/**
 * Agent Storage Module
 * 
 * Persistent storage for agent state, conversations, and results.
 * Uses filesystem for persistence.
 */

import { writeFileSync, readFileSync, existsSync, mkdirSync, readdirSync, unlinkSync } from 'fs';
import { join } from 'path';

const STORAGE_DIR = join(process.cwd(), '.agent-storage');

export interface StoredConversation {
  id: string;
  agentId: string;
  messages: Array<{
    role: 'user' | 'assistant' | 'system';
    content: string;
    timestamp: string;
  }>;
  metadata?: Record<string, unknown>;
  createdAt: string;
  updatedAt: string;
}

export interface StoredTask {
  id: string;
  type: string;
  status: string;
  input: unknown;
  output?: unknown;
  error?: string;
  createdAt: string;
  completedAt?: string;
}

export interface StoredAgentState {
  id: string;
  name: string;
  type: string;
  status: string;
  memory: Record<string, unknown>;
  createdAt: string;
  updatedAt: string;
}

/**
 * AgentStorage - Persistent storage for agents
 */
export class AgentStorage {
  private baseDir: string;

  constructor(baseDir: string = STORAGE_DIR) {
    this.baseDir = baseDir;
    this.ensureDirectory();
  }

  /**
   * Ensure storage directory exists
   */
  private ensureDirectory(): void {
    if (!existsSync(this.baseDir)) {
      mkdirSync(this.baseDir, { recursive: true });
    }
    
    const subdirs = ['conversations', 'tasks', 'agents'];
    for (const subdir of subdirs) {
      const dir = join(this.baseDir, subdir);
      if (!existsSync(dir)) {
        mkdirSync(dir, { recursive: true });
      }
    }
  }

  /**
   * Save a conversation
   */
  saveConversation(conversation: StoredConversation): void {
    const path = join(this.baseDir, 'conversations', `${conversation.id}.json`);
    writeFileSync(path, JSON.stringify(conversation, null, 2), 'utf-8');
  }

  /**
   * Load a conversation
   */
  loadConversation(id: string): StoredConversation | null {
    try {
      const path = join(this.baseDir, 'conversations', `${id}.json`);
      if (!existsSync(path)) return null;
      return JSON.parse(readFileSync(path, 'utf-8'));
    } catch {
      return null;
    }
  }

  /**
   * List all conversations
   */
  listConversations(agentId?: string): StoredConversation[] {
    const dir = join(this.baseDir, 'conversations');
    if (!existsSync(dir)) return [];

    const files = readdirSync(dir).filter(f => f.endsWith('.json'));
    
    return files.map(file => {
      const content = readFileSync(join(dir, file), 'utf-8');
      return JSON.parse(content) as StoredConversation;
    }).filter(conv => !agentId || conv.agentId === agentId);
  }

  /**
   * Delete a conversation
   */
  deleteConversation(id: string): boolean {
    try {
      const path = join(this.baseDir, 'conversations', `${id}.json`);
      if (existsSync(path)) {
        unlinkSync(path);
        return true;
      }
      return false;
    } catch {
      return false;
    }
  }

  /**
   * Save a task
   */
  saveTask(task: StoredTask): void {
    const path = join(this.baseDir, 'tasks', `${task.id}.json`);
    writeFileSync(path, JSON.stringify(task, null, 2), 'utf-8');
  }

  /**
   * Load a task
   */
  loadTask(id: string): StoredTask | null {
    try {
      const path = join(this.baseDir, 'tasks', `${id}.json`);
      if (!existsSync(path)) return null;
      return JSON.parse(readFileSync(path, 'utf-8'));
    } catch {
      return null;
    }
  }

  /**
   * List all tasks
   */
  listTasks(status?: string): StoredTask[] {
    const dir = join(this.baseDir, 'tasks');
    if (!existsSync(dir)) return [];

    const files = readdirSync(dir).filter(f => f.endsWith('.json'));
    
    return files.map(file => {
      const content = readFileSync(join(dir, file), 'utf-8');
      return JSON.parse(content) as StoredTask;
    }).filter(task => !status || task.status === status);
  }

  /**
   * Save agent state
   */
  saveAgentState(state: StoredAgentState): void {
    const path = join(this.baseDir, 'agents', `${state.id}.json`);
    writeFileSync(path, JSON.stringify(state, null, 2), 'utf-8');
  }

  /**
   * Load agent state
   */
  loadAgentState(id: string): StoredAgentState | null {
    try {
      const path = join(this.baseDir, 'agents', `${id}.json`);
      if (!existsSync(path)) return null;
      return JSON.parse(readFileSync(path, 'utf-8'));
    } catch {
      return null;
    }
  }

  /**
   * List all agent states
   */
  listAgentStates(): StoredAgentState[] {
    const dir = join(this.baseDir, 'agents');
    if (!existsSync(dir)) return [];

    const files = readdirSync(dir).filter(f => f.endsWith('.json'));
    
    return files.map(file => {
      const content = readFileSync(join(dir, file), 'utf-8');
      return JSON.parse(content) as StoredAgentState;
    });
  }

  /**
   * Clear all storage
   */
  clearAll(): void {
    const subdirs = ['conversations', 'tasks', 'agents'];
    for (const subdir of subdirs) {
      const dir = join(this.baseDir, subdir);
      if (existsSync(dir)) {
        const files = readdirSync(dir).filter(f => f.endsWith('.json'));
        for (const file of files) {
          unlinkSync(join(dir, file));
        }
      }
    }
  }

  /**
   * Get storage stats
   */
  getStats(): {
    conversations: number;
    tasks: number;
    agents: number;
  } {
    return {
      conversations: this.listConversations().length,
      tasks: this.listTasks().length,
      agents: this.listAgentStates().length
    };
  }
}

// Default storage instance
export const defaultStorage = new AgentStorage();