refactor podcast schema and generate unique episode paths (#373)

closes #350

fileutil/fileutil_test.go

@@ -0,0 +1,56 @@
+package fileutil
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestUniquePath(t *testing.T) {
+	unq := func(base, filename string, count uint) string {
+		r, err := unique(base, filename, count)
+		require.NoError(t, err)
+		return r
+	}
+
+	require.Equal(t, "test/wow.mp3", unq("test", "wow.mp3", 0))
+	require.Equal(t, "test/wow (1).mp3", unq("test", "wow.mp3", 1))
+	require.Equal(t, "test/wow (2).mp3", unq("test", "wow.mp3", 2))
+
+	require.Equal(t, "test", unq("test", "", 0))
+	require.Equal(t, "test (1)", unq("test", "", 1))
+
+	base := filepath.Join(t.TempDir(), "a")
+
+	require.NoError(t, os.MkdirAll(base, os.ModePerm))
+
+	next := base + " (1)"
+	require.Equal(t, next, unq(base, "", 0))
+
+	require.NoError(t, os.MkdirAll(next, os.ModePerm))
+
+	next = base + " (2)"
+	require.Equal(t, next, unq(base, "", 0))
+
+	_, err := os.Create(filepath.Join(base, "test.mp3"))
+	require.NoError(t, err)
+	require.Equal(t, filepath.Join(base, "test (1).mp3"), unq(base, "test.mp3", 0))
+}
+
+func TestFirst(t *testing.T) {
+	base := t.TempDir()
+	name := filepath.Join(base, "test")
+	_, err := os.Create(name)
+	require.NoError(t, err)
+
+	p := func(name string) string {
+		return filepath.Join(base, name)
+	}
+
+	r, err := First(p("one"), p("two"), p("test"), p("four"))
+	require.NoError(t, err)
+	require.Equal(t, p("test"), r)
+
+}