Initial commit

internal/feed/yahoo.go

@@ -0,0 +1,102 @@
+package feed
+
+import (
+	"fmt"
+	"log/slog"
+	"net/http"
+)
+
+type stockResponseJson struct {
+	Chart struct {
+		Result []struct {
+			Meta struct {
+				Symbol             string  `json:"symbol"`
+				RegularMarketPrice float64 `json:"regularMarketPrice"`
+				ChartPreviousClose float64 `json:"chartPreviousClose"`
+			} `json:"meta"`
+			Indicators struct {
+				Quote []struct {
+					Close []float64 `json:"close,omitempty"`
+				} `json:"quote"`
+			} `json:"indicators"`
+		} `json:"result"`
+	} `json:"chart"`
+}
+
+type StockRequest struct {
+	Symbol string
+	Name   string
+}
+
+// TODO: allow changing chart time frame
+const stockChartDays = 21
+
+func FetchStocksDataFromYahoo(stockRequests []StockRequest) (Stocks, error) {
+	requests := make([]*http.Request, 0, len(stockRequests))
+
+	for i := range stockRequests {
+		request, _ := http.NewRequest("GET", fmt.Sprintf("https://query1.finance.yahoo.com/v8/finance/chart/%s?range=1mo&interval=1d", stockRequests[i].Symbol), nil)
+		requests = append(requests, request)
+	}
+
+	job := newJob(decodeJsonFromRequestTask[stockResponseJson](defaultClient), requests)
+	responses, errs, err := workerPoolDo(job)
+
+	if err != nil {
+		return nil, fmt.Errorf("%w: %v", ErrNoContent, err)
+	}
+
+	stocks := make(Stocks, 0, len(responses))
+	var failed int
+
+	for i := range responses {
+		if errs[i] != nil {
+			failed++
+			slog.Error("Failed to fetch stock data", "symbol", stockRequests[i].Symbol, "error", errs[i])
+			continue
+		}
+
+		response := responses[i]
+
+		if len(response.Chart.Result) == 0 {
+			failed++
+			slog.Error("Stock response contains no data", "symbol", stockRequests[i].Symbol)
+			continue
+		}
+
+		prices := response.Chart.Result[0].Indicators.Quote[0].Close
+
+		if len(prices) > stockChartDays {
+			prices = prices[len(prices)-stockChartDays:]
+		}
+
+		previous := response.Chart.Result[0].Meta.RegularMarketPrice
+
+		if len(prices) >= 2 && prices[len(prices)-2] != 0 {
+			previous = prices[len(prices)-2]
+		}
+
+		points := SvgPolylineCoordsFromYValues(100, 50, maybeCopySliceWithoutZeroValues(prices))
+
+		stocks = append(stocks, Stock{
+			Name:   stockRequests[i].Name,
+			Symbol: response.Chart.Result[0].Meta.Symbol,
+			Price:  response.Chart.Result[0].Meta.RegularMarketPrice,
+			PercentChange: percentChange(
+				response.Chart.Result[0].Meta.RegularMarketPrice,
+				previous,
+			),
+			SvgChartPoints: points,
+		})
+	}
+
+	if len(stocks) == 0 {
+		return nil, ErrNoContent
+	}
+
+	if failed > 0 {
+		return stocks, fmt.Errorf("%w: could not fetch data for %d stock(s)", ErrPartialContent, failed)
+	}
+
+	return stocks, nil
+}