Wworking on improving the tool

internal/datasource/epics/cf_client.go

@@ -0,0 +1,67 @@
+package epics
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strings"
+	"time"
+)
+
+// cfChannel is the JSON structure returned by the Channel Finder Service.
+type cfChannel struct {
+	Name       string       `json:"name"`
+	Owner      string       `json:"owner"`
+	Properties []cfProperty `json:"properties"`
+	Tags       []cfTag      `json:"tags"`
+}
+
+type cfProperty struct {
+	Name  string `json:"name"`
+	Value string `json:"value"`
+	Owner string `json:"owner"`
+}
+
+type cfTag struct {
+	Name  string `json:"name"`
+	Owner string `json:"owner"`
+}
+
+// queryChannelFinder fetches channels from CFS matching the given query string.
+func queryChannelFinder(cfURL, query string) ([]cfChannel, error) {
+	if cfURL == "" {
+		return nil, nil
+	}
+
+	url := strings.TrimRight(cfURL, "/") + "/resources/channels"
+	if query != "" {
+		if strings.Contains(query, "=") || strings.Contains(query, "~") {
+			// Query is already a structured filter (e.g. area=L1)
+			url += "?" + query
+		} else {
+			// Query is just a PV name pattern
+			url += "?~name=*" + query + "*"
+		}
+	}
+
+	client := &http.Client{Timeout: 10 * time.Second}
+	slog.Info("CFS query", "url", url)
+	resp, err := client.Get(url)
+	if err != nil {
+		return nil, fmt.Errorf("CFS request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("CFS returned status %d", resp.StatusCode)
+	}
+
+	var channels []cfChannel
+	if err := json.NewDecoder(resp.Body).Decode(&channels); err != nil {
+		return nil, fmt.Errorf("CFS response parse error: %w", err)
+	}
+	slog.Info("CFS results", "count", len(channels))
+
+	return channels, nil
+}