package vfs

import (
	"context"
	"fmt"
	"os"
	"time"

	cdssdk "gitlink.org.cn/cloudream/common/sdks/storage"
	"gitlink.org.cn/cloudream/storage/client2/internal/mount/fuse"
	"gitlink.org.cn/cloudream/storage/client2/internal/mount/vfs/cache"
	"gitlink.org.cn/cloudream/storage/common/pkgs/db2"
	"gorm.io/gorm"
)

type FuseBucket struct {
	vfs     *Vfs
	name    string
	modTime time.Time
}

func newBucketFromCache(c cache.CacheEntryInfo, vfs *Vfs) fuse.FsDir {
	return &FuseBucket{
		vfs:     vfs,
		name:    c.PathComps[len(c.PathComps)-1],
		modTime: c.ModTime,
	}
}

func (r *FuseBucket) PathComps() []string {
	return []string{r.name}
}

func (r *FuseBucket) Name() string {
	return r.name
}

func (r *FuseBucket) Size() int64 {
	return 0
}

func (r *FuseBucket) Mode() os.FileMode {
	return os.ModeDir | 0755
}

func (r *FuseBucket) ModTime() time.Time {
	return r.modTime
}

func (r *FuseBucket) IsDir() bool {
	return true
}

func (r *FuseBucket) SetModTime(time time.Time) error {
	dir := r.loadCacheDir()
	if dir == nil {
		return fuse.ErrNotExists
	}

	return dir.SetModTime(time)
}

// 如果不存在，应该返回ErrNotExists
func (r *FuseBucket) Child(ctx context.Context, name string) (fuse.FsEntry, error) {
	childPathComps := []string{r.name, name}
	ca := r.vfs.cache.Stat(childPathComps)

	if ca == nil {
		// TODO UserID

		pkg, err := r.vfs.db.Package().GetUserPackageByName(r.vfs.db.DefCtx(), 1, r.name, name)
		if err == nil {
			dir := r.vfs.cache.LoadDir(childPathComps, &cache.CreateDirOption{
				ModTime: pkg.CreateTime,
			})
			if dir == nil {
				return nil, fuse.ErrNotExists
			}

			return newPackageFromCache(dir.Info(), r.vfs), nil
		}

		if err == gorm.ErrRecordNotFound {
			return nil, fuse.ErrNotExists
		}

		return nil, err
	}

	if ca.IsDir {
		return newPackageFromCache(*ca, r.vfs), nil
	}

	return newFileFromCache(*ca, r.vfs), nil
}

func (r *FuseBucket) Children(ctx context.Context) ([]fuse.FsEntry, error) {
	return r.listChildren()
}

func (r *FuseBucket) ReadChildren() (fuse.DirReader, error) {
	ens, err := r.listChildren()
	if err != nil {
		return nil, err
	}

	return newFuseDirReader(ens), nil
}

func (r *FuseBucket) listChildren() ([]fuse.FsEntry, error) {
	var ens []fuse.FsEntry

	infos := r.vfs.cache.StatMany([]string{r.name})

	pkgs, err := r.vfs.db.Package().GetBucketPackagesByName(r.vfs.db.DefCtx(), r.name)
	if err != nil {
		return nil, err
	}

	pkgMap := make(map[string]*cdssdk.Package)
	for _, pkg := range pkgs {
		p := pkg
		pkgMap[pkg.Name] = &p
	}

	for _, c := range infos {
		delete(pkgMap, c.PathComps[len(c.PathComps)-1])

		if c.IsDir {
			ens = append(ens, newPackageFromCache(c, r.vfs))
		} else {
			ens = append(ens, newFileFromCache(c, r.vfs))
		}
	}

	for _, pkg := range pkgMap {
		dir := r.vfs.cache.LoadDir([]string{r.name, pkg.Name}, &cache.CreateDirOption{
			ModTime: pkg.CreateTime,
		})
		if dir == nil {
			continue
		}

		ens = append(ens, newPackageFromCache(dir.Info(), r.vfs))
	}

	return ens, nil
}

func (r *FuseBucket) NewDir(ctx context.Context, name string) (fuse.FsDir, error) {
	cache := r.vfs.cache.CreateDir([]string{r.name, name})
	if cache == nil {
		return nil, fuse.ErrPermission
	}

	// TODO 用户ID，失败了可以打个日志
	// TODO 生成系统事件
	// 不关注创建是否成功，仅尝试一下
	r.vfs.db.DoTx(func(tx db2.SQLContext) error {
		db := r.vfs.db
		bkt, err := db.Bucket().GetByName(tx, name)
		if err != nil {
			return fmt.Errorf("get bucket: %v", err)
		}

		_, err = db.Package().Create(tx, bkt.BucketID, name)
		if err != nil {
			return fmt.Errorf("create package: %v", err)
		}

		return err
	})

	return newPackageFromCache(cache.Info(), r.vfs), nil
}

func (r *FuseBucket) NewFile(ctx context.Context, name string, flags uint32) (fuse.FileHandle, error) {
	cache := r.vfs.cache.CreateFile([]string{r.name, name})
	if cache == nil {
		return nil, fuse.ErrPermission
	}
	// Open之后会给cache的引用计数额外+1，即使cache先于FileHandle被关闭，
	// 也有有FileHandle的计数保持cache的有效性

	fileNode := newFileFromCache(cache.Info(), r.vfs)

	if flags&uint32(os.O_WRONLY) != 0 {
		hd := cache.Open(false)
		return newFileHandle(fileNode, hd), nil
	}

	if flags&uint32(os.O_RDONLY) != 0 {
		hd := cache.Open(true)
		return newFileHandle(fileNode, hd), nil
	}

	return nil, fuse.ErrPermission
}

func (r *FuseBucket) RemoveChild(ctx context.Context, name string) error {
	err := r.vfs.cache.Remove([]string{r.name, name})
	if err != nil {
		return err
	}

	// TODO 生成系统事件
	// 不关心是否成功
	r.vfs.db.DoTx(func(tx db2.SQLContext) error {
		d := r.vfs.db

		pkg, err := d.Package().GetUserPackageByName(tx, 1, r.name, name)
		if err != nil {
			if err == gorm.ErrRecordNotFound {
				return nil
			}
		}

		return d.Package().DeleteComplete(tx, pkg.PackageID)
	})

	return nil
}

func (r *FuseBucket) MoveChild(ctx context.Context, oldName string, newName string, newParent fuse.FsDir) error {

	// TODO 有问题

	newParentNode := newParent.(FuseNode)
	_, err := r.vfs.cache.Move([]string{r.name, oldName}, append(newParentNode.PathComps(), newName))
	if err != nil {
		return err
	}

	return nil
}

func (r *FuseBucket) loadCacheDir() *cache.CacheDir {
	var createOpt *cache.CreateDirOption
	bkt, err := r.vfs.db.Bucket().GetByName(r.vfs.db.DefCtx(), r.name)
	if err == nil {
		createOpt = &cache.CreateDirOption{
			ModTime: bkt.CreateTime,
		}
	}

	return r.vfs.cache.LoadDir([]string{r.name}, createOpt)
}

var _ fuse.FsDir = (*FuseBucket)(nil)
var _ FuseNode = (*FuseBucket)(nil)