# Data Aggregation Strategy

## Overview

This document describes the comprehensive data aggregation strategy used in the TCP Trading Platform for converting real-time trade data into OHLCV (Open, High, Low, Close, Volume) candles across multiple timeframes.

## Core Principles

### 1. Right-Aligned Timestamps (Industry Standard)

The system follows the **RIGHT-ALIGNED timestamp** convention used by major exchanges:

- **Candle timestamp = end time of the interval (close time)**
- This represents when the candle period **closes**, not when it opens
- Aligns with Binance, OKX, Coinbase, and other major exchanges
- Ensures consistency with historical data APIs

**Examples:**
```
5-minute candle with timestamp 09:05:00:
├─ Represents data from 09:00:01 to 09:05:00
├─ Includes all trades in the interval [09:00:01, 09:05:00]
└─ Candle "closes" at 09:05:00

1-hour candle with timestamp 14:00:00:
├─ Represents data from 13:00:01 to 14:00:00  
├─ Includes all trades in the interval [13:00:01, 14:00:00]
└─ Candle "closes" at 14:00:00
```

### 2. Future Leakage Prevention

**CRITICAL**: The system implements strict safeguards to prevent future leakage:

- **Only emit completed candles** when time boundary is definitively crossed
- **Never emit incomplete candles** during real-time processing
- **No timer-based completion** - only trade timestamp-driven
- **Strict time validation** for all trade additions

## Aggregation Process

### Real-Time Processing Flow

```mermaid
graph TD
    A[Trade Arrives from WebSocket] --> B[Extract Timestamp T]
    B --> C[For Each Timeframe]
    C --> D[Calculate Bucket Start Time]
    D --> E{Bucket Exists?}
    E -->|No| F[Create New Bucket]
    E -->|Yes| G{Same Time Period?}
    G -->|Yes| H[Add Trade to Current Bucket]
    G -->|No| I[Complete Previous Bucket]
    I --> J[Emit Completed Candle]
    J --> K[Store in market_data Table]
    K --> F
    F --> H
    H --> L[Update OHLCV Values]
    L --> M[Continue Processing]
```

### Time Bucket Calculation

The system calculates which time bucket a trade belongs to based on its timestamp:

```python
def get_bucket_start_time(timestamp: datetime, timeframe: str) -> datetime:
    """
    Calculate the start time of the bucket for a given trade timestamp.
    
    This determines the LEFT boundary of the time interval.
    The RIGHT boundary (end_time) becomes the candle timestamp.
    """
    # Normalize to remove seconds/microseconds
    dt = timestamp.replace(second=0, microsecond=0)
    
    if timeframe == '1m':
        # 1-minute: align to minute boundaries
        return dt
    elif timeframe == '5m':
        # 5-minute: 00:00, 00:05, 00:10, 00:15, etc.
        return dt.replace(minute=(dt.minute // 5) * 5)
    elif timeframe == '15m':
        # 15-minute: 00:00, 00:15, 00:30, 00:45
        return dt.replace(minute=(dt.minute // 15) * 15)
    elif timeframe == '1h':
        # 1-hour: align to hour boundaries
        return dt.replace(minute=0)
    elif timeframe == '4h':
        # 4-hour: 00:00, 04:00, 08:00, 12:00, 16:00, 20:00
        return dt.replace(minute=0, hour=(dt.hour // 4) * 4)
    elif timeframe == '1d':
        # 1-day: align to midnight UTC
        return dt.replace(minute=0, hour=0)
```

### Detailed Examples

#### 5-Minute Timeframe Processing

```
Current time: 09:03:45
Trade arrives at: 09:03:45

Step 1: Calculate bucket start time
├─ timeframe = '5m'
├─ minute = 3
├─ bucket_minute = (3 // 5) * 5 = 0
└─ bucket_start = 09:00:00

Step 2: Bucket boundaries
├─ start_time = 09:00:00 (inclusive)
├─ end_time = 09:05:00 (exclusive)
└─ candle_timestamp = 09:05:00 (right-aligned)

Step 3: Trade validation
├─ 09:00:00 <= 09:03:45 < 09:05:00 ✓
└─ Trade belongs to this bucket

Step 4: OHLCV update
├─ If first trade: set open price
├─ Update high/low prices
├─ Set close price (latest trade)
├─ Add to volume
└─ Increment trade count
```

#### Boundary Crossing Example

```
Scenario: 5-minute timeframe, transition from 09:04:59 to 09:05:00

Trade 1: timestamp = 09:04:59
├─ bucket_start = 09:00:00
├─ Belongs to current bucket [09:00:00 - 09:05:00)
└─ Add to current bucket

Trade 2: timestamp = 09:05:00  
├─ bucket_start = 09:05:00
├─ Different from current bucket (09:00:00)
├─ TIME BOUNDARY CROSSED!
├─ Complete previous bucket → candle with timestamp 09:05:00
├─ Store completed candle in market_data table
├─ Create new bucket [09:05:00 - 09:10:00)
└─ Add Trade 2 to new bucket
```

## Data Storage Strategy

### Storage Tables

#### 1. `raw_trades` Table
**Purpose**: Store every individual piece of data as received
**Data**: Trades, orderbook updates, tickers
**Usage**: Debugging, compliance, detailed analysis

```sql
CREATE TABLE raw_trades (
    id SERIAL PRIMARY KEY,
    exchange VARCHAR(50) NOT NULL,
    symbol VARCHAR(20) NOT NULL,
    timestamp TIMESTAMPTZ NOT NULL,
    data_type VARCHAR(20) NOT NULL,  -- 'trade', 'orderbook', 'ticker'
    raw_data JSONB NOT NULL
);
```

#### 2. `market_data` Table  
**Purpose**: Store completed OHLCV candles for trading decisions
**Data**: Only completed candles with right-aligned timestamps
**Usage**: Bot strategies, backtesting, analysis

```sql
CREATE TABLE market_data (
    id SERIAL PRIMARY KEY,
    exchange VARCHAR(50) NOT NULL,
    symbol VARCHAR(20) NOT NULL,
    timeframe VARCHAR(5) NOT NULL,
    timestamp TIMESTAMPTZ NOT NULL,  -- RIGHT-ALIGNED (candle close time)
    open DECIMAL(18,8) NOT NULL,
    high DECIMAL(18,8) NOT NULL,
    low DECIMAL(18,8) NOT NULL,
    close DECIMAL(18,8) NOT NULL,
    volume DECIMAL(18,8) NOT NULL,
    trades_count INTEGER
);
```

### Storage Flow

```
WebSocket Message
├─ Contains multiple trades
├─ Each trade stored in raw_trades table
└─ Each trade processed through aggregation

Aggregation Engine
├─ Groups trades by timeframe buckets
├─ Updates OHLCV values incrementally  
├─ Detects time boundary crossings
└─ Emits completed candles only

Completed Candles
├─ Stored in market_data table
├─ Timestamp = bucket end time (right-aligned)
├─ is_complete = true
└─ Available for trading strategies
```

## Future Leakage Prevention

### Critical Safeguards

#### 1. Boundary Crossing Detection
```python
# CORRECT: Only complete when boundary definitively crossed
if current_bucket.start_time != trade_bucket_start:
    # Time boundary crossed - safe to complete previous bucket
    if current_bucket.trade_count > 0:
        completed_candle = current_bucket.to_candle(is_complete=True)
        emit_candle(completed_candle)
```

#### 2. No Premature Completion
```python
# WRONG: Never complete based on timers or external events
if time.now() > bucket.end_time:
    completed_candle = bucket.to_candle(is_complete=True)  # FUTURE LEAKAGE!

# WRONG: Never complete incomplete buckets during real-time
if some_condition:
    completed_candle = current_bucket.to_candle(is_complete=True)  # WRONG!
```

#### 3. Strict Time Validation
```python
def add_trade(self, trade: StandardizedTrade) -> bool:
    # Only accept trades within bucket boundaries
    if not (self.start_time <= trade.timestamp < self.end_time):
        return False  # Reject trades outside time range
    
    # Safe to add trade
    self.update_ohlcv(trade)
    return True
```

#### 4. Historical Consistency
```python
# Same logic for real-time and historical processing
def process_trade(trade):
    """Used for both real-time WebSocket and historical API data"""
    return self._process_trade_for_timeframe(trade, timeframe)
```

## Testing Strategy

### Validation Tests

1. **Timestamp Alignment Tests**
   - Verify candle timestamps are right-aligned
   - Check bucket boundary calculations
   - Validate timeframe-specific alignment

2. **Future Leakage Tests**
   - Ensure no incomplete candles are emitted
   - Verify boundary crossing detection
   - Test with edge case timestamps

3. **Data Integrity Tests**
   - OHLCV calculation accuracy
   - Volume aggregation correctness
   - Trade count validation

### Test Examples

```python
def test_right_aligned_timestamps():
    """Test that candle timestamps are right-aligned"""
    trades = [
        create_trade("09:01:30", price=100),
        create_trade("09:03:45", price=101),
        create_trade("09:05:00", price=102),  # Boundary crossing
    ]
    
    candles = process_trades(trades, timeframe='5m')
    
    # First candle should have timestamp 09:05:00 (right-aligned)
    assert candles[0].timestamp == datetime(hour=9, minute=5)
    assert candles[0].start_time == datetime(hour=9, minute=0)
    assert candles[0].end_time == datetime(hour=9, minute=5)

def test_no_future_leakage():
    """Test that incomplete candles are never emitted"""
    processor = RealTimeCandleProcessor(symbol='BTC-USDT', timeframes=['5m'])
    
    # Add trades within same bucket
    trade1 = create_trade("09:01:00", price=100)
    trade2 = create_trade("09:03:00", price=101)
    
    # Should return empty list (no completed candles)
    completed = processor.process_trade(trade1)
    assert len(completed) == 0
    
    completed = processor.process_trade(trade2)  
    assert len(completed) == 0
    
    # Only when boundary crossed should candle be emitted
    trade3 = create_trade("09:05:00", price=102)
    completed = processor.process_trade(trade3)
    assert len(completed) == 1  # Previous bucket completed
    assert completed[0].is_complete == True
```

## Performance Considerations

### Memory Management
- Keep only current buckets in memory
- Clear completed buckets immediately after emission
- Limit maximum number of active timeframes

### Database Optimization  
- Batch insert completed candles
- Use prepared statements for frequent inserts
- Index on (symbol, timeframe, timestamp) for queries

### Processing Efficiency
- Process all timeframes in single trade iteration
- Use efficient bucket start time calculations
- Minimize object creation in hot paths

## Conclusion

This aggregation strategy ensures:

✅ **Industry Standard Compliance**: Right-aligned timestamps matching major exchanges  
✅ **Future Leakage Prevention**: Strict boundary detection and validation  
✅ **Data Integrity**: Accurate OHLCV calculations and storage  
✅ **Performance**: Efficient real-time and batch processing  
✅ **Consistency**: Same logic for real-time and historical data  

The implementation provides a robust foundation for building trading strategies with confidence in data accuracy and timing.