<?php

declare(strict_types=1);

// Run from the project checkout: php server/scripts/install_tcm_ancient_books.php
// Build the local search index from the corpus tracked in this repository.

require dirname(__DIR__) . '/vendor/autoload.php';

use app\common\service\TcmAncientBooksReference;

if (PHP_SAPI !== 'cli') {
    fwrite(STDERR, "CLI only\n");
    exit(1);
}

$root = dirname(__DIR__) . '/knowledge/tcm-ancient-books';
$indexPath = TcmAncientBooksReference::indexPath();

try {
    if (!is_dir($root)) {
        throw new RuntimeException('Bundled corpus directory is missing: ' . $root);
    }

    $terms = TcmAncientBooksReference::searchTerms();
    $termBytes = [];
    $chapterMarker = mb_convert_encoding('<篇名>', 'GB18030', 'UTF-8');
    foreach ($terms as $term) {
        $termBytes[$term] = mb_convert_encoding($term, 'GB18030', 'UTF-8');
    }
    $paths = glob($root . '/*.txt') ?: [];
    sort($paths, SORT_STRING);
    if (count($paths) !== 701) {
        throw new RuntimeException('Expected 701 source text files, found ' . count($paths));
    }

    $byTerm = array_fill_keys($terms, []);
    $chapterTerms = [];
    $invalidLineCount = 0;
    foreach ($paths as $path) {
        $filename = basename($path);
        $title = preg_replace('/^\d+[\-.]/u', '', preg_replace('/\.txt$/u', '', $filename) ?? $filename) ?? $filename;
        $chapter = '';
        $chapterTerm = '';
        $chapterBodyLines = 0;
        $bookHits = [];
        $file = new SplFileObject($path, 'r');
        $lineNumber = 0;
        while (!$file->eof()) {
            $raw = $file->fgets();
            if ($raw === false) {
                break;
            }
            $lineNumber++;
            if (!mb_check_encoding($raw, 'GB18030')) {
                // A few upstream files have malformed bytes. Preserve their original
                // line numbers and omit only those lines from the search index.
                $invalidLineCount++;
                continue;
            }
            if (str_contains($raw, $chapterMarker)) {
                $chapter = trim(mb_convert_encoding(str_replace($chapterMarker, '', $raw), 'UTF-8', 'GB18030'));
                $chapter = mb_substr($chapter, 0, 80, 'UTF-8');
                $chapterTerm = preg_replace('/第[一二三四五六七八九十百千万零〇0-9].*$/u', '', $chapter) ?? $chapter;
                $chapterTerm = preg_replace('/(?:脉证|病证|诸证|篇|论)$/u', '', $chapterTerm) ?? $chapterTerm;
                $chapterTerm = trim($chapterTerm, " \t\r\n　：:");
                if (mb_strlen($chapterTerm, 'UTF-8') < 2 || mb_strlen($chapterTerm, 'UTF-8') > 6
                    || preg_match('/^\p{Han}+$/u', $chapterTerm) !== 1
                    || in_array($chapterTerm, ['序言', '总论', '凡例', '目录', '医论', '医案', '方论', '药论', '本草', '脉法', '用药', '病机', '证治', '杂病'], true)) {
                    $chapterTerm = '';
                }
                $chapterBodyLines = 0;
                continue;
            }
            $line = trim(mb_convert_encoding($raw, 'UTF-8', 'GB18030'));
            if ($line === '' || str_starts_with($line, '书名：') || str_starts_with($line, '作者：')
                || str_starts_with($line, '<目录>')) {
                continue;
            }
            $chapterBodyLines++;
            if ($chapterTerm !== '' && $chapterBodyLines === 1) {
                $chapterTerms[$chapterTerm][] = [
                    'title' => $title, 'chapter' => $chapter,
                    'path' => $filename, 'line' => $lineNumber,
                    'excerpt' => mb_substr(preg_replace('/^内容：/u', '', $line) ?? $line, 0, 120, 'UTF-8'),
                    'score' => 12,
                ];
            }
            $matched = [];
            foreach ($termBytes as $term => $encoded) {
                $bodyMatch = str_contains($raw, $encoded);
                $chapterMatch = $chapterBodyLines <= 3 && mb_strpos($chapter, $term, 0, 'UTF-8') !== false;
                if ($bodyMatch || $chapterMatch) {
                    $matched[$term] = [$bodyMatch, $chapterMatch];
                }
            }
            if ($matched === []) {
                continue;
            }
            $line = preg_replace('/^内容：/u', '', $line) ?? $line;
            $line = preg_replace('/\s+/u', ' ', $line) ?? $line;
            foreach ($matched as $term => [$bodyMatch, $chapterMatch]) {
                $pos = mb_strpos($line, $term, 0, 'UTF-8');
                $start = max(0, (int) $pos - 55);
                $excerpt = mb_substr($line, $start, 180, 'UTF-8');
                $score = ($bodyMatch ? 5 : 0) + ($chapterMatch ? 10 : 0)
                    + (mb_strpos($title, $term, 0, 'UTF-8') !== false ? 3 : 0);
                if ($score > (int) ($bookHits[$term]['score'] ?? -1)) {
                    $bookHits[$term] = [
                        'title' => $title, 'chapter' => $chapter,
                        'path' => $filename, 'line' => $lineNumber,
                        'excerpt' => $excerpt, 'score' => $score,
                    ];
                }
            }
        }
        foreach ($bookHits as $term => $hit) {
            $byTerm[$term][] = $hit;
        }
    }
    foreach ($byTerm as &$hits) {
        usort($hits, static fn (array $a, array $b): int =>
            ($b['score'] <=> $a['score']) ?: strcmp($a['path'], $b['path']));
        $hits = array_slice($hits, 0, 30);
    }
    unset($hits);
    foreach ($chapterTerms as &$hits) {
        usort($hits, static fn (array $a, array $b): int => strcmp($a['path'], $b['path']));
        $hits = array_slice($hits, 0, 3);
    }
    unset($hits);
    $shardDirectory = TcmAncientBooksReference::shardDirectory();
    if (!is_dir($shardDirectory) && !mkdir($shardDirectory, 0755, true)) {
        throw new RuntimeException('Could not create chapter index directory');
    }
    $shards = [];
    foreach ($chapterTerms as $term => $hits) {
        $prefix = substr(hash('sha256', (string) $term), 0, 2);
        $shards[$prefix][$term] = $hits;
    }
    foreach ($shards as $prefix => $entries) {
        $shard = json_encode([
            'commit' => TcmAncientBooksReference::COMMIT,
            'index_version' => TcmAncientBooksReference::INDEX_VERSION,
            'terms' => $entries,
        ], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR);
        $shardPath = $shardDirectory . '/' . $prefix . '.json';
        $shardTemporary = $shardPath . '.tmp.' . getmypid();
        if (file_put_contents($shardTemporary, $shard, LOCK_EX) === false
            || !rename($shardTemporary, $shardPath)) {
            throw new RuntimeException('Could not write chapter index shard ' . $prefix);
        }
    }
    $index = [
        'repository' => 'local:tcm-ancient-books',
        'commit' => TcmAncientBooksReference::COMMIT,
        'index_version' => TcmAncientBooksReference::INDEX_VERSION,
        'encoding' => 'GB18030',
        'book_count' => count($paths),
        'skipped_invalid_lines' => $invalidLineCount,
        'terms' => $byTerm,
        'chapter_term_list' => array_keys($chapterTerms),
    ];
    $encoded = json_encode($index, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR);
    $temporary = $indexPath . '.tmp.' . getmypid();
    if (file_put_contents($temporary, $encoded, LOCK_EX) === false || !rename($temporary, $indexPath)) {
        throw new RuntimeException('Could not write index');
    }
    echo 'Indexed ' . count($paths) . ' books from source commit ' . TcmAncientBooksReference::COMMIT . ', ' . strlen($encoded)
        . ' index bytes, skipped ' . $invalidLineCount . " malformed lines.\n";
} catch (Throwable $error) {
    fwrite(STDERR, $error->getMessage() . "\n");
    exit(1);
}