<?php

namespace app\common;

/**
 * 引用相关性检测服务（PubMed + embedding）
 *
 * 依赖：
 * - PubmedService：用 DOI 抓取 title/abstract/mesh/publication_types
 * - CrossrefService：撤稿/更正识别（补充）
 *
 * embedding：
 * - 使用你们内部大模型的 embedding 接口（无需 token 付费，但速度慢）
 * - 通过构造参数传入 embedding_url / headers / timeout
 * - 内置文件缓存，减少重复 embedding 成本
 */
class CitationRelevanceService
{
    private $pubmed;
    private $crossref;

    private $embeddingUrl = '';
    private $embeddingHeaders = [];
    private $timeout = 120;
    private $chatUrl = '';
    private $chatModel = '';
    private $embeddingDim = 256;
    private $chatMaxTokens = 1200;

    public function __construct(PubmedService $pubmed = null, CrossrefService $crossref = null, array $config = [])
    {
        $this->pubmed = $pubmed ?: new PubmedService();
        $this->crossref = $crossref ?: new CrossrefService();

        if (isset($config['embedding_url'])) $this->embeddingUrl = (string)$config['embedding_url'];
        if (isset($config['embedding_headers']) && is_array($config['embedding_headers'])) $this->embeddingHeaders = $config['embedding_headers'];
        if (isset($config['timeout'])) $this->timeout = max(10, intval($config['timeout']));
        if (isset($config['chat_url'])) $this->chatUrl = (string)$config['chat_url'];
        if (isset($config['chat_model'])) $this->chatModel = (string)$config['chat_model'];
        if (isset($config['embedding_dim'])) $this->embeddingDim = max(32, intval($config['embedding_dim']));
        if (isset($config['chat_max_tokens'])) $this->chatMaxTokens = max(256, intval($config['chat_max_tokens']));
    }

    /**
     * 单条引用相关性检测
     *
     * @param string $contextText 引用处上下文（英文）
     * @param array $referRow production_article_refer 行（至少含 refer_doi/doilink/title/author/joura/dateno）
     * @param array $options
     *  - sentence_is_background(bool) 若外部已判断为背景堆引用，可直接降级
     *  - sim_related(float) related 阈值，默认 0.75
     *  - sim_unsure(float) unsure 阈值，默认 0.60
     *  - check_retraction(bool) 是否检查撤稿/更正，默认 true
     */
    public function checkOne(string $contextText, array $referRow, array $options = []): array
    {
        $contextText = trim($contextText);
        $simRelated = isset($options['sim_related']) ? (float)$options['sim_related'] : 0.75;
        $simUnsure = isset($options['sim_unsure']) ? (float)$options['sim_unsure'] : 0.60;
        $checkRetraction = isset($options['check_retraction']) ? (bool)$options['check_retraction'] : true;
        $isBackground = !empty($options['sentence_is_background']);

        // 1) 问题条目（退稿/更正）：先 Crossref（有 DOI 才能判断）
        $problemFlag = 'unknown';
        $problemReason = '';
        if ($checkRetraction) {
            $qc = $this->crossref->qcCitation($contextText, $referRow, ['check_retraction' => true]);
            $problemFlag = $qc['problem_flag'] ?? 'unknown';
            $problemReason = $qc['problem_reason'] ?? '';
        }

        // 2) PubMed 抓取 abstract/mesh（提升语义）
        $doi = $this->extractDoiFromRefer($referRow);
        $pub = $doi ? $this->pubmed->fetchByDoi($doi) : null;

        $pubText = '';
        $pubTypes = [];
        if ($pub) {
            $pubTypes = $pub['publication_types'] ?? [];
            $mesh = $pub['mesh_terms'] ?? [];
            $pubText = trim(
                ($pub['title'] ?? '') . "\n" .
                ($pub['abstract'] ?? '') . "\n" .
                (!empty($mesh) ? ('MeSH: ' . implode('; ', $mesh)) : '')
            );
        }

        // 3) embedding 相似度（context vs pubmed_text），无 pubmed_text 则退化为 crossref 的证据法
        if ($pubText !== '') {
            $v1 = $this->embedCached($contextText);
            $v2 = $this->embedCached($pubText);
            $sim = ($v1 && $v2) ? $this->cosine($v1, $v2) : 0.0;

            $relevanceFlag = 'unsure';
            if ($sim >= $simRelated) {
                $relevanceFlag = 'related';
            } elseif ($sim >= $simUnsure) {
                $relevanceFlag = 'unsure';
            } else {
                $relevanceFlag = $isBackground ? 'unsure_background' : 'suspicious_unrelated';
            }

            // PubMed 自身也能提示撤稿/更正（作为补充）
            if ($checkRetraction && $problemFlag !== 'retracted_or_corrected' && !empty($pubTypes)) {
                $ptLower = strtolower(implode(' | ', $pubTypes));
                if (strpos($ptLower, 'retracted publication') !== false
                    || strpos($ptLower, 'retraction of publication') !== false
                    || strpos($ptLower, 'published erratum') !== false
                ) {
                    $problemFlag = 'retracted_or_corrected';
                    $problemReason = 'PubMed publication type indicates retraction/correction';
                }
            }

            return [
                'problem_flag' => $problemFlag,
                'problem_reason' => $problemReason,
                'relevance_flag' => $relevanceFlag,
                'relevance_score' => round($sim, 4),
                'reason' => $pubText !== '' ? 'embedding(context,pubmed_text)' : 'embedding_unavailable',
                'pubmed' => [
                    'pmid' => $pub['pmid'] ?? '',
                    'year' => $pub['year'] ?? '',
                    'journal' => $pub['journal'] ?? '',
                    'publication_types' => $pubTypes,
                ],
            ];
        }

        // 退化：没有 PubMed 信息时，用 CrossrefService 证据法（会偏保守）
        $fallback = $this->crossref->qcCitation($contextText, $referRow, ['check_retraction' => false]);
        $fallback['problem_flag'] = $problemFlag;
        $fallback['problem_reason'] = $problemReason;
        $fallback['reason'] = 'fallback_crossref_evidence; ' . ($fallback['reason'] ?? '');
        return $fallback;
    }

    // ---------------- embedding ----------------

    private function embedCached(string $text): ?array
    {
        $text = trim($text);
        if ($text === '') return null;

        $key = 'emb_' . sha1($text);
        $cached = $this->cacheGet($key, 90 * 86400);
        if (is_array($cached) && !empty($cached)) return $cached;

        $vec = $this->embed($text);
        if (is_array($vec) && !empty($vec)) {
            $this->cacheSet($key, $vec);
            return $vec;
        }
        return null;
    }

    /**
     * 调用内部 embedding 接口
     * 兼容返回格式：
     * - OpenAI embeddings: {data:[{embedding:[...] }]}
     * - {embedding:[...]}
     * - 直接返回数组 [...]
     */
    private function embed(string $text): ?array
    {
        // 1) 优先使用独立 embeddings 接口
        if ($this->embeddingUrl !== '') {
            $payload = json_encode(['text' => $text], JSON_UNESCAPED_UNICODE);
            $ch = curl_init();
            curl_setopt($ch, CURLOPT_URL, $this->embeddingUrl);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
            curl_setopt($ch, CURLOPT_TIMEOUT, $this->timeout);
            curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
            curl_setopt($ch, CURLOPT_POST, true);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);

            $headers = array_merge(['Content-Type: application/json'], $this->embeddingHeaders);
            curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

            $res = curl_exec($ch);
            curl_close($ch);
            if (!is_string($res) || trim($res) === '') return null;

            $decoded = json_decode($res, true);
            if (is_array($decoded)) {
                if (isset($decoded['data'][0]['embedding']) && is_array($decoded['data'][0]['embedding'])) {
                    return $this->normalizeVector($decoded['data'][0]['embedding']);
                }
                if (isset($decoded['embedding']) && is_array($decoded['embedding'])) {
                    return $this->normalizeVector($decoded['embedding']);
                }
                $isVec = isset($decoded[0]) && (is_float($decoded[0]) || is_int($decoded[0]));
                if ($isVec) return $this->normalizeVector($decoded);
            }
            return null;
        }

        // 2) 没有 embeddings 接口时，使用 chat/completions 生成固定维度向量
        if ($this->chatUrl === '' || $this->chatModel === '') {
            return null;
        }

        $sys = "You are an embedding generator. Output ONLY valid JSON in this exact shape: {\"embedding\":[...]}.\n"
            . "Rules:\n"
            . "- embedding must be an array of exactly {$this->embeddingDim} floats\n"
            . "- each float must be between -1 and 1\n"
            . "- do not include any other keys or any extra text\n";

        $payload = json_encode([
            'model' => $this->chatModel,
            'temperature' => 0,
            'max_tokens' => $this->chatMaxTokens,
            'messages' => [
                ['role' => 'system', 'content' => $sys],
                ['role' => 'user', 'content' => $text],
            ],
        ], JSON_UNESCAPED_UNICODE);

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->chatUrl);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_TIMEOUT, $this->timeout);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);

        $headers = array_merge(['Content-Type: application/json'], $this->embeddingHeaders);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

        $res = curl_exec($ch);
        curl_close($ch);
        if (!is_string($res) || trim($res) === '') return null;

        $decoded = json_decode($res, true);
        $content = '';
        if (is_array($decoded) && isset($decoded['choices'][0]['message']['content'])) {
            $content = (string)$decoded['choices'][0]['message']['content'];
        }
        $content = trim($content);
        if ($content === '') return null;

        // content 可能被包裹在 ```json ... ```
        if (preg_match('/```(?:json)?\\s*([\\s\\S]*?)\\s*```/i', $content, $m)) {
            $content = trim($m[1]);
        }
        $j = json_decode($content, true);
        if (!is_array($j) || !isset($j['embedding']) || !is_array($j['embedding'])) {
            return null;
        }

        $vec = $j['embedding'];
        if (count($vec) !== $this->embeddingDim) {
            return null;
        }
        return $this->normalizeVector($vec);
    }

    private function cosine(array $a, array $b): float
    {
        $n = min(count($a), count($b));
        if ($n <= 0) return 0.0;
        $dot = 0.0; $na = 0.0; $nb = 0.0;
        for ($i = 0; $i < $n; $i++) {
            $x = (float)$a[$i];
            $y = (float)$b[$i];
            $dot += $x * $y;
            $na += $x * $x;
            $nb += $y * $y;
        }
        if ($na <= 0.0 || $nb <= 0.0) return 0.0;
        return $dot / (sqrt($na) * sqrt($nb));
    }

    private function normalizeVector(array $v): array
    {
        $sum = 0.0;
        $out = [];
        foreach ($v as $x) {
            $fx = (float)$x;
            $out[] = $fx;
            $sum += $fx * $fx;
        }
        if ($sum <= 0.0) return $out;
        $norm = sqrt($sum);
        for ($i = 0; $i < count($out); $i++) {
            $out[$i] = $out[$i] / $norm;
        }
        return $out;
    }

    private function extractDoiFromRefer(array $referRow): string
    {
        // 复用 CrossrefService 内部逻辑（通过 qcCitation 的抽取函数不可直接访问，所以这里简单实现）
        $doi = trim((string)($referRow['refer_doi'] ?? ''));
        if ($doi !== '') return $doi;

        $doilink = trim((string)($referRow['doilink'] ?? ''));
        if ($doilink === '') return '';
        if (preg_match('#doi\\.org/([^?#]+)#i', $doilink, $m)) {
            return trim((string)$m[1]);
        }
        return $doilink;
    }

    // ---------------- cache ----------------

    private function cacheDir(): string
    {
        return rtrim(ROOT_PATH, '/') . '/runtime/embed_cache';
    }

    private function cacheGet(string $key, int $ttlSeconds)
    {
        $file = $this->cacheDir() . '/' . $key . '.json';
        if (!is_file($file)) return null;
        $mtime = filemtime($file);
        if (!$mtime || (time() - $mtime) > $ttlSeconds) return null;
        $raw = @file_get_contents($file);
        $decoded = json_decode((string)$raw, true);
        return $decoded;
    }

    private function cacheSet(string $key, $value): void
    {
        $dir = $this->cacheDir();
        if (!is_dir($dir)) @mkdir($dir, 0777, true);
        $file = $dir . '/' . $key . '.json';
        @file_put_contents($file, json_encode($value, JSON_UNESCAPED_UNICODE));
    }
}