package fs

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

func TestCopySourceFileToExistingDestination(t *testing.T) {
	dir := t.TempDir()
	sourcePath := path.Join(dir, "source.txt")
	if err := os.WriteFile(sourcePath, []byte("abc"), 0666); err != nil {
		t.Fatalf("%v", err)
	}

	destPath := path.Join(dir, "dest.txt")
	if err := os.WriteFile(destPath, []byte("defghi"), 0666); err != nil {
		t.Fatalf("%v", err)
	}

	if err := CopyFile(sourcePath, destPath, 0666); err != nil {
		t.Fatalf("%v", err)
	}

	contents, err := os.ReadFile(destPath)
	if err != nil {
		t.Fatalf("%v", err)
	}

	if string(contents) != "abc" {
		t.Fatalf("expected dest.txt to have contents 'abc' after copying source.txt; got %s", string(contents))
	}
}

func TestCopyDir(t *testing.T) {
	var err error

	src := t.TempDir()
	dst := t.TempDir()

	testData := []struct {
		path string
		data string
	}{
		{
			"a/b.txt",
			"abc",
		},
		{
			"a/c/d.txt",
			"def",
		},
		{
			"a/c/e.txt",
			"ghi",
		},
	}

	for _, data := range testData {
		srcDir := path.Join(src, filepath.Dir(data.path))
		err = os.MkdirAll(srcDir, 0777)
		if err != nil {
			t.Fatalf("could not make dir %s: %v", srcDir, err)
		}
		srcPath := path.Join(src, data.path)
		err = os.WriteFile(srcPath, []byte(data.data), 0666)
		if err != nil {
			t.Fatalf("could not write data to file %s: %v", srcPath, err)
		}
	}

	err = CopyDir(src, dst, 0777)
	if err != nil {
		t.Fatalf("failed to copy %s to %s: %v", src, dst, err)
	}

	for _, data := range testData {
		dstPath := path.Join(dst, data.path)
		contents, err := os.ReadFile(dstPath)
		if err != nil {
			t.Fatalf("could not read contents for %s: %v", dstPath, err)
		}
		if !bytes.Equal(contents, []byte(data.data)) {
			t.Fatalf("wrong contents for %s (expected %s, got %s)", dstPath, contents, data.data)
		}
	}
}