package filestore

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

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

func TestMemoryBackend(t *testing.T) {
	t.Parallel()

	t.Run("it is a valid backend", func(t *testing.T) {
		m := new(MemoryBackend)
		ValidateBackend(t, m)
	})

	t.Run("read then write a file", func(t *testing.T) {
	})
}

func TestOSBackend(t *testing.T) {
	t.Parallel()

	t.Run("it is a valid backend", func(t *testing.T) {
		tmpDir := t.TempDir()
		m := NewOSBackend(tmpDir)

		ValidateBackend(t, m)
	})

	t.Run("it returns an error if the directory cannot be created", func(t *testing.T) {
		assert := require.New(t)

		tmpDir := t.TempDir()
		fullpath := filepath.Join(tmpDir, "foo")
		m := NewOSBackend(fullpath)

		err := os.WriteFile(fullpath, []byte(filecontent), 0o600)
		assert.NoError(err)

		wc, err := m.Create("foo")
		assert.Error(err)
		assert.Nil(wc)
	})
}

//revive:disable:cognitive-complexity
func ValidateBackend(t *testing.T, b Backend) {
	t.Helper()

	filecontent := []byte("file content")

	setupBackend(t, b)

	t.Run("validate Sub", func(t *testing.T) {
		t.Run("it must not be nil", func(t *testing.T) {
			s := b.Sub("foo")
			require.NotNil(t, s, "Sub must not return a nil value")
		})
	})

	t.Run("validate Create", func(t *testing.T) {
		t.Run("it must create a file if it does not exist", func(t *testing.T) {
			assert := require.New(t)

			precondFileNotExists(t, b, "create-1")

			wc, err := b.Create("create-1")
			assert.NoError(err, "Create must not return an error in case of success")
			assert.NotNil(wc, "Create must return a non nil value in case of success")

			_, err = wc.Write(filecontent)
			assert.NoError(err)

			wc.Close()

			assert.True(b.Exists("create-1"), "The file must exist after "+
				"Create has been successfully called")

			rc, err := b.Open("create-1")
			assert.NoError(err)

			newcontent, err := io.ReadAll(rc)
			assert.NoError(err)
			assert.Equal(filecontent, newcontent, "The content of the created "+
				"file must be correct")
		})

		t.Run("it should replace a file if it exists", func(t *testing.T) {
			assert := require.New(t)

			precondFileExists(t, b, "create-2")

			wc, err := b.Create("create-2")
			assert.NoError(err, "Create must not return an error if the file "+
				"already exists")

			_, err = wc.Write(filecontent)
			assert.NoError(err)

			wc.Close()

			rc, err := b.Open("create-2")
			assert.NoError(err)

			newcontent, err := io.ReadAll(rc)
			assert.NoError(err)
			assert.NotEqual([]byte("hello world"), newcontent, "Create should "+
				"overwrite the file when it already existed")
			assert.Equal(filecontent, newcontent, "Create should "+
				"overwrite the file when it already existed")
		})

		t.Run("when the file cannot be created", func(t *testing.T) {
			t.Skip("do not know how to implement that!")
			// maybe we should require that a directory already exists in the backend
			assert := require.New(t)

			wc, err := b.Create("create-3")
			assert.NoError(err)
			assert.Nil(wc, "the file access must be nil if Create returns an error")
		})
	})

	t.Run("validate Open", func(t *testing.T) {
		t.Run("it should return an open file if it exists", func(t *testing.T) {
			assert := require.New(t)
			precondFileExists(t, b, "open-1")

			rc, err := b.Open("open-1")
			assert.NoError(err, "Open must not return an error when successful")
			assert.NotNil(rc, "Open must not return a nil value when successful")

			rc.Close()
		})

		t.Run("when the file does not exist", func(t *testing.T) {
			assert := require.New(t)
			precondFileNotExists(t, b, "open-2")

			rc, err := b.Open("open-2")
			assert.Error(err, "Open must return an error when the file does not exist")
			assert.Nil(rc, "Open must return a nil value when the file does not exist")
		})

		t.Run("when the file cannot be opened", func(t *testing.T) {
			t.Skip("do not know how to implement that test!")
			precondFileExists(t, b, "open-3")
		})
	})

	t.Run("validate Delete", func(t *testing.T) {
		t.Run("it should remove a file if it exists", func(t *testing.T) {
			assert := require.New(t)
			precondFileExists(t, b, "delete-1")

			err := b.Delete("delete-1")
			assert.NoError(err, "Delete must not return an error in case of success")

			assert.False(b.Exists("delete-1"), "File must not exist anymore "+
				"after a successful delete")
		})

		t.Run("when the file does not exist", func(t *testing.T) {
			assert := require.New(t)
			precondFileNotExists(t, b, "delete-2")

			err := b.Delete("delete-2")
			assert.NoError(err, "Delete must not return an error if the file "+
				"does not exist")
		})

		t.Run("when the file cannot be deleted", func(t *testing.T) {
			t.Skip("don't know ho to test that!")
			assert := require.New(t)
			precondFileExists(t, b, "delete-3")

			err := b.Delete("delete-3")
			assert.Error(err, "Delete must return an error when the file "+
				"cannot be deleted")
		})
	})

	t.Run("validate Exists", func(t *testing.T) {
		t.Run("it should return true if the file exists", func(t *testing.T) {
			wc, err := b.Create("exists1")
			require.NoError(t, err)
			require.NotNil(t, wc)

			_, err = wc.Write(filecontent)
			wc.Close()
			require.NoError(t, err)

			require.True(t, b.Exists("exists1"))
		})

		t.Run("it should return false if the file does not exist", func(t *testing.T) {
			require.False(t, b.Exists("exists2"))
		})
	})
}

func setupBackend(t *testing.T, b Backend) {
	t.Helper()

	assert := require.New(t)

	wc, err := b.Create("create-2")
	assert.NoError(err)
	defer wc.Close()
	_, err = wc.Write([]byte("hello world"))
	assert.NoError(err)

	wc, err = b.Create("open-1")
	assert.NoError(err)
	defer wc.Close()
	_, err = wc.Write([]byte(filecontent))
	assert.NoError(err)

	wc, err = b.Create("delete-1")
	assert.NoError(err)
	defer wc.Close()
	_, err = wc.Write([]byte(filecontent))
	assert.NoError(err)
}

func precondFileExists(t *testing.T, b Backend, name string) {
	t.Helper()

	require.True(t, b.Exists(name), "PRECOND: file %q must exist for this test",
		name)
}

func precondFileNotExists(t *testing.T, b Backend, name string) {
	t.Helper()

	require.False(t, b.Exists(name), "PRECOND: file %q must not exist for this test",
		name)
}