# Secure Storage Implementation Guide for TimeSafari App

## Overview

This document outlines the implementation of secure storage for the TimeSafari app. The implementation focuses on:

1. **Platform-Specific Storage Solutions**:
   - Web: SQLite with IndexedDB backend (absurd-sql)
   - Electron: SQLite with Node.js backend
   - Native: (Planned) SQLCipher with platform-specific secure storage

2. **Key Features**:
   - SQLite-based storage using absurd-sql for web
   - Platform-specific service factory pattern
   - Consistent API across platforms
   - Migration support from Dexie.js

## Quick Start

### 1. Installation

```bash
# Core dependencies
npm install @jlongster/sql.js
npm install absurd-sql

# Platform-specific dependencies (for future native support)
npm install @capacitor/preferences
npm install @capacitor-community/biometric-auth
```

### 2. Basic Usage

```typescript
// Using the platform service
import { PlatformServiceFactory } from '../services/PlatformServiceFactory';

// Get platform-specific service instance
const platformService = PlatformServiceFactory.getInstance();

// Example database operations
async function example() {
  try {
    // Query example
    const result = await platformService.dbQuery(
      "SELECT * FROM accounts WHERE did = ?",
      [did]
    );

    // Execute example
    await platformService.dbExec(
      "INSERT INTO accounts (did, public_key_hex) VALUES (?, ?)",
      [did, publicKeyHex]
    );

    } catch (error) {
    console.error('Database operation failed:', error);
  }
}
```

### 3. Platform Detection

```typescript
// src/services/PlatformServiceFactory.ts
export class PlatformServiceFactory {
  static getInstance(): PlatformService {
    if (process.env.ELECTRON) {
      // Electron platform
      return new ElectronPlatformService();
    } else {
      // Web platform (default)
      return new AbsurdSqlDatabaseService();
    }
  }
}
```

### 4. Current Implementation Details

#### Web Platform (AbsurdSqlDatabaseService)

The web platform uses absurd-sql with IndexedDB backend:

```typescript
// src/services/AbsurdSqlDatabaseService.ts
export class AbsurdSqlDatabaseService implements PlatformService {
  private static instance: AbsurdSqlDatabaseService | null = null;
  private db: AbsurdSqlDatabase | null = null;
  private initialized: boolean = false;
      
  // Singleton pattern
  static getInstance(): AbsurdSqlDatabaseService {
    if (!AbsurdSqlDatabaseService.instance) {
      AbsurdSqlDatabaseService.instance = new AbsurdSqlDatabaseService();
    }
    return AbsurdSqlDatabaseService.instance;
  }

  // Database operations
  async dbQuery(sql: string, params: unknown[] = []): Promise<QueryExecResult[]> {
    await this.waitForInitialization();
    return this.queueOperation<QueryExecResult[]>("query", sql, params);
    }

  async dbExec(sql: string, params: unknown[] = []): Promise<void> {
    await this.waitForInitialization();
    await this.queueOperation<void>("run", sql, params);
  }
}
```

Key features:
- Uses absurd-sql for SQLite in the browser
- Implements operation queuing for thread safety
- Handles initialization and connection management
- Provides consistent API across platforms

### 5. Migration from Dexie.js

The current implementation supports gradual migration from Dexie.js:

```typescript
// Example of dual-storage pattern
async function getAccount(did: string): Promise<Account | undefined> {
  // Try SQLite first
  const platform = PlatformServiceFactory.getInstance();
  let account = await platform.dbQuery(
    "SELECT * FROM accounts WHERE did = ?",
    [did]
  );

  // Fallback to Dexie if needed
  if (USE_DEXIE_DB && !account) {
    account = await db.accounts.get(did);
  }

  return account;
   }
   ```

## Success Criteria

1. **Functionality**
   - [x] Basic CRUD operations work correctly
   - [x] Platform service factory pattern implemented
   - [x] Error handling in place
   - [ ] Native platform support (planned)

2. **Performance**
   - [x] Database operations complete within acceptable time
   - [x] Operation queuing for thread safety
   - [x] Proper initialization handling
   - [ ] Performance monitoring (planned)

3. **Security**
   - [x] Basic data integrity
   - [ ] Encryption (planned for native platforms)
   - [ ] Secure key storage (planned)
   - [ ] Platform-specific security features (planned)

4. **Testing**
   - [x] Basic unit tests
   - [ ] Comprehensive integration tests (planned)
   - [ ] Platform-specific tests (planned)
   - [ ] Migration tests (planned)

## Next Steps

1. **Native Platform Support**
   - Implement SQLCipher for iOS/Android
   - Add platform-specific secure storage
   - Implement biometric authentication

2. **Enhanced Security**
   - Add encryption for sensitive data
   - Implement secure key storage
   - Add platform-specific security features

3. **Testing and Monitoring**
   - Add comprehensive test coverage
   - Implement performance monitoring
   - Add error tracking and analytics

4. **Documentation**
   - Add API documentation
   - Create migration guides
   - Document security measures