package hw3test

import (
	"bytes"
	"io"
	"os"
	"path/filepath"
	"testing"
)

func TestWriteToDiskSelected(t *testing.T) {
	selected := &EnvFile{GenSeed: 42, Size: 4096}
	unused := &EnvFile{GenSeed: 43, Size: 4096}
	root := &EnvDir{Listing: map[string]EnvNode{
		"nested": &EnvDir{Listing: map[string]EnvNode{
			"selected": selected,
			"unused":   unused,
		}},
	}}
	location := filepath.Join(t.TempDir(), "environment")
	if err := root.WriteToDiskSelected(location, map[string]bool{"nested/selected": true}); err != nil {
		t.Fatal(err)
	}

	gotSelected, err := os.ReadFile(filepath.Join(location, "nested", "selected"))
	if err != nil {
		t.Fatal(err)
	}
	wantSelected, err := io.ReadAll(selected.Open())
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(gotSelected, wantSelected) {
		t.Fatal("selected file contents differ from generated contents")
	}

	gotUnused, err := os.ReadFile(filepath.Join(location, "nested", "unused"))
	if err != nil {
		t.Fatal(err)
	}
	if len(gotUnused) != int(unused.Size) || !bytes.Equal(gotUnused, make([]byte, unused.Size)) {
		t.Fatal("unused file must retain its size without generated contents")
	}
}