// vfs.go
package models

import (
	"crypto/rand"
	"database/sql"
	"errors"
	"fmt"
	"path"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

type Vfs struct {
	DB *sql.DB
}

type VfsNodeType int

const (
	VfsNodeTypeFile VfsNodeType = iota
	VfsNodeTypeService
	VfsNodeTypeDirectory
	VfsNodeTypeSymlink
)

type VfsNode struct {
	ID        uint64
	Name      string
	ParentID  uint64
	Type      VfsNodeType
	CreatedAt time.Time
	UpdatedAt time.Time
}

type VfsUser struct {
	Name  string
	Token string
}

type VfsDirEntry struct {
	ID   uint64
	Name string
	Type VfsNodeType
}

// NewVfs 创建新的 VFS 实例
func NewVfs(dbPath string) (*Vfs, error) {
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		return nil, err
	}

	_, err = db.Exec(`
	CREATE TABLE IF NOT EXISTS vfs_nodes (
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		name TEXT NOT NULL,
		parent_id INTEGER,
		type INTEGER NOT NULL,
		created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
		updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
		UNIQUE(parent_id, name)
	)`)
	if err != nil {
		return nil, err
	}

	_, err = db.Exec(`
    CREATE TABLE IF NOT EXISTS vfs_users (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT NOT NULL UNIQUE,
        token TEXT NOT NULL UNIQUE,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    )`)
	if err != nil {
		return nil, err
	}

	err = createInitialDirectories(db)
	if err != nil {
		return nil, err
	}

	return &Vfs{DB: db}, nil
}

// 创建初始目录结构
func createInitialDirectories(db *sql.DB) error {
	var err error
	// 创建 /home 目录
	_, err = db.Exec(`
        INSERT OR IGNORE INTO vfs_nodes (name, parent_id, type, created_at, updated_at) 
        VALUES ('home', 0, ?, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)`,
		VfsNodeTypeDirectory)
	if err != nil {
		return err
	}

	// 创建 /public 目录
	_, err = db.Exec(`
        INSERT OR IGNORE INTO vfs_nodes (name, parent_id, type, created_at, updated_at) 
        VALUES ('public', 0, ?, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)`,
		VfsNodeTypeDirectory)
	if err != nil {
		return err
	}

	return nil
}

func generateToken() string {
	bytes := make([]byte, 16)
	if _, err := rand.Read(bytes); err != nil {
		// fallback to time-based token
		return fmt.Sprintf("%x", time.Now().UnixNano())
	}
	return fmt.Sprintf("%x", bytes)
}

// 添加用户相关操作
func (v *Vfs) CreateUser(username string) (string, error) {
	// 生成随机token
	token := generateToken()

	// 检查用户是否已存在
	_, err := v.GetUserByName(username)
	if err == nil {
		return "", errors.New("user already exists")
	}

	// 插入用户（不使用事务）
	_, err = v.DB.Exec("INSERT INTO vfs_users (name, token) VALUES (?, ?)", username, token)
	if err != nil {
		return "", err
	}

	// 使用 defer 确保出错时能清理已创建的用户
	defer func() {
		if err != nil {
			v.DB.Exec("DELETE FROM vfs_users WHERE name = ? AND token = ?", username, token)
		}
	}()

	// 确保 /home 目录存在
	homeDir, getHomeErr := v.GetNodeByPath("/home/")
	if getHomeErr != nil {
		// 如果 /home 不存在，创建它
		homeDir = &VfsNode{
			Name:     "home",
			ParentID: 0,
			Type:     VfsNodeTypeDirectory,
		}
		if createHomeErr := v.CreateVFSNode(homeDir); createHomeErr != nil {
			err = createHomeErr
			return "", err
		}
	}

	// 创建用户目录 /home/username
	userDir := &VfsNode{
		Name:      username,
		ParentID:  homeDir.ID,
		Type:      VfsNodeTypeDirectory,
		CreatedAt: time.Now(),
		UpdatedAt: time.Now(),
	}
	if createDirErr := v.CreateVFSNode(userDir); createDirErr != nil {
		err = createDirErr
		return "", err
	}

	return token, nil
}

func (v *Vfs) DeleteUser(username string) error {
	// TODO: 递归删除用户相关文件
	// 这里暂时只删除用户记录
	_, err := v.DB.Exec("DELETE FROM vfs_users WHERE name = ?", username)
	return err
}

func (v *Vfs) GetUserByToken(token string) (*VfsUser, error) {
	user := &VfsUser{}
	err := v.DB.QueryRow("SELECT name, token FROM vfs_users WHERE token = ?", token).
		Scan(&user.Name, &user.Token)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, errors.New("user not found")
		}
		return nil, err
	}
	return user, nil
}

func (v *Vfs) GetUserByName(username string) (*VfsUser, error) {
	user := &VfsUser{}
	err := v.DB.QueryRow("SELECT name, token FROM vfs_users WHERE name = ?", username).
		Scan(&user.Name, &user.Token)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, errors.New("user not found")
		}
		return nil, err
	}
	return user, nil
}

// GetChildrenID 获取目录下所有子项的 ID
func (v *Vfs) GetChildren(parentID uint64) ([]VfsDirEntry, error) {
	rows, err := v.DB.Query("SELECT id, name, type FROM vfs_nodes WHERE parent_id = ?", parentID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var dirEntrys []VfsDirEntry
	for rows.Next() {
		var entry VfsDirEntry
		if err := rows.Scan(&entry.ID, &entry.Name, &entry.Type); err != nil {
			return nil, err
		}
		dirEntrys = append(dirEntrys, entry)
	}

	return dirEntrys, nil
}

// GetParentID 根据父路径查找父节点 ID
// parentPath 应该是 ParsePathComponents 的第一个返回值
func (v *Vfs) GetParentID(parentPath string) (uint64, error) {
	// 根目录特殊处理
	if parentPath == "/" || parentPath == "" {
		return 0, nil
	}

	// 递归查找父路径ID
	// 先解析父路径的父路径和节点名
	grandParentPath, parentName, _, err := ParsePathComponents(parentPath)
	if err != nil {
		return 0, err
	}

	// 递归获取祖父节点ID
	grandParentID, err := v.GetParentID(grandParentPath)
	if err != nil {
		return 0, err
	}

	// 在祖父节点下查找父节点
	var parentID uint64
	err = v.DB.QueryRow("SELECT id FROM vfs_nodes WHERE parent_id = ? AND name = ?",
		grandParentID, parentName).Scan(&parentID)

	if err != nil {
		if err == sql.ErrNoRows {
			return 0, errors.New("parent path not found")
		}
		return 0, err
	}

	return parentID, nil
}

// GetNodeByPath 根据完整路径查找节点
func (v *Vfs) GetNodeByPath(fullPath string) (*VfsNode, error) {
	// 根目录特殊处理
	if path.Clean(fullPath) == "/" {
		return &VfsNode{
			ID:        0,
			Name:      "/",
			ParentID:  0,
			Type:      VfsNodeTypeDirectory,
			CreatedAt: time.Now(),
			UpdatedAt: time.Now(),
		}, nil
	}

	// 使用 ParsePathComponents 解析路径
	parentPath, nodeName, nodeType, err := ParsePathComponents(fullPath)
	if err != nil {
		return nil, err
	}

	// 获取父节点ID
	parentID, err := v.GetParentID(parentPath)
	if err != nil {
		return nil, err
	}

	// 根据 parentID, nodeName, nodeType 查找或创建节点
	node, err := v.GetNodeByParentIDAndName(parentID, nodeName)
	if err != nil {
		// 如果节点不存在，可以选择创建它或者返回错误
		// 这里根据你的需求决定是返回错误还是创建节点
		return nil, err
	}

	if node.Type != nodeType {
		return nil, errors.New("node type mismatch")
	}

	return node, nil
}

// GetNodeByParentIDAndName 根据父ID和名称查找节点
func (v *Vfs) GetNodeByParentIDAndName(parentID uint64, name string) (*VfsNode, error) {
	node := &VfsNode{}
	err := v.DB.QueryRow(`
        SELECT id, name, parent_id, type, created_at, updated_at 
        FROM vfs_nodes 
        WHERE parent_id = ? AND name = ?`, parentID, name).Scan(
		&node.ID, &node.Name, &node.ParentID, &node.Type, &node.CreatedAt, &node.UpdatedAt)

	if err != nil {
		if err == sql.ErrNoRows {
			return nil, errors.New("node not found")
		}
		return nil, err
	}

	return node, nil
}

// CreateNodeByComponents 根据路径组件创建节点
func (v *Vfs) CreateNodeByComponents(parentPath, nodeName string, nodeType VfsNodeType) (*VfsNode, error) {
	// 获取父节点ID
	parentID, err := v.GetParentID(parentPath)
	if err != nil {
		return nil, err
	}

	// 创建新节点
	node := &VfsNode{
		Name:      nodeName,
		ParentID:  parentID,
		Type:      nodeType,
		CreatedAt: time.Now(),
		UpdatedAt: time.Now(),
	}

	// 保存到数据库
	result, err := v.DB.Exec(`
        INSERT INTO vfs_nodes (name, parent_id, type, created_at, updated_at) 
        VALUES (?, ?, ?, ?, ?)`,
		node.Name, node.ParentID, node.Type, node.CreatedAt, node.UpdatedAt)

	if err != nil {
		return nil, err
	}

	// 获取插入的ID
	id, err := result.LastInsertId()
	if err != nil {
		return nil, err
	}

	node.ID = uint64(id)
	return node, nil
}

func ParsePathComponents(pathStr string) (parentPath, nodeName string, nodeType VfsNodeType, err error) {
	// FIXME: 路径判断以及update的类型判断
	abspath := path.Clean(pathStr)
	if !path.IsAbs(abspath) {
		return "", "", 0, errors.New("path must be absolute")
	}

	// 特殊处理根路径
	if abspath == "/" {
		return "", "", VfsNodeTypeDirectory, nil
	}

	// 判断是文件还是目录
	nodeType = VfsNodeTypeFile
	// 如果原始路径以 / 结尾，则为目录
	if len(pathStr) > 1 && pathStr[len(pathStr)-1] == '/' {
		nodeType = VfsNodeTypeDirectory
	}
	if nodeType == VfsNodeTypeFile && path.Ext(pathStr) == ".api" {
		nodeType = VfsNodeTypeService
	}

	// 分割路径
	parentPath, nodeName = path.Split(abspath)

	// 清理父路径
	if parentPath != "/" && parentPath != "" {
		parentPath = path.Clean(parentPath)
	}

	// 处理特殊情况
	if parentPath == "." {
		parentPath = "/"
	}

	return parentPath, nodeName, nodeType, nil
}

// MoveToPath 将节点移动到指定路径
func (v *Vfs) MoveToPath(node *VfsNode, destPath string) error {
	// 1. 解析目标路径
	parentPath, nodeName, _, err := ParsePathComponents(destPath)
	if err != nil {
		return fmt.Errorf("invalid destination path: %w", err)
	}

	// 2. 查找目标父节点
	parentID, err := v.GetParentID(parentPath)
	if err != nil {
		return fmt.Errorf("failed to find parent directory '%s': %w", parentPath, err)
	}

	// 3. 检查目标位置是否已存在同名节点
	_, err = v.GetNodeByParentIDAndName(parentID, nodeName)
	if err == nil {
		return fmt.Errorf("destination path '%s' already exists", destPath)
	}
	if err.Error() != "node not found" {
		return fmt.Errorf("error checking destination path: %w", err)
	}

	// 4. 更新节点的父节点ID和名称
	node.ParentID = parentID
	node.Name = nodeName
	node.UpdatedAt = time.Now()

	// 5. 更新数据库中的节点信息
	_, err = v.DB.Exec(`
		UPDATE vfs_nodes 
		SET name = ?, parent_id = ?, updated_at = ? 
		WHERE id = ?`,
		node.Name, node.ParentID, node.UpdatedAt, node.ID)
	if err != nil {
		return fmt.Errorf("failed to update node: %w", err)
	}

	return nil
}

func (v *Vfs) CreateVFSNode(p *VfsNode) error {
	_, err := v.DB.Exec(`
		INSERT INTO vfs_nodes (name, parent_id, type, created_at, updated_at) 
		VALUES (?, ?, ?, ?, ?)`,
		p.Name, p.ParentID, p.Type, time.Now(), time.Now())
	return err
}

func (v *Vfs) DeleteVFSNode(p *VfsNode) error {
	_, err := v.DB.Exec("DELETE FROM vfs_nodes WHERE id = ?", p.ID)
	return err
}

func (v *Vfs) GetVFSNode(p *VfsNode) *VfsNode {
	node := &VfsNode{}
	err := v.DB.QueryRow(`
		SELECT id, name, parent_id, type, created_at, updated_at 
		FROM vfs_nodes 
		WHERE id = ?`, p.ID).Scan(
		&node.ID, &node.Name, &node.ParentID, &node.Type, &node.CreatedAt, &node.UpdatedAt)

	if err != nil {
		return nil
	}

	return node
}

func (v *Vfs) UpdateVFSNode(p *VfsNode) error {
	_, err := v.DB.Exec(`
		UPDATE vfs_nodes 
		SET name = ?, parent_id = ?, type = ?, updated_at = ? 
		WHERE id = ?`,
		p.Name, p.ParentID, p.Type, time.Now(), p.ID)
	return err
}