package local

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

	stgtypes "gitlink.org.cn/cloudream/jcs-pub/common/pkgs/storage/types"
	jcstypes "gitlink.org.cn/cloudream/jcs-pub/common/types"
)

type DirReader struct {
	// 完整的根路径（包括ReadDir的path参数），比如包括了盘符
	absRootPath string
	// ReadDir函数传递进来的path参数
	rootJPath  jcstypes.JPath
	init       bool
	curEntries []dirEntry
}

func (r *DirReader) Next() (stgtypes.DirEntry, error) {
	if !r.init {
		info, err := os.Stat(r.absRootPath)
		if err != nil {
			return stgtypes.DirEntry{}, err
		}

		if !info.IsDir() {
			r.init = true
			return stgtypes.DirEntry{
				Path:    r.rootJPath,
				Size:    info.Size(),
				ModTime: info.ModTime(),
				IsDir:   false,
			}, nil
		}

		es, err := os.ReadDir(r.absRootPath)
		if err != nil {
			return stgtypes.DirEntry{}, err
		}

		for _, e := range es {
			r.curEntries = append(r.curEntries, dirEntry{
				dir:   jcstypes.JPath{},
				entry: e,
			})
		}

		r.init = true
	}
	if len(r.curEntries) == 0 {
		return stgtypes.DirEntry{}, io.EOF
	}

	entry := r.curEntries[0]
	r.curEntries = r.curEntries[1:]

	if entry.entry.IsDir() {
		es, err := os.ReadDir(filepath.Join(r.absRootPath, entry.dir.OSString(), entry.entry.Name()))
		if err != nil {
			return stgtypes.DirEntry{}, err
		}

		// 多个entry对象共享同一个JPath对象，但因为不会修改JPath，所以没问题
		dir := entry.dir.Clone()
		dir.Push(entry.entry.Name())
		for _, e := range es {
			r.curEntries = append(r.curEntries, dirEntry{
				dir:   dir,
				entry: e,
			})
		}
	}

	info, err := entry.entry.Info()
	if err != nil {
		return stgtypes.DirEntry{}, err
	}

	p := r.rootJPath.ConcatNew(entry.dir)
	p.Push(entry.entry.Name())

	if entry.entry.IsDir() {
		return stgtypes.DirEntry{
			Path:    p,
			Size:    0,
			ModTime: info.ModTime(),
			IsDir:   true,
		}, nil
	}

	return stgtypes.DirEntry{
		Path:    p,
		Size:    info.Size(),
		ModTime: info.ModTime(),
		IsDir:   false,
	}, nil
}

func (r *DirReader) Close() {

}

type dirEntry struct {
	dir   jcstypes.JPath
	entry os.DirEntry
}