feat: done vibing

internal/fetch/finnhub.go

@@ -0,0 +1,178 @@
+package fetch
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/ytshih/stonks/internal/config"
+)
+
+func init() {
+	Register("finnhub", newFinnhubFetcher)
+}
+
+const finnhubBaseURL = "https://finnhub.io/api/v1"
+
+// finnhubParams is the plugin-specific config for the finnhub fetcher.
+type finnhubParams struct {
+	// APIKeyEnvVar names the environment variable holding the Finnhub API
+	// key. Defaults to FINNHUB_API_KEY.
+	APIKeyEnvVar string `yaml:"api_key_env_var"`
+	// NewsLookbackDays controls how far back company-news headlines are
+	// pulled. Defaults to 1 (yesterday through today).
+	NewsLookbackDays int `yaml:"news_lookback_days"`
+}
+
+// finnhubFetcher fetches equity quotes and per-ticker company news from
+// Finnhub's free tier (documented, key-based — a more stable second price
+// source than the unofficial yfinance-equivalent fetcher). Finnhub's free
+// tier does not cover crypto or futures symbols, so this fetcher only
+// covers targets.Equities.
+type finnhubFetcher struct {
+	apiKey           string
+	newsLookbackDays int
+	client           *http.Client
+}
+
+func newFinnhubFetcher(cfg config.PluginConfig) (Fetcher, error) {
+	params := finnhubParams{
+		APIKeyEnvVar:     "FINNHUB_API_KEY",
+		NewsLookbackDays: 1,
+	}
+	if err := cfg.DecodeParams(&params); err != nil {
+		return nil, err
+	}
+
+	apiKey := os.Getenv(params.APIKeyEnvVar)
+	if apiKey == "" {
+		return nil, fmt.Errorf("finnhub: environment variable %q is not set", params.APIKeyEnvVar)
+	}
+
+	return &finnhubFetcher{
+		apiKey:           apiKey,
+		newsLookbackDays: params.NewsLookbackDays,
+		client:           &http.Client{Timeout: 15 * time.Second},
+	}, nil
+}
+
+func (f *finnhubFetcher) Name() string { return "finnhub" }
+
+func (f *finnhubFetcher) Fetch(ctx context.Context, targets config.Targets) (Result, error) {
+	var result Result
+	var errs []error
+
+	for _, symbol := range targets.Equities {
+		q, err := f.fetchQuote(ctx, symbol)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("finnhub quote %s: %w", symbol, err))
+			continue
+		}
+		result.Quotes = append(result.Quotes, q)
+
+		news, err := f.fetchCompanyNews(ctx, symbol)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("finnhub news %s: %w", symbol, err))
+			continue
+		}
+		result.News = append(result.News, news...)
+	}
+
+	return result, joinErrs(errs)
+}
+
+type finnhubQuoteResponse struct {
+	Current       float64 `json:"c"`
+	Change        float64 `json:"d"`
+	PercentChange float64 `json:"dp"`
+}
+
+func (f *finnhubFetcher) fetchQuote(ctx context.Context, symbol string) (Quote, error) {
+	var resp finnhubQuoteResponse
+	if err := f.get(ctx, "/quote", url.Values{"symbol": {symbol}}, &resp); err != nil {
+		return Quote{}, err
+	}
+	if resp.Current == 0 {
+		return Quote{}, fmt.Errorf("no data returned (symbol may be invalid or unsupported on this tier)")
+	}
+	return Quote{
+		Symbol:        symbol,
+		Label:         symbol,
+		Price:         resp.Current,
+		ChangePercent: resp.PercentChange,
+		Currency:      "USD",
+		Source:        "finnhub",
+	}, nil
+}
+
+type finnhubNewsItem struct {
+	Datetime int64  `json:"datetime"`
+	Headline string `json:"headline"`
+	Source   string `json:"source"`
+	Summary  string `json:"summary"`
+	URL      string `json:"url"`
+}
+
+func (f *finnhubFetcher) fetchCompanyNews(ctx context.Context, symbol string) ([]NewsItem, error) {
+	to := time.Now().UTC()
+	from := to.AddDate(0, 0, -f.newsLookbackDays)
+
+	var resp []finnhubNewsItem
+	params := url.Values{
+		"symbol": {symbol},
+		"from":   {from.Format("2006-01-02")},
+		"to":     {to.Format("2006-01-02")},
+	}
+	if err := f.get(ctx, "/company-news", params, &resp); err != nil {
+		return nil, err
+	}
+
+	items := make([]NewsItem, 0, len(resp))
+	for _, n := range resp {
+		items = append(items, NewsItem{
+			Title:     fmt.Sprintf("[%s] %s", symbol, n.Headline),
+			Source:    n.Source,
+			URL:       n.URL,
+			Published: time.Unix(n.Datetime, 0).UTC(),
+			Summary:   n.Summary,
+		})
+	}
+	return items, nil
+}
+
+func (f *finnhubFetcher) get(ctx context.Context, path string, params url.Values, out any) error {
+	params.Set("token", f.apiKey)
+	reqURL := finnhubBaseURL + path + "?" + params.Encode()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
+	if err != nil {
+		return err
+	}
+
+	resp, err := f.client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected status %d", resp.StatusCode)
+	}
+	return json.NewDecoder(resp.Body).Decode(out)
+}
+
+// joinErrs combines multiple errors into one, or returns nil if errs is empty.
+func joinErrs(errs []error) error {
+	if len(errs) == 0 {
+		return nil
+	}
+	msg := fmt.Sprintf("%d error(s) occurred:", len(errs))
+	for _, e := range errs {
+		msg += "\n  - " + e.Error()
+	}
+	return fmt.Errorf("%s", msg)
+}