import fs from 'fs';
import path from 'path';
import { logger } from './logger.js';

interface SessionData {
  claudeSessionId: string;
  createdAt: string;
  lastUsedAt: string;
}

export class SessionStore {
  constructor(private sessionDir: string) {
    fs.mkdirSync(this.sessionDir, { recursive: true });
  }

  private filePath(id: string): string {
    const safe = id.replace(/[^a-zA-Z0-9_-]/g, '_');
    return path.join(this.sessionDir, `${safe}.json`);
  }

  get(id: string): string | null {
    const fp = this.filePath(id);
    if (!fs.existsSync(fp)) return null;
    try {
      const data: SessionData = JSON.parse(fs.readFileSync(fp, 'utf-8'));
      return data.claudeSessionId;
    } catch (err) {
      logger.warn({ err, id }, 'Failed to read session');
      return null;
    }
  }

  save(id: string, claudeSessionId: string): void {
    const fp = this.filePath(id);
    const existing = fs.existsSync(fp);
    const data: SessionData = {
      claudeSessionId,
      createdAt: existing
        ? JSON.parse(fs.readFileSync(fp, 'utf-8')).createdAt
        : new Date().toISOString(),
      lastUsedAt: new Date().toISOString(),
    };
    fs.writeFileSync(fp, JSON.stringify(data, null, 2));
    logger.debug({ id, claudeSessionId }, 'Session saved');
  }

  list(): string[] {
    try {
      return fs.readdirSync(this.sessionDir)
        .filter(f => f.endsWith('.json'))
        .map(f => f.replace(/\.json$/, ''));
    } catch {
      return [];
    }
  }
}