<?php
/**
 * tools/ingest_knowledge.php
 *
 * CLI script: ingests soil science PDF books into the knowledge_chunks table.
 * Each page is split into overlapping chunks, embedded via Ollama, and stored.
 *
 * Usage:
 *   php tools/ingest_knowledge.php --file="path/to/book.pdf" --author="William A. Albrecht"
 *   php tools/ingest_knowledge.php --dir="path/to/books/" --author="Various"
 *   php tools/ingest_knowledge.php --list          (show all indexed sources)
 *   php tools/ingest_knowledge.php --clear="Book Title"   (remove a source)
 *
 * Requirements:
 *   composer require smalot/pdfparser
 *   Ollama running with nomic-embed-text pulled:
 *     ollama pull nomic-embed-text
 *
 * The embedding model (nomic-embed-text) produces 768-dimensional vectors.
 * Each chunk is ~500 words with a 100-word overlap to preserve context across boundaries.
 */

// ── Must run from CLI ────────────────────────────────────────────────────────
if (PHP_SAPI !== 'cli') {
    die("This script must be run from the command line.\n");
}

define('ROOT', dirname(__DIR__));

require ROOT . '/vendor/autoload.php';
require ROOT . '/config/database.php';

use Smalot\PdfParser\Parser;

// ── Config ───────────────────────────────────────────────────────────────────
define('OLLAMA_EMBED_URL', 'http://192.168.8.73:11434/api/embeddings');
define('EMBED_MODEL',      'nomic-embed-text');
define('CHUNK_WORDS',      500);   // target words per chunk
define('OVERLAP_WORDS',    80);    // overlap between consecutive chunks

// ── Parse args ───────────────────────────────────────────────────────────────
$opts = getopt('', ['file:', 'dir:', 'author:', 'list', 'clear:', 'help']);

if (isset($opts['help']) || (empty($opts['file']) && empty($opts['dir']) && !isset($opts['list']) && empty($opts['clear']))) {
    echo <<<HELP
Usage:
  php tools/ingest_knowledge.php --file="book.pdf" --author="William A. Albrecht"
  php tools/ingest_knowledge.php --dir="books/"    --author="Various"
  php tools/ingest_knowledge.php --list
  php tools/ingest_knowledge.php --clear="Soil Fertility and Animal Health"

Options:
  --file    Path to a single PDF file
  --dir     Path to a directory of PDF files (processed recursively)
  --author  Author name to tag all chunks from this run
  --list    List all indexed sources with chunk counts
  --clear   Remove all chunks from a named source

HELP;
    exit(0);
}

$pdo = getDBConnection();

// ── List mode ────────────────────────────────────────────────────────────────
if (isset($opts['list'])) {
    $stmt = $pdo->query(
        "SELECT source, author, COUNT(*) AS chunks, MAX(created_at) AS indexed_at
         FROM knowledge_chunks GROUP BY source, author ORDER BY source"
    );
    $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
    if (!$rows) {
        echo "No sources indexed yet.\n";
    } else {
        printf("%-55s %-25s %6s  %s\n", 'Source', 'Author', 'Chunks', 'Indexed');
        echo str_repeat('-', 100) . "\n";
        foreach ($rows as $r) {
            printf("%-55s %-25s %6d  %s\n",
                substr($r['source'], 0, 54),
                substr($r['author'], 0, 24),
                $r['chunks'],
                $r['indexed_at']
            );
        }
    }
    exit(0);
}

// ── Clear mode ───────────────────────────────────────────────────────────────
if (!empty($opts['clear'])) {
    $title = $opts['clear'];
    $stmt  = $pdo->prepare('SELECT COUNT(*) FROM knowledge_chunks WHERE source = ?');
    $stmt->execute([$title]);
    $count = (int)$stmt->fetchColumn();
    if ($count === 0) {
        echo "No chunks found for source: $title\n";
        exit(0);
    }
    $del = $pdo->prepare('DELETE FROM knowledge_chunks WHERE source = ?');
    $del->execute([$title]);
    echo "Deleted $count chunks for: $title\n";
    exit(0);
}

// ── Collect PDF files ────────────────────────────────────────────────────────
$files  = [];
$author = trim($opts['author'] ?? 'Unknown');

if (!empty($opts['file'])) {
    $path = $opts['file'];
    if (!is_file($path)) {
        die("File not found: $path\n");
    }
    $files[] = $path;
}

if (!empty($opts['dir'])) {
    $dir = rtrim($opts['dir'], '/\\');
    if (!is_dir($dir)) {
        die("Directory not found: $dir\n");
    }
    $it = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir));
    foreach ($it as $f) {
        if ($f->isFile() && strtolower($f->getExtension()) === 'pdf') {
            $files[] = $f->getPathname();
        }
    }
    if (!$files) {
        die("No PDF files found in: $dir\n");
    }
}

echo "Found " . count($files) . " PDF file(s) to ingest.\n\n";

// ── Process each file ────────────────────────────────────────────────────────
$parser = new Parser();

foreach ($files as $filePath) {
    $source = pathinfo($filePath, PATHINFO_FILENAME);
    echo "Processing: $source\n";

    // Check if already indexed
    $chk = $pdo->prepare('SELECT COUNT(*) FROM knowledge_chunks WHERE source = ?');
    $chk->execute([$source]);
    if ((int)$chk->fetchColumn() > 0) {
        echo "  Already indexed — skipping. Use --clear=\"$source\" to re-index.\n\n";
        continue;
    }

    try {
        $pdf   = $parser->parseFile($filePath);
        $pages = $pdf->getPages();
    } catch (Exception $e) {
        echo "  ERROR parsing PDF: " . $e->getMessage() . "\n\n";
        continue;
    }

    echo "  Pages: " . count($pages) . "\n";

    $totalChunks  = 0;
    $totalTokens  = 0;
    $pageBuffer   = [];  // accumulate pages into a rolling word buffer

    $insertStmt = $pdo->prepare(
        'INSERT INTO knowledge_chunks (source, author, page, chunk_index, chunk_text, embedding)
         VALUES (?, ?, ?, ?, ?, ?)'
    );

    $chunkIndex  = 0;
    $wordBuffer  = [];
    $bufferPages = [];  // page numbers corresponding to words in buffer

    foreach ($pages as $pageNum => $page) {
        $pageText = cleanText($page->getText());
        if (strlen($pageText) < 50) continue;  // skip blank/image-only pages

        $words = explode(' ', $pageText);
        foreach ($words as $word) {
            $wordBuffer[]  = $word;
            $bufferPages[] = $pageNum + 1;
        }

        // Flush when buffer reaches chunk size
        while (count($wordBuffer) >= CHUNK_WORDS) {
            $chunkWords  = array_slice($wordBuffer, 0, CHUNK_WORDS);
            $chunkText   = implode(' ', $chunkWords);
            $chunkPage   = $bufferPages[0];

            if (strlen(trim($chunkText)) > 50) {
                $embedding = getEmbedding($chunkText);
                if ($embedding === null) {
                    echo "  WARNING: embedding failed for chunk $chunkIndex — skipping.\n";
                } else {
                    $insertStmt->execute([
                        $source,
                        $author,
                        $chunkPage,
                        $chunkIndex,
                        $chunkText,
                        json_encode($embedding),
                    ]);
                    $chunkIndex++;
                    $totalChunks++;
                }
            }

            // Slide window with overlap
            $step        = CHUNK_WORDS - OVERLAP_WORDS;
            $wordBuffer  = array_slice($wordBuffer, $step);
            $bufferPages = array_slice($bufferPages, $step);

            if ($chunkIndex % 20 === 0 && $chunkIndex > 0) {
                echo "  ...{$chunkIndex} chunks embedded\n";
            }
        }
    }

    // Flush remaining words as final chunk
    if (count($wordBuffer) > 30) {
        $chunkText = implode(' ', $wordBuffer);
        $embedding = getEmbedding($chunkText);
        if ($embedding !== null) {
            $insertStmt->execute([
                $source, $author, $bufferPages[0] ?? 0, $chunkIndex,
                $chunkText, json_encode($embedding),
            ]);
            $chunkIndex++;
            $totalChunks++;
        }
    }

    echo "  Done: $totalChunks chunks stored.\n\n";
}

echo "Ingestion complete.\n";
exit(0);

// ── Helpers ──────────────────────────────────────────────────────────────────

/**
 * Normalise extracted PDF text: collapse whitespace, fix ligatures, etc.
 */
function cleanText(string $text): string
{
    // Common PDF ligature replacements
    $ligatures = [
        'ﬁ' => 'fi', 'ﬂ' => 'fl', 'ﬀ' => 'ff',
        'ﬃ' => 'ffi', 'ﬄ' => 'ffl', 'ﬅ' => 'st',
    ];
    $text = strtr($text, $ligatures);

    // Collapse multiple spaces / newlines into single space
    $text = preg_replace('/\s+/', ' ', $text);

    // Remove non-printable characters except newlines
    $text = preg_replace('/[^\x09\x0A\x0D\x20-\x7E\xA0-\xFF]/u', '', $text);

    return trim($text);
}

/**
 * Call Ollama's /api/embeddings and return float[] or null on failure.
 */
function getEmbedding(string $text): ?array
{
    $payload = json_encode([
        'model'  => EMBED_MODEL,
        'prompt' => $text,
    ]);

    $ch = curl_init(OLLAMA_EMBED_URL);
    curl_setopt_array($ch, [
        CURLOPT_POST           => true,
        CURLOPT_POSTFIELDS     => $payload,
        CURLOPT_HTTPHEADER     => ['Content-Type: application/json'],
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT        => 30,
        CURLOPT_CONNECTTIMEOUT => 5,
    ]);

    $response = curl_exec($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if (!$response || $httpCode !== 200) {
        return null;
    }

    $data = json_decode($response, true);
    $embedding = $data['embedding'] ?? null;

    if (!is_array($embedding) || count($embedding) === 0) {
        return null;
    }

    return $embedding;
}