                'title' => $doc['title'],
                'url' => $doc['url']
            ];
        }

        usort($scores, function($a, $b) { return $b['score'] <=> $a['score']; });
        return array_slice($scores, 0, $topK);
    }
}

try {
    // 1. Search
    $searcher = new MDSearch();
    $results = $searcher->search($userMessage, $googleApiKey, 5);
    
    $context = "";
    if (empty($results)) {
        $context = "관련된 도움말 문서를 찾을 수 없습니다.";
    } else {
        // Simple Dedupe
        $processed = [];
        foreach ($results as $doc) {
            if ($doc['score'] < 0.5) continue; // Threshold
            $context .= "문서: {$doc['title']}\n내용:\n{$doc['text']}\n---\n";
        }
    }

    // 2. Generation
    $url = "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=" . $googleApiKey;
    $headers = ['Content-Type: application/json'];
    
    // Debug Data Collection
    $debugInfo = [];
    $context = "";
    
    if (empty($results)) {
        $context = "관련된 도움말 문서를 찾을 수 없습니다.";
        $debugInfo['message'] = "No results found from vector search.";
    } else {
        // Simple Dedupe
        $processed = [];
        $debugInfo['candidates'] = [];
        
        foreach ($results as $doc) {
            // Log all candidates to debug
            $debugInfo['candidates'][] = [
                'title' => $doc['title'],
                'score' => round($doc['score'], 4),
                'text_preview' => mb_substr($doc['text'], 0, 100) . "..."
            ];

            // Threshold Check (Lowered to 0.4)
            if ($doc['score'] < 0.4) continue; 
            
            $context .= "문서: {$doc['title']}\n내용:\n{$doc['text']}\n---\n";
        }
        
        if (empty($context)) {
             $context = "검색된 문서들의 유사도가 너무 낮습니다. (Threshold < 0.4)";
        }
    }

    // Construct Prompt
    $systemInstruction = "You are a helpful assistant for 'Tenant Knowledge Base'. 
    Answer the user's question using ONLY the provided [Context].
    If the answer is not in the context, say '죄송합니다. 제공된 도움말 문서에 해당 내용이 없습니다.'
    
    [Context]
    $context";

    $data = [
        'contents' => [['parts' => [['text' => $userMessage]]]],
        'systemInstruction' => ['parts' => [['text' => $systemInstruction]]]
    ];

    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    $response = curl_exec($ch);
    curl_close($ch);
    
    $responseData = json_decode($response, true);
    $reply = $responseData['candidates'][0]['content']['parts'][0]['text'] ?? "죄송합니다. 응답 생성 중 오류가 발생했습니다.";

    ob_clean();
    echo json_encode(['reply' => $reply, 'debug' => $debugInfo]);

} catch (Exception $e) {
    ob_clean();
    echo json_encode(['reply' => "System Error: " . $e->getMessage()]);
}
?>