package main

import (
	"io/fs"
	"io/ioutil"
	"path/filepath"
	"os"
	"reflect"
	"testing"
)

func TestFileExists(t *testing.T) {
	tmpd := t.TempDir()
	existsFile := filepath.Join(tmpd, "exists.txt")
	ioutil.WriteFile(existsFile, []byte("\n"), 0644)
	if !fileExists(existsFile) {
		t.Errorf("%s should exist, but does not", existsFile)
	}

	notExistsFile := filepath.Join(tmpd, "not_exists.txt")
	if fileExists(notExistsFile) {
		t.Errorf("%s should not exist, but does", notExistsFile)
	}

	if fileExists(tmpd) {
		t.Errorf("%s should not exist as a file, it is a dir", tmpd)
	}
}

func TestFilesMatchByLine(t *testing.T) {
	tmpd := t.TempDir()

	type fileSpec struct {
		name string
		contents string
	}

	aFileSpec := fileSpec {
			name: "a.txt",
			contents: "a\n",
		}
		bFileSpec := fileSpec{
			name: "b.txt",
			contents: "b\n",
		}
		abFileSpec := fileSpec{
			name: "ab.txt",
			contents: "a\nb\n",
		}
		acFileSpec := fileSpec{
			name: "ac.txt",
			contents: "a\nc\n",
		}

	files := []fileSpec{
		aFileSpec, bFileSpec, abFileSpec, acFileSpec,
	}

	for _, f := range files {
		file := filepath.Join(tmpd, f.name)
		ioutil.WriteFile(file, []byte(f.contents), 0644)
	}

	match := func(fs1 fileSpec, fs2 fileSpec) bool {
		return filesMatchByLine(
			filepath.Join(tmpd, fs1.name),
			filepath.Join(tmpd, fs2.name),
		)
	}

	testCases := []struct{
		left fileSpec
		right fileSpec
		expectMatch bool
	}{

		{
			left: aFileSpec,
			right: aFileSpec,
			expectMatch: true,
		},
		{
			left: bFileSpec,
			right: bFileSpec,
			expectMatch: true,
		},
		{
			left: abFileSpec,
			right: abFileSpec,
			expectMatch: true,
		},
		{
			left: acFileSpec,
			right: acFileSpec,
			expectMatch: true,
		},
		{
			left: aFileSpec,
			right: bFileSpec,
			expectMatch: false,
		},
		{
			left: bFileSpec,
			right: aFileSpec,
			expectMatch: false,
		},
		{
			left: aFileSpec,
			right: abFileSpec,
			expectMatch: false,
		},
		{
			left: abFileSpec,
			right: aFileSpec,
			expectMatch: false,
		},
		{
			left: aFileSpec,
			right: acFileSpec,
			expectMatch: false,
		},
		{
			left: acFileSpec,
			right: aFileSpec,
			expectMatch: false,
		},
	}

	for _, tc := range testCases {
		actual := match(tc.left, tc.right)
		if actual != tc.expectMatch {
			t.Errorf("Matching %s vs. %s should have been %v, but got %v", tc.left.name, tc.right.name, tc.expectMatch, actual)
		}
	}
}

func TestCopyFileWithMode(t *testing.T) {
	tmpd := t.TempDir()

	var mode fs.FileMode = 0600
	testFile := filepath.Join(tmpd, "private.txt")
	ioutil.WriteFile(testFile, []byte("\n"), mode)

	copyFile := filepath.Join(tmpd, "copy.txt")
	err := copyFileWithMode(copyFile, testFile)
	if err != nil {
		t.Fatalf("Error copying file: %s", copyFile)
	}

	copyF, err := os.Open(copyFile)
	if err != nil {
		t.Fatalf("Failed to read the file that was just written, %s", copyFile)
	}
	info, err := copyF.Stat()
	if err != nil {
		t.Fatalf("Failed to stat the written file, %s", copyFile)
	}
	if info.Mode() != mode {
		t.Errorf("File modes mismatched.  Want: %o, Got: %o", mode, info.Mode())
	}
}

func TestRemoveIfAbsentRootDoesNotExist(t *testing.T) {
	tmpdDst := t.TempDir()

	var mode fs.FileMode = 0644
	ioutil.WriteFile(filepath.Join(tmpdDst, "b.txt"), []byte("z\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "c.txt"), []byte("w\n"), mode)

	keepers := map[string]bool{}  // value doesn't matter
	removed, err := removeIfAbsent(filepath.Join(tmpdDst, "subdir_not_exist"), keepers)
	if err != nil {
		t.Errorf("Expected no error, but got: %v", err)
	}
	if removed {
		t.Errorf("Expected that nothing was removed, but got: %v", removed)
	}
}

func TestRemoveIfAbsentPartialRemove(t *testing.T) {
	tmpdSrc := t.TempDir()
	tmpdDst := t.TempDir()

	var mode fs.FileMode = 0644
	ioutil.WriteFile(filepath.Join(tmpdSrc, "a.txt"), []byte("x\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdSrc, "b.txt"), []byte("y\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "b.txt"), []byte("z\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "c.txt"), []byte("w\n"), mode)

	keepers := listFilesDirsRecursively(tmpdSrc)
	removed, err := removeIfAbsent(tmpdDst, keepers)
	if err != nil {
		t.Fatalf("Expected no error, but got: %v", err)
	}
	actualRemainder := listFilesDirsRecursively(tmpdDst)
	expectedRemainder := map[string]bool{
		"b.txt": false,
	}
	if !removed {
		t.Errorf("Expected that something was removed, but got: %v", removed)
	}

	if !reflect.DeepEqual(actualRemainder, expectedRemainder) {
		t.Errorf("Expected dir contents %v, but got %v", expectedRemainder, actualRemainder)
	}
}

func TestRemoveIfAbsentRemoveNothing(t *testing.T) {
	tmpdDst := t.TempDir()

	var mode fs.FileMode = 0644
	ioutil.WriteFile(filepath.Join(tmpdDst, "j.txt"), []byte("z\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "k.txt"), []byte("w\n"), mode)

	keepers := map[string]bool{
		"j.txt": false,
		"k.txt": false,
	}
	removed, err := removeIfAbsent(tmpdDst, keepers)
	if err != nil {
		t.Fatalf("Expected no error, but got: %v", err)
	}
	actualRemainder := listFilesDirsRecursively(tmpdDst)

	if removed {
		t.Errorf("Expected that nothing was removed, but got: %v", removed)
	}
	if !reflect.DeepEqual(actualRemainder, keepers) {
		t.Errorf("Expected dir contents %v, but got %v", keepers, actualRemainder)
	}
}

func TestRemoveIfAbsentRemoveEverything(t *testing.T) {
	tmpdDst := t.TempDir()

	var mode fs.FileMode = 0644
	ioutil.WriteFile(filepath.Join(tmpdDst, "p.txt"), []byte("z\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "q.txt"), []byte("w\n"), mode)

	keepers := map[string]bool{}
	removed, err := removeIfAbsent(tmpdDst, keepers)
	if err != nil {
		t.Fatalf("Expected no error, but got: %v", err)
	}
	actualRemainder := listFilesDirsRecursively(tmpdDst)

	if !removed {
		t.Errorf("Expected that something was removed, but got: %v", removed)
	}
	if !reflect.DeepEqual(actualRemainder, keepers) {
		t.Errorf("Expected dir contents %v, but got %v", keepers, actualRemainder)
	}
}

func TestRemoveIfAbsentPartialRemoveInSubdirs(t *testing.T) {
	tmpdSrc := t.TempDir()
	tmpdDst := t.TempDir()

	var mode fs.FileMode = 0644

	if err := os.Mkdir(filepath.Join(tmpdSrc, "sub"), os.ModePerm); err != nil {
		t.Fatalf("Error creating dir: %v", err)
	}
	if err := os.Mkdir(filepath.Join(tmpdDst, "sub"), os.ModePerm); err != nil {
		t.Fatalf("Error creating dir: %v", err)
	}

	ioutil.WriteFile(filepath.Join(tmpdSrc, "sub", "a.txt"), []byte("x\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdSrc, "sub", "b.txt"), []byte("y\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "sub", "b.txt"), []byte("z\n"), mode)
	ioutil.WriteFile(filepath.Join(tmpdDst, "sub", "c.txt"), []byte("w\n"), mode)

	keepers := listFilesDirsRecursively(tmpdSrc)
	removed, err := removeIfAbsent(tmpdDst, keepers)
	if err != nil {
		t.Fatalf("Expected no error, but got: %v", err)
	}
	actualRemainder := listFilesDirsRecursively(tmpdDst)
	expectedRemainder := map[string]bool{
		"sub": true,
		"sub/b.txt": false,
	}

	if !removed {
		t.Errorf("Expected that something was removed, but got: %v", removed)
	}
	if !reflect.DeepEqual(actualRemainder, expectedRemainder) {
		t.Errorf("Expected dir contents %v, but got %v", expectedRemainder, actualRemainder)
	}
}