/**
 * ContextBuilder - Integrates OpenViking memories into chat context
 *
 * Responsible for:
 * 1. Building enhanced system prompts with relevant memories (L0/L1/L2)
 * 2. Extracting and saving memories after conversations end
 * 3. Managing context compaction with memory flush
 * 4. Reading and injecting agent identity files
 *
 * This module bridges the VikingAdapter with chatStore/gateway-client.
 */

import { VikingAdapter, getVikingAdapter, type EnhancedContext } from './viking-adapter';

// === Types ===

export interface AgentIdentity {
  soul: string;
  instructions: string;
  userProfile: string;
  heartbeat?: string;
}

export interface ContextBuildResult {
  systemPrompt: string;
  memorySummary: string;
  tokensUsed: number;
  memoriesInjected: number;
}

export interface CompactionResult {
  compactedMessages: ChatMessage[];
  summary: string;
  memoriesFlushed: number;
}

export interface ChatMessage {
  role: 'system' | 'user' | 'assistant';
  content: string;
}

export interface ContextBuilderConfig {
  enabled: boolean;
  maxMemoryTokens: number;
  compactionThresholdTokens: number;
  compactionReserveTokens: number;
  memoryFlushOnCompact: boolean;
  autoExtractOnComplete: boolean;
  minExtractionMessages: number;
}

const DEFAULT_CONFIG: ContextBuilderConfig = {
  enabled: true,
  maxMemoryTokens: 6000,
  compactionThresholdTokens: 15000,
  compactionReserveTokens: 4000,
  memoryFlushOnCompact: true,
  autoExtractOnComplete: true,
  minExtractionMessages: 4,
};

// === Token Estimation ===

function estimateTokens(text: string): number {
  const cjkChars = (text.match(/[\u4e00-\u9fff\u3400-\u4dbf]/g) || []).length;
  const otherChars = text.length - cjkChars;
  return Math.ceil(cjkChars * 1.5 + otherChars * 0.4);
}

function estimateMessagesTokens(messages: ChatMessage[]): number {
  return messages.reduce((sum, m) => sum + estimateTokens(m.content) + 4, 0);
}

// === ContextBuilder Implementation ===

export class ContextBuilder {
  private viking: VikingAdapter;
  private config: ContextBuilderConfig;
  private identityCache: Map<string, { identity: AgentIdentity; cachedAt: number }> = new Map();
  private static IDENTITY_CACHE_TTL = 5 * 60 * 1000; // 5 min

  constructor(config?: Partial<ContextBuilderConfig>) {
    this.config = { ...DEFAULT_CONFIG, ...config };
    this.viking = getVikingAdapter();
  }

  // === Core: Build Context for a Chat Message ===

  async buildContext(
    userMessage: string,
    agentId: string,
    _existingMessages: ChatMessage[] = []
  ): Promise<ContextBuildResult> {
    if (!this.config.enabled) {
      return {
        systemPrompt: '',
        memorySummary: '',
        tokensUsed: 0,
        memoriesInjected: 0,
      };
    }

    // Check if OpenViking is available
    const connected = await this.viking.isConnected();
    if (!connected) {
      console.warn('[ContextBuilder] OpenViking not available, skipping memory injection');
      return {
        systemPrompt: '',
        memorySummary: '',
        tokensUsed: 0,
        memoriesInjected: 0,
      };
    }

    // Step 1: Load agent identity
    const identity = await this.loadIdentity(agentId);

    // Step 2: Build enhanced context with memories
    const enhanced = await this.viking.buildEnhancedContext(
      userMessage,
      agentId,
      { maxTokens: this.config.maxMemoryTokens, includeTrace: true }
    );

    // Step 3: Compose system prompt
    const systemPrompt = this.composeSystemPrompt(identity, enhanced);

    // Step 4: Build summary for UI display
    const memorySummary = this.buildMemorySummary(enhanced);

    return {
      systemPrompt,
      memorySummary,
      tokensUsed: enhanced.totalTokens + estimateTokens(systemPrompt),
      memoriesInjected: enhanced.memories.length,
    };
  }

  // === Identity Loading ===

  async loadIdentity(agentId: string): Promise<AgentIdentity> {
    // Check cache
    const cached = this.identityCache.get(agentId);
    if (cached && Date.now() - cached.cachedAt < ContextBuilder.IDENTITY_CACHE_TTL) {
      return cached.identity;
    }

    // Try loading from OpenViking first, fall back to defaults
    let soul = '';
    let instructions = '';
    let userProfile = '';
    let heartbeat = '';

    try {
      [soul, instructions, userProfile, heartbeat] = await Promise.all([
        this.viking.getIdentityFromViking(agentId, 'soul').catch(() => ''),
        this.viking.getIdentityFromViking(agentId, 'instructions').catch(() => ''),
        this.viking.getIdentityFromViking(agentId, 'user_profile').catch(() => ''),
        this.viking.getIdentityFromViking(agentId, 'heartbeat').catch(() => ''),
      ]);
    } catch {
      // OpenViking not available, use empty defaults
    }

    const identity: AgentIdentity = {
      soul: soul || DEFAULT_SOUL,
      instructions: instructions || DEFAULT_INSTRUCTIONS,
      userProfile: userProfile || '',
      heartbeat: heartbeat || '',
    };

    this.identityCache.set(agentId, { identity, cachedAt: Date.now() });
    return identity;
  }

  // === Context Compaction ===

  async checkAndCompact(
    messages: ChatMessage[],
    agentId: string
  ): Promise<CompactionResult | null> {
    const totalTokens = estimateMessagesTokens(messages);
    if (totalTokens < this.config.compactionThresholdTokens) {
      return null; // No compaction needed
    }

    let memoriesFlushed = 0;

    // Step 1: Memory flush before compaction
    if (this.config.memoryFlushOnCompact) {
      const keepCount = 5;
      const messagesToFlush = messages.slice(0, -keepCount);
      if (messagesToFlush.length >= this.config.minExtractionMessages) {
        try {
          const result = await this.viking.extractAndSaveMemories(
            messagesToFlush.map(m => ({ role: m.role, content: m.content })),
            agentId,
            'compaction'
          );
          memoriesFlushed = result.saved;
          console.log(`[ContextBuilder] Memory flush: saved ${memoriesFlushed} memories before compaction`);
        } catch (err) {
          console.warn('[ContextBuilder] Memory flush failed:', err);
        }
      }
    }

    // Step 2: Create summary of older messages
    const keepCount = 5;
    const oldMessages = messages.slice(0, -keepCount);
    const recentMessages = messages.slice(-keepCount);

    const summary = this.createCompactionSummary(oldMessages);

    const compactedMessages: ChatMessage[] = [
      { role: 'system', content: `[之前的对话摘要]\n${summary}` },
      ...recentMessages,
    ];

    return {
      compactedMessages,
      summary,
      memoriesFlushed,
    };
  }

  // === Post-Conversation Memory Extraction ===

  async extractMemoriesFromConversation(
    messages: ChatMessage[],
    agentId: string,
    conversationId?: string
  ): Promise<{ saved: number; userMemories: number; agentMemories: number }> {
    if (!this.config.autoExtractOnComplete) {
      return { saved: 0, userMemories: 0, agentMemories: 0 };
    }

    if (messages.length < this.config.minExtractionMessages) {
      return { saved: 0, userMemories: 0, agentMemories: 0 };
    }

    const connected = await this.viking.isConnected();
    if (!connected) {
      return { saved: 0, userMemories: 0, agentMemories: 0 };
    }

    try {
      const result = await this.viking.extractAndSaveMemories(
        messages.map(m => ({ role: m.role, content: m.content })),
        agentId,
        conversationId
      );
      console.log(
        `[ContextBuilder] Extracted ${result.saved} memories (user: ${result.userMemories}, agent: ${result.agentMemories})`
      );
      return result;
    } catch (err) {
      console.warn('[ContextBuilder] Memory extraction failed:', err);
      return { saved: 0, userMemories: 0, agentMemories: 0 };
    }
  }

  // === Identity Sync ===

  async syncIdentityFiles(
    agentId: string,
    files: { soul?: string; instructions?: string; userProfile?: string; heartbeat?: string }
  ): Promise<void> {
    const connected = await this.viking.isConnected();
    if (!connected) return;

    const syncTasks: Promise<void>[] = [];

    if (files.soul) {
      syncTasks.push(this.viking.syncIdentityToViking(agentId, 'SOUL.md', files.soul));
    }
    if (files.instructions) {
      syncTasks.push(this.viking.syncIdentityToViking(agentId, 'AGENTS.md', files.instructions));
    }
    if (files.userProfile) {
      syncTasks.push(this.viking.syncIdentityToViking(agentId, 'USER.md', files.userProfile));
    }
    if (files.heartbeat) {
      syncTasks.push(this.viking.syncIdentityToViking(agentId, 'HEARTBEAT.md', files.heartbeat));
    }

    await Promise.allSettled(syncTasks);

    // Invalidate cache
    this.identityCache.delete(agentId);
  }

  // === Configuration ===

  updateConfig(config: Partial<ContextBuilderConfig>): void {
    this.config = { ...this.config, ...config };
  }

  getConfig(): Readonly<ContextBuilderConfig> {
    return { ...this.config };
  }

  isEnabled(): boolean {
    return this.config.enabled;
  }

  // === Private Helpers ===

  private composeSystemPrompt(identity: AgentIdentity, enhanced: EnhancedContext): string {
    const sections: string[] = [];

    if (identity.soul) {
      sections.push(identity.soul);
    }

    if (identity.instructions) {
      sections.push(identity.instructions);
    }

    if (identity.userProfile) {
      sections.push(`## 用户画像\n${identity.userProfile}`);
    }

    if (enhanced.systemPromptAddition) {
      sections.push(enhanced.systemPromptAddition);
    }

    return sections.join('\n\n');
  }

  private buildMemorySummary(enhanced: EnhancedContext): string {
    if (enhanced.memories.length === 0) {
      return '无相关记忆';
    }

    const parts: string[] = [
      `已注入 ${enhanced.memories.length} 条相关记忆`,
      `Token 消耗: L0=${enhanced.tokensByLevel.L0} L1=${enhanced.tokensByLevel.L1} L2=${enhanced.tokensByLevel.L2}`,
    ];

    return parts.join(' | ');
  }

  private createCompactionSummary(messages: ChatMessage[]): string {
    // Create a concise summary of compacted messages
    const userMessages = messages.filter(m => m.role === 'user');
    const assistantMessages = messages.filter(m => m.role === 'assistant');

    const topics = userMessages
      .map(m => {
        const text = m.content.trim();
        return text.length > 50 ? text.slice(0, 50) + '...' : text;
      })
      .slice(0, 5);

    const summary = [
      `对话包含 ${messages.length} 条消息（${userMessages.length} 条用户消息，${assistantMessages.length} 条助手回复）`,
      topics.length > 0 ? `讨论主题：${topics.join('；')}` : '',
    ].filter(Boolean).join('\n');

    return summary;
  }
}

// === Default Identity Content ===

const DEFAULT_SOUL = `# ZCLAW 人格

你是 ZCLAW（小龙虾），一个基于 OpenClaw 定制的中文 AI 助手。

## 核心特质

- **高效执行**: 你不只是出主意，你会真正动手完成任务
- **中文优先**: 默认使用中文交流，必要时切换英文
- **专业可靠**: 对技术问题给出精确答案，不确定时坦诚说明
- **主动服务**: 定期检查任务清单，主动推进未完成的工作

## 语气

简洁、专业、友好。避免过度客套，直接给出有用信息。`;

const DEFAULT_INSTRUCTIONS = `# Agent 指令

## 操作规范

1. 执行文件操作前，先确认目标路径
2. 执行 Shell 命令前，评估安全风险
3. 长时间任务需定期汇报进度

## 记忆管理

- 重要的用户偏好自动记录
- 项目上下文保存到工作区
- 对话结束时总结关键信息`;

// === Singleton ===

let _instance: ContextBuilder | null = null;

export function getContextBuilder(config?: Partial<ContextBuilderConfig>): ContextBuilder {
  if (!_instance || config) {
    _instance = new ContextBuilder(config);
  }
  return _instance;
}

export function resetContextBuilder(): void {
  _instance = null;
}