Initial commit

README.md

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+# B3 Lib
+
+    Dragon: "My name is Balthromaw. Breaker of skies, slayer of mountain."
+    Rick: "Rule 1: You're now scooper of your own poops, or I will take you down like the black-light poster you are."
+
+![Stonks](https://i.kym-cdn.com/photos/images/newsfeed/001/499/826/2f0.png) 
+
+#### From Bezunca Labs

b3lib.go

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+package b3lib
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// New function to setup B3 fetch and cache prices
+func New(cacheTimeout time.Duration, client *http.Client) func(tickers []string) ([]FetchedPrice, []error) {
+
+	cache := make(map[string]tickerEntry)
+
+	return func(tickers []string) (prices []FetchedPrice, err []error) {
+
+		var newTickers []string
+		for _, ticker := range tickers {
+			if entry, ok := cache[ticker]; !ok || time.Since(entry.Timestamp) > cacheTimeout {
+				newTickers = append(newTickers, ticker)
+			} else {
+				prices = append(prices, entry.Price)
+			}
+		}
+
+		var fetched []FetchedPrice
+		if len(newTickers) > 0 {
+			fetched, err = fetchNewPrices(client, newTickers)
+			for _, price := range fetched {
+				cache[price.Ticker] = tickerEntry{
+					Price:     price,
+					Timestamp: time.Now(),
+				}
+			}
+		}
+
+		return append(prices, fetched...), err
+	}
+}
+
+func fetchNewPrices(client *http.Client, tickers []string) ([]FetchedPrice, []error) {
+	today := time.Now()
+	todayWeekday := today.Weekday()
+	if todayWeekday == time.Sunday {
+		today = today.Add(-48 * time.Hour)
+	} else if todayWeekday == time.Saturday || today.Hour() < 6 {
+		// B3 only got prices values after market opening, so before 6AM, we get yesterday values
+		// If it's after 6AM, we zero the prices values, waiting for market opening
+		today = today.Add(-24 * time.Hour)
+	}
+	date := today.Format("2006-01-02")
+
+	fetchedPricesChan := make(chan FetchedPrice, len(tickers))
+	errChan := make(chan error)
+	defer func() {
+		close(fetchedPricesChan)
+		close(errChan)
+	}()
+
+	for _, ticker := range tickers {
+		go getCurrentPrice(client, date, ticker, fetchedPricesChan, errChan)
+	}
+
+	var fetchedPrices []FetchedPrice
+	var errors []error
+	for i := 0; i < len(tickers); i++ {
+		select {
+		case fetchedPrice := <-fetchedPricesChan:
+			fetchedPrices = append(fetchedPrices, fetchedPrice)
+		case err := <-errChan:
+			errors = append(errors, err)
+		}
+	}
+
+	if len(errors) != 0 {
+		return nil, errors
+	}
+
+	return fetchedPrices, nil
+}
+
+func getCurrentPrice(client *http.Client, date string, ticker string, prices chan<- FetchedPrice, errChan chan<- error) {
+	url := fmt.Sprintf("https://arquivos.b3.com.br/apinegocios/ticker/%v/%v", ticker, date)
+	response, err := client.Get(url)
+	if err != nil {
+		errChan <- &FetchError{ticker, date, err}
+		return
+	}
+	defer func() {
+		if err = response.Body.Close(); err != nil {
+			errChan <- &CloseBodyError{ticker, date, err}
+		}
+	}()
+
+	b3Response := new(b3PriceResponse)
+	decoder := json.NewDecoder(response.Body)
+	decoder.DisallowUnknownFields()
+	if err := decoder.Decode(b3Response); err != nil {
+		errChan <- &JSONDecodeError{ticker, date, err}
+		return
+	}
+
+	price := 0
+	if len(b3Response.Values) != 0 {
+		price, _ = strconv.Atoi(
+			strings.ReplaceAll(fmt.Sprint(b3Response.Values[0][2].(float64)), ".", ""),
+		)
+	}
+
+	prices <- FetchedPrice{
+		Ticker:   b3Response.Name,
+		IntPrice: price,
+	}
+}

b3lib_test.go

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+package b3lib
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFetch(t *testing.T) {
+
+	fetch := New(5*time.Second, http.DefaultClient)
+
+	tickers := []string{"ITSA4", "HSML11", "VRTA11"}
+
+	prices, errs := fetch(tickers)
+	t.Logf("Prices: %+v\nErrors: %#v", prices, errs)
+
+	t.Logf("Trying ITSA4 again with cache")
+	prices2, errs2 := fetch([]string{"ITSA4", "CVCB3"})
+	t.Logf("Prices: %+v\nErrors: %#v", prices2, errs2)
+
+	t.Logf("Sleeping")
+	<-time.After(6 * time.Second)
+	t.Logf("Woke")
+
+	t.Logf("Trying ITSA4 again without cache")
+	prices3, errs3 := fetch([]string{"ITSA4"})
+	t.Logf("Prices: %+v\nErrors: %#v", prices3, errs3)
+
+	assert.Equal(t, len(tickers)+1, len(prices)+len(errs)+1)
+}

errors.go

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+package b3lib
+
+import (
+	"errors"
+	"fmt"
+)
+
+// FetchError for when we had an error while fetching a quotation from B3
+type FetchError struct {
+	Ticker string
+	Date   string
+	Err    error
+}
+
+// Error method to comply with error interface
+func (e *FetchError) Error() string {
+	return fmt.Sprintf("failed to fetch B3 quotation for %v on %v: %v", e.Ticker, e.Date, e.Err)
+}
+
+// Unwrap method to comply with errors.Unwrap
+func (e *FetchError) Unwrap() error {
+	return e.Err
+}
+
+// Is method to comply with errors.Is
+func (e *FetchError) Is(target error) bool {
+	tar, ok := target.(*FetchError)
+	if !ok {
+		return false
+	}
+
+	if tar.Ticker == "" && tar.Date == "" && tar.Err == nil {
+		return true
+	}
+
+	return e.Ticker == tar.Ticker && e.Date == tar.Date && errors.Is(e.Err, tar.Err)
+}
+
+// CloseBodyError for when we had an error while closing body from B3 response
+type CloseBodyError struct {
+	Ticker string
+	Date   string
+	Err    error
+}
+
+// Error method to comply with error interface
+func (e *CloseBodyError) Error() string {
+	return fmt.Sprintf("failed to close B3 response body for %v on %v: %v", e.Ticker, e.Date, e.Err)
+}
+
+// Unwrap method to comply with errors.Unwrap
+func (e *CloseBodyError) Unwrap() error {
+	return e.Err
+}
+
+// Is method to comply with errors.Is
+func (e *CloseBodyError) Is(target error) bool {
+	tar, ok := target.(*CloseBodyError)
+	if !ok {
+		return false
+	}
+
+	if tar.Ticker == "" && tar.Date == "" && tar.Err == nil {
+		return true
+	}
+
+	return e.Ticker == tar.Ticker && e.Date == tar.Date && errors.Is(e.Err, tar.Err)
+}
+
+// JSONDecodeError for when we had an error while decoding json body from B3 response
+type JSONDecodeError struct {
+	Ticker string
+	Date   string
+	Err    error
+}
+
+// Error method to comply with error interface
+func (e *JSONDecodeError) Error() string {
+	return fmt.Sprintf("failed to decode B3 quotation for %v on %v: %v", e.Ticker, e.Date, e.Err)
+}
+
+// Unwrap method to comply with errors.Unwrap
+func (e *JSONDecodeError) Unwrap() error {
+	return e.Err
+}
+
+// Is method to comply with errors.Is
+func (e *JSONDecodeError) Is(target error) bool {
+	tar, ok := target.(*JSONDecodeError)
+	if !ok {
+		return false
+	}
+
+	if tar.Ticker == "" && tar.Date == "" && tar.Err == nil {
+		return true
+	}
+
+	return e.Ticker == tar.Ticker && e.Date == tar.Date && errors.Is(e.Err, tar.Err)
+}

go.mod

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+module github.com/Bezunca/b3lib
+
+go 1.14
+
+require github.com/stretchr/testify v1.6.1

go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

types.go

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+package b3lib
+
+import (
+	"time"
+)
+
+type (
+	// FetchedPrice struct to group ticker and it's current price
+	FetchedPrice struct {
+		Ticker   string `json:"ticker"`
+		IntPrice int    `json:"int_price"`
+	}
+
+	b3PriceColumns struct {
+		Name            string `json:"name"`
+		FriendlyName    string `json:"friendlyName"`
+		FriendlyNamePt  string `json:"friendlyNamePt"`
+		FriendlyNameEn  string `json:"friendlyNameEn"`
+		Type            int    `json:"type"`
+		Format          string `json:"format"`
+		ColumnAlignment int    `json:"columnAlignment"`
+		ValueAlignment  int    `json:"valueAlignment"`
+	}
+
+	b3PriceResponse struct {
+		Name         string           `json:"name"`
+		FriendlyName string           `json:"friendlyName"`
+		Columns      []b3PriceColumns `json:"columns"`
+		Values       [][6]interface{} `json:"values"`
+		// Inner slices follows columns order
+	}
+
+	tickerEntry struct {
+		Price     FetchedPrice
+		Timestamp time.Time
+	}
+)