<?php

namespace app\common;

use think\Env;

/**
 * 中华医学会期刊 DOI（cma.j.cn）文献抓取：优先中文数据源。
 *
 * 1. 可选：Yiigle 机构资源 API（需配置 yiigle_api_base + yiigle_api_key）
 * 2. OpenAlex：常含中文摘要（abstract_inverted_index），中华期刊在 PubMed 无摘要时仍可用
 */
class CmaJournalLiteratureService
{
    private $timeout = 20;
    private $mailto = '';
    private $yiigleApiBase = '';
    private $yiigleApiKey = '';
    private $skipYiigle = false;

    public function __construct(array $config = [])
    {
        if (isset($config['mailto'])) {
            $this->mailto = trim((string)$config['mailto']);
        } else {
            $this->mailto = trim((string)Env::get('crossref_mailto', Env::get('pubmed_email', '')));
        }
        $this->yiigleApiBase = rtrim(trim((string)($config['yiigle_api_base'] ?? Env::get('yiigle_api_base', ''))), '/');
        $this->yiigleApiKey = trim((string)($config['yiigle_api_key'] ?? Env::get('yiigle_api_key', '')));
        $this->skipYiigle = !empty($config['skip_yiigle']);
    }

    public static function isCmaJournalDoi($doi)
    {
        $doi = strtolower(trim((string)$doi));

        return $doi !== '' && strpos($doi, 'cma.j.cn') !== false;
    }

    /**
     * @return array{
     *   title:string,journal:string,year:string,abstract:string,content:string,
     *   pmid:string,blocks:array,sources:array,fetch_log:string
     * }|null
     */
    public function fetchByDoi($doi)
    {
        $doi = $this->normalizeDoi($doi);
        if ($doi === '' || !self::isCmaJournalDoi($doi)) {
            return null;
        }

        $cacheKey = 'cma_lit_' . sha1(strtolower($doi));
        $cached = $this->cacheGet($cacheKey, 7 * 86400);
        if (is_array($cached)) {
            return $cached;
        }

        $blocks = [];
        $sources = [];
        $abstract = '';
        $content = '';
        $title = '';
        $journal = '';
        $year = '';
        $pmid = '';
        $logs = [];

        if (!$this->skipYiigle && $this->yiigleApiBase !== '' && $this->yiigleApiKey !== '') {
            $yiigle = $this->fetchFromYiigleApi($doi);
            if (is_array($yiigle)) {
                $sources[] = 'cma_yiigle';
                $title = $this->pickNonEmpty($title, $yiigle['title'] ?? '');
                $journal = $this->pickNonEmpty($journal, $yiigle['journal'] ?? '');
                $year = $this->pickNonEmpty($year, $yiigle['year'] ?? '');
                if (trim((string)($yiigle['abstract'] ?? '')) !== '') {
                    $abstract = trim((string)$yiigle['abstract']);
                }
                if (trim((string)($yiigle['content'] ?? '')) !== '') {
                    $content = trim((string)$yiigle['content']);
                }
                if (!empty($yiigle['block'])) {
                    $blocks[] = (string)$yiigle['block'];
                }
                $logs[] = 'yiigle=' . ($yiigle['status'] ?? 'ok');
            }
        }

        $openAlex = $this->fetchFromOpenAlex($doi);
        if (is_array($openAlex)) {
            $sources[] = 'cma_openalex';
            $title = $this->pickNonEmpty($title, $openAlex['title'] ?? '');
            $journal = $this->pickNonEmpty($journal, $openAlex['journal'] ?? '');
            $year = $this->pickNonEmpty($year, $openAlex['year'] ?? '');
            $pmid = $this->pickNonEmpty($pmid, $openAlex['pmid'] ?? '');
            if ($abstract === '' && trim((string)($openAlex['abstract'] ?? '')) !== '') {
                $abstract = trim((string)$openAlex['abstract']);
            }
            if (!empty($openAlex['block'])) {
                $blocks[] = (string)$openAlex['block'];
            }
            $logs[] = 'openalex=' . ($abstract !== '' ? 'abstract' : 'meta');
        }

        if ($abstract === '' && $content === '' && empty($blocks)) {
            return null;
        }

        $result = [
            'title'     => $title,
            'journal'   => $journal,
            'year'      => $year,
            'abstract'  => $abstract,
            'content'   => $content,
            'pmid'      => $pmid,
            'blocks'    => array_values(array_filter($blocks)),
            'sources'   => array_values(array_unique($sources)),
            'fetch_log' => 'cma_doi=' . $doi . '; ' . implode('; ', $logs),
        ];
        $this->cacheSet($cacheKey, $result);

        return $result;
    }

    private function fetchFromOpenAlex($doi)
    {
        $url = 'https://api.openalex.org/works/https://doi.org/' . rawurlencode($doi);
        if ($this->mailto !== '') {
            $url .= '?mailto=' . rawurlencode($this->mailto);
        }

        $raw = $this->httpGet($url);
        $json = json_decode((string)$raw, true);
        if (!is_array($json)) {
            return null;
        }

        $title = trim((string)($json['title'] ?? $json['display_name'] ?? ''));
        $journal = trim((string)($json['primary_location']['raw_source_name'] ?? ''));
        if ($journal === '') {
            $journal = trim((string)($json['primary_location']['source']['display_name'] ?? ''));
        }
        if (strcasecmp($journal, 'PubMed') === 0) {
            $journal = '';
        }
        $year = trim((string)($json['publication_year'] ?? ''));
        $abstract = $this->reconstructOpenAlexAbstract($json['abstract_inverted_index'] ?? null);
        if ($abstract === '') {
            $abstract = trim((string)($json['abstract'] ?? ''));
        }

        $pmid = '';
        $pmidRaw = (string)($json['ids']['pmid'] ?? '');
        if (preg_match('/(\d+)/', $pmidRaw, $m)) {
            $pmid = $m[1];
        }

        $lines = ['=== 中华医学期刊 / OpenAlex (DOI ' . $doi . ') ==='];
        if ($title !== '') {
            $lines[] = 'Title: ' . $title;
        }
        if ($journal !== '') {
            $lines[] = 'Journal: ' . $journal;
        }
        if ($year !== '') {
            $lines[] = 'Year: ' . $year;
        }
        if ($abstract !== '') {
            $lines[] = 'Abstract: ' . $abstract;
        }

        return [
            'title'     => $title,
            'journal'   => $journal,
            'year'      => $year,
            'abstract'  => $abstract,
            'pmid'      => $pmid,
            'block'     => implode("\n", $lines),
        ];
    }

    /**
     * 可选：机构购买的 Yiigle 资源 API（未配置则跳过）。
     */
    private function fetchFromYiigleApi($doi)
    {
        $url = $this->yiigleApiBase . '/resource/queryByDoi?doi=' . rawurlencode($doi);
        $raw = $this->httpGet($url, [
            'Authorization: Bearer ' . $this->yiigleApiKey,
            'Accept: application/json',
        ]);
        $json = json_decode((string)$raw, true);
        if (!is_array($json)) {
            return ['status' => 'empty'];
        }

        $data = $json['data'] ?? $json;
        if (!is_array($data)) {
            return ['status' => 'invalid'];
        }

        $abstract = trim((string)($data['abstract'] ?? $data['summary'] ?? ''));
        $content = trim((string)($data['content'] ?? $data['fullText'] ?? ''));
        $title = trim((string)($data['title'] ?? ''));
        $journal = trim((string)($data['journal'] ?? $data['journalName'] ?? ''));
        $year = trim((string)($data['year'] ?? $data['pubYear'] ?? ''));

        $block = '';
        if ($abstract !== '' || $content !== '') {
            $lines = ['=== 中华医学期刊网 Yiigle (DOI ' . $doi . ') ==='];
            if ($title !== '') {
                $lines[] = 'Title: ' . $title;
            }
            if ($abstract !== '') {
                $lines[] = 'Abstract: ' . $abstract;
            }
            if ($content !== '') {
                $lines[] = 'Content: ' . mb_substr($content, 0, 8000);
            }
            $block = implode("\n", $lines);
        }

        return [
            'status'   => ($abstract !== '' || $content !== '') ? 'ok' : 'no_text',
            'title'    => $title,
            'journal'  => $journal,
            'year'     => $year,
            'abstract' => $abstract,
            'content'  => $content,
            'block'    => $block,
        ];
    }

    private function reconstructOpenAlexAbstract($invertedIndex)
    {
        if (!is_array($invertedIndex) || empty($invertedIndex)) {
            return '';
        }

        $tokens = [];
        foreach ($invertedIndex as $token => $positions) {
            if (!is_array($positions)) {
                continue;
            }
            foreach ($positions as $pos) {
                $tokens[intval($pos)] = (string)$token;
            }
        }
        if (empty($tokens)) {
            return '';
        }
        ksort($tokens, SORT_NUMERIC);

        return trim(implode(' ', $tokens));
    }

    private function normalizeDoi($doi)
    {
        $doi = preg_replace('#^https?://(dx\.)?doi\.org/#i', '', trim((string)$doi));
        return trim($doi, " \t\n\r\0\x0B/");
    }

    private function pickNonEmpty($current, $candidate)
    {
        $current = trim((string)$current);
        $candidate = trim((string)$candidate);
        if ($current !== '') {
            return $current;
        }

        return $candidate;
    }

    private function httpGet($url, array $headers = [])
    {
        $headers = array_merge([
            'User-Agent: TMRjournals-CmaJournal/1.0',
            'Accept: application/json, text/plain, */*',
        ], $headers);

        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_CONNECTTIMEOUT => 10,
            CURLOPT_TIMEOUT        => $this->timeout,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_HTTPHEADER     => $headers,
        ]);
        $body = curl_exec($ch);
        $code = (int)curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($body === false || $code < 200 || $code >= 300) {
            return '';
        }

        return is_string($body) ? $body : '';
    }

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

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

        return is_array($decoded) ? $decoded : null;
    }

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