package vfs

import (
	"context"
	"os"
	"testing"

	"github.com/rclone/rclone/fs"
	"github.com/rclone/rclone/fstest"
	"github.com/rclone/rclone/vfs/vfscommon"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"golang.org/x/text/unicode/norm"
)

func TestCaseSensitivity(t *testing.T) {
	r := fstest.NewRun(t)

	if r.Fremote.Features().CaseInsensitive {
		t.Skip("Can't test case sensitivity - this remote is officially not case-sensitive")
	}

	// Create test files
	ctx := context.Background()
	file1 := r.WriteObject(ctx, "FiLeA", "data1", t1)
	file2 := r.WriteObject(ctx, "FiLeB", "data2", t2)
	r.CheckRemoteItems(t, file1, file2)

	// Create file3 with name differing from file2 name only by case.
	// On a case-Sensitive remote this will be a separate file.
	// On a case-INsensitive remote this file will either not exist
	// or overwrite file2 depending on how file system diverges.
	// On a box.com remote this step will even fail.
	file3 := r.WriteObject(ctx, "FilEb", "data3", t3)

	// Create a case-Sensitive and case-INsensitive VFS
	optCS := vfscommon.Opt
	optCS.CaseInsensitive = false
	vfsCS := New(r.Fremote, &optCS)
	defer cleanupVFS(t, vfsCS)

	optCI := vfscommon.Opt
	optCI.CaseInsensitive = true
	vfsCI := New(r.Fremote, &optCI)
	defer cleanupVFS(t, vfsCI)

	// Run basic checks that must pass on VFS of any type.
	assertFileDataVFS(t, vfsCI, "FiLeA", "data1")
	assertFileDataVFS(t, vfsCS, "FiLeA", "data1")

	// Detect case sensitivity of the underlying remote.
	remoteIsOK := true
	if !checkFileDataVFS(t, vfsCS, "FiLeA", "data1") {
		remoteIsOK = false
	}
	if !checkFileDataVFS(t, vfsCS, "FiLeB", "data2") {
		remoteIsOK = false
	}
	if !checkFileDataVFS(t, vfsCS, "FilEb", "data3") {
		remoteIsOK = false
	}

	// The remaining test is only meaningful on a case-Sensitive file system.
	if !remoteIsOK {
		t.Skip("Can't test case sensitivity - this remote doesn't comply as case-sensitive")
	}

	// Continue with test as the underlying remote is fully case-Sensitive.
	r.CheckRemoteItems(t, file1, file2, file3)

	// See how VFS handles case-INsensitive flag
	assertFileDataVFS(t, vfsCI, "FiLeA", "data1")
	assertFileDataVFS(t, vfsCI, "fileA", "data1")
	assertFileDataVFS(t, vfsCI, "filea", "data1")
	assertFileDataVFS(t, vfsCI, "FILEA", "data1")

	assertFileDataVFS(t, vfsCI, "FiLeB", "data2")
	assertFileDataVFS(t, vfsCI, "FilEb", "data3")

	fd, err := vfsCI.OpenFile("fileb", os.O_RDONLY, 0777)
	assert.Nil(t, fd)
	assert.Error(t, err)
	assert.NotEqual(t, err, ENOENT)

	fd, err = vfsCI.OpenFile("FILEB", os.O_RDONLY, 0777)
	assert.Nil(t, fd)
	assert.Error(t, err)
	assert.NotEqual(t, err, ENOENT)

	// Run the same set of checks with case-Sensitive VFS, for comparison.
	assertFileDataVFS(t, vfsCS, "FiLeA", "data1")

	assertFileAbsentVFS(t, vfsCS, "fileA")
	assertFileAbsentVFS(t, vfsCS, "filea")
	assertFileAbsentVFS(t, vfsCS, "FILEA")

	assertFileDataVFS(t, vfsCS, "FiLeB", "data2")
	assertFileDataVFS(t, vfsCS, "FilEb", "data3")

	assertFileAbsentVFS(t, vfsCS, "fileb")
	assertFileAbsentVFS(t, vfsCS, "FILEB")
}

func checkFileDataVFS(t *testing.T, vfs *VFS, name string, expect string) bool {
	fd, err := vfs.OpenFile(name, os.O_RDONLY, 0777)
	if fd == nil || err != nil {
		return false
	}
	defer func() {
		// File must be closed - otherwise Run.cleanUp() will fail on Windows.
		_ = fd.Close()
	}()

	fh, ok := fd.(*ReadFileHandle)
	if !ok {
		return false
	}

	size := len(expect)
	buf := make([]byte, size)
	num, err := fh.Read(buf)
	if err != nil || num != size {
		return false
	}

	return string(buf) == expect
}

func assertFileDataVFS(t *testing.T, vfs *VFS, name string, expect string) {
	fd, errOpen := vfs.OpenFile(name, os.O_RDONLY, 0777)
	assert.NotNil(t, fd)
	assert.NoError(t, errOpen)

	defer func() {
		// File must be closed - otherwise Run.cleanUp() will fail on Windows.
		if errOpen == nil && fd != nil {
			_ = fd.Close()
		}
	}()

	fh, ok := fd.(*ReadFileHandle)
	require.True(t, ok)

	size := len(expect)
	buf := make([]byte, size)
	numRead, errRead := fh.Read(buf)
	assert.NoError(t, errRead)
	assert.Equal(t, numRead, size)

	assert.Equal(t, string(buf), expect)
}

func assertFileAbsentVFS(t *testing.T, vfs *VFS, name string) {
	fd, err := vfs.OpenFile(name, os.O_RDONLY, 0777)
	defer func() {
		// File must be closed - otherwise Run.cleanUp() will fail on Windows.
		if err == nil && fd != nil {
			_ = fd.Close()
		}
	}()
	assert.Nil(t, fd)
	assert.Error(t, err)
	assert.Equal(t, err, ENOENT)
}

func TestUnicodeNormalization(t *testing.T) {
	r := fstest.NewRun(t)

	var (
		nfc  = norm.NFC.String(norm.NFD.String("測試_Русский___ě_áñ"))
		nfd  = norm.NFD.String(nfc)
		both = "normal name with no special characters.txt"
	)

	// Create test files
	ctx := context.Background()
	file1 := r.WriteObject(ctx, both, "data1", t1)
	file2 := r.WriteObject(ctx, nfc, "data2", t2)
	r.CheckRemoteItems(t, file1, file2)

	// Create VFS
	opt := vfscommon.Opt
	vfs := New(r.Fremote, &opt)
	defer cleanupVFS(t, vfs)

	// assert that both files are found under NFD-normalized names
	assertFileDataVFS(t, vfs, norm.NFD.String(both), "data1")
	assertFileDataVFS(t, vfs, nfd, "data2")

	// change ci.NoUnicodeNormalization to true and verify that only file1 is found
	ci := fs.GetConfig(ctx) // need to set the global config here as the *Dir methods don't take a ctx param
	oldVal := ci.NoUnicodeNormalization
	defer func() { fs.GetConfig(ctx).NoUnicodeNormalization = oldVal }() // restore the prior value after the test
	ci.NoUnicodeNormalization = true
	assertFileDataVFS(t, vfs, norm.NFD.String(both), "data1")
	assertFileAbsentVFS(t, vfs, nfd)
}