// ═══════════════════════════════════════════════════════════════════════════
// query-expansion.js - 完整输入，不截断
// ═══════════════════════════════════════════════════════════════════════════

import { callLLM, parseJson } from './llm-service.js';
import { xbLog } from '../../../../core/debug-core.js';
import { filterText } from '../utils/text-filter.js';

const MODULE_ID = 'query-expansion';
const SESSION_ID = 'xb6';

const SYSTEM_PROMPT = `你是检索词生成器。根据最近对话，输出用于检索历史剧情的关键词。

只输出JSON：
{"e":["显式人物/地名"],"i":["隐含人物/情绪/话题"],"q":["检索短句"]}

规则：
- e: 对话中明确提到的人名/地名，1-4个
- i: 推断出的相关人物/情绪/话题，1-5个
- q: 用于向量检索的短句，2-3个，每个15字内
- 关注：正在讨论什么、涉及谁、情绪氛围`;

/**
 * Query Expansion
 * @param {Array} messages - 完整消息数组（最后2-3轮）
 */
export async function expandQuery(messages, options = {}) {
    const { timeout = 6000 } = options;

    if (!messages?.length) {
        return { entities: [], implicit: [], queries: [] };
    }

    // 完整格式化，不截断
    const input = messages.map(m => {
        const speaker = m.is_user ? '用户' : (m.name || '角色');
        const text = filterText(m.mes || '').trim();
        return `【${speaker}】\n${text}`;
    }).join('\n\n');

    const T0 = performance.now();

    try {
        const response = await callLLM([
            { role: 'system', content: SYSTEM_PROMPT },
            { role: 'user', content: input },
        ], {
            temperature: 0.15,
            max_tokens: 250,
            timeout,
            sessionId: SESSION_ID,
        });

        const parsed = parseJson(response);
        if (!parsed) {
            xbLog.warn(MODULE_ID, 'JSON解析失败', response?.slice(0, 200));
            return { entities: [], implicit: [], queries: [] };
        }

        const result = {
            entities: Array.isArray(parsed.e) ? parsed.e.slice(0, 5) : [],
            implicit: Array.isArray(parsed.i) ? parsed.i.slice(0, 6) : [],
            queries: Array.isArray(parsed.q) ? parsed.q.slice(0, 4) : [],
        };

        xbLog.info(MODULE_ID, `完成 (${Math.round(performance.now() - T0)}ms) e=${result.entities.length} i=${result.implicit.length} q=${result.queries.length}`);
        return result;

    } catch (e) {
        xbLog.error(MODULE_ID, '调用失败', e);
        return { entities: [], implicit: [], queries: [] };
    }
}

// 缓存
const cache = new Map();
const CACHE_TTL = 300000;

function hashMessages(messages) {
    const text = messages.slice(-2).map(m => (m.mes || '').slice(0, 100)).join('|');
    let h = 0;
    for (let i = 0; i < text.length; i++) h = ((h << 5) - h + text.charCodeAt(i)) | 0;
    return h.toString(36);
}

export async function expandQueryCached(messages, options = {}) {
    const key = hashMessages(messages);
    const cached = cache.get(key);
    if (cached && Date.now() - cached.time < CACHE_TTL) return cached.result;

    const result = await expandQuery(messages, options);
    if (result.entities.length || result.queries.length) {
        if (cache.size > 50) cache.delete(cache.keys().next().value);
        cache.set(key, { result, time: Date.now() });
    }
    return result;
}

export function buildSearchText(expansion) {
    return [...(expansion.entities || []), ...(expansion.implicit || []), ...(expansion.queries || [])]
        .filter(Boolean).join(' ');
}