package com.wok.supportbot.service;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.wok.supportbot.config.EmbeddingModelFactory;
import com.wok.supportbot.dao.KnowledgeFaqMapper;
import com.wok.supportbot.entity.KnowledgeFaq;
import com.wok.supportbot.rag.CategoryFilter;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.ai.embedding.EmbeddingModel;
import org.springframework.ai.embedding.EmbeddingRequest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;

import java.util.*;
import java.util.concurrent.CompletableFuture;

/**
 * FAQ 三级匹配引擎
 * 1. 精确匹配：问题文本完全一致
 * 2. 关键词匹配：similar_questions 字段包含用户问题中的关键词
 * 3. 语义匹配：基于向量余弦距离的相似度匹配
 */
@Service
@Slf4j
public class FaqMatchEngine {

    @Autowired
    private KnowledgeFaqMapper faqMapper;

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Autowired
    private EmbeddingModelFactory embeddingModelFactory;

    @Autowired
    private CategoryFilter categoryFilter;

    @Autowired
    private PipelineToggleService pipelineToggleService;

    /** 向量维度，与 PgVectorStore 保持一致 */
    @Value("${knowledge.vector.dimension:1024}")
    private int vectorDimension;

    /** 语义匹配相似度阈值 */
    @Value("${knowledge.faq.semantic-threshold:0.85}")
    private double semanticThreshold;

    private final ObjectMapper objectMapper = new ObjectMapper();

    // ==================== 匹配结果内部类 ====================

    /**
     * FAQ 匹配结果
     */
    @Data
    @AllArgsConstructor
    public static class FaqMatchResult {
        /** 匹配到的 FAQ */
        private KnowledgeFaq faq;
        /** 匹配类型: EXACT / KEYWORD / SEMANTIC */
        private String matchType;
        /** 匹配分数 (0.0 ~ 1.0) */
        private double score;
    }

    // ==================== 核心匹配方法 ====================

    /**
     * 对用户问题进行三级匹配
     *
     * @param question    用户问题
     * @param categoryIds 角色授权分类 ID 列表（null/空表示不限制），未设置分类的 FAQ 一并可见
     * @return 匹配结果（可能为空）
     */
    public Optional<FaqMatchResult> match(String question, List<Long> categoryIds) {
        if (question == null || question.isBlank()) {
            return Optional.empty();
        }
        String trimmedQuestion = question.trim();

        // 第一级：精确匹配
        Optional<FaqMatchResult> exactResult = exactMatch(trimmedQuestion, categoryIds);
        if (exactResult.isPresent()) {
            log.info("FAQ 精确匹配命中: question={}", trimmedQuestion);
            return exactResult;
        }

        // 第二级：关键词匹配
        Optional<FaqMatchResult> keywordResult = keywordMatch(trimmedQuestion, categoryIds);
        if (keywordResult.isPresent()) {
            log.info("FAQ 关键词匹配命中: question={}", trimmedQuestion);
            return keywordResult;
        }

        // 第三级：语义匹配
        // 性能开关：pipeline_faq_semantic_enabled 关闭时跳过，只保留前两级（精确/关键词，均为本地 SQL，无网络调用）
        if (!pipelineToggleService.isFaqSemanticEnabled()) {
            log.info("FAQ 语义匹配已被后台关闭，跳过第三级: question={}", trimmedQuestion);
            return Optional.empty();
        }
        Optional<FaqMatchResult> semanticResult = semanticMatch(trimmedQuestion, categoryIds);
        if (semanticResult.isPresent()) {
            log.info("FAQ 语义匹配命中: question={}, score={}", trimmedQuestion, semanticResult.get().getScore());
            return semanticResult;
        }

        log.debug("FAQ 未匹配: question={}", trimmedQuestion);
        return Optional.empty();
    }

    // ==================== 第一级：精确匹配 ====================

    /**
     * 精确匹配：问题文本完全一致
     */
    private Optional<FaqMatchResult> exactMatch(String question, List<Long> categoryIds) {
        try {
            List<Object> params = new ArrayList<>();
            params.add(question);
            String categorySql = buildCategoryFilter(categoryIds, params, "category_id");
            List<KnowledgeFaq> results = jdbcTemplate.query(
                    "SELECT * FROM knowledge_faq WHERE question = ? AND status = 'ENABLED' AND is_delete = false"
                            + categorySql + " ORDER BY priority DESC LIMIT 1",
                    (rs, rowNum) -> mapRowToFaq(rs),
                    params.toArray()
            );
            if (!results.isEmpty()) {
                KnowledgeFaq faq = results.get(0);
                incrementHitCount(faq.getId());
                return Optional.of(new FaqMatchResult(faq, "EXACT", 1.0));
            }
        } catch (Exception e) {
            log.error("FAQ 精确匹配异常", e);
        }
        return Optional.empty();
    }

    // ==================== 第二级：关键词匹配 ====================

    /**
     * 关键词匹配：从用户问题中提取关键词，检查 similar_questions 是否包含
     */
    private Optional<FaqMatchResult> keywordMatch(String question, List<Long> categoryIds) {
        try {
            List<String> keywords = extractKeywords(question);
            if (keywords.isEmpty()) {
                return Optional.empty();
            }

            // 构建 ILIKE 条件
            StringBuilder sqlBuilder = new StringBuilder(
                    "SELECT * FROM knowledge_faq WHERE status = 'ENABLED' AND is_delete = false AND ("
            );
            List<Object> params = new ArrayList<>();
            for (int i = 0; i < keywords.size(); i++) {
                if (i > 0) {
                    sqlBuilder.append(" OR ");
                }
                sqlBuilder.append("similar_questions ILIKE ?");
                params.add("%" + keywords.get(i) + "%");
            }
            sqlBuilder.append(")");
            sqlBuilder.append(buildCategoryFilter(categoryIds, params, "category_id"));
            sqlBuilder.append(" ORDER BY priority DESC LIMIT 5");

            List<KnowledgeFaq> results = jdbcTemplate.query(
                    sqlBuilder.toString(),
                    (rs, rowNum) -> mapRowToFaq(rs),
                    params.toArray()
            );

            if (!results.isEmpty()) {
                KnowledgeFaq faq = results.get(0);
                return Optional.of(new FaqMatchResult(faq, "KEYWORD", 0.9));
            }
        } catch (Exception e) {
            log.error("FAQ 关键词匹配异常", e);
        }
        return Optional.empty();
    }

    /**
     * 简单分词：按空格、标点切分，过滤短词
     */
    private List<String> extractKeywords(String question) {
        String[] tokens = question.split("[\\s,，。？！?!、;；:：\"\"''\\(\\)（）\\[\\]【】]+");
        List<String> keywords = new ArrayList<>();
        for (String token : tokens) {
            String trimmed = token.trim();
            // 过滤长度小于2的token（避免单字匹配过于宽泛）
            if (trimmed.length() >= 2) {
                keywords.add(trimmed);
            }
        }
        return keywords;
    }

    // ==================== 第三级：语义匹配 ====================

    /**
     * 语义匹配：计算问题向量，在 faq_embedding 表中做余弦距离查询
     */
    private Optional<FaqMatchResult> semanticMatch(String question, List<Long> categoryIds) {
        try {
            // P2 门控：先确认作用域内确有可语义匹配的 FAQ（faq_embedding 有向量记录）。
            // 为空直接返回未命中，省掉一次注定失败的语义 embedding HTTP（豆包多模态模型逐条调用较慢）。
            List<Object> gateParams = new ArrayList<>();
            String gateSql = "SELECT 1 FROM faq_embedding fe " +
                    "JOIN knowledge_faq kf ON fe.faq_id = kf.id " +
                    "WHERE kf.status = 'ENABLED' AND kf.is_delete = false" +
                    buildCategoryFilter(categoryIds, gateParams, "kf.category_id") + " LIMIT 1";
            if (jdbcTemplate.queryForList(gateSql, gateParams.toArray()).isEmpty()) {
                log.debug("FAQ 语义候选为空，跳过语义 embedding: question={}", question);
                return Optional.empty();
            }

            EmbeddingModel embeddingModel = embeddingModelFactory.getEmbeddingModel();
            float[] embedding = embeddingModel.call(new EmbeddingRequest(List.of(question), null))
                    .getResult().getOutput();

            // 将向量转为 PGVector 格式字符串
            String vectorStr = toPgVectorFormat(embedding);

            List<Object> params = new ArrayList<>();
            params.add(vectorStr);
            String categorySql = buildCategoryFilter(categoryIds, params, "kf.category_id");

            // 余弦距离查询：<=> 运算符返回余弦距离，相似度 = 1 - distance
            List<Map<String, Object>> results = jdbcTemplate.queryForList(
                    "SELECT fe.faq_id, fe.embedding <=> ?::vector AS distance, " +
                            "kf.id, kf.question, kf.answer, kf.similar_questions, kf.category, kf.category_id, " +
                            "kf.status, kf.priority, kf.hit_count, kf.source, kf.create_time, kf.update_time, kf.is_delete " +
                            "FROM faq_embedding fe " +
                            "JOIN knowledge_faq kf ON fe.faq_id = kf.id " +
                            "WHERE kf.status = 'ENABLED' AND kf.is_delete = false" +
                            categorySql +
                            " ORDER BY distance ASC LIMIT 5",
                    params.toArray()
            );

            if (!results.isEmpty()) {
                Map<String, Object> topResult = results.get(0);
                double distance = ((Number) topResult.get("distance")).doubleValue();
                double similarity = 1.0 - distance;

                if (similarity >= semanticThreshold) {
                    KnowledgeFaq faq = mapResultToFaq(topResult);
                    incrementHitCount(faq.getId());
                    return Optional.of(new FaqMatchResult(faq, "SEMANTIC", similarity));
                }
            }
        } catch (Exception e) {
            log.error("FAQ 语义匹配异常", e);
        }
        return Optional.empty();
    }

    // ==================== 向量化方法 ====================

    /**
     * 计算并保存单条 FAQ 的向量嵌入
     *
     * @param faqId    FAQ ID
     * @param question FAQ 问题文本
     */
    public void computeAndSaveEmbedding(Long faqId, String question) {
        try {
            EmbeddingModel embeddingModel = embeddingModelFactory.getEmbeddingModel();
            float[] embedding = embeddingModel.call(new EmbeddingRequest(List.of(question), null))
                    .getResult().getOutput();

            String vectorStr = toPgVectorFormat(embedding);

            // 获取当前模型名称用于记录
            String modelName = "unknown";
            try {
                var config = embeddingModel.getClass().getSimpleName();
                modelName = config;
            } catch (Exception ignored) {
            }

            // 先删除旧记录，再插入新记录
            jdbcTemplate.update("DELETE FROM faq_embedding WHERE faq_id = ?", faqId);
            jdbcTemplate.update(
                    "INSERT INTO faq_embedding (faq_id, embedding, model_name) VALUES (?, ?::vector, ?)",
                    faqId, vectorStr, modelName
            );

            log.info("FAQ 向量已保存: faqId={}, dimension={}", faqId, embedding.length);
        } catch (Exception e) {
            log.error("FAQ 向量计算/保存失败: faqId={}", faqId, e);
        }
    }

    /**
     * 批量异步计算 FAQ 向量嵌入
     *
     * @param faqIds FAQ ID 列表
     */
    public void batchComputeEmbeddings(List<Long> faqIds) {
        CompletableFuture.runAsync(() -> {
            log.info("开始批量计算 FAQ 向量: count={}", faqIds.size());
            int success = 0;
            int fail = 0;
            for (Long faqId : faqIds) {
                try {
                    // 查询 FAQ 问题文本
                    String question = jdbcTemplate.queryForObject(
                            "SELECT question FROM knowledge_faq WHERE id = ? AND is_delete = false",
                            String.class, faqId
                    );
                    if (question != null) {
                        computeAndSaveEmbedding(faqId, question);
                        success++;
                    }
                } catch (Exception e) {
                    log.error("批量计算 FAQ 向量失败: faqId={}", faqId, e);
                    fail++;
                }
            }
            log.info("批量计算 FAQ 向量完成: success={}, fail={}", success, fail);
        });
    }

    // ==================== 工具方法 ====================

    /**
     * 构建 FAQ 分类过滤 SQL 片段。
     * 规则：授权分类（category_id IN ...）与未设置分类（category_id IS NULL 或 0）均可见，
     * 其余分类被隔离；分类列表为空时不加过滤（检索全部）。
     *
     * @param categoryIds 角色授权分类 ID 列表，可为 null/空
     * @param params      参数集合，本方法追加分类占位符参数
     * @param column      分类列名（单表为 category_id，联表为 kf.category_id）
     * @return SQL 片段（分类为空时返回空串）
     */
    private String buildCategoryFilter(List<Long> categoryIds, List<Object> params, String column) {
        List<String> ids = categoryFilter.normalize(categoryIds);
        if (ids.isEmpty()) {
            return "";
        }
        StringBuilder sb = new StringBuilder(" AND (").append(column).append(" IN (");
        for (int i = 0; i < ids.size(); i++) {
            if (i > 0) {
                sb.append(", ");
            }
            sb.append("?");
            params.add(Long.valueOf(ids.get(i)));
        }
        sb.append(") OR ").append(column).append(" IS NULL OR ").append(column).append(" = 0)");
        return sb.toString();
    }

    /**
     * 将 float[] 转为 PGVector 格式字符串: [0.1,0.2,0.3]
     */
    private String toPgVectorFormat(float[] embedding) {
        StringBuilder sb = new StringBuilder("[");
        for (int i = 0; i < embedding.length; i++) {
            if (i > 0) {
                sb.append(",");
            }
            sb.append(embedding[i]);
        }
        sb.append("]");
        return sb.toString();
    }

    /**
     * 增加 FAQ 命中次数
     */
    private void incrementHitCount(Long faqId) {
        try {
            jdbcTemplate.update("UPDATE knowledge_faq SET hit_count = hit_count + 1 WHERE id = ?", faqId);
        } catch (Exception e) {
            log.warn("更新 FAQ 命中次数失败: faqId={}", faqId, e);
        }
    }

    /**
     * 从 ResultSet 映射为 KnowledgeFaq 实体
     */
    private KnowledgeFaq mapRowToFaq(java.sql.ResultSet rs) throws java.sql.SQLException {
        KnowledgeFaq faq = new KnowledgeFaq();
        faq.setId(rs.getLong("id"));
        faq.setQuestion(rs.getString("question"));
        faq.setAnswer(rs.getString("answer"));
        faq.setSimilarQuestions(rs.getString("similar_questions"));
        faq.setCategory(rs.getString("category"));
        faq.setCategoryId(rs.getObject("category_id") != null ? rs.getLong("category_id") : null);
        faq.setStatus(rs.getString("status"));
        faq.setPriority(rs.getInt("priority"));
        faq.setHitCount(rs.getLong("hit_count"));
        faq.setSource(rs.getString("source"));
        faq.setCreateTime(rs.getTimestamp("create_time"));
        faq.setUpdateTime(rs.getTimestamp("update_time"));
        faq.setDelete(rs.getBoolean("is_delete"));
        return faq;
    }

    /**
     * 从 Map 结果映射为 KnowledgeFaq 实体（语义匹配使用）
     */
    private KnowledgeFaq mapResultToFaq(Map<String, Object> result) {
        KnowledgeFaq faq = new KnowledgeFaq();
        faq.setId(((Number) result.get("id")).longValue());
        faq.setQuestion((String) result.get("question"));
        faq.setAnswer((String) result.get("answer"));
        faq.setSimilarQuestions((String) result.get("similar_questions"));
        faq.setCategory((String) result.get("category"));
        faq.setCategoryId(result.get("category_id") != null ? ((Number) result.get("category_id")).longValue() : null);
        faq.setStatus((String) result.get("status"));
        faq.setPriority(((Number) result.get("priority")).intValue());
        faq.setHitCount(((Number) result.get("hit_count")).longValue());
        faq.setSource((String) result.get("source"));
        faq.setCreateTime(result.get("create_time") instanceof java.sql.Timestamp ts ? new Date(ts.getTime()) : null);
        faq.setUpdateTime(result.get("update_time") instanceof java.sql.Timestamp ts ? new Date(ts.getTime()) : null);
        faq.setDelete(Boolean.TRUE.equals(result.get("is_delete")));
        return faq;
    }
}