<?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) + 期刊信息 (name / scope 等)，
 * 生成一段 2-3 句的个性化描述，用于邮件模板变量 {{llm_description}}。
 *
 * 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 兜底描述（LLM 不可用 / 调用失败时使用）
 *
 * 返回约定：
 *   ['status' => 1|2|3, 'text' => string]
 *     1 = LLM 成功生成
 *     2 = LLM 调用失败，text = 兜底文案
 *     3 = 跳过（缺少代表作等前置条件），text = 兜底文案
 */
class PromotionLlmService
{
    private $url;
    private $model;
    private $timeout;
    private $apiKey;
    private $fallback;

    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.'));
    }

    /**
     * 生成个性化描述
     *
     * @param array $expert  至少包含 name / representative_work_title / fields / affiliation
     * @param array $journal 至少包含 title (name) / aims (可选) / databases (可选)
     * @return array ['status' => 1|2|3, 'text' => string]
     */
    public function generateDescription(array $expert, array $journal): array
    {
        $paperTitle  = trim((string)($expert['representative_work_title'] ?? ''));
        $expertName  = trim((string)($expert['name'] ?? ''));
        $journalName = trim((string)($journal['title'] ?? ''));

        if ($paperTitle === '' || $journalName === '') {
            return ['status' => 3, 'text' => $this->fallback];
        }

        if ($this->url === '' || $this->model === '') {
            return ['status' => 2, 'text' => $this->fallback];
        }

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

        $system = 'You are an academic editorial assistant. '
            . 'Write a short, warm, professional English paragraph (2-3 sentences, <=50 words) '
            . 'that: (1) briefly appreciates the author\'s recent paper, '
            . '(2) explains why it fits the journal\'s scope, '
            . '(3) gently invites a future submission. '
            . 'Do NOT use placeholders, do NOT add greetings, do NOT add signatures, '
            . 'output plain text only (no markdown).';

        $userLines = [];
        $userLines[] = 'Author name: ' . ($expertName !== '' ? $expertName : '(unknown)');
        if ($expertField !== '') {
            $userLines[] = 'Author research field: ' . $expertField;
        }
        $userLines[] = 'Recent paper title: ' . $paperTitle;
        $userLines[] = 'Target journal: ' . $journalName;
        if ($journalAims !== '') {
            $userLines[] = 'Journal aims & scope: ' . mb_substr($journalAims, 0, 500);
        }
        if ($journalDbs !== '') {
            $userLines[] = 'Journal indexing: ' . mb_substr($journalDbs, 0, 200);
        }
        $userLines[] = 'Return only the paragraph, nothing else.';
        $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 ['status' => 2, 'text' => $this->fallback];
        }

        $content = $this->cleanContent($content);
        if ($content === '') {
            return ['status' => 2, 'text' => $this->fallback];
        }

        return ['status' => 1, 'text' => $content];
    }

    /**
     * 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;
    }

    /**
     * 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);
    }

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