package musicfs

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestDeriveSubdir(t *testing.T) {
	tests := []struct {
		name        string
		originRoot  string
		contentPath string
		expected    string
	}{
		{
			name:        "normal subdirectory",
			originRoot:  "/downloads/music",
			contentPath: "/downloads/music/Metallica - Master of Puppets (1986) [FLAC]",
			expected:    "Metallica - Master of Puppets (1986) [FLAC]",
		},
		{
			name:        "nested subdirectory",
			originRoot:  "/downloads/music",
			contentPath: "/downloads/music/Metal/Metallica/Master of Puppets",
			expected:    "Metal/Metallica/Master of Puppets",
		},
		{
			name:        "same directory",
			originRoot:  "/downloads/music",
			contentPath: "/downloads/music",
			expected:    ".",
		},
		{
			name:        "outside origin root falls back to empty",
			originRoot:  "/downloads/music",
			contentPath: "/tmp/other/path",
			expected:    "",
		},
		{
			name:        "parent directory falls back to empty",
			originRoot:  "/downloads/music/sub",
			contentPath: "/downloads/music",
			expected:    "",
		},
		{
			name:        "trailing slash on root",
			originRoot:  "/downloads/music/",
			contentPath: "/downloads/music/Album",
			expected:    "Album",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := DeriveSubdir(tt.originRoot, tt.contentPath)
			assert.Equal(t, tt.expected, result)
		})
	}
}