package com.vincent.rsf.server.ai.service.impl.conversation;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.vincent.rsf.framework.common.Cools;
import com.vincent.rsf.framework.exception.CoolException;
import com.vincent.rsf.server.ai.config.AiDefaults;
import com.vincent.rsf.server.ai.dto.AiChatMemoryDto;
import com.vincent.rsf.server.ai.dto.AiChatMessageDto;
import com.vincent.rsf.server.ai.dto.AiChatSessionDto;
import com.vincent.rsf.server.ai.entity.AiChatMessage;
import com.vincent.rsf.server.ai.entity.AiChatSession;
import com.vincent.rsf.server.ai.mapper.AiChatMessageMapper;
import com.vincent.rsf.server.ai.mapper.AiChatSessionMapper;
import com.vincent.rsf.server.ai.store.AiConversationCacheStore;
import com.vincent.rsf.server.system.enums.StatusType;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

@Service
@RequiredArgsConstructor
public class AiConversationQueryService {

    private final AiChatSessionMapper aiChatSessionMapper;
    private final AiChatMessageMapper aiChatMessageMapper;
    private final AiConversationCacheStore aiConversationCacheStore;

    public AiChatMemoryDto getMemory(Long userId, Long tenantId, String promptCode, Long sessionId) {
        ensureIdentity(userId, tenantId);
        String resolvedPromptCode = requirePromptCode(promptCode);
        AiChatMemoryDto cached = aiConversationCacheStore.getMemory(tenantId, userId, resolvedPromptCode, sessionId);
        if (cached != null) {
            return cached;
        }
        AiChatSession session = sessionId == null
                ? findLatestSession(userId, tenantId, resolvedPromptCode)
                : getSession(sessionId, userId, tenantId, resolvedPromptCode);
        AiChatMemoryDto memory;
        if (session == null) {
            memory = AiChatMemoryDto.builder()
                    .sessionId(null)
                    .memorySummary(null)
                    .memoryFacts(null)
                    .recentMessageCount(0)
                    .persistedMessages(List.of())
                    .shortMemoryMessages(List.of())
                    .build();
            aiConversationCacheStore.cacheMemory(tenantId, userId, resolvedPromptCode, sessionId, memory);
            return memory;
        }
        List<AiChatMessageDto> persistedMessages = listMessages(session.getId());
        List<AiChatMessageDto> shortMemoryMessages = tailMessagesByRounds(persistedMessages, AiDefaults.MEMORY_RECENT_ROUNDS);
        memory = AiChatMemoryDto.builder()
                .sessionId(session.getId())
                .memorySummary(session.getMemorySummary())
                .memoryFacts(session.getMemoryFacts())
                .recentMessageCount(shortMemoryMessages.size())
                .persistedMessages(persistedMessages)
                .shortMemoryMessages(shortMemoryMessages)
                .build();
        aiConversationCacheStore.cacheMemory(tenantId, userId, resolvedPromptCode, session.getId(), memory);
        if (sessionId == null || !session.getId().equals(sessionId)) {
            aiConversationCacheStore.cacheMemory(tenantId, userId, resolvedPromptCode, null, memory);
        }
        return memory;
    }

    public List<AiChatSessionDto> listSessions(Long userId, Long tenantId, String promptCode, String keyword) {
        ensureIdentity(userId, tenantId);
        String resolvedPromptCode = requirePromptCode(promptCode);
        List<AiChatSessionDto> cached = aiConversationCacheStore.getSessionList(tenantId, userId, resolvedPromptCode, keyword);
        if (cached != null) {
            return cached;
        }
        List<AiChatSession> sessions = aiChatSessionMapper.selectList(new LambdaQueryWrapper<AiChatSession>()
                .eq(AiChatSession::getUserId, userId)
                .eq(AiChatSession::getTenantId, tenantId)
                .eq(AiChatSession::getPromptCode, resolvedPromptCode)
                .eq(AiChatSession::getDeleted, 0)
                .eq(AiChatSession::getStatus, StatusType.ENABLE.val)
                .like(StringUtils.hasText(keyword), AiChatSession::getTitle, keyword == null ? null : keyword.trim())
                .orderByDesc(AiChatSession::getPinned)
                .orderByDesc(AiChatSession::getLastMessageTime)
                .orderByDesc(AiChatSession::getId));
        if (Cools.isEmpty(sessions)) {
            aiConversationCacheStore.cacheSessionList(tenantId, userId, resolvedPromptCode, keyword, List.of());
            return List.of();
        }
        List<Long> sessionIds = sessions.stream().map(AiChatSession::getId).toList();
        Map<Long, AiChatMessage> latestMessageMap = new LinkedHashMap<>();
        for (AiChatMessage message : aiChatMessageMapper.selectLatestMessagesBySessionIds(sessionIds)) {
            latestMessageMap.put(message.getSessionId(), message);
        }
        List<AiChatSessionDto> result = new ArrayList<>();
        for (AiChatSession session : sessions) {
            result.add(buildSessionDto(session, latestMessageMap.get(session.getId())));
        }
        aiConversationCacheStore.cacheSessionList(tenantId, userId, resolvedPromptCode, keyword, result);
        return result;
    }

    public void evictConversationCaches(Long tenantId, Long userId) {
        aiConversationCacheStore.evictUserConversationCaches(tenantId, userId);
    }

    public AiChatSession findLatestSession(Long userId, Long tenantId, String promptCode) {
        return aiChatSessionMapper.selectOne(new LambdaQueryWrapper<AiChatSession>()
                .eq(AiChatSession::getUserId, userId)
                .eq(AiChatSession::getTenantId, tenantId)
                .eq(AiChatSession::getPromptCode, promptCode)
                .eq(AiChatSession::getDeleted, 0)
                .eq(AiChatSession::getStatus, StatusType.ENABLE.val)
                .orderByDesc(AiChatSession::getLastMessageTime)
                .orderByDesc(AiChatSession::getId)
                .last("limit 1"));
    }

    public AiChatSession getSession(Long sessionId, Long userId, Long tenantId, String promptCode) {
        AiChatSession session = aiChatSessionMapper.selectOne(new LambdaQueryWrapper<AiChatSession>()
                .eq(AiChatSession::getId, sessionId)
                .eq(AiChatSession::getUserId, userId)
                .eq(AiChatSession::getTenantId, tenantId)
                .eq(AiChatSession::getPromptCode, promptCode)
                .eq(AiChatSession::getDeleted, 0)
                .eq(AiChatSession::getStatus, StatusType.ENABLE.val)
                .last("limit 1"));
        if (session == null) {
            throw new CoolException("AI 会话不存在或无权访问");
        }
        return session;
    }

    public AiChatSession requireOwnedSession(Long sessionId, Long userId, Long tenantId) {
        if (sessionId == null) {
            throw new CoolException("AI 会话 ID 不能为空");
        }
        AiChatSession session = aiChatSessionMapper.selectOne(new LambdaQueryWrapper<AiChatSession>()
                .eq(AiChatSession::getId, sessionId)
                .eq(AiChatSession::getUserId, userId)
                .eq(AiChatSession::getTenantId, tenantId)
                .eq(AiChatSession::getDeleted, 0)
                .eq(AiChatSession::getStatus, StatusType.ENABLE.val)
                .last("limit 1"));
        if (session == null) {
            throw new CoolException("AI 会话不存在或无权访问");
        }
        return session;
    }

    public List<AiChatMessageDto> listMessages(Long sessionId) {
        List<AiChatMessage> records = listMessageRecords(sessionId);
        if (Cools.isEmpty(records)) {
            return List.of();
        }
        List<AiChatMessageDto> messages = new ArrayList<>();
        for (AiChatMessage record : records) {
            if (!StringUtils.hasText(record.getContent())) {
                continue;
            }
            AiChatMessageDto item = new AiChatMessageDto();
            item.setRole(record.getRole());
            item.setContent(record.getContent());
            messages.add(item);
        }
        return messages;
    }

    public List<AiChatMessage> listMessageRecords(Long sessionId) {
        return aiChatMessageMapper.selectList(new LambdaQueryWrapper<AiChatMessage>()
                .eq(AiChatMessage::getSessionId, sessionId)
                .eq(AiChatMessage::getDeleted, 0)
                .orderByAsc(AiChatMessage::getSeqNo)
                .orderByAsc(AiChatMessage::getId));
    }

    public int findNextSeqNo(Long sessionId) {
        AiChatMessage lastMessage = aiChatMessageMapper.selectOne(new LambdaQueryWrapper<AiChatMessage>()
                .eq(AiChatMessage::getSessionId, sessionId)
                .eq(AiChatMessage::getDeleted, 0)
                .orderByDesc(AiChatMessage::getSeqNo)
                .orderByDesc(AiChatMessage::getId)
                .last("limit 1"));
        return lastMessage == null || lastMessage.getSeqNo() == null ? 1 : lastMessage.getSeqNo() + 1;
    }

    public String resolveUpdatedTitle(String currentTitle, List<AiChatMessageDto> memoryMessages) {
        if (StringUtils.hasText(currentTitle)) {
            return currentTitle;
        }
        for (AiChatMessageDto item : memoryMessages) {
            if ("user".equals(item.getRole()) && StringUtils.hasText(item.getContent())) {
                return buildSessionTitle(item.getContent());
            }
        }
        return null;
    }

    public String buildSessionTitle(String titleSeed) {
        if (!StringUtils.hasText(titleSeed)) {
            throw new CoolException("AI 会话标题不能为空");
        }
        String title = titleSeed.trim()
                .replace("\r", " ")
                .replace("\n", " ")
                .replaceAll("\\s+", " ");
        int punctuationIndex = findSummaryBreakIndex(title);
        if (punctuationIndex > 0) {
            title = title.substring(0, punctuationIndex).trim();
        }
        return title.length() > 48 ? title.substring(0, 48) : title;
    }

    public List<AiChatMessageDto> tailMessagesByRounds(List<AiChatMessageDto> source, int rounds) {
        if (Cools.isEmpty(source) || rounds <= 0) {
            return List.of();
        }
        int userCount = 0;
        int startIndex = source.size();
        for (int i = source.size() - 1; i >= 0; i--) {
            AiChatMessageDto item = source.get(i);
            startIndex = i;
            if (item != null && "user".equalsIgnoreCase(item.getRole())) {
                userCount++;
                if (userCount >= rounds) {
                    break;
                }
            }
        }
        return new ArrayList<>(source.subList(Math.max(0, startIndex), source.size()));
    }

    public List<AiChatMessage> tailMessageRecordsByRounds(List<AiChatMessage> source, int rounds) {
        if (Cools.isEmpty(source) || rounds <= 0) {
            return List.of();
        }
        int userCount = 0;
        int startIndex = source.size();
        for (int i = source.size() - 1; i >= 0; i--) {
            AiChatMessage item = source.get(i);
            startIndex = i;
            if (item != null && "user".equalsIgnoreCase(item.getRole())) {
                userCount++;
                if (userCount >= rounds) {
                    break;
                }
            }
        }
        return new ArrayList<>(source.subList(Math.max(0, startIndex), source.size()));
    }

    public String compactText(String content, int maxLength) {
        if (!StringUtils.hasText(content)) {
            return null;
        }
        String normalized = content.trim()
                .replace("\r", " ")
                .replace("\n", " ")
                .replaceAll("\\s+", " ");
        return normalized.length() > maxLength ? normalized.substring(0, maxLength) : normalized;
    }

    public String requirePromptCode(String promptCode) {
        if (!StringUtils.hasText(promptCode)) {
            throw new CoolException("Prompt 编码不能为空");
        }
        return promptCode;
    }

    public void ensureIdentity(Long userId, Long tenantId) {
        if (userId == null) {
            throw new CoolException("当前登录用户不存在");
        }
        if (tenantId == null) {
            throw new CoolException("当前租户不存在");
        }
    }

    private int findSummaryBreakIndex(String title) {
        String[] separators = {"。", "！", "？", ".", "!", "?"};
        int result = -1;
        for (String separator : separators) {
            int index = title.indexOf(separator);
            if (index > 0 && (result < 0 || index < result)) {
                result = index;
            }
        }
        return result;
    }

    private AiChatSessionDto buildSessionDto(AiChatSession session, AiChatMessage lastMessage) {
        return AiChatSessionDto.builder()
                .sessionId(session.getId())
                .title(session.getTitle())
                .promptCode(session.getPromptCode())
                .pinned(session.getPinned() != null && session.getPinned() == 1)
                .lastMessagePreview(buildLastMessagePreview(lastMessage))
                .lastMessageTime(session.getLastMessageTime())
                .build();
    }

    private String buildLastMessagePreview(AiChatMessage message) {
        if (message == null || !StringUtils.hasText(message.getContent())) {
            return null;
        }
        String preview = message.getContent().trim()
                .replace("\r", " ")
                .replace("\n", " ")
                .replaceAll("\\s+", " ");
        String prefix = "assistant".equalsIgnoreCase(message.getRole()) ? "AI: " : "你: ";
        String normalized = prefix + preview;
        return normalized.length() > 80 ? normalized.substring(0, 80) : normalized;
    }
}