<?php

namespace app\common;

use think\Env;

/**
 * 推广邮件 LLM 服务
 *
 * 作用：基于 expert 的代表作 (paper_title)、expert 的研究领域、期刊信息 (name / scope / fields 等)，
 *      通过一次 LLM 调用同时生成两段邮件内容：
 *        - description    个性化赞美 + 邀稿段落（对应模板变量 {{ai_content_analysis}} / {{llm_description}}）
 *        - advised_topics "我们特别关注 X / Y / Z 领域" 段落（对应模板变量 {{ai_advised_topics}}）
 *
 * 单次调用返回 JSON，避免两次 LLM 请求导致的延迟翻倍；任一段失败可独立兜底。
 *
 * 配置（.env 的 [promotion] 段）：
 *   PROMOTION_LLM_URL               chat/completions 接口地址
 *   PROMOTION_LLM_MODEL             模型名
 *   PROMOTION_LLM_TIMEOUT           超时时间(秒)，默认 30
 *   PROMOTION_LLM_FALLBACK          description 兜底文案
 *   PROMOTION_LLM_ADVISED_FALLBACK  advised_topics 兜底文案
 *
 * 状态约定：
 *   1 = LLM 成功生成
 *   2 = LLM 调用失败 / 解析失败，使用兜底
 *   3 = 前置条件不足（缺代表作、缺交集等），使用兜底
 */
class PromotionLlmService
{
    private $url;
    private $model;
    private $timeout;
    private $apiKey;
    private $fallback;
    private $advisedFallback;

    public function __construct()
    {
        $this->url      = trim((string)Env::get('promotion.promotion_llm_url', ''));
        $this->model    = trim((string)Env::get('promotion.promotion_llm_model', ''));
        $this->timeout  = max(5, intval(Env::get('promotion.promotion_llm_timeout', 30)));
        $this->apiKey   = trim((string)Env::get('promotion.promotion_llm_api_key', ''));
        $this->fallback = trim((string)Env::get('promotion.promotion_llm_fallback',
            'Your recent work aligns closely with the scope of our journal, and we would be honored to consider a contribution from you.'));
        $this->advisedFallback = trim((string)Env::get('promotion.promotion_llm_advised_fallback',
            'We are especially interested in the research directions that align with your expertise, and warmly welcome your future submissions in these areas.'));
    }

    /**
     * 一次 LLM 调用生成邮件两段内容。
     *
     * @param array $expert         expert 行（含 name / representative_work_title / fields 等）
     * @param array $journal        journal 行（含 title / aims / databases 等）
     * @param array $overlapFields  预先计算的 expert & journal 领域交集（可能为空）
     * @param array $journalFields  journal（或 task/工厂）的目标领域
     * @param array $expertFields   expert 的研究领域
     * @return array [
     *   'description'            => string,
     *   'description_status'     => 1|2|3,
     *   'advised_topics'         => string,
     *   'advised_topics_status'  => 1|2|3,
     * ]
     */
    public function generateEmailContent(
        array $expert,
        array $journal,
        array $overlapFields = [],
        array $journalFields = [],
        array $expertFields = []
    ): array {
        $paperTitle  = trim((string)($expert['representative_work_title'] ?? ''));
        $expertName  = trim((string)($expert['name'] ?? ''));
        $journalName = trim((string)($journal['title'] ?? ''));

        $overlapList  = $this->cleanList($overlapFields);
        $journalList  = $this->cleanList($journalFields);
        $expertList   = $this->cleanList($expertFields);

        $hasDescInput    = ($paperTitle !== '' && $journalName !== '');
        $hasAdvisedInput = (!empty($overlapList) || (!empty($journalList) && !empty($expertList)));

        // 两段都缺输入时直接走双兜底
        if (!$hasDescInput && !$hasAdvisedInput) {
            return $this->allFallback(3, 3);
        }

        // LLM 未配置
        if ($this->url === '' || $this->model === '') {
            return $this->allFallback(
                $hasDescInput ? 2 : 3,
                $hasAdvisedInput ? 2 : 3
            );
        }

        $expertField = trim((string)($expert['fields'] ?? ($expert['field'] ?? '')));
        $journalAims = trim((string)($journal['aims'] ?? ''));
        $journalDbs  = trim((string)($journal['databases'] ?? ''));

        $system = 'You are an academic editorial assistant. '
            . 'You will receive context about an author, their recent paper, and a target journal, '
            . 'and you must produce TWO English paragraphs for an invitation email. '
            . 'Output STRICT MINIFIED JSON ONLY with exactly these keys:'
            . '{"description":"...","advised_topics":"..."} '
            . 'Rules for "description": 2-3 sentences, <=50 words, warm and professional; '
            . '(a) briefly appreciate the author\'s recent paper, '
            . '(b) explain why it fits the journal\'s scope, '
            . '(c) gently invite a future submission. '
            . 'Rules for "advised_topics": 1-2 sentences, <=40 words; '
            . 'emphasize that the journal is particularly interested in the research directions '
            . 'where the journal\'s focus and the author\'s work overlap; '
            . 'mention the overlapping topics explicitly (use the provided overlap list when non-empty, '
            . 'otherwise choose the best semantic overlap between journal focus and author fields); '
            . 'end by inviting contributions leaning toward those directions. '
            . 'No greetings, no signatures, no placeholders, no markdown, no code fences. '
            . 'If a section genuinely cannot be produced, return an empty string for that key.';

        $userLines = [];
        $userLines[] = 'Author name: ' . ($expertName !== '' ? $expertName : '(unknown)');
        if ($expertField !== '') {
            $userLines[] = 'Author research field (raw): ' . $expertField;
        }
        if (!empty($expertList)) {
            $userLines[] = 'Author research fields (list): ' . implode(', ', $expertList);
        }
        $userLines[] = 'Recent paper title: ' . ($paperTitle !== '' ? $paperTitle : '(none)');
        $userLines[] = 'Target journal: ' . ($journalName !== '' ? $journalName : '(unknown)');
        if (!empty($journalList)) {
            $userLines[] = 'Journal focus fields: ' . implode(', ', $journalList);
        }
        if (!empty($overlapList)) {
            $userLines[] = 'Overlap topics (exact match): ' . implode(', ', $overlapList);
        } else {
            $userLines[] = 'Overlap topics (exact match): (none, infer semantically from the two field lists above)';
        }
        if ($journalAims !== '') {
            $userLines[] = 'Journal aims & scope: ' . mb_substr($journalAims, 0, 500);
        }
        if ($journalDbs !== '') {
            $userLines[] = 'Journal indexing: ' . mb_substr($journalDbs, 0, 200);
        }
        $userLines[] = 'Return only minified JSON {"description":"...","advised_topics":"..."}.';
        $user = implode("\n", $userLines);

        $payload = [
            'model'       => $this->model,
            'temperature' => 0.4,
            'messages'    => [
                ['role' => 'system', 'content' => $system],
                ['role' => 'user',   'content' => $user],
            ],
        ];

        $content = $this->postChat($payload);
        if ($content === null) {
            return $this->allFallback(
                $hasDescInput ? 2 : 3,
                $hasAdvisedInput ? 2 : 3
            );
        }

        $parsed = $this->parseJson($content);
        if ($parsed === null) {
            return $this->allFallback(
                $hasDescInput ? 2 : 3,
                $hasAdvisedInput ? 2 : 3
            );
        }

        $desc    = $this->cleanContent((string)($parsed['description'] ?? ''));
        $advised = $this->cleanContent((string)($parsed['advised_topics'] ?? ''));

        $descStatus = 1;
        if ($desc === '') {
            $desc = $this->fallback;
            $descStatus = $hasDescInput ? 2 : 3;
        }

        $advisedStatus = 1;
        if ($advised === '') {
            $advised = $this->advisedFallback;
            $advisedStatus = $hasAdvisedInput ? 2 : 3;
        }

        return [
            'description'           => $desc,
            'description_status'    => $descStatus,
            'advised_topics'        => $advised,
            'advised_topics_status' => $advisedStatus,
        ];
    }

    /**
     * 兼容旧接口：单段 description 生成（仍走 generateEmailContent，取第一段）
     *
     * @return array ['status' => 1|2|3, 'text' => string]
     */
    public function generateDescription(array $expert, array $journal): array
    {
        $r = $this->generateEmailContent($expert, $journal);
        return [
            'status' => intval($r['description_status']),
            'text'   => (string)$r['description'],
        ];
    }

    /**
     * 调用 chat/completions 接口，返回 content 字符串；失败返回 null。
     */
    private function postChat(array $payload)
    {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->url);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload, JSON_UNESCAPED_UNICODE));
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, min(10, $this->timeout));
        curl_setopt($ch, CURLOPT_TIMEOUT, $this->timeout);

        $headers = ['Content-Type: application/json'];
        if ($this->apiKey !== '') {
            $headers[] = 'Authorization: Bearer ' . $this->apiKey;
        }
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

        $raw = curl_exec($ch);
        if ($raw === false) {
            curl_close($ch);
            return null;
        }
        $httpCode = intval(curl_getinfo($ch, CURLINFO_HTTP_CODE));
        curl_close($ch);
        if ($httpCode < 200 || $httpCode >= 300) {
            return null;
        }

        $data = json_decode($raw, true);
        if (!is_array($data)) return null;

        if (isset($data['choices'][0]['message']['content'])) {
            return (string)$data['choices'][0]['message']['content'];
        }
        if (isset($data['content'])) {
            return (string)$data['content'];
        }
        return null;
    }

    /**
     * 从模型原始输出里提取 JSON 对象；失败返回 null。
     */
    private function parseJson(string $raw)
    {
        $raw = trim($raw);
        if ($raw === '') return null;
        $raw = preg_replace('/^```[a-zA-Z]*\s*|```$/m', '', $raw);
        $raw = trim($raw);

        // 直接 decode
        $obj = json_decode($raw, true);
        if (is_array($obj)) return $obj;

        // 抓出第一个 {...} 块再 decode
        if (preg_match('/\{.*\}/s', $raw, $m)) {
            $obj = json_decode($m[0], true);
            if (is_array($obj)) return $obj;
        }
        return null;
    }

    /**
     * 清洗 LLM 输出：去除 markdown 包裹、多余空白、首尾引号、过长截断。
     */
    private function cleanContent(string $text): string
    {
        $text = trim($text);
        $text = preg_replace('/^```[a-zA-Z]*\s*|```$/m', '', $text);
        $text = trim($text);
        $text = trim($text, "\"' \t\n\r\0\x0B");
        $text = preg_replace('/\s+/', ' ', $text);
        if (mb_strlen($text) > 800) {
            $text = mb_substr($text, 0, 800);
        }
        return trim($text);
    }

    /**
     * 对领域列表做 trim / 去空 / 去重，保留首次出现顺序。
     */
    private function cleanList(array $list): array
    {
        $out = [];
        $seen = [];
        foreach ($list as $item) {
            $v = trim((string)$item);
            if ($v === '') continue;
            $key = strtolower($v);
            if (isset($seen[$key])) continue;
            $seen[$key] = true;
            $out[] = $v;
        }
        return $out;
    }

    private function allFallback(int $descStatus, int $advisedStatus): array
    {
        return [
            'description'           => $this->fallback,
            'description_status'    => $descStatus,
            'advised_topics'        => $this->advisedFallback,
            'advised_topics_status' => $advisedStatus,
        ];
    }

    public function getFallback(): string
    {
        return $this->fallback;
    }

    public function getAdvisedFallback(): string
    {
        return $this->advisedFallback;
    }
}