import logger from '../utils/logger.js';
import fs from 'fs/promises';
import path from 'path';

class ContextMemory {
  constructor(options = {}) {
    this._memory = new Map();
    this._conversationHistory = [];
    this._decisions = [];
    this._maxHistory = options.maxHistorySize || 500;
    this._maxDecisions = options.maxDecisionsSize || 200;
    this._persistFile = options.persistFile || 'data/memory.json';
    this._persistInterval = options.persistInterval || 15 * 60 * 1000;
    this._lastPersist = 0;
    this._initialized = false;
  }

  async initialize() {
    if (this._initialized) return;

    try {
      await this._load();
      this._initialized = true;
      logger.info(`Memory initialized: ${this._memory.size} entries, ${this._conversationHistory.length} conversations`);
    } catch (error) {
      logger.warn(`Could not load memory: ${error.message}, starting fresh`);
      this._initialized = true;
    }
  }

  remember(key, value, metadata = {}) {
    this._memory.set(key, {
      value,
      metadata,
      timestamp: Date.now(),
    });

    this._maybePersist();
  }

  recall(key) {
    const entry = this._memory.get(key);
    if (!entry) return null;
    return entry.value;
  }

  recallWithMetadata(key) {
    return this._memory.get(key) || null;
  }

  forget(key) {
    this._memory.delete(key);
    this._maybePersist();
  }

  has(key) {
    return this._memory.has(key);
  }

  getAllByTag(tag) {
    const results = [];
    for (const [key, entry] of this._memory.entries()) {
      if (entry.metadata.tags?.includes(tag)) {
        results.push({ key, ...entry });
      }
    }
    return results;
  }

  addConversation(entry) {
    this._conversationHistory.push({
      ...entry,
      timestamp: Date.now(),
      id: crypto.randomUUID(),
    });

    if (this._conversationHistory.length > this._maxHistory) {
      this._conversationHistory = this._conversationHistory.slice(-this._maxHistory);
    }

    this._maybePersist();
  }

  getConversationHistory(limit = 50) {
    return this._conversationHistory.slice(-limit);
  }

  getConversationByIssue(issueNumber) {
    return this._conversationHistory.filter(
      c => c.issueNumber === issueNumber || c.prNumber === issueNumber
    );
  }

  addDecision(decision) {
    this._decisions.push({
      ...decision,
      timestamp: Date.now(),
      id: crypto.randomUUID(),
    });

    if (this._decisions.length > this._maxDecisions) {
      this._decisions = this._decisions.slice(-this._maxDecisions);
    }

    this._maybePersist();
  }

  getDecisions(limit = 50) {
    return this._decisions.slice(-limit);
  }

  getRecentDecisions(hours = 24) {
    const cutoff = Date.now() - hours * 60 * 60 * 1000;
    return this._decisions.filter(d => d.timestamp > cutoff);
  }

  getContextSummary() {
    const recentDecisions = this.getRecentDecisions(24);
    const recentConversations = this._conversationHistory.slice(-20);

    return {
      totalMemories: this._memory.size,
      recentDecisions: recentDecisions.length,
      recentConversations: recentConversations.length,
      lastActivity: this._conversationHistory.length > 0
        ? this._conversationHistory[this._conversationHistory.length - 1].timestamp
        : null,
    };
  }

  getPersonaContext() {
    return {
      currentRole: this.recall('currentRole') || 'full-stack',
      workingOn: this.recall('currentTask') || null,
      recentFocus: this.recall('recentFocus') || null,
      preferences: this.recall('developerPreferences') || {},
      ongoingDiscussions: this.getAllByTag('discussion').length,
      openPRs: this.getAllByTag('open-pr').length,
      activeIssues: this.getAllByTag('active-issue').length,
    };
  }

  cleanup(maxAge = 7 * 24 * 60 * 60 * 1000) {
    const cutoff = Date.now() - maxAge;
    let cleaned = 0;

    for (const [key, entry] of this._memory.entries()) {
      if (entry.timestamp < cutoff) {
        this._memory.delete(key);
        cleaned++;
      }
    }

    this._conversationHistory = this._conversationHistory.filter(
      c => c.timestamp > cutoff
    );

    this._decisions = this._decisions.filter(d => d.timestamp > cutoff);

    if (cleaned > 0) {
      logger.info(`Memory cleanup: removed ${cleaned} old entries`);
      this._persist();
    }

    return cleaned;
  }

  clear() {
    this._memory.clear();
    this._conversationHistory = [];
    this._decisions = [];
    this._persist();
  }

  export() {
    return {
      memory: Array.from(this._memory.entries()),
      conversations: this._conversationHistory,
      decisions: this._decisions,
      version: '1.0',
      exportedAt: new Date().toISOString(),
    };
  }

  import(data) {
    if (data.memory) {
      this._memory = new Map(data.memory);
    }
    if (data.conversations) {
      this._conversationHistory = data.conversations;
    }
    if (data.decisions) {
      this._decisions = data.decisions;
    }
    this._initialized = true;
  }

  async forcePersist() {
    await this._persist();
  }

  _maybePersist() {
    const now = Date.now();
    if (now - this._lastPersist > this._persistInterval) {
      this._persist();
    }
  }

  async _persist() {
    try {
      const data = this.export();
      const dir = path.dirname(this._persistFile);
      await fs.mkdir(dir, { recursive: true });
      await fs.writeFile(this._persistFile, JSON.stringify(data, null, 2), 'utf8');
      this._lastPersist = Date.now();
    } catch (error) {
      logger.error(`Failed to persist memory: ${error.message}`);
    }
  }

  async _load() {
    try {
      const content = await fs.readFile(this._persistFile, 'utf8');
      const data = JSON.parse(content);
      this.import(data);
    } catch (error) {
      if (error.code === 'ENOENT') {
        return;
      }
      throw error;
    }
  }
}

export default ContextMemory;