feat(cli): interactive numbered picker (stdin/stderr separated)

cli/picker.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// parseChoice reads a 1-based integer from r, validated in [1, max].
+func parseChoice(r io.Reader, max int) (int, error) {
+	scanner := bufio.NewScanner(r)
+	if !scanner.Scan() {
+		return 0, fmt.Errorf("no input")
+	}
+	text := strings.TrimSpace(scanner.Text())
+	if text == "" {
+		return 0, fmt.Errorf("enter a number between 1 and %d", max)
+	}
+	n, err := strconv.Atoi(text)
+	if err != nil || n < 1 || n > max {
+		return 0, fmt.Errorf("enter a number between 1 and %d", max)
+	}
+	return n, nil
+}
+
+func pickProduct(products []Product) (Product, error) {
+	fmt.Fprintln(os.Stderr, "\nSelect a product:")
+	for i, p := range products {
+		fmt.Fprintf(os.Stderr, "  %2d. %s\n", i+1, p.Name)
+	}
+	fmt.Fprint(os.Stderr, "\nChoice: ")
+	n, err := parseChoice(os.Stdin, len(products))
+	if err != nil {
+		return Product{}, err
+	}
+	return products[n-1], nil
+}
+
+func pickLanguage(langs []Language) (Language, error) {
+	fmt.Fprintln(os.Stderr, "\nSelect a language:")
+	for i, l := range langs {
+		fmt.Fprintf(os.Stderr, "  %2d. %s\n", i+1, l.Language)
+	}
+	fmt.Fprint(os.Stderr, "\nChoice: ")
+	n, err := parseChoice(os.Stdin, len(langs))
+	if err != nil {
+		return Language{}, err
+	}
+	return langs[n-1], nil
+}
+
+func pickEvalProduct(products []EvalProduct) (EvalProduct, error) {
+	fmt.Fprintln(os.Stderr, "\nSelect an evaluation product:")
+	for i, p := range products {
+		fmt.Fprintf(os.Stderr, "  %2d. %s\n", i+1, p.Name)
+	}
+	fmt.Fprint(os.Stderr, "\nChoice: ")
+	n, err := parseChoice(os.Stdin, len(products))
+	if err != nil {
+		return EvalProduct{}, err
+	}
+	return products[n-1], nil
+}

cli/picker_test.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseChoice_valid(t *testing.T) {
+	cases := []struct {
+		input string
+		max   int
+		want  int
+	}{
+		{"1\n", 3, 1},
+		{"3\n", 3, 3},
+		{"  2  \n", 5, 2},
+	}
+	for _, c := range cases {
+		got, err := parseChoice(strings.NewReader(c.input), c.max)
+		if err != nil {
+			t.Errorf("input %q: unexpected error: %v", c.input, err)
+			continue
+		}
+		if got != c.want {
+			t.Errorf("input %q: got %d, want %d", c.input, got, c.want)
+		}
+	}
+}
+
+func TestParseChoice_outOfRange(t *testing.T) {
+	cases := []string{"0\n", "4\n"}
+	for _, input := range cases {
+		_, err := parseChoice(strings.NewReader(input), 3)
+		if err == nil {
+			t.Errorf("input %q: expected error for out-of-range, got nil", input)
+		}
+	}
+}
+
+func TestParseChoice_nonNumeric(t *testing.T) {
+	_, err := parseChoice(strings.NewReader("abc\n"), 3)
+	if err == nil {
+		t.Error("expected error for non-numeric input, got nil")
+	}
+}
+
+func TestParseChoice_emptyInput(t *testing.T) {
+	_, err := parseChoice(strings.NewReader("\n"), 3)
+	if err == nil {
+		t.Error("expected error for empty input, got nil")
+	}
+}