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// Copyright © 2015 Steve Francia <[email protected]>.
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// Copyright 2013 tsuru authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mem
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import (
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	"bytes"
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	"errors"
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	"io"
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	"io/fs"
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	"os"
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	"path/filepath"
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	"sync"
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	"sync/atomic"
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	"time"
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	"github.com/spf13/afero/internal/common"
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)
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const FilePathSeparator = string(filepath.Separator)
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var _ fs.ReadDirFile = &File{}
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type File struct {
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	// atomic requires 64-bit alignment for struct field access
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	at           int64
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	readDirCount int64
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	closed       bool
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	readOnly     bool
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	fileData     *FileData
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}
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func NewFileHandle(data *FileData) *File {
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	return &File{fileData: data}
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}
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func NewReadOnlyFileHandle(data *FileData) *File {
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	return &File{fileData: data, readOnly: true}
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}
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func (f File) Data() *FileData {
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	return f.fileData
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}
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type FileData struct {
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	sync.Mutex
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	name    string
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	data    []byte
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	memDir  Dir
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	dir     bool
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	mode    os.FileMode
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	modtime time.Time
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	uid     int
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	gid     int
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}
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func (d *FileData) Name() string {
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	d.Lock()
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	defer d.Unlock()
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	return d.name
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}
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func CreateFile(name string) *FileData {
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	return &FileData{name: name, mode: os.ModeTemporary, modtime: time.Now()}
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}
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func CreateDir(name string) *FileData {
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	return &FileData{name: name, memDir: &DirMap{}, dir: true, modtime: time.Now()}
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}
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func ChangeFileName(f *FileData, newname string) {
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	f.Lock()
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	f.name = newname
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	f.Unlock()
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}
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func SetMode(f *FileData, mode os.FileMode) {
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	f.Lock()
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	f.mode = mode
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	f.Unlock()
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}
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func SetModTime(f *FileData, mtime time.Time) {
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	f.Lock()
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	setModTime(f, mtime)
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	f.Unlock()
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}
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func setModTime(f *FileData, mtime time.Time) {
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	f.modtime = mtime
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}
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func SetUID(f *FileData, uid int) {
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	f.Lock()
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	f.uid = uid
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	f.Unlock()
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}
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func SetGID(f *FileData, gid int) {
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	f.Lock()
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	f.gid = gid
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	f.Unlock()
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}
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func GetFileInfo(f *FileData) *FileInfo {
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	return &FileInfo{f}
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}
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func (f *File) Open() error {
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	atomic.StoreInt64(&f.at, 0)
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	atomic.StoreInt64(&f.readDirCount, 0)
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	f.fileData.Lock()
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	f.closed = false
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	f.fileData.Unlock()
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	return nil
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}
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func (f *File) Close() error {
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	f.fileData.Lock()
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	f.closed = true
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	if !f.readOnly {
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		setModTime(f.fileData, time.Now())
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	}
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	f.fileData.Unlock()
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	return nil
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}
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func (f *File) Name() string {
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	return f.fileData.Name()
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}
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func (f *File) Stat() (os.FileInfo, error) {
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	return &FileInfo{f.fileData}, nil
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}
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func (f *File) Sync() error {
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	return nil
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}
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func (f *File) Readdir(count int) (res []os.FileInfo, err error) {
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	if !f.fileData.dir {
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		return nil, &os.PathError{
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			Op:   "readdir",
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			Path: f.fileData.name,
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			Err:  errors.New("not a dir"),
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		}
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	}
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	var outLength int64
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	f.fileData.Lock()
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	files := f.fileData.memDir.Files()[f.readDirCount:]
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	if count > 0 {
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		if len(files) < count {
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			outLength = int64(len(files))
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		} else {
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			outLength = int64(count)
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		}
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		if len(files) == 0 {
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			err = io.EOF
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		}
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	} else {
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		outLength = int64(len(files))
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	}
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	f.readDirCount += outLength
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	f.fileData.Unlock()
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	res = make([]os.FileInfo, outLength)
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	for i := range res {
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		res[i] = &FileInfo{files[i]}
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	}
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	return res, err
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}
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func (f *File) Readdirnames(n int) (names []string, err error) {
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	fi, err := f.Readdir(n)
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	names = make([]string, len(fi))
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	for i, f := range fi {
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		_, names[i] = filepath.Split(f.Name())
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	}
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	return names, err
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}
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// Implements fs.ReadDirFile
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func (f *File) ReadDir(n int) ([]fs.DirEntry, error) {
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	fi, err := f.Readdir(n)
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	if err != nil {
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		return nil, err
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	}
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	di := make([]fs.DirEntry, len(fi))
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	for i, f := range fi {
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		di[i] = common.FileInfoDirEntry{FileInfo: f}
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	}
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	return di, nil
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}
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func (f *File) Read(b []byte) (n int, err error) {
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	f.fileData.Lock()
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	defer f.fileData.Unlock()
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	if f.closed {
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		return 0, ErrFileClosed
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	}
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	if len(b) > 0 && int(f.at) == len(f.fileData.data) {
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		return 0, io.EOF
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	}
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	if int(f.at) > len(f.fileData.data) {
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		return 0, io.ErrUnexpectedEOF
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	}
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	if len(f.fileData.data)-int(f.at) >= len(b) {
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		n = len(b)
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	} else {
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		n = len(f.fileData.data) - int(f.at)
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	}
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	copy(b, f.fileData.data[f.at:f.at+int64(n)])
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	atomic.AddInt64(&f.at, int64(n))
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	return
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}
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func (f *File) ReadAt(b []byte, off int64) (n int, err error) {
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	prev := atomic.LoadInt64(&f.at)
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	atomic.StoreInt64(&f.at, off)
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	n, err = f.Read(b)
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	atomic.StoreInt64(&f.at, prev)
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	return
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}
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func (f *File) Truncate(size int64) error {
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	if f.closed {
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		return ErrFileClosed
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	}
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	if f.readOnly {
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		return &os.PathError{
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			Op:   "truncate",
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			Path: f.fileData.name,
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			Err:  errors.New("file handle is read only"),
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		}
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	}
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	if size < 0 {
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		return ErrOutOfRange
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	}
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	f.fileData.Lock()
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	defer f.fileData.Unlock()
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	if size > int64(len(f.fileData.data)) {
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		diff := size - int64(len(f.fileData.data))
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		f.fileData.data = append(f.fileData.data, bytes.Repeat([]byte{0o0}, int(diff))...)
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	} else {
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		f.fileData.data = f.fileData.data[0:size]
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	}
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	setModTime(f.fileData, time.Now())
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	return nil
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}
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func (f *File) Seek(offset int64, whence int) (int64, error) {
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	if f.closed {
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		return 0, ErrFileClosed
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	}
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	switch whence {
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	case io.SeekStart:
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		atomic.StoreInt64(&f.at, offset)
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	case io.SeekCurrent:
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		atomic.AddInt64(&f.at, offset)
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	case io.SeekEnd:
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		atomic.StoreInt64(&f.at, int64(len(f.fileData.data))+offset)
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	}
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	return f.at, nil
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}
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func (f *File) Write(b []byte) (n int, err error) {
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	if f.closed {
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		return 0, ErrFileClosed
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	}
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	if f.readOnly {
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		return 0, &os.PathError{
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			Op:   "write",
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			Path: f.fileData.name,
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			Err:  errors.New("file handle is read only"),
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		}
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	}
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	n = len(b)
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	cur := atomic.LoadInt64(&f.at)
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	f.fileData.Lock()
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	defer f.fileData.Unlock()
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	diff := cur - int64(len(f.fileData.data))
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	var tail []byte
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	if n+int(cur) < len(f.fileData.data) {
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		tail = f.fileData.data[n+int(cur):]
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	}
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	if diff > 0 {
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		f.fileData.data = append(
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			f.fileData.data,
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			append(bytes.Repeat([]byte{0o0}, int(diff)), b...)...)
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		f.fileData.data = append(f.fileData.data, tail...)
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	} else {
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		f.fileData.data = append(f.fileData.data[:cur], b...)
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		f.fileData.data = append(f.fileData.data, tail...)
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	}
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	setModTime(f.fileData, time.Now())
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	atomic.AddInt64(&f.at, int64(n))
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	return
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}
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func (f *File) WriteAt(b []byte, off int64) (n int, err error) {
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	atomic.StoreInt64(&f.at, off)
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	return f.Write(b)
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}
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func (f *File) WriteString(s string) (ret int, err error) {
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	return f.Write([]byte(s))
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}
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func (f *File) Info() *FileInfo {
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	return &FileInfo{f.fileData}
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}
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type FileInfo struct {
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	*FileData
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}
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// Implements os.FileInfo
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func (s *FileInfo) Name() string {
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	s.Lock()
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	_, name := filepath.Split(s.name)
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	s.Unlock()
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	return name
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}
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func (s *FileInfo) Mode() os.FileMode {
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	s.Lock()
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	defer s.Unlock()
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	return s.mode
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}
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func (s *FileInfo) ModTime() time.Time {
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	s.Lock()
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	defer s.Unlock()
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	return s.modtime
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}
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func (s *FileInfo) IsDir() bool {
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	s.Lock()
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	defer s.Unlock()
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	return s.dir
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}
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func (s *FileInfo) Sys() interface{} { return nil }
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func (s *FileInfo) Size() int64 {
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	if s.IsDir() {
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		return int64(42)
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	}
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	s.Lock()
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	defer s.Unlock()
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	return int64(len(s.data))
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}
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var (
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	ErrFileClosed        = errors.New("File is closed")
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	ErrOutOfRange        = errors.New("out of range")
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	ErrTooLarge          = errors.New("too large")
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	ErrFileNotFound      = os.ErrNotExist
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	ErrFileExists        = os.ErrExist
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	ErrDestinationExists = os.ErrExist
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)
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