tacitus/postgres/trade_service.go

package postgres

import (
	"database/sql"
	"time"

	"github.com/kcotugno/tacitus"
)

const (
	trade_columns = `trade_id, product, price, size, buy, sell, timestamp`
	trade_insert  = `INSERT INTO trades (` + trade_columns + `) VALUES ` +
		`($1, $2, $3, $4, $5, $6, $7) RETURNING id;`
	trade_find          = `SELECT id, ` + trade_columns + ` FROM trades WHERE id = $1;`
	trade_find_trade_id = `SELECT id, ` + trade_columns + ` FROM trades ` +
		`WHERE trade_id = $1 AND product = $2;`
	trade_delete        = `DELETE FROM trades WHERE id = $1;`
	trade_in_date_range = `SELECT id, ` + trade_columns + ` FROM ` +
		`trades WHERE product = $1 AND timestamp >= $2 AND timestamp < $3;`
	trade_first = `SELECT id, ` + trade_columns + ` FROM trades WHERE ` +
		`product = $1 ORDER BY trade_id ASC LIMIT $2;`
	trade_last = `SELECT id, ` + trade_columns + ` FROM trades WHERE ` +
		`product = $1 ORDER BY trade_id DESC LIMIT $2;`
	trade_after = `SELECT id, ` + trade_columns + ` FROM trades ` +
		`WHERE product = $1 AND trade_id < $2 ORDER BY trade_id DESC LIMIT $3;`
	trade_before = `SELECT id, ` + trade_columns + ` FROM trades ` +
		`WHERE product = $1 AND trade_id > $2 ORDER BY trade_id ASC LIMIT $3;`
)

type TradeService struct {
	client *Client
}

func (t *TradeService) Trade(id int) (*tacitus.Trade, error) {
	var tr tacitus.Trade

	t.client.logQuery(trade_find, id)
	row := t.client.db.QueryRow(trade_find, id)
	if err := row.Scan(&tr.Id, &tr.TradeId, &tr.Product, &tr.Price, &tr.Size, &tr.Buy,
		&tr.Sell, &tr.Timestamp); err != nil {
		t.client.logError(trade_find, err, id)

		return nil, err
	}

	return &tr, nil
}

func (t *TradeService) TradeByTradeId(id int, prod string) (*tacitus.Trade, error) {
	var tr tacitus.Trade

	t.client.logQuery(trade_find_trade_id, id, prod)
	row := t.client.db.QueryRow(trade_find_trade_id, id, prod)
	if err := row.Scan(&tr.Id, &tr.TradeId, &tr.Product, &tr.Price,
		&tr.Size, &tr.Buy, &tr.Sell, &tr.Timestamp); err != nil {

		t.client.logError(trade_find_trade_id, err, id, prod)

		return nil, err
	}

	return &tr, nil
}

func (t *TradeService) CreateTrade(trade *tacitus.Trade) error {
	var id int
	params := []interface{}{trade.TradeId, trade.Product, trade.Price,
		trade.Size, trade.Buy, trade.Sell, trade.Timestamp}

	t.client.logQuery(trade_insert, params...)
	res := t.client.db.QueryRow(trade_insert, params...)
	if err := res.Scan(&id); err != nil {
		t.client.logError(trade_insert, err, params...)
		return err
	}

	trade.Id = id

	return nil
}

func (t *TradeService) DeleteTrade(id int) {
	t.client.logQuery(trade_delete, id)

	_, err := t.client.db.Exec(trade_delete, id)
	if err != nil {
		t.client.logError(trade_delete, err, id)
	}
}

func (t *TradeService) TradesInDateRange(product string, start,
	end time.Time) ([]tacitus.Trade, error) {

	t.client.logQuery(trade_in_date_range, product, start, end)
	rows, err := t.client.db.Query(trade_in_date_range, product, start, end)
	if err != nil {
		t.client.logError(trade_in_date_range, err, product, start, end)

		return nil, err
	}

	return deserializeTrades(rows)
}

func (t *TradeService) FirstTrades(product string, limit int) ([]tacitus.Trade, error) {
	t.client.logQuery(trade_first, product, limit)
	rows, err := t.client.db.Query(trade_first, product, limit)
	if err != nil {
		t.client.logError(trade_first, err, product, limit)

		return nil, err
	}

	return deserializeTrades(rows)
}

func (t *TradeService) LastTrades(product string, limit int) ([]tacitus.Trade, error) {
	t.client.logQuery(trade_last, product, limit)
	rows, err := t.client.db.Query(trade_last, product, limit)
	if err != nil {
		t.client.logError(trade_last, err, product, limit)

		return nil, err
	}

	return deserializeTrades(rows)
}

func (t *TradeService) TradesAfter(product string, id, limit int) ([]tacitus.Trade, error) {
	t.client.logQuery(trade_after, product, id, limit)
	rows, err := t.client.db.Query(trade_after, product, id, limit)
	if err != nil {
		t.client.logError(trade_after, err, product, id, limit)

		return nil, err
	}

	return deserializeTrades(rows)

}

func (t *TradeService) TradesBefore(product string, id, limit int) ([]tacitus.Trade, error) {
	t.client.logQuery(trade_before, product, id, limit)
	rows, err := t.client.db.Query(trade_before, product, id, limit)
	if err != nil {
		t.client.logError(trade_before, err, product, id, limit)

		return nil, err
	}

	return deserializeTrades(rows)

}

func deserializeTrades(rows *sql.Rows) ([]tacitus.Trade, error) {
	defer rows.Close()

	trades := make([]tacitus.Trade, 0)

	for rows.Next() {
		var trade tacitus.Trade
		if err := rows.Scan(&trade.Id, &trade.TradeId, &trade.Product, &trade.Price,
			&trade.Size, &trade.Buy, &trade.Sell, &trade.Timestamp); err != nil {

			return nil, err
		}

		trades = append(trades, trade)
	}

	if rows.Err() != nil {
		return nil, rows.Err()
	}

	return trades, nil
}