package vfs

import (
	"bytes"
	"context"
	"io/fs"
	"path"
	"time"
)

type MemoryFs struct {
	name  string
	files map[string]*MemoryFile
}

var _ Filesystem = (*MemoryFs)(nil)

// ModTime implements Filesystem.
func (mfs *MemoryFs) ModTime() time.Time {
	return time.Time{}
}

// Mode implements Filesystem.
func (mfs *MemoryFs) Mode() fs.FileMode {
	return fs.ModeDir
}

// Size implements Filesystem.
func (fs *MemoryFs) Size() int64 {
	return 0
}

// Sys implements Filesystem.
func (fs *MemoryFs) Sys() any {
	return nil
}

// FsKind implements Filesystem.
func (fs *MemoryFs) FsName() string {
	return "memoryfs"
}

// Info implements Filesystem.
func (fs *MemoryFs) Info() (fs.FileInfo, error) {
	return newDirInfo(fs.name), nil
}

// IsDir implements Filesystem.
func (fs *MemoryFs) IsDir() bool {
	return true
}

// Name implements Filesystem.
func (fs *MemoryFs) Name() string {
	return fs.name
}

// Type implements Filesystem.
func (mfs *MemoryFs) Type() fs.FileMode {
	return fs.ModeDir
}

func NewMemoryFS(name string, files map[string]*MemoryFile) *MemoryFs {
	return &MemoryFs{
		name:  name,
		files: files,
	}
}

func (m *MemoryFs) Open(ctx context.Context, filename string) (File, error) {
	return getFile(m.files, filename)
}

func (fs *MemoryFs) ReadDir(ctx context.Context, path string) ([]fs.DirEntry, error) {
	return listDirFromFiles(fs.files, path)
}

// Stat implements Filesystem.
func (mfs *MemoryFs) Stat(ctx context.Context, filename string) (fs.FileInfo, error) {
	file, ok := mfs.files[filename]
	if !ok {
		return nil, ErrNotExist
	}
	return newFileInfo(path.Base(filename), file.Size()), nil
}

// Unlink implements Filesystem.
func (fs *MemoryFs) Unlink(ctx context.Context, filename string) error {
	return ErrNotImplemented
}

var _ File = (*MemoryFile)(nil)

type MemoryFile struct {
	name string
	data *bytes.Reader
}

func NewMemoryFile(name string, data []byte) *MemoryFile {
	return &MemoryFile{
		name: name,
		data: bytes.NewReader(data),
	}
}

// Name implements File.
func (d *MemoryFile) Name() string {
	return d.name
}

// Type implements File.
func (d *MemoryFile) Type() fs.FileMode {
	return roMode
}

func (d *MemoryFile) Info() (fs.FileInfo, error) {
	return newFileInfo(d.name, int64(d.data.Len())), nil
}

func (d *MemoryFile) Size() int64 {
	return int64(d.data.Len())
}

func (d *MemoryFile) IsDir() bool {
	return false
}

func (d *MemoryFile) Close(ctx context.Context) (err error) {
	return
}

// Read implements File.
func (d *MemoryFile) Read(ctx context.Context, p []byte) (n int, err error) {
	return d.data.Read(p)
}

// ReadAt implements File.
func (d *MemoryFile) ReadAt(ctx context.Context, p []byte, off int64) (n int, err error) {
	return d.data.ReadAt(p, off)
}