package s3

import (
	"context"
	"io"
	"os"
	"path"

	"github.com/minio/minio-go/v7"
)

type File struct {
	fs     *Fs
	key    string
	r      io.ReadSeekCloser
	w      io.WriteCloser
	werrc  <-chan error
	cancel context.CancelFunc
}

// implements io.Closer
func (f *File) Close() error {
	defer f.cancel()
	if f.r != nil {
		return f.r.Close()
	}
	if f.w != nil {
		f.w.Close()
		return <-f.werrc
	}
	return nil
}

// implements io.Reader
func (f *File) Read(b []byte) (int, error) {
	if f.r == nil {
		return 0, ErrUnsupported
	}
	n, err := f.r.Read(b)
	if err != nil {
		return n, transformError(err)
	}
	return n, nil
}

// implements io.ReaderAt
func (f *File) ReadAt(p []byte, off int64) (int, error) {
	panic("not implemented")
}

// implements io.Writer
func (f *File) Write(p []byte) (int, error) {
	if f.w == nil {
		return 0, ErrUnsupported
	}

	n, err := f.w.Write(p)
	if err != nil {
		return n, transformError(err)
	}
	return n, nil
}

// implements io.WriterAt
func (f *File) WriteAt(p []byte, off int64) (int, error) {
	panic("not implemented")
}

func (f *File) Name() string {
	return path.Base(f.key)
}

func (f *File) readdir(count int, onlyDir bool) ([]os.FileInfo, error) {
	if !isDirPath(f.key) {
		return nil, ErrNotDirectory
	}
	if count == 0 {
		return []os.FileInfo{}, nil
	}
	ctx, cancel := f.fs.contextWithTimeout()
	defer cancel()
	objectsCh := f.fs.client.ListObjects(ctx, f.fs.bucket, minio.ListObjectsOptions{Prefix: f.key})
	n := 0
	lastDir := f.key
	results := make([]os.FileInfo, 0)
	for objectInfo := range objectsCh {
		base := path.Base(objectInfo.Key)
		dir := path.Dir(objectInfo.Key) + "/"
		if lastDir != dir {
			lastDir = dir
			results = append(results, &FileInfo{
				name:  base,
				isDir: true,
			})
			if onlyDir {
				n += 1
			}
		}
		if !onlyDir {
			results = append(results, transformObjectInfo(objectInfo))
			n += 1
		}
		if n > count {
			break
		}
	}

	return results, nil
}

func (f *File) Readdir(count int) ([]os.FileInfo, error) {
	return f.readdir(count, false)
}

func (f *File) Readdirnames(n int) ([]string, error) {
	results, err := f.readdir(n, true)
	if err != nil {
		return nil, err
	}
	list := make([]string, 0, len(results))
	for _, info := range results {
		list = append(list, info.Name())
	}
	return list, nil
}

func (f *File) Seek(offset int64, whence int) (int64, error) {
	if f.r == nil {
		return 0, ErrUnsupported
	}
	return f.r.Seek(offset, whence)
}

func (f *File) Stat() (os.FileInfo, error) {
	return f.fs.Stat(f.key)
}

func (f *File) Sync() error {
	panic("not implemented")
}

func (f *File) Truncate(size int64) error {
	panic("not implemented")
}

func (f *File) WriteString(s string) (ret int, err error) {
	return f.Write([]byte(s))
}